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DEPARTMENT OF THE INTERIOR.

HE PORT

UNITED STATES GEOLOGICAL SURVEY

THE TERRITORIES

IF. V. HAYDEN,

UNITED STATES GEOLOG I ST-I N-C H AUll E.

VOLUME XII.

WASHINGTON:

GOVKllNJIENT PRINTING OFFICE.

1879.

LETTER TO THE SECRETARY.

Office United States Geological and

Geographical Survey of the Territories,

Washington, D. C, January 1, 1879.

Sir : I have the honor to transmit herewith, for your approval and
for publication, Volume XII of the Final Reports of the Survey under my
direction.

This volume has been prepared by Prof. Joseph Leidy, the eminent
comparative anatomist and microscopist, who is well known as one of the
most valued collaborators of the Survey, and the author of the first volume
of the quarto series of Reports, entitled " Contributions to the Extinct Ver-
tebrate Fauna of the Western Territories."

Professor Leidy spent the greater portion of two seasons in the West
under the auspices of the Survey. During this time he made a careful
exploration of the country about Fort Bridger, Uinta Mountains, and the
Salt Lake Basin, in search of the materials for this memoir.

The use of the microscope in all branches of natural science has
become so universal that the publication of the present volume in con-
nection with the Survey needs no explanation. It is intended as a guide
and aid to students in this new or little-known field of observation. The
facility with which these small objects for study can be obtained all around
us will render the work still more timely and useful to the students of this
country. There are also a number of closely allied fields of inquiry, as the
Diatoms, Desmids, Infusoria, Rotifera, Entomostraca, and Aquatic insects,
etc., which, when pui'sued with the same skill and devotion, will prove equally
fruitful in results.

The Rhizopods are the lowest and simplest forms of animals, mostly
minute, and requiring high power of the microscope to distinguish their
structure. While most of them construct shells of great beauty and variety,

1V LETTER TO THE SECRETARY.

their soft part consists of a jelly-like substance. This the animal has the
power of extending in threads or finger-like processes, which are used as
organs of locomotion and prehension, often branching. From the appear-
ance of their temporary organs, resembling roots, the class of animals has
received its name of Rhizopoda, meaning literally root-footed.

In compensation for the smallness of these creatures, they make up in
numbers, and it is questionable whether any other class of animals exceeds
them in importance in the economy of nature. Geological evidence sliows
that they were the starting-point of animal life in time, and their agency
in rock-making has not been exceeded by later higher and more visible
forms.

With the marine kind, known as Foraminifera, we have been longest
familiar. Their beautiful many-chambered shells — for the most part just
visible to the naked eye — form a large portion of the ocean-mud and the
sands of the ocean-shore. Shells of Foraminifera likewise form the basis
of miles of strata of limestone, such as the chalk of England and the lime-
stones of which Paris and the pyramids of Egypt are built.

Fresh-water Rhizopods, though not so abundant as marine forms, are
nevertheless very numerous. They mainly inhabit our lakes, ponds, and
standing waters, but they also swarm in sphagnous swamps and even live
in moist earth. Professor Leidy has devoted several years of study to
the Fresh-water Rhizopods of the eastern portion of our country, and his
especial object in his western expeditions was to investigate those which are
to be found in the elevated regions of the Rocky Mountains.

The beautiful plates which illustrate this volume were engraved by
Messrs Sinclair & Son, Philadelphia, and to this firm the thanks of the Sur-
vey are due for their care -and skill.
Very respectfully,

F. V. ITAYDEN,

United States Geologist.

To the Secretary of the Interior.

ROBERT T, JACKSON.

UNITED STATES GEOLOGICAL SURVEY OF THE TERRITORIES.

FRESH-WATER

RHIZOPODS

NORTH AMERICA.

BY

JOSEPH LEIDY, M. D.,

PROFESSOR OF ANATOMY IN THE UNIVERSITY OF PENNSYLVANIA, AND OF NATURAL
niSTORY IX SWAETHMORE COLLEGE, PENNSYLVANIA.

WASHINGTON:

GOVERNMENT PRINTING OFFICE.
1879.

LETTER OF TRANSMITTAL.

Philadelphia, January 1, 1879.

Dear Sir : On several occasions you have expressed a desire, that, in
my trips to the Western Territories, I should undertake the investigation of
the microscopic forms of life which inhabit the waters. During the last
four years I have studied one important class — the Rhizopods, as they occur
in all fresh waters of the country, from the Atlantic border to an altitude
of 10,000 feet in the Rocky Mountains. The marine forms of Rhizopods,
in all times, have extensively contributed to the construction of stratified
rocks The determination of the living fresh-water forms may serve as a
guide to the discovery and determination of fossil forms in the vast lacus-
trine formations in the interior of our continent. Herewith, I transmit my
report for examination and publication, trusting it may meet with your
approbation.

Respectfully,

JOSEPH LEIDY.
Dr. F. V. Hayden,

U. S. Geologist, Washington, D. C.

TABLE OF CONTENTS.

Pago.

Title of Volume XII of the Final Reports i

Letter to the Secretary - iii

Title of Fresh-water Rhizopods v

Letter of Transmittal vii

Table of Contents is

Introduction - 1

General Remarks on the Rhizopods 4

Fresh-water Rhizopoda , 23

Protoplasta - 23

Protoplasta Lobosa 23

Aniccba 30

Amoeba proteus 30

verrucosa 53

radiosa 58

villosa 62

Ourarnceba 66

Ourainoeba vorax - 67

botulicauda 71

Pelomyxa -. - 72

Pelomyxa villosa 76

Dinamoeba 80

Dinamoeba mirabilis 81

Hy alodiscus - 94

Hyalodiscus rubicundus 94

Difflugia 95

Difflugia globulosa 96

pyriformis 98

urceolata *- 106

cratera - 108

acuminata 109

lobostoma 112

arcula 116

corona - - 117

constricta - 120

spiralis 124

Hyalosphenia 128

Hy alosphenia cuneata 129

papilio 131

tincta 138

elegana 140

Quadrula 142

Quadrula symmetrica 142

Nebela \ 145

Nebela collaris 145

ix

X TABLE OF CONTENTS.

Page.
Nebela — Continued.

Nebela flabellulum 152

carinata - - - 1°*

bippocrepis 1 ;, 6

ansata 1^°

barbata I -'

caudata 1^0

Heleopera 1™

Heleopera picta ">*

petricola 1° 5

Arcella ^ 6

Arcella vulgaris 1 ' ^

discoides - ""

mitrata "5

dentata 1''

artocrea 1'°

Centropyxis ■ *°"

Centropyxis aeuleata 1°"

Cocbliopodium 1^*

Cochliopodiuni bilimbosum 184

vestitum 1^°

Protoplasta Filosa 1™

Paiupbagus - '■•"'

Pamphagus mutabilis 1^1

bvalmus 1^1

curvus • i "' u

avidus - *■•">

Pseudodifflugia 1"'

Pseudodifflugia gracilis 1"°

Cypboderia ""1

Cypboderia ampulla 202

Campascus 204

Campaacus cornutus 205

Euglypba 206

Euglypba alveolata 207

ciliata 214

cristata 218

mucronata - - ^^

bracbiata 220

Placocista 221

Placocista spinosa 221

Assulina - *'"*

Assulina seminuluru "*a

Trinema 226

Trinema encbely s 22b

Spbenodena **"

Spbenoderia lenta 22'J

niacrolepis - ***

Heliozoa 233

Actiuopbrys * _

Actinopbrys sol 23o

picta 241

Heteropbrys ■***

Heteropbrys nvyriapoda 243

Eapbidiopbrys - ~

Rapbidiopbrys viridis 2*°

elegans *°

TABLE OF CONTENTS. XI

Page.

Vampyrella - -.-- 253

Vampyrella lateritia 253

Diplopkrys 256

Diploplirys archeri 256

Actinospbarium 258

Actinosphseriuin eichhornii 259

Acanthocystis - 264

Acanthocystis chsetophora 264

? 268

? 270

Hyalolampe 271

Hyalolampe fenestrata 271

Clathrulina 372

Clatlmilkia olegans 273

Foraniinifera - 277

Gromia 277

Grornia terricola 277

Biomy xa 281

Biomyxa vagans 231

Lists of Fresh-water Ehizopods, indicating the many forms which occur together in certain

localities 2S9

Concluding Remarks 294

Chief works and communications relating to the Fresh-water Rhizopods, with lists of the forms
described, and a partial and probable reference of these to corresponding forms described in

the body of the present work 297

Index 321

INTRODUCTION

The revelations of the microscope are perhaps not exceeded in impor-
tance by those of the telescope. While exciting, our curiosity, our wonder
and admiration, they have proved of infinite service in advancing our
knowledge of things around us. The present work, founded on such
revelations, I have attempted to prepare in a manner to render it easy of
comprehension, with the view of promoting and encouraging a taste for
microscopic investigation.

Dr. Carpenter, the eminent English physiologist and naturalist, in his
treatise 'The Microscope and its Revelations', remarks that " it is a ten-
dency common to all observers, and not by any means peculiar to micro-
scopists, to describe what they believe and infer, rather than what they
actually witness."

There are certainly peculiar difficulties in arriving at a faithful inter-
pretation of microscopic observations, arising from many causes, of which
a common one is the difficulty of handling minute objects, especially active
living animals, so as to examine them from every point of view. While I
have endeavored to describe things as they appeared to be, I am conscious
of having been unable to avoid the usual proportion of errors, for which I
beg indulgence, and which I leave for others who shall pursue the same
path of investigation to correct.

What are Rhizopods 1 is a question that will be asked by perhaps most
persons whose attention may be directed to the present work. They are
the simplest or lowest forms of animal life, constituting the first class of the
Protozoa (Greek, protos, primitive ; soon, animal).

The Rhizopoda (Gr. rhiza, root; pom, foot: — root-footed animals) are
mostly microscopic beings, rarely just visible to the naked eye ; though
some are sufficiently large to appear as conspicuous objects. Their minute-
ness is amply compensated by their multitude and world-wide distribution;
1 khiz i

2 FRESHWATER RHIZOPODS OF NORTH AMERICA.

essentially aquatic, they occur wherever there is moisture. Commencing
from one's own doorstep, they may be found in almost every damp nook
and crevice, savanna and marsh, pool and ditch, pond and lake, sea and
ocean, and from the greatest depths of the latter to the snow-line of mount-
ains. By far the greater proportion are marine, and their tiny shells enter
abundantly into the composition of the ocean mud and abound in the sands
of every ocean shore. They appear to have been the first representatives
of animal life on earth; and if there is any truth in the theory of evolution,
they represent our own remotest ancestors. Having existed for ages, their
remains have largely contributed to the formation of the marine sediment-
ary rocks.

The particular Rhizopods which form the subjects of the present work
are those usually designated as the 'Fresh-water Rhizopods', living mainly
in comparatively still fresh waters, in the mud of bogs, among algse and
mosses, and even on the ground in damp, shaded places. My investigations
were commenced four years ago, and have been continued during that time,
in intervals of leisure from teaching and ordinary business pursuits, until
last summer, when I began the preparation of my report for publication.
In the study of the Rhizopods, my attention has been more particularly
directed to the discovery and determination of the various forms occurring
in this country, rather than to the elaboration of details of structure, habits,
modes of development, and other matters pertaining to their history,
though these have not been entirely neglected. In the latter respects, my
researches fall short of those of some of the able naturalists of England and
Germany: — Wallich, Carter, and Archer of the former, and Hertwig and
Lesser, Greeff, Cienkowski, and Schulze of the latter country.

The illustrations accompanying the work, done in chromo-lithography,
are not equal in execution to my desire, though they represent the charac-
teristic appearance of the subjects in all cases, I believe, sufficiently well to
enable the student to recognize these when found. The original drawings,
made by myself, I think may be fairly viewed as approximating accuracy,
at least so far as relates to the outlines, which have invariably been drawn
to a scale of measurements, so as to preserve the proportions of all parts.
Faults in perspective and other qualities are partially due to my own want
of ability as an artist, and partially to the difficulty of correctly interpret-
ing the views of objects as ordinarily seen through the microscope. Many

INTRODUCTION. 3

of the illustrations exhibit various degrees of imperfection in some of the
details, clue to exaggeration of defects in the original drawings, which the
artists, without an}^ knowledge of the subjects, have attempted closely to
imitate. It has Ion" - been a matter of regret to me that I have not been
able to secure the services of accomplished artists, educated for the special
purpose to give us faithful and beautiful representations of natural-history
subjects, such as we so frequently see in the scientific periodicals and other
works especially of Germany and France.

I think it worth while to embrace the opportunity of informing students
that microscopic observations, such as those which form the basis of the
present work, do not require elaborate and high-priced instruments. Such
a microscope as is made by Zentmayer of Philadelphia, Beck of London,
or Hartnack of Paris, and sold at prices ranging from 850 to $100,
answers all ordinary purposes. The instrument should be furnished with
two objective powers, of which the higher should be at least Jth or -jith of
an inch focus. A still higher power being occasionally required, I have
found an £th or j th objective of great service. I have now in use a
little instrument of Beck, called the Economic Microscope, with 1-inch
and ^-inch object-glasses and two eye-pieces, sold by W. II. Walmsley,
No. 921 Chestnut street, Philadelphia, for $50. An important addition to
the instrument, for measuring, is a micrometer, divided into fractions of a
millimetre, which may be purchased for a couple of dollars.

I give the above statement, not with any disposition to detract from
the value of the various magnificent microscopes so much in vogue, but
with the object of dispelling a common impression widely prevalent, at least
among those with whom I habitually come into contact, that the kind of
work such as I now put forth can be done only with the help of elaborate
and expensive instruments.

In aid of my researches among the Rhizopods of the Rocky Mountain
Region I acknowledge the services of my friend Dr. J. Van A Carter, for-
merly of Fort Bridger, now of Evanston, Wyoming Territory. It was not
only under his hospitable roof that I was enabled to pursue my investiga-
tions, but he conducted my expeditions into the Uinta Mountains and other
places to collect materials, and withal defrayed the expenses of our trips
Dr. Carter, in his appreciation of scientific matters, has been of eminent
service to geologists and other naturalists visiting his region of country.

4 FRESH- WATER RHIZOPODS OF NORTH AMERICA.

Some of my most delightful recollections are associated with expe-
ditions into the Uinta Mountains conducted by Judge W. A. Carter, of
Ft. Bridger, or his son-in-law Dr. J. Van A. Carter. At an elevation of
from eight to ten thousand feet the mountains are covered with forests,
chiefly of Fir and Pine, with a most wonderful profusion of beautiful flow-
ering plants beneath. The forests here and there enclose bright, grassy
meadows and ponds, favorite resorts of deer, and in these I obtained rich
materials for my investigations.

Whatever may be thought of the pertinence of publishing such works
as the present one with the Reports of the Geological Survey of the
Territories, to remove any misapprehension in the matter I deem it proper
to state that my contribution has been given without pecuniary recompense.
In my own judgment, Prof. Hayden has acted with the most enlightened
view in authorizing and encouraging such natural-history investigations
as woidd be facilitated by explorations of the country in which his
geological surveys were conducted. With the exception of the cost of
publishing the present Report, the only additional expense to which I put
the Survey during my explorations in the West amounted to about $222.
Much expense was saved through the liberality of various railroad compa-
nies in giving me the privilege of free travel and travel on half-fare.

GENERAL REMARKS ON THE RHIZOPODS.

The simplest kinds of Rhizopods are unprovided with a protection or
support of hard parts of any kind, possessing, at least in their ordinary
active condition, neither a shell nor an investing membrane. In all kinds,
the soft substance of the animal mainly consists of a fluent, viscid, albumi-
noid jelly, endowed with an extensile and a contractile power, by which the
creature is enabled to execute all those movements which ordinarily distin-
guish animal life.

The motile jelly of the Rhizopod is regarded to be of the nature of the
common elementary basis of organic bodies in general, and, like it, is called
the protoplasm (Gr. protos, first ; plasso, I mould : — the primitive material
from which organic bodies are moulded). Its resemblance in motive power
to muscular tissue, or the flesh of more complex animals, led the French
naturalist Dujardin, who was the first to indicate the true nature of the
Rhizopods, to give it the name of sarcode (Gr. sarx, flesh ; eidos, form).

GENERAL REMARKS ON THE RHIZOPODS. 5

The soft mass of protoplasm, or sarcode, forming the essential part of
the body of all Rhizopods, has no internal cavity like the body-cavity of
higher animals, neither has it a mouth like the higher Protozoa, nor has it
stomach or intestine. Without trace of nerve elements, and without defi-
nite, fixed organs of any kind, internal or external, the Rhizopod, — simplest
of all animals, a mere jelly-speck, — moves about with the apparent purposes
of more complex creatures. It selects and swallows its appropriate food,
digests it, and rejects the insoluble remains. It grows and reproduces its
kind. It evolves a wonderful variety of distinctive forms, often of the
utmost beauty, and, indeed, it altogether exhibits such marvelous attributes,
that one is led to ask the question in what consists the superiority of ani-
mals usually regarded as much higher in the scale of life.

In this relationship, Dr. Carpenter remarks of the Rhizopods, " If the
views which I have expressed as to the nature and relations of their living
substance be correct, that substance does not present any such differentia-
tion as is necessary to constitute what is commonly understood as ' organi-
zation ' even of the lowest degree and simplest kind ; so that the physiolo-
gist has here a case in which those vital operations which he is accustomed
to see carried on by an elaborate apparatus, are jierformed without any
special instruments whatever, — a little particle of apparently homogeneous
jelly changing itself into a greater variety of forms than the fabled Proteus,
lajdng hold of its food without members, swallowing it without a mouth,
digesting it without a stomach, appropriating its nutritious material without
absorbent vessels or a circulating system, moving from place to place with-
out muscles, feeling (if it has any power to do so) without nerves, propa-
gating itself without genital apparatus, — and not only this, but in many
instances forming shelly coverings of a symmetry and complexity not sur-
passed by those of any testaceous animals."*

Through the motile power of the Rhizopod, it projects or extends
portions of its protoplasm, which act as temporary organs of locomotion
and prehension, and it again withdraws or contracts them so that they melt
away in the mass and leave no trace of their previous existence. From
their function, the extensions of protoplasm have received the appropriate
name of pseudopods (Gr. pseudos, false; pons, foot). These appear, in gen-
eral, in different kinds of Rhizopods, in the condition of threads of extreme

* Introduction to tin- Study of the Foramimfera. Preface, vii.

6 FEESH- WATER RHIZOPODS OF NORTH AMERICA.

delicacy, of coarser finger-like processes, or of rounded lobes. They often
branch and assume a more or less root-like appearance, whence Dujardin
gave the class the name of Rhizopods.

As previously intimated, the simplest kinds of Rhizopods are unpro-
vided with hard parts, or even a membranous investment, and they present
to the outside medium in which they live nothing but the naked mass of
protoplasm of which they consist. By far the greater number of the class
are protected and supported by some kind of skeleton of hard material,
consisting of spicules or a trellis-work of silex, or a shell of chitinoid
membrane, of limestone, or of the former material. Mostly the hard part is
intrinsic, or pertains to the inherent structure of the animal, but frequently
is also more or less extrinsic. In the latter instances, the shell usually
consists of siliceous particles, commonly hyaline quartz sand, diatom cases,
and sponge spicules.

Besides some general differences in the character of the soft parts, the
sustaining skeleton, or protective shell, of the Rhizopods, exhibits a great
variety in form, construction, and arrangement of structure ; frequently is
highly intricate and often remarkable for beauty of apparent design.

On the general differences observed in the soft body-mass and its
pseudopods, and on the absence or presence of hard parts with their form
and constitution, the ordinal and other subdivisions of the Rhizopods are
founded. It however appears from the researches, especially of British
authorities, such as Carpenter, Williamson, Wallich, Brady, Parker, and
Jones, that the members of the class are infinitely variable, and that indeed
no absolute distinctions of species and genera exist, such as appear more
definitely to characterize the higher forms of animal life. My own investi-
gations rather confirm this view, and, under the circumstances, we can only
regard the more conspicuous and prevailing forms as so many nominal
species, in likeness with the species of higher organic forms, more or less
intimately related, and by intermediate forms or varieties merging into one
another.

As is the case with all other groups of organic beings, few authorities
agree in the classification of the Rhizopods ; and it is for convenience
rather than from studied opinion that I have adopted the following ordinal
arrangement

CLASSIFICATION OF THE EHIZOPODS. 7

Class. RHIZOPODA.
Order I. Protoplasta ; II. Heliozoa ; III. Radiolaria ;

IV. FORAMINIFERA; V. MoNEKA.

The distinguished French naturalist Dujardin, who first recognized the
nature of the Rhizopoda, and applied to them this name, included in the
class the Foraminifera and the group of Protoplasta, excepting only the
genus Amoeba, although he fully understood the relationship of this with
the former. The Heliozoa he viewed as another division of the Protozoa,
and in his day the Radiolaria were not sufficiently known to hold a recog-
nized position in zoological systems.

Prof. Haeckel, one of the latest and highest authorities on all that
concerns the lowest forms of life, includes in the class the Foraminifera,
the Heliozoa, and the Radiolaria. The Protoplasta and the Monera, which
names originated with him, he regards as two distinct and additional classes
in his proposed kingdom of Protista (protiston, primordial).

Prof. Carpenter includes all the ordinal groups above indicated as
Rhizopoda, but associates the Heliozoa in the order of Radiolaria.

Dr. Wallich* divides the class into three orders: the Herpnemata, the
Protodermata, and the Proteina. In the first are included the Gromida,
Foraminifera, and Polycystina ; in the second, the Thalassicollidse and
Acanthometrina ; and in the third, or highest order, the Actinophryna,
Lagynidse, and Amcebina.

Prof. Huxley drops the name of Rhizopoda altogether, and distributes
the groups into two divisions of the Protozoa: the Monera and the Endo-
plastica To the former he refers the Monera of Haeckel and the Fora-
minifera ; to the latter he refers the Radiolaria, including the Heliozoa, the
Protoplasta, the Gregarinidae, the Catallacta, and the Infusoria. The essen-
tial character of the Monera, according to Haeckel, the founder of the order,
is the absence of a nucleus, but this has recently been shown by Hertwig
and Schulze to exist in the Foraminifera, Carter, Greeff, and others, speak
of the Heliozoa as fresh-water Radiolaria. Hertwig and Lesser, who gave
the name of Heliozoa to the ordinal group, regard them as of a distinct class
from the Radiolaria, and, excluding these, they associate the former together

"Annals and Magazine of Natural History, 18G:i, si, p. 438.

8 FRESH- WATER RHIZOPODS OF NORTH AMERICA.

with the Foraminifera, Protoplasta, and Monera, as Rhizopoda, but propose
for this class to substitute the name of Sarcodina.

In my studies of the Protozoa, or animals of the lowest subkingdom,
I have habitually viewed as Rhizopods the five ordinal groups indicated
in the above classification. This accords with the views of Prof. F. E.
Schulze, an able investigator of the class. In a recent number of the
Archiv fur Mikroscopische Anatomie for 1877, p. 21, he remarks, that his
researches led him to consider as pertaining to the Rhizopods, as an
essentially harmonious whole, all those low forms which, during the greater
part of their life, and especially during the period of their highest perfec-
tion, hold intercourse with the exterior world, move about, and obtain food,
by means of extensile processes of the viscid body-substance, which are
again capable of flowing back completely into the latter.

The first two orders of the Rhizopods — the Protoplasta and the Heliozoa —
are those which are commonly designated as the 'Fresh-water Rhizopods';
the Radiolaria and the Foraminifera, with part of the Monera, are marine.

Fresh-water Rhizopods are to be found almost everywhere in positions
kept continuously damp or wet, and not too much shaded. They are
especially frequent and abundant in comparatively cpiiet waters; clear, and
neither too cold, nor too much heated by the sun, such as lakes, ponds,
ditches, and pools. They are also frequent in wet bogs and savannas,
among mosses, in springy places, on dripping rocks, the vicinity of water-
falls, springs, and fountains, and in marshes, wherever the ground is suffi-
ciently damp or moist to promote the growth of alga? They are also to
be found in damp shaded places, among alga?, liverworts aud mosses, about
the roots of sedges, rushes and grasses, or those of shrubs and trees grow-
ing in or at the borders of bogs and ponds or along ditches and sluggish
watercourses. They are likewise to be found with algae in damp shaded
positions in the depressions and fissures of rocks, in the mouths of caves,
among decaying logs, among mosses and lichens, on the bark of growing
trees, and even in the crevices of walls and pavements about old dwellings
and in cities.

The favorite habitation of many kinds of Rhizopods is the light super-
ficial ooze at the bottom of still waters, where they live in association witli
diatoms, desmids, and other minute alga?, which form the chief food of
most of these little creatures. They never penetrate into the deeper and

PLACES WHERE RHIZOPODS MAY BE FOUND. 9

usually black mud, which indeed is almost universally devoid of life of
any kind.

Rhizopods also occur in the flocculent materials and slimy matter
adherent to most submerged objects, such as rocks, the dead boughs of
trees, and the stems and leaves of aquatic plants. A frequent position is
the under side of floating leaves, such as those of the Ponddily, Nympkcea
odorata; the Spatter-dock, Nuphar advena; and the Nelumbo, Nelumbium
luteiim. Certain kinds of Rhizopods, especially the Heliozoa, or Sun-ani-
malcules, are most frequent among floating plants, such as Duck-meat,
Lemna; Hornwort, Ceratophyllum ; Bladderwort, Utricularia; and the
various Confervas, as Zygnema, Spirogyra, Oscillatoria, and the Water-purse,
Hydrodktyon.

In no other position have I found Rhizopods of the kind under con-
sideration in such profusion, number, and beauty of form as in sphagnous
bogs, living in the moist or wet Bog-moss, or Sphagnum. Sometimes I
have found this particular moss actually to swarm with multitudes of these
creatures of the most extraordinary kinds and in the most highly developed
condition. A drop of water squeezed from a little pinch of Bog-moss has
often yielded scores of half a dozen genera and a greater number of species.
Frequently, however, the Sphagnum of many localities contains compara-
tively few Rhizopods, though I have rarely found them entirely absent
from this moss. Other mosses and liverworts I have not observed to be
specially favorite habitations of the Rhizopods, not even such aquatic kinds
as the Fontinalis.

Notwithstanding the experience of four years' exploration and obser-
vation, I have not been able to determine the exact conditions under which
particular Rhizopods are to be obtained with certainty and in any consid-
erable numbers. In general, they are to be found in greatest number and
variety under the peculiar conditions favorable to them, in old established
ponds, bogs, etc., which are not liable to become completely dried up in the
summer season. At times, however, I have found a profusion of one or
two forms in some localities, in which, in another season, I could find but
few or none. Sometimes I have found many individuals of a particular
kind in a shallow pond of recent origin, which, after drying up in the
summer and being renewed the following spring, yielded no more of the
same. Sometimes the most unpromising places have produced an unex-

10 FRESH-WATER RHIZOPODS OF NORTH AMERICA.

pected and occasionally a surprisingly rich supply of Rhizopods, and
repeatedly the most promising places have yielded exceedingly few.

The Rhizopods may be found at all temperate seasons of the year;
and even in winter, when out of the influence of a freezing cold, a few
may be discovered, though mostly in a comparatively inactive state. Frost
or a freezing- temperature appears to destroy them.

They do not live among actively decaying vegetal matter, nor are
they to be found in foul water. I have further not been able to discover
them in brackish waters on the sea-coast, though I detected a few forms in
feebly saline or alkaline waters in the Bridger Valley of Wyoming Territory.

The Fresh-water Rhizopods appear to inhabit indiscriminately almost
any kind of country, no matter what may be its rocky constitution, except
it be limestone. According to my experience, they are comparatively
rare in limestone districts, and I have repeatedly been disappointed in
my expectation of finding them in some large limestone springs in which
grew a profusion of Anacharis, Chara, and other aquatic plants. This has
appeared the more surprising when it is considered that the allied marine
order, the Foraminifera, have so largely contributed to the formation of the
limestone rocks.

The mode I have habitually adopted for collecting Rhizopods, which
is also equally well adapted for collecting man} other microscopic organ-
isms, plants, and animals, is as follows :

For ponds, ditches, or other waters, I use a small tin ladle, or dipper,
such as is commonly employed for domestic purposes Into the handle I
insert a stick of convenient length, and for this I usually carry with me
a jointed pole of two or three pieces, each about five feet. The dipper
is used by slowly skimming the edge along the bottom of the water so as
to take up only the most superficial portion of the ooze, which is then
gently raised from the water and transferred to a glass jar. A small hole
in the bottom of the ladle favors the retention of the collected material,
but care should be taken that it is not so large as to permit the material
to stream through. After the collecting-jar is full, if more of the material
is wanted, after allowing that in the bottle to settle, I pour off a portion
of the water and supply an additional quantity from the locality.

Usually, I have proved more successful in obtaining Rhizopods from
the ooze near the shores of lakes and ponds than I have in deeper water;

COLLECTION AND EXAMINATION OF RHIZOPODS. 1 1

but this I suspect was mainly due to the circumstance that near the shore
I could see the ooze at the bottom of the water, and could much better
manage to collect the desired material.

Aquatic plants, if rooted in the mud, should be carefully cut off
and gently lifted from the water so as to disturb as little as possible the
adherent materials. A sufficient quantity being placed in a tin preserving-
can or other vessel, water from other portions of the plants may be
squeezed upon that which is retained.

Wet Sphagnum may be collected and put in tin preserving-cans, and
the water of other portions may be squeezed upon the portion preserved.
The same process may be pursued with other mosses.

From the surface of the ground in wet places,.to co^ect the Rhizopods,
it is sufficient to scrape up, with the broad blade of a knife, the green algous
material with which the animals are usually associated.

The materials collected from waters I have preserved, for convenient
examination from time to time, by putting them in dishes about three inches
in depth, filling them with fresh water, and placing them in the window
where they obtain an abundance of light, but without receiving the direct
rays of the sun. If exposed to the sun, the water becomes unduly heated,
and all living things speedily die and decompose. Care should also be
observed not to have too much material in the same dish ; and I have found
it best to preserve a stratum of ooze which, when settled, is not more than
from a line to the eighth of an inch in depth. Some Duck-meat, Lemna,
Bladderwort, Utricularia, Spirogyra, or other plant, collected, and placed in
the water, greatly promotes its freshness and continued purity. The dishes
should be covered with panes of glass to exclude the dust and prevent
evaporation. A day or two after the materials have been placed in dishes,
the sediment has deposited and the water become clear. In this condition,
there may usually be observed on the surface of the sediment a continuous
thin film, or patches of a yellowish, yellowish-green, or green color. The film,
or patches of the same material, is more tenacious than the deposit beneath,
and consists of the various living organisms, especially diatoms, desmids,
rhizopods, etc., which have extricated themselves from the ooze to occupy
the most favorable position to continue their functions. Indeed, it is a
remarkable phenomenon to observe with what ease and rapidity these
extremely minute living creatures can free themselves from the depths of

12 FEESH- WATER RHIZOPODS OF NORTH AMERICA.

the mud in which they had been buried, to occupy a position on its surface,
where they receive the full benefit of the conditions necessary to their life.

From the living' film, as it might not inappropriately be called, the
desired objects for examination are to be obtained. Portions ma} r be lifted
with a glass tube closed at the upper end by the finger, and then with the
other end brought into contact gently with the surface of the ooze. By
raising the finger, the pressure of the water forces a portion of the ooze into
the tube, when, the finger being replaced, a drop of the contents of the tube
may be transferred to a glass slide or an animalcula cage for the field of
the microscope.

The materials collected and disposed of in the manner above described
may be preserved in a good condition for examination for weeks together,
and indeed without any further care in this way I have kept a stock of
Rhizopods alive during the winter.

The Rhizopods collected with wet Sphagnum, or other mosses, or on
damp earth, .may be readily kept in good condition for examination in glass
cases, for which purpose common wide-mouthed candy -jars answer. They
should be kept in the light in the same manner as the dishes of water.
With Sphagnum I have retained its peculiar Rhizopods alive the whole year
through.

To examine the Rhizopods of Sphagnum or other mosses, or from the
algous film of damp places, wet a fragment, teaze it with a knife and
forceps, and press the water from the pulpy mass into a watch-crystal. A
drop of the sediment collected is then to be transferred to the field of the
microscope.

The different forms of fresh- water Rhizopods are not generally restricted
to different localities or positions, but are commonly found more or less in
association together. Usually the naked forms, and especially the larger
ones, the Difiiugias and the Arcellas, are found most frequently, abundantly
and best developed, in the ooze of bodies of water. The Euglyphas,
Nebelas, and their nearer allies, are in like manner most frequent in the
moist Sphagnum of bogs ; and the Heliozoa in the positions previously
indicated.

The chief localities from which I have myself collected the materials
of the present work are as follows :

ORDERS OP RHIZOPODS— RADIOLARIA. 13

Ponds, springs, and marshes in the vicinity of Philadelphia, but espe-
cially the ditches which traverse the great meadows below the city, in the
alluvial triangle called the Neck, between the Delaware River and the
mouth of the Schuylkill River.

Ponds, marshes, etc , along the course of the Delaware River, both in
Pennsylvania and New Jersey, from Philadelphia to the Delaware "Water
Gap.

Sphagnous bogs, pools, and ponds on the Pokono Mountain, Monroe
County, and on Broad Mountain, Schuylkill County, Pennsylvania

The lower part of the State of New Jersey, along the course of the
Camden and Atlantic City Railway, and along the course of the Camden
and Cape May Railway. Throughout this broad region materials were col-
lected from many localities: ponds and pools, sphagnous bogs, cedar swamps,
savannas, and cranberry lands. Also Lake Hattacawana,' or Budd's Lake,
on Schooley's Mountain, Morris County, New Jersey.

The vicinity of Noank, on the coast of Connecticut, and of Newport,
Rhode Island.

Bridger Valley, in the southwestern corner of Wyoming Territory, and
the Uinta Mountains to the height of 10,000 feet, in the same region.

Partridge Island, at the head of the Bay of Fundy, Nova Scotia.

Before entering in detail upon the special subjects of my studies, the
Fresh-water Rhizopods, nearly all of which pertain to the orders of the
Protoplasta and the Heliozoa, some remarks on the characters of the other
orders of the class may not be out of place.

The RadaoBaria (radiolus, a little ray) are the subjects of an ela-
borate and magnificent work by Dr. Ernst Haeckel, Professor of Natural
History, in Jena.* They are exclusively marine Rhizopods, comprising
many wonderfully beautiful forms, living and swimming in vast multitudes
in the superficial waters of the ocean. They are generally minute, and are
the most complex in their constitution of an}* of the Rhizopods. They are
commonl}* furnished with a siliceous or flinty skeleton, which, in variety of
form, symmetry, and intricacy of construction, is a marvel of beauty. The
material of the skeleton is derived from the exceedingly small proportion

* Die Radiolarien (Rhizopoda Radiolaria), Berlin, 1882.

14 FRESH-WATER RHIZOPODS OF NORTH AMERICA.

of silex contained in the sea-water. After death, the skeletons of the Radio-
laria sink to the bottom of the ocean, where they accumulate as an abun-
dant component of the mud.

In the island of Barbadoes, extensive rock strata of the Tertiary period,
1100 feet in thickness, consisting of marls, tripoli, and ferruginous sand-
stones, are largely composed of the siliceous skeletons of Radiolaria.
Material from these strata called 'Barbadoes earth' is well known to
microscopists, and is highly jjrized for the perfection and beauty of the
forms it supplies. Like-wise, in the Nicobar Islands, of the Indian Archi-
pelago, the solid nucleus of the islands, consisting of clays, marls and
ai-enaceous marls of Tertiary age, 2000 feet in thickness, is largely com-
posed of the remains of Radiolaria.

According to Haeckel, the soft body of the Radiolaria is more highly
organized than that of the Foraminifera and Heliozoa. It contains a cen-
tral capsule of firm membrane enclosing masses of minute cells. The
exterior protoplasm commonly contains numerous yellow cells enclosing
starch-grains, and in some forms also lai-ge vacuoles, and from it emanate
in all directions countless pseudopodal rajs.

Most Radiolaria possess a highly complex skeleton composed of
silex, exhibiting in different kinds a wonderful variety of the strangest and
most elegant forms. Sometimes it consists of a simple trellised ball, some-
times a series of several such balls enclosed concentrically in one another,
and connected together by radial bars. Generally delicate spines, often
branching, radiate from the surface of the balls. In other instances, the
skeleton consists of a star mostly composed of twenty spines, arranged in
definite order and united in a common centre. In some Radiolaria, the
skeleton is a delicate, many-chambered shell, as in the Foraminifera.
Indeed, says Prof. Haeckel, no other group of organisms develop in
the construction of their skeleton such a variety of fundamental forms,
with such geometrical regularity, and such elegant architecture.

The Foraniisiifera {foramen, an aperture; fero, to bear) constitute
by far the most important order of the Rhizopods, especially from the vast
quantities in which they have existed in all times from the earliest known
appearance of life on earth until now, and from the enormous extent in
which their remains have contributed to the formation of rocks. They are
marine shell-bearing animals, mostly living at the bottom of oceans and

OEDEES OF EHIZOFODS— FOEAMINIFEEA. 15

seas, some attached, but generally free, and creeping on the surface of sea-
weeds, on the mud, the sands and rocks, or on dead shells and corals, or
the lifeless fixed hard parts of other living animals, as the shells of mollusks,
corals, sertularians, and sponges. Large numbers are pelagic, or live on
the high seas, swimming in the superficial water, while their dead shells
form an incessant rain, and contribute largely to the formation of the ocean
mud.

Of their class, the Foraminifera have been longest and best known,
and their tiny and beautiful shells have been the subjects of many descrip-
tions and illustrations. The characters of ihe order have been especially
elaborated in more recent works, among which may be mentioned the
"Organization of the Polythalamia" by Dr. Max S. Schultze, and the
"Introduction to the Study of the Foraminifera" by Dr. William B. Car-
penter.

The Foraminifera, though generally too minute to be distinguished by
the naked eye, are readily detected with a good pocket-lens. They are
commonly largest in tropical seas, and even the same species are better
developed in warmer than in colder latitudes. A few, the giants of their
kind, are conspicuous for their size, and range even to the diameter of seve-
ral inches. In former ages they frequently reached a greater growth, so
that fossil forms are commonly larger than those now living - . Some of the
extinct species exceed in size double that of any known existing ones.

The Foraminifera are provided with a shell, mostly calcareous, but
often partially calcareous with incorporated siliceous sand, or it is composed
of sand-grains alone cemented together. With few exceptions, the shells
are partitioned into many chambers, and the most common forms, which
are spiral, so nearly resemble the shells of the Nautilus and Ammonite, that
until a comparatively late period all were classed together as Polythalamia
(Gr. polus, many; thalamos, chamber) or Cephalopoda (the Cuttle-fishes).
D'Orbigny, recognizing in the shells of the Nautilus and Ammonite that the
chambers were traversed by a tube, while in the shells of the so-called
microscopic Cephalopods the chambers communicated by one or more holes,
called the former Siphonifera (siphon, a tube; fero, I carry) and the latter
Foraminifera. In a systematic arrangement of the Cephalopods in 1825,
D'Orbigny still retained the Foraminifera as an order. Dr. Carpenter
remarks that "no suspicion appears at that time to have crossed the mind

16 FRESH- WATER EHIZOPODS OF NORTH AMERICA.

of M. D'Orbigny that the place of these organisms might be among the
lowest instead of among the highest of the Invertebrata."

The true nature of the Foraminifera, and their relationship with
Amoeba, Difflugia, and other animals of the kind, was first recognized by
the accurate observer M. Dujardin.

In the Annales des Sciences Naturelles for 1835, there are two
articles from M. Dujardin, entitled " New Observations on the Micro-
scopic Cephalopods" and "New Observations on the pretended Micro-
scopic Cephalopods". The author remarks that he has observed several
genera of these animals from the Mediterranean in a living condition, nota-
bly Miliola, Rotalia, etc. The segments of the shell successively augment
in volume, and are occupied with a red or orange-colored animal matter, of
thfe consistence of thick mucus, veiy contractile, and susceptible of length-
ening into threads. In conclusion, the author remarks that "if one wishes
to assign to these animals their place in the animal kingdom, in considering
the absence of organs, the homogeneity and simplicity of their material —
a sort of mucus endowed with spontaneous movement and contractility —
one is led to place them in the lowest rank I first designated them under
the name of Symplectomeres, only having in view the succession of similar
parts rolled together, in the known species ; but the observation of Gromia
has led me to prefer the name Pihizopods, to express their singular mode of
creeping by means of threads, which extend and branch like roots."

Dr. Carpenter divides the Foraminifera into two suborders: the Imper-
forata and the Perforata, founded on the circumstances that in the former
the shell has mostly but a single orifice of communication with the exterior
for the emission of the pseudopods, while in the latter the shell has its outer
walls everywhere minutely perforated for the same purpose

The sarcode of the Foraminifera consists of a viscid protoplasm, usu-
ally more or less colored yellowish, brown, or red; the color being deepest
in the earlier formed chambers of the shell, and becoming less towards the
last one, in which it is very feeble or absent altogether. The protoplasm
contains granular matter, and vacuoles, or drops of more liquid matter than
that of the general mass of the sarcode. Nuclei have commonly been sup-
posed to be absent, but recent researches of Hertwig* and Schulzef have
proved their existence. The pseudopods of the Foraminifera extend as

Mnuiisclio Zeitschrift, x, 1876,41. tArchiv f. Mikros. Aiiat. 1877,9.

ORDERS OF RHIZOPODS— FORAMINIFERA. 17

exceedingly delicate threads, often in large number, from the one or several
mouths or numerous pores of the shell. They divide and subdivide into
finer and finer threads, which inosculate freely where they come into con-
tact with one another, so as to produce an intricate net. From this condi-
tion, Dr. Carpenter has applied to the order the name of Reticulata.
The pseudopods exhibit continual changes in their arrangement, and an
incessant circulation in their course. In the larger threads, two streams
are observed at the same time, passing in opposite directions ; in the finest
threads, a single stream moves outward or inward. The currents carry
along granules of the protoplasm, and also convey particles of food which
may be caught in the way of the pseudopods.

Sea-sands contain as an important constituent the dead shells of
recent Foraminifera, though in very variable proportions. They are
generally most abundant in the sands of warmer latitudes, and especially
on shores profusely furnished with sea-weeds.

Plancus,* who, according to D'Orbigny,t was the first to describe and
figure the shells of Foraminifera, counted 6000 individuals in an ounce of
sand from the Adriatic. D'Orbigny estimated that there were 160,000 in
a gramme of selected sand from the Antilles. SchultzeJ gives 1,500,000 as
the number he found in fifteen grammes of sand from Gaeta on the coast
of Sicily.

Even on the comparatively barren shores of New Jersey, consisting of
quartz sand, foraminiferous shells occur in notable quantity. In a portion
scraped from the surface between tides, at Atlantic City, I estimated that
there were 18,700 shells to the ounce avoirdupois, all of a single species of
Nonionina In another sample, from Cape May, I obtained 38,400 shells to
the ounce, likewise of the one species.

In sand collected by scraping up the long white lines on the bathing
beach at Newport, Rhode Island, occupying an indenture of the rocky
coast, covered with sea-weeds, foraminiferous shells were found to be much
more numerous, but, excepting in the case of some examples of Miliola, of
smaller size. In an ounce of the sand, I estimated that there were about
280,000 shells, of several genera and species.

It would appear as if the deep-sea mud almost universally was mainly

*Aiimmensis de conchis minus notis. Venice 1739.

tForamiuiferes: La Sagra, L'islo de Cuba. Paris, 1839. Introduction, vii.

{Organismus d. Polythalamien, 1854, p. ?5.

2 RUIZ

18 FRESH-WATER RHIZOPODS OF NORTH AMERICA.

derived from the shells of Foraminifera. The sediment of the Atlantic
Ocean is so largely constituted of one kind of foraminiferous shell, the
Globigerina buUoidcs, that the mud is now frequently spoken of as the 'Glo-
bigerina ooze'; and this material is likewise found in the Pacific and other
oceans and seas.

In speaking of the composition of the ocean mud, Mr. Thomson re-
marks : "The dredging at 2435 fathoms at the mouth of the Bay of Biscay
gave a very fair idea of the condition of the bottom of the sea over an
enormous area, as we know from many observations which have now been
made, with the various sounding instruments contrived to bring up a
sample of the bottom. On that occasion the dredge brought up about one
and a half cwt. of calcareous mud. The matter contained in the dredge
consisted mainly of a compact 'mortar', of a bluish color, passing into a
thin — evidently superficial — layer, much softer and more creamy in consist-
ence and of a yellowish color. Under the microscope the surface layer
was found to consist chiefly of entire shells of Globigerina bulloides, large
and small, and fragments of such shells mixed with a quantity of amorphous
calcareous matter in fine particles, little fine sand, etc. Below the surface
layer the sediment becomes gradually more compact, and a slight grey
color, due probably to the decomposing organic matter, becomes more pro-
nounced, while perfect shells of Globigerina almost entirely disappear, frag-
ments become smaller, and calcareous mud, structureless and in a fine state
of division, is in greatly preponderating proportion.

"One can have no doubt, on examining this sediment, that it is formed
in the main by the accumulation and disintegration of the shells of Globi-
gerina — the shells fresh, whole and living in the surface layer of the deposit,
and in the lower layers dead and gradually crumbling down by the decom-
position of their organic cement, and by the pressure of the layers above —
an animal formation in fact being formed very much in the same way as
in the accumulation of vegetal matter in a peat bog, by life and growth
above, and death, retarded decomposition and compression beneath."*

When we are thus informed of the constitution of ocean mud, we are
fully prepared to learn that vast rock-formations of past ages are composed
of the shells of Foraminifera. D'Orbigny observes that the ' calcaire gros-
sier' of the Paris basin, a coarse limestone of Tertiary age, is chiefly com-

*The Depths of the Sea, p. 410.

OEDEES OF EHIZOPODS— MONEEA. 19

posed of the shells of these animals. As this rock is employed for building,
he remarks that it is no exaggeration to say that Paris, as well as the towns
and villages of some of the surrounding departments, are almost built up
of Foraminifera.

The limestones of early Tertiary age of Southern Europe and Asia
and of Northern Africa are largely constituted of Nummulites (nummidus, a
small coin), — foraminiferous shells resembling money in shape, and ranging
from the size of a pin-head to that of a dollar. This 'Nummulitic Lime-
stone ' attains a thickness of several thousand feet, and contributes to form
those great mountain chains, the Pyrenees, Alps, Apennines, Carpathians,
and the Himalayas, often including their snow-clad peaks. It extends
through the Mediterranean basin, Asia Minor, and Persia, into India. In
Egypt, it furnished building-stone for the great Pyramids.

The chalk of Europe, a soft limestone of an earlier time than the
former, is also chiefly composed of the shells and their decomposed remains
of Foraminifera. The so-called green-sands, like those of our neighboring
States, New Jersey and Delaware, of the same and other periods, from the
earliest to the latest times, have been largely due to Foraminifera, Prof.
Bailey has further shown that a similar material to the green-sand is now
in process of formation in the Gulf of Mexico, through the same agency.

The fossil-bearing rocks of earliest time present illustrations of the
same character. Limestones of the Carboniferous age have been largely
due to foraminiferous shells, and one kind has been specially named
'Fusulina Limestone', from the abundance of shells it contains of the
foraminiferous genus Fusulina,

The group of organic beings designated as Monera (Gr. moneres,
simple) was first definitely characterized by Prof. Haeckel, who describes
it in his Monograph as follows :

Organisms without organs, which in the perfectly developed condition
consist of a freely movable, naked body, composed of a completely struc-
tureless and homogeneous sarcode (protoplasm). Never differentiating
nuclei within the homogeneous protoplasm. Motion occurs through con-
tractions of the homogeneous body- substance, and through extension of
variable processes (pseudopods), which either remain simple, or branch and
anastomose Nourishment occurs in various ways, mostly after the manner
of Rhizopods Reproduction takes place only in an asexual manner,

20 FRESH-WATER RHIZOPODS OF NORTH AMERICA.

through division. Often, though not always, the free moving condition
interchanges with one of rest, during which the body excretes and encloses
itself in a structureless investment.*

Though Prof. Haeckel has indicated and described a number of fresh-
water species of Monera, I am not sure that I have had the opportunity
of finding any of them, excepting perhaps the genus Vampyrella of Cien-
kowski, which he ascribes to the same order.

In his History of Creation, Prof. Haeckel observes: "In a state of
rest most Monera appear as small globules of slime, invisible or barely visi-
ble to the naked eye, and at most about the size of a pin-head. When the
Moner moves, there are produced on the surface of the little slime ball, finger-
like processes or very fine radiating threads, the so-called false feet or
pseudopods. The latter are simple continuous processes of the structure-
less albumen-like mass of which the body consists. We are unable to
perceive different parts in it, and we can obtain direct proof of the absolute
simplicity of the semi-fluid mass of albumen, for with the aid of the micro-
scope we can follow the Moner as it receives its nourishment. When
minute bodies suitable for food, as, for instance, small particles of decayed
organic bodies or microscopic plants and infusoria, accidentally come into
contact with the Moner, they remain hanging to the sticky surface of the
semi-fluid mass of slime, and here produce an irritation, which is followed
by a strong afflux from the slimy mass of the body, and they become finally
completely enclosed by it, or they are drawn into the body of the Moner
by displacement of the several albuminous particles and there digested,
being absorbed by simple diffusion (endosmosis).

"Just as simple as is the nourishment, is the mode of reproduction of
these primitive beings, which one cannot positively call animal or plant.
All Monera propagate themselves only in an asexual manner by self-
division. When such a speck, for example, a Protamceba or a Protogenes,
has attained a certain size by the assimilation of foreign albuminous matter,
it falls into two pieces ; there is formed a constriction around the middle,
which finally leads to the separation of the two halves. Each half becomes
rounded, and then appears as an independent individual, which commences
anew the simple play of the vital phenomena of nutrition and propagation.
In other Monera {Vampyrella) the body in the process of propagation,

* Biologische Studien, 1870, 68.

OEDEES OF EHIZOFODS— CHALLENGEELDA. 21

instead of two, falls into four equal parts, and in others again (Protomonas,
Protomyza, Myxastruni) at once into a large number of small globules of
slime, each of which again by simple growth becomes like the parent
body." *

Sir Wyville Thomson, in the Voyage of the Challenger, briefly
describes certain Rhizopods, which he refers to a new order. On page
341 of the work indicated, he says: "In the investigations with the
towing-net, made by Mr. Murray during the' latter part of the cruise, at all
depths, about thirty species or more were procured of a beautiful group of
minute forms approaching, but in many important points differing from the
Radiolarians. This order have apparently hitherto escaped observation,
and I retain for the type genus the name Cliallengeria, and for the Order that
of 'Challengerida'. As a rule these forms are extremely minute, although
some of them approach in size the smaller Radiolarians. They consist
usually of a single chamber of silica varying greatly in form, sometimes
triangular, sometimes lenticular, and frequently globular or flask-shaped ;
with a single opening usually guarded by a beautifully formed and fre-
quently highly-ornamented lip. The contents of the shell consist of a mass
of granular sarcode, with one or more large well defined granular nuclei,
and a number of dark brown, sometimes nearly black, rounded compound
granular masses. The Challengerida are essentially Rhizopods with mono-
thalamous siliceous shells ; and their zoological position may be not very far
from such forms as Gromia."

Nothing is said of the characters of the pseudopods ; but should they
be of the same kind as those of Gromia, this, with the new forms, might
conveniently be associated in the same order.

* Natiirliclie Schopfungsgeschichte, 1872, 166.

FRESH-WATER RHIZOPODS.

PROTOPLASTA. ■

Proton, first ; plasso, I form or mould.

The ProtopDasJa comprise by far the greater number of the Fresh-
water Rhizopods, and include nearly all the known forms except the Heli-
ozoa, or Sun-animalcules. They are divisible into two sub-orders, the
Lobosa and the Fiflosa, founded mainly on the difference of the pseudo-
pods, which in the former are comparatively thick, finger-like or lobose,
and in the latter filamentous and of extreme delicacy.

Some of the Protoplasts are naked, usually have no real distinction in
the relative position of parts, and emit pseudopods from any portion of the
body-mass, though even most of these when in movement, for the time
being, may have the body more or less differentiated into an anterior and a
posterior region.

The greater number of the Protoplasts are provided with an exterior
shell, commonly of a more or less flask- or vase-like shape, and, with
few exceptions, having a single orifice, from which the pseudopods are
projected. The shell is an excreted membrane, chitinoid or siliceous in
character, or it is constructed of siliceous sand or particles of similar con-
stitution, but, so far as known, appears never to be composed of carbonate
of lime.

PROTOPLASTA LOBOSA.

The Lobose Protoplasts, represented by the familiar Amoeba,
Difflugia, Arcella, as well as by many other less known genera, are princi-
pally characterized, as indicated in the name, from the comparatively thick,
lobe-like, or blunt finger-like form of the pseudopods.

23

24 FRESHWATER RHIZOPODS OF NORTH AMERICA.

In the Lobose Protoplasts, more than in any other Rhizopods, the sar-
code mass of the body exhibits a tendency to differentiate an exterior,
usually more consistent layer of protoplasm, which, though actually con-
tinuous with the interior, ordinarily more fluent protoplasm, seems like an
investing membrane, preventing the escape of the latter. For convenience,
the two portions of protoplasm, differently related in position, have been
appropriately termed the Endosarc and the Ectosarc (Gr endon, within ;
ektos, outside ; sarx, flesh).

The ectosarc appears as the exterior clear protoplasm ; the endosarc
as the interior granular protoplasm, though high puwers of the microscope
generally reveal an infinitely fine granular constitution also to the former.

Dr. Wallich regards the endosarc and ectosarc as temporarily distinct
portions of the sarcode, mutually convertible into one another. The ecto-
sarc becomes differentiated from the endosarc by contact with the outside
medium in which the animal lives, and from time to time reverts again to
the condition of the more fluent endosarc within.

From this view, as intimated by Dr. AVallich himself, the ectosarc is
due to a temporary and partial coagulation of the endosarc coming into
contact with the water in which the animal lives, and again reverts to the
condition of the more fluent endosarc as it retreats to the mass of the latter
within the body. The process reminds one of the cooling of a molten mass
of metal at the sides of a crucible, and the melting-away again of the crust
as it is stirred from the sides into the remainder of the molten mass within.

In the movements of the sarcode mass of the body, as exemplified in
an Amoeba, a temporary increase of the ectosarc may occur in one or
more positions, accompanied with a proportionate flow or drain of hyaline
protoplasm from the contiguous endosarc. A reduction in thickness of the
ectosarc follows an absorption of the clear protoplasm among the more
visible granular constituents of the endosarc.

The pseudopods of the Lobosa commence as projections of the clear
ectosarc, and may continue as such in their extension unless unusually pro-
longed or thick. In the latter cases they are accompanied to a variable
extent with an influx of the endosarc. They are mostly digitiform or
finger-like processes, or, in other words, are cylindrical, with rounded ends,
variable in number and length, often simple, frequently more or less
ramose, but almost never anastomosing. Sometimes they are pointed, and

PEOTOPLASTA— THE LOBOSE PEOTOPLASTS. 25

indeed in the same species under different circumstances they may be either
blunt or pointed.

The endosarc is essentially granular ; that is to say, it consists of a
motile hyaline protoplasm, not differentiated from the ectosarc, except in
its less consistence and in the thorough diffusion of conspicuous granular
elements. These occur in all gradations of size, from those which are
immeasurably fine and indistinct up to the largest granules which are
more or less darkly defined, and resemble oil-molecules. Besides the more
generally diffused granular constituents, the endosarc contains variable pro-
portions of larger spherical corpuscles, clear or finely granular, and mostly
colorless or pale yellowish, but in some species usually of a bright green
color, and apparently of the nature of chlorophyl.

An important element of the endosarc is the nucleus, a comparatively
large spherical or compressed spherical corpuscle, colorless, and mostly clear,
but sometimes finely granular, or more distinctly coarsely and uniformly
granular. In the naked forms of the Lobosa, while in motion, the nucleus
usually occupies a position at the posterior part of the body, or at least is
placed back of the centre In most of the shell-covered forms it occupies
a corresponding position ; that is to say, in the part most remote from the
mouth of the shell, — in the fundus or upper part of the body. In some
forms, as in Arcella, there are two or more nuclei occupying a position on
each side of the fundus.

Another element of the endosarc, usually situated at its confines and
encroaching on the ectosarc, is the contractile or pulsating vesicle. This
appears as a clear, colorless, or pale roseate sphere, which is observed very
slowly to enlarge, then rather abruptly to collapse and for the moment dis-
appear, again to reappear, commonly in the same position. The successive
movements of the vesicle occur with a certain degree of regularity, or
rhythm, whence the name of pulsating vesicle. It appears to be due to a
gradual concentration of water from all parts of the sarcode mass of the
body, forming a drop, which when it reaches a certain size excites con-
traction and is expelled. The phenomenon is remarkable, and is in a
measure subservient to a respiratory as well as to an excretory function.

In the naked Lobosa, the contractile vesicle usually occupies a position
posterior to the nucleus or at the back of the body near the surface. In
the shell-covered kinds of flask- or vase-like shape, there are commonly

26 FRESH- WATER ROIZOPODS OF NORTH AMERICA.

several contractile vesicles situated at the periphery of the body adjacent
to the nucleus. In Arcella, the gi-eatest number of contractile vesicles
occur, and are ordinarily seen, as the animals are viewed from above or
below, along the border of the sarcode mass.

Food swallowed by the Lobosa and other Rhizopods, and indeed by
most of the Protozoa, appears in the endosarc, commonly in spherical balls,
mingled with the other constituents. These balls, or rather the spaces
occupied by them, have been called vacuoles, and are usually regarded as
of temporary character. Ehrenberg supposed them to be actual stomachs,
and hence the name of Polygastrica (Gr. polus, many ; gaster, stomach),
which he applied to all the Protozoa, including other forms now generally
regarded as pertaining to the vegetal kingdom.

Dr. Wallich considers the so-called vacuoles, or food-vesicles, not in the
light of mere spaces, but as temporary vesicles of ectosarc, due to inver-
sion of portions of the exterior ectosarc at the time of the inception of the
food, or to the contact of water with portions of the endosarc. The food-
balls commonly appear with some degree of uniformity in size, and they
vary in color and constitution according to the nature of the food and the
changes it undergoes during digestion in the endosarc. The solid food in
the balls often appears surrounded with a more translucent area than the
contiguous endosarc, due to water swallowed with the food Frequently,
however, the solid food appears without the translucent area, and in direct
contact with the endosarc, in which cases liquid originally ingested with the
food and altered in some way has probably been drained off into the con-
tiguous endosarc.

Among the food constituents of the endosarc there frequently occur
solid bodies of different forms and extremely different sizes, with or without
surrounding liquid, such as diatoms, desmids, fragments of vegetal tissues,
and even other Rhizopods included in their shells.

Associated in like manner with the ordinary food-balls, there are fre-
quently to be noticed drops of liquid, clear and colorless, or colored,
mingled with the other materials of the endosarc. These particular liquid
drops, water-vacuoles or vesicles containing liquid, are due to water swal-
lowed in drops, or imbibed and accumulated in drops, or they are the result
of more consistent food liquefied in the process of digestion.

The food appears to be swallowed by the Lobosa, not by a mere

PEOTOPLASTA— THE LOBOSE PROTOPLASTS. 27

adherence of the material to a viscid substance, and a gradual entangle-
ment and sinking of the food into the body, but through an active exten-
sion or flowing of the ectosarc over it, with or without the aid of the pseudo-
pods. In the naked forms, the inception may occur in any position of the
exterior surface of the body, but, according to the researches of Prof.
Duncan,* would appear ordinarily to take place at the posterior extremity,
where the endosarc is nearest to or actually reaches the surface. Some of
my latest observations apparently confirm this view.

Whatever may be the position of ingestion in the naked Lobosa, excreta
are ordinarily discharged at the posterior extremity of the body adjacent
to the position of the contractile vesicle Although there is no true vent,
like the positions of the contractile vesicle and nucleus, the position of dis-
charge of excrement maintains a certain degree of constancy.

In the shell-covered Lobosa, the food and water are ingested at the
mouth of the shell, usually through the agency of the pseudopods, and the
egesta are discharged in the same position at the base of the pseudopods,
if these happen to be protruded.

Many of the Lobosa exhibit, among the constituents of the endosarc,
variable proportions of clear, colorless or yellowish oil-globules, and also
starch-granules. The latter are no doubt often swallowed as part of the
food; but in many cases they appear as if they were an intrinsic element
of the endosarc.

Most of the naked Lobosa frequently contain in the endosarc more or
less angular particles of quartz sand ; sometimes a few grains, sometimes
in large and truly astonishing, quantities. The shell-covered Lobosa usually
do not contain this material, at least in any obvious quantity.

Another frequent constituent of the endosarc, especially in some of
the Amoebne, consists of minute crystals, often quite distinct, though it is not
easy to make out their exact form and constitution. They sometimes
appear as octahedrons, rhombohedrons, and hexagonal tables. Auerbachf
supposes them to be of a fatty nature ; Carter J describes them as octahe-
drons, or modifications of the same, and as probably consisting of oxalate
of lime; and Wallich§ speaks of them as rhombohedrons, probably of car-

* Popular Science Review, 1877, 217.

t Zeitsclirift f. wis. Zoologie, 1856, 309.

t Annals and Magazine of Natural History, 1863, xii, 33.

« Ibidem, 1863. xi, 434 ; xii, 135.

28 FRESH- WATER RHIZOPODS OF NORTH AMERICA.

bonate of lime, and again he refers them to the hexagonal system. The
crystals sometimes occur in notable quantity, even in young specimens of
Amoeba, and are quite conspicuous ; at other times, even in what appear
to be the same species, they are few and small, or not clearly evident, The
crystals, unlike the quartz sand, appear to be an intrinsic element of the
animal.

There is yet little positively known in relation to the modes of repro-
duction of Rhizopods, though it is certain that a common mode is by
division, as has been observed in some of the naked Lobosa, Heliozoa,
and Monera. The opportunities for observing the process have appeared
to me to be by no means frequent ; for in all the four years of my study
of the Fresh- water Rhizopods, I met with an Amoeba in the state of division
in but few instances, and the common Sun-animalcule, Actinophrys sol, but
rarely.

The shell-covered Protoplasts are frequently found in pairs, with the
shells mouth to mouth. When the shells are sufficiently translucent to
allow the soft parts within to be seen, at times it is observed that these
become confluent in one mass, which flows to and fro from one shell to the
other. The mass finally dividing again into two, the individuals with their
shells become separated without apparent change from the original state.
This condition of union of a pair is commonly named 'conjugation', and
has been supposed to hold a relation with the act of reproduction, though
it has not been positively proved to be so.

From certain appearances, hereafter to be considered in the special
cases, I have suspected that many of the supposed examples of conjuga-
tion are really due to reproduction through division. From the appear-
ances alluded to, there is reason to suspect that from time to time the shell-
covered Protoplasts, under appropriate conditions, — such as are induced by
being well fed, so that the animal is in a highly active condition, and the
shell is surchai-ged with sarcode, — quickly project one half the mass of
sarcode, which as quickly assumes the shape and size of the parent. The
exuded mass at the same time may be supposed to rapidly secrete a shell ;
or, if this is composed of foreign matters, as in the case of a Diffhigia, it
may be immediately formed by the adherence of particles to the exuded
sarcode. If such shall be proved to be one of the modes of reproduction
of the shell-covered Protoplasts, it is one which we may suppose would

PEOTOPLASTA— THE LOBOSE PEOTOPLASTS. 29

assure comparative uniformity of character in the shape, size, and consti-
tution of the shell, just as buds of the same plant ordinarily assure the
same varieties of flowers and fruit. On the other hand, reproduction of
the Rhizopods from germs or spores would probably furnish a partial
explanation of the multitudinous varieties of form.

The naked Protoplasts, as represented by species of Amoeba, etc., at
times which are apparently related with circumstances unfavorable to
activity, even of an opposite character, as extremes of temperature, cold
or heat, assume a condition of complete quiescence, reminding one of the
winter or summer sleep of higher animals. The condition is preceded by
retirement into the deeper part of the ooze in which these lowly creatures
live, or by concealment in dirt and other materials accumulated around and
adherent to them. Contracted into a globular form, they are purged of all
remains of food and other materials, such as sand, etc., swallowed with the
former. They then become gradually invested with a structureless mem-
brane consisting of one or several layers, apparently the product of exuda-
tion and coagulation of a portion of the protoplasm of the sarcode mass
of the body. In this encysted condition, the Protoplast remains an indefi-
nite period, and perhaps usually undergoes transformation into reproductive
germs or spores. Often, however, if the circumstances are changed for one
favorable to activity, the creature bursts its envelope and creeps forth to
feed in the ordinary manner, as if it had been passing a time in sleep.

The shell-covered Protoplasts are frequently found with the sarcode
mass contracted into a ball commonly defined by a membrane of variable
thickness, and apparently due to the coagulation or condensation of the
ectosarc, or of an exterior more clear and homogeneous layer of the soft
structure. In the formation of these quiescent balls, they are purged of all
remains of the food which is often seen occupying the space between the
ball and the mouth of the shell. Frequently, also, in the quiescent or
encysted condition of the sarcode, the mouth of the shell is closed by an
operculum apparently formed by the accumulation of successive layers of
matters discharged from the sarcode ball.

The encysted ball of the shell-covered Protoplasts in many instances
appears to be resolved into globules, or coarse granules of nearly uniform
size, which are probably to be viewed as germs or spores.

From the researches of Mr. Carter* it would appear that in Amoeba

"Annals and Magazine of Natural History, xviii, 1856, p. 226.

30 FRESH-WATER RHIZOPODS OF NORTH AMERICA.

and Euglypha, representatives of the Lobose and Filose Protoplasts, the
endosarc becomes resolved into nucleated cells, which are of the nature of
ova, while the nucleus is resolved into granuliferous non-nucleated cells,
finally breaking up into their constituent granules, which are of the nature
of spermatozoids.

AMCEBA.

Greek, amoibos, changing.

Tolvox: Linnfeus, 17(30. Chaos: Linnaeus, 17G7. Proteus: Miiller, 1766. Vibrio: Gmelin, 1788. Amiba:
Bory, 18-24. Amoeba: Ehrenberg, 1831.

Animal, when at rest, a spherical or oval mass of soft, hyaline, color-
less, homogeneous, pale granular protoplasm, possessing extensile and con-
tractile power, and in the active condition devoid of an investing membrane,
or any kind of covering. In motion, mostly of exceedingly variable and
ever-changing form, and with no absolute distinction of parts, though fre-
quently exhibiting more or less disposition to differentiation into an anterior
and a posterior region. Ectosarc hyaline, crystal-clear, but, with high mag-
nifying power, exhibiting more or less of an infinitely fine granular consti-
tution. Endosarc continuous with the former, finely and coarsely granular,
mingled with corpuscles of intrinsic and varied character, together with
various ingesta, consisting of food, water-drops, sand, etc. Containing also
a nucleus and a contractile or pulsating vesicle, or sometimes more than one
of either or both of these constituents.

Body with no external appendages of a fixed or permanent character.
Pseudopods digitate, simple or branching, cylindroid and blunt, or more or
less tapering- and pointed, or short and broadly lobate, consisting of exten-
sions of the ectosarc with variable proportions of the endosarc, or of the
former alone.

Animal in the quiescent state, purged of food and other ingested mat-
ters, globular in form, and invested with a structureless membrane, appa-
rently produced by coagulation of a portion of the ectosarc.

AMCEBA PROTEUS.

Plates I, figs. 1-8; II, figs. 1-13; IV, figs. 22-25; VII, figs. 13-19; VIII, figs. 17-30.

Dcr Jcleine Proteus. Rosel: Iusecten Belustigung, 1755, iii, 621, tab. ci.

Voieox Chaos. Linmeus: Syatema Naturae, ed. x, 17C0, i, 821.

Vol fox Proteus. Pallas: Eloncbus Zoophytorum, 1766, 417.

Chaos Prothcus. Limueus: Systema Natura), ed. 12 et 13, 1767, i, 1326.

Volvox Spheerula. Miiller: Verm. Terres. Fluviat. 1773, 31.

GENUS AMCEBA— AMCEBA PROTEUS. 31

Proteus difflueus. M tiller: Animalcula Infusoria, 1786, 9, tab. ii, figs. 1-12. — Surriray : Diet. Sci. Nat. 1820.

Vibrio Proteus. Ginelin: Lin. Syst. Nat., ed. 13, 1788, 3899.

Amiba diver gens. Bory: Diet. Clas. Hist. Nat. 1822, 261.

Amiba Pocsili. Bory: Encyc. M6th., Hist. Nat. Zoophytes, 1824, 46. — Dujardin: Hist. Nat. Zoophytes,

Infus. 1841, 232.
Amiba Miilleri. Bory: Encyc. Me"th., Hist. Nat. Zoophytes, 1824, 46.
AmoSba princeps. Ehrenberg: Abh. Ak. Wis. Berlin, 1831, 28, 79; Infusionsthierchen, 1838, 126, Taf. viii,

Fig. x. — Perty: Kenntniss kleinst. Lebensformen, 18o2, 188. — Auerbacb: Zeitsch. wissens.

Zool. 1856, 407, Taf. xxii, Fig. 1-10.— Leidy: Pr. Ac. Nat. Sc. 1874, 14, 143.
Amiba princeps. Dujardin: Hist. Nat. Zoophytes, Infus. 1841, £32, pi. i, fig. 11.
Amoeba ramosa. Fromentel: Etudes ilierozoaires, 346, pi. xxviii, fig. 2.
Amoeba communis. Duncan: Pop. Sc. Review, 1877, 233.
Amoeba chaos. Leidy: Pr. Ac. Nat. Sc. 1878, 99.
Amoeba proteus. Leidy: Pr. Ac. Nat. Sc. 1878, 99.

Species comparatively large, nearly colorless, or more or less black
by transmitted light, pale yellowish by reflected light; spheroidal or ovoidal
when at rest; very variable and ever changing in shape when in motion,
ordinarily ramose, palmate, or radiate; comparatively active, creeping, with
a disposition to differentiate into an anterior and a posterior region. Pseu-
dopods digitate, simple or branching, and blunt, sometimes tapering and
pointed. Posterior part of the body in contraction receding in the advan-
cing psendopods, sometimes assuming a mulbeny-like appearance. Nucleus
usually single, discoid, habitually posterior. Contractile vesicle usually
single and large, habitually behind the former. Ectosarc thinly differen-
tiated. Endosarc finely and coarsely granular, with many and varied ele-
ments, contributing in its flow to the extension of the pseudopods.

Size, in the globular form to 0.2 mm.; in the ovoidal form to 0.3 by
15 mm.; extended in a dendroid form, occupying a space of 0.5 mm. in length
by 0.4 mm. in breadth; in a palmate form 0.5 mm. long by 0.35 mm. broad;
in a radiate form from 0.2 mm. to 0.5 by 0.4 mm.; in an irregularly cylindroid
form to 1 mm. long. The largest observed occupied a space of 0.6 by 0.2
and 0.35 mm.

Zoc«/^/.— Common in the superficial ooze of ponds and ditches almost
everywhere, though rarely in large numbers. Ditches below Philadelphia
and brick-ponds in the vicinity. Ponds in the neighboring counties,
including Delaware, Chester, Montgomery, Bucks, Berks, and Northamp-
ton; Broad Mountain, Schuylkill County; Pokono Mountain, Monroe
County, Pennsylvania; at Absecom, Hammonton, Woodstown, Vineland,
Cape May, and other places in New Jersey; Newport and Narragansett,
Rhode Island ; and lakes of the Uinta Mountains, Wyoming Territory.

A large Amoeba is the subject of the earliest notice of a Fresh-watei

32 FRESH- WATER RHIZOPODS OF NORTH AMERICA.

Rhizopod. It was discovered by Rosel, and described in a work entitled
"Insecten Belustigung ", or Recreation among Insects, published in Nurn-
berg in 1755. Rosel calls the animal the little Proteus, and accompanies
his description with nineteen well-executed and colored figures engraved
by himself.

Linnaeus, in the Systema Naturae, referring to Rosel's animal, named
it Volvox Chaos, and subsequently Chaos Protheus. Pallas called it Volvox
Proteus. Miiller afterwards named it Volvox Sphceruta, but later, after having
himself observed the animal, described and figured it under the name of
Proteus diffluens.

As the generic name of Proteus had been previously appropriated for
the well-known Salamandroid of Adelsberg, Bory de St. Vincent substituted
that of Amiba for the animal of Rosel and Miiller, calling it by the various
names of Amiba divergens, A. Bcesili, and A. Mulleri.

Ehrenberg, in the Transactions of the Academ};- of Sciences of Berlin
for 1830, indicated and figured a comparatively small Amoeba, the ^th of a
line (pp. 39, 75, pi. I, figs. 5), under the name of Amoeba diffluens, regarding
it as the same as the Proteus diffluens of Miiller.

In the Transactions of the following 3-ear, Ehrenberg described what
he considered to be a new species with the name of Amoeba princeps. The
characters given of this are as follows : Diameter ith of a line; body trans-
parent, yellowish, with many easily and voluntarily movable blunt pro-
cesses; four times larger than the Proteus.

This description is accompanied with one of Amoeba diffluens {Proteus
diffluens, Miiller), as follows: Diameter ith of a line; body transparent as
water, mostly with only three or four variable processes; four times smaller
than the preceding species.

In his great work, the Infusionsthierchen, 1838, Ehrenberg described
Amoeba princeps as '"large, yellowish, equalling Jth of a line, provided with
a variable number of cylindrical appendages, thick and rounded at the end."
The accompanying figures (Taf. VIII, Fig. X) accord with the description,
and agree with the familiar common large Amoeba.

In the same work, Amoeba diffluens is described as " rarely surpassing
the ,^th of a line, hyaline; processes variable, moderately long and robust
and subacute." Under this species, Ehrenberg places as synonyms the

GENUS AMOEBA— AMCEBA PROTEUS. 33

names of all forms of Amoeba previously described by others, including
the one first discovered, the little Proteus of Rosel

In the earlier description of Amoeba princeps, Ehrenberg says it is four
times larger than the Proteus, meaning- the Proteus diffluens of Midler and
his own Amoeba diffluens, but not the Proteus of Rosel; for this, according
to the actual representation of the latter, is four times larger than Amoeba
princeps, and sixteen times larger than Amoeba diffluens, according to the
measurements of these given by Ehrenberg.

In the remarks on Amoeba princeps, in the Infusionsthierchen, Ehren-
berg says " it is true that Rosel described a larger species of Proteus of
which the dimension accords with this, but the blunt processes, of the species
occurring in Berlin, do not agree well with those of Rosel's figures, but
rather approximate those of larger individuals of Amoeba diffluens."

It is natural to suppose that an Amoeba discovered by the earliest
microscopic observers would be one of the more common large forms, and
that such was the case appears to be fairly proved by figures and descrip-
tions.

Rosel, in referring to one of his figures of the little Proteus, remarks
that in its natural size it looked like A. Now, this figure A represents the
animal in its quiescent state, in globular form, and the figure measures just
four fifths of a line. No Amoeba has since been recorded, in the same
condition, so large as this, and it is not unfair to suppose that the figure is
somewhat exaggerated, which could readily occur in absence of the accurate
means of measurement which came subsequently into use.

Rosel refers to his having held his little Proteus at rest with a pointed
feather, which is alone sufficient to prove that he had under his observation
one of the largest forms of Amoeba.

In size, according to the actual measurements given, Rosel's Proteus
is as much larger than Amoeba princeps as this is than Amoeba diffluens.

In all other characters ascribed by Ehrenberg to Amoeba princeps, it
appears to the writer to agree with the Proteus of Rosel, and this without
doubt better than does the Amoeba diffluens as described by Ehrenberg.

Amoeba princeps is said by the latter to be yellowish, while the Amoeba
diffluens is said to be clear as water. Though Rosel says nothing of the
color of the Proteus, his figures, carefully colored, exhibit the granular

6 EHIZ

34 FRESH-WATER RHIZOPODS OF NORTH AMERICA.

contents yellowish, and the exterior investment colorless, just as our large
common Amoeba appears under partially reflected and transmitted light.

Most of Rosel's figures exhibit the characteristic changes of form of
the Proteus, and these certainly agree with those of our common large
Amoeba, and better with those of Ehrenberg's figures of Amoeba princeps
than with those of the same author's figures of Amoeba diffluens. Of the
figures of Rosel, one he likens in its branching to the antler of a deer, a
resemblance which all must have seen who are familiar with the large
Amoeba commonly regarded as the Amoeba princeps.

As regards both size and color of the Proteus of Rosel, it might refer
to other large Amcebag than A. princeps, as for instance the A. villosa of
Wallich, or the Pelomyxa palustris of Greeff ; but the changes of form and
the extension and shape of the pseudopods rather approximate it to the
former.

Midler's description and figures of Proteus diffluens, which that author
regarded to be the same as Rosel's Proteus, appear to apply to the same
animal as Ehrenberg's Amoeba princeps, rather than to the Amoeba diffluens
of the latter.

From the review thus presented, I think it will be admitted that the
little Proteus of Rosel, the Proteus diffluens of Midler, the Amoeba princeps
of Ehrenberg, and our large familiar Amoeba, are to be regarded as one
and the same animal.

It has been suggested that all forms of Amoeba may eventually be
found to be transitory phases of the same species ; but even this view does
not render the determinations of Ehrenberg and those who follow him in
relation to Amoeba princeps and Amoeba diffluens any the less incorrect.

Having arrived at the conclusion that our common large Amoeba,
usually called Amoeba princeps, is the same as Rosel's Proteus, the question
arises as to its appropriate name.

Ehrenberg changed the name of Amiba of Bory into Amoeba ; and
had it not been that the latter mode of spelling the word had come into
such common use, I would have dropped the ugly diphthong, and resumed
the word Amiba, as employed by Bory arid Dujardm.

Of the specific names employed for the little Proteus, that of chaos in
Volvox Chaos of Linnpeus is oldest ; but that of proteus in Volvox Proteus of
Pallas appears more appropriate, and would at the same time serve to

GENUS AMOEBA— AMCEBA PBOTEUS. 35

perpetuate the name given to the animal by its discoverer. I therefore
suggest that the name of Amoeba proteus should be employed for the
common large Amoeba, recognizable as the Proteus of Rosel and the
Amoeba princeps of Ehrenberg ; otherwise, according to the strict rules of
scientific nomenclature, it should be Amoeba chaos.

Auacpfoa proteus (pis. I, II) is one of the largest forms of the genus,
and is the one which is perhaps the most familiar to those who are accustomed
to the examination of the microscopic life abounding in fresh waters. It is
commonly found in the superficial ooze of clear and comparatively quiet
waters, such as ponds, lakes, and ditches. It also occurs among- Duck-meat
and on the under surface of leaves of aquatic plants floating on the surface of
water. In some instances, in certain localities, ithiav be found in profusion;
but frequently in similar places, or even at other seasons in the same
place, I have failed to obtain it after the most diligent search. Specimens
often vary, especially in different localities, to such a degree that it is
difficult to decide whether to regard them as really pertaining to this or
some other described species.

The habitual appearance of characteristic forms as they have come
within my notice may be described as follows :

The Amoeba, if observed immediately after having been transferred
from the material in which it lived to the object-glass of the microscope,
appears as a globular or ovoidal, granular ball, translucent and of a blackish
hue by transmitted light, or faintly yellowish white by reflected light.
Often, however, from the first moment of observation, the animal appears of
irregular shape, with projected pseudopods already in movement, apparently
as if it had been little affected by disturbance.

The globular or ovoidal quiescent Amoeba after a little while puts
forth from every part of the body a multitude of clear, rounded extensions
of the ectosarc, which give one the impression that the creature had sud-
denly exuded, or, if I may use the term, sweated, numerous drops of liquid.
These quickly elongate, and assume the form of digitate pseudopods, in
which condition the animal may present the appearance seen in fig. 1, pi.
I. A number of the pseudopods continue to elongate and become thicker,
not only from an extension of the ectosarc, but by the attendant influx of
the endosarc. The greater number of the pseudopods originally seen are

36 FRESH- WATER RHIZOPODS OF NORTH AMERICA.

withdrawn and altogether disappear. The growing psendopods are cylin-
drical or digitate, with blunt extremities. They extend in all directions,
are usually more or less curved, and frequently branch. In this condition,
the Amoeba may present the appearance represented in fig. 2.

Occasionally the rounded or ovoidal mass composing the body of the
Amoeba, after putting forth numerous processes in the manner above
described, withdraws the most of these, while a few others rapidly elongate,
and diverge on each side, and the animal may assume a shape reminding
one of a great spider. A specimen in this condition is represented in fig. 1,
pi. II.

Commonly, while one or two, and occasionally more, of the pseudo-
pods, continue to extend and branch, others shorten and disappear, and the
principal mass of the body is diminished at the expense of the growth of
the advancing psendopods, and it may to a greater or less extent merge into
them. As the Amoeba advances through the extension of one or more prin-
cipal psendopods in a particular direction, the whole together becomes more
or less differentiated into an anterior and a posterior region. The posterior
extremity of the body, in its contraction through the flow of its endosarc
into the advancing psendopods, frequently assumes a more or less mammil-
lary appearance. In this condition, the Amoeba, in its form and branching,
may remind one of the antler of an elk, and such specimens are represented
in figs. 3, 4, pi. I.

In the continued extension and branching of one or more of the chief
pseudopods, the Amoeba progresses more or less rapidly, the body appear-
ing incessantly to exhaust itself in the continued growth or elongation of
the pseudopods and in the production of new ones, while it is as incessantly
replenished by the contraction and melting-away of pre-existing pseudo-
pods. While the animal moves along, its direction may change at any
moment by the more active prolongation of any one of the pseudopods.

The changes of form produced by the extension and branching of cer-
tain of the pseudopods, with the recession, melting-away, and total disap-
pearance of others, is endless. Sometimes the animal creeps onward in a
flowing manner with comparatively simple cylindroid form, occasionally
emitting a single pseudopod, on one side or the other. More commonly
in movement it assumes a dendroid or palmate form, or sometimes, diver-
ging from the directly onward course, it becomes more radiate in appearance.

GENUS AMCEBA— AMCEBA PROTEUS. 37

Not infrequently it assumes more or less grotesque shapes, in which almost
every conceivable likeness may be imagined.

Usually Amoeba proteus creeps along surfaces, mainly extending its
pseudopods, and advancing in the same general direction. The pseudopods
may, however, be extended or produced in any direction, and in their pro-
duction the direction of motion of the animal may be completely reversed,
or it may occur in the direction of extension or production of any pseudo-
pod. There is no fixed distinction or differentiation of parts or regions,
and any point of the animal may become central or peripheral, forward or
backward, or lateral.

In the movements of Amoeba proteus, as certain of the pseudopods
are extended, and the mass of the body is proportionately reduced, other
pseudopods may more or less gradually recede and merge into the advan-
cing ones, or they may become shriveled and maminillary in appearance, as
is frequently the case with the posterior extremity of the body itself, and
as represented in figs. 3-7, pi. I.

The mammillary appearance assumed by the posterior extremity of
the animal may persist for a considerable time, though undergoing con-
tinued variation. Any of its processes may become the source of new
pseudopods, and the whole may, at any moment, contract and merge into
the general mass of the body.

When Amoeba proteus is free and floating or suspended in water, it
often assumes a more or less radiate or stellate appearance, with the
pseudopods more or less tapering, and it then looks like a giant form of
Amoeba radiosa, as represented in fig. 2, pi. II.

When creeping on flat surfaces, the body and pseudopods of the
Amoeba are more or less depressed; but when the animal is floating, they
are more rounded.

The ordinary shape of the pseudopods is digitate or finger-like, or
depressed cylindroid, with blunt rounded ends. They may be straight or
more or less curved, even or crimped, and simple or branched. Sometimes
they are more or less tapering and bluntly pointed, or they may be clavate,
or thicken in approaching the end.

The projection of the pseudopods is always preceded by a flow of the
more hyaline portion of the protoplasm of the body, or of the ectosarc,
followed closely and incessnntlv by an influx of the endosarc. The flow

38 FRESH-WATER RHIZOPODS OF NORTH AMERICA.

of the endosarc proceeds from the interior of the body, and is continuous
through the axis of the latter, back of the source of the pseudopod ; and if
this forms the fore part of the body, the current may be continuous its entire
length. If a growing pseudopod proceeds from an intermediate position,
currents of endosarc may flow from opposite directions to promote its
extension.

The flow in the current of endosarc is always most active axially, both
within the body and the pseudopods. As it approaches the end of a
pseudopod, formed by the advancing ectosarc, it usually enters to one side
and turns upon itself, as represented in fig. 11, pi. II.

New pseudopods start more or less abruptly, and give one the impres-
sion as if they proceeded from a sudden escape of a portion of the contents
of the body, through an accidental rupture of its surface. In their extension
they appear to flow onward like a liquid stream, as previously intimated,
always preceded by a portion of the clear ectosarc, followed by an inces-
sant influx of the endosarc. In the precedence of the ectosarc, it looks
as if it were a clear liquid, incessantly drained from the endosarc, and
flowing off in a stream; but apparently before the ectosarc has a chance of
accumulating to any considerable extent, it is constantly followed by
granular endosarc, as if this was forced into it from behind by contraction
of the body.

The progress of the animal may continue steadily for a time, induced
by the equally steady extension and advance of one or more pseudopods,
accompanied with a more or less brisk flow of the endosarc of the body,
continuing in one stream, or dividing into several, according to the number
of the advancing pseudopods.

While there is no absolute distinction between the ectosarc and endo-
sarc, the two being continuations of the same protoplasmic mass, in the
movements of the animal the endosarc appears to flow within walls, more
or less thick, formed by the ectosarc. With the exhaustion of the endosarc
from behind, the including ectosarc contracts, and melts away into the
advancing portion of the body.

Ama'ba proteus, while steadily pursuing its course, may slacken its
speed and altogether cease its onward movement ; and after a brief interval,
a new pseudopod may start forth, and with its extension in the same direc-
tion the course of the animal may be entirely changed from the former one.

GENUS AMCBBA— AMCEBA PROTEUS. 39

Not unfrequently dining the extension of one or more pseudopods
in advance, another may originate, and extend in a widely divergent or
even opposite direction from the former. In such instances, after a little
while, the previously advancing pseudopods become retarded in their course,
then recede, and go to contribute to supply the new pseudopod moving in
another direction.

Occasionally clearer and wider expansions than usual of the ectosarc
appear at the root of a pseudopod, or like a web in the crotch of a pair of
pseudopods, as seen in figs. 3, 5, V, pi. I. Similar expansions at times
extend as longitudinal folds along the body and principal pseudopods, as
represented in fig. 7.

Sometimes a pair of pseudopods start together from near the same
point, extend side by side, and, as they advance, become confluent from
their root onward Very rarely do contiguous pseudopods, approaching
one another and coming into contact at the ends, become connate, or
fused together, though I have observed this to occur in the capture of an
animalcule, as represented in fig. 5 c, pi. I.

The fundamental structure of Amoeba proteus consists of a thin, color-
less, jelly-like, pale, and finely granular protoplasm, or sarcode, endowed
with extensile, contractile, and other less well defined attributes, in which,
however, a chemical or digestive power may be included. The exterior
clearer portion of the protoplasmic mass constitutes the ectosarc, while the
interior portion, mingled with various elements, intrinsic and extrinsic, con-
stitutes the endosarc.

The clear ectosarc, examined by the higher powers of the microscope
under favorable conditions of light, appears never to be perfectly structure-
less, but exhibits an infinitely fine granular constitution.

The endosarc, with its mingled coarser elements in its relationship with
the ectosarc, may be compared with the circulating blood in the capillaries
of the higher animals. The endosarc is comparable to the rapidly flowing
current of blood, mingled with its corpuscles, in the axes of the vessels,
while the ectosarc is comparable to the slower moving blood-liquor next
the walls of the vessels.

The ordinarily distinguishable elements of the endosarc of Amoeba
proteus have appeared to me to be as follows :

1 . Granules, from those of the finest, most diffuse, and scarcely per-

40 FRESH-WATER RHIZOPODS OF NORTH AMERICA.

ceptible kind, such as are commonly to be detected in a favorable light and
with the highest microscopic powers, in the clear limiting ectosarc, to such
as are distinct, darkly defined, and resemble the finest molecules of oil.

2. Variable quantities of rather large, spherical, homogeneous, or indis-
tinctly granular corpuscles, usually colorless or faintly yellowish, apparently
liquid or semi liquid.

3. Different proportions of round, oval, or irregularly oval bodies of
various sizes, clear, colorless, and highly refractive, apparently of the nature
of starch-granules, and resembling them in their chemical reaction.

4. Variable quantities of round or oval globules darkly defined and
highly refractive, clear and colorless, or of different shades of yellow,
passing at times into brown, apparently oleaginous in character. These are
often altogether absent.

5 Widely different proportions of food-balls, mostly spherical and of
pretty uniform size, and very variable in composition and color, according
to the nature of the food and the changes it has undergone through diges-
tion. The colored balls are commonly pale yellow, passing to darker
yellow and different shades of brown, even sometimes approaching to black-
ness. Often some of the balls appear bright green or yellowish green,
and are frequently recognizable as being- composed of round single-celled
algae.

Generally the food-balls appear surrounded wilh a clear halo indicating
the presence of liquid enclosing the more solid matter, and consisting of
water swallowed with the food. Often the balls exhibit no vestige of such
a halo, in which cases we may infer that the water which may have been
swallowed with the food and had surrounded the ball, in an altered condi-
tion, has been imbibed by the including endosarc.

Besides the more solid food-balls, there are frequently to be observed
globules of colored or colorless liquid or semi-liquid matters, which may
consist of water-drops swallowed as such, and of dissolved food resulting
from digestion.

Sometimes large numbers of clear water-drops are not only seen within
the endosarc, but are actually observed to be developed as if from a con-
centration of the more liquid part of the protoplasm, and these are again
often seen slowly to disappear as if gradually absorbed by the contiguous
protoplasm.

GENUS AMCEBA— AMCEBA PROTEUS. 41

Independently of the food-balls, which ordinarily are formed from soft
and readily yielding materials, the endosarc is often observed to contain
other food of a more consistent character, greatly differing in the size
of the morsels and frequently more or less readily recognizable from their
form. Such materials cornmonty consist of the various diatoms, desmids,
green unicellular alga?, and zoospores of the filamentous alga3. Consid-
erable fragments of the latter, such as Oscillaria, Zygnema, etc., are also
often seen among the food contents. Occasionally animal forms may
be detected in the food materials of the endosarc, among the most com-
mon of which are the Rotifers, and in several instances I have observed
with them an unfortunate Arcella, a Difflugia, or a Trinema.

These more consistent and persistent food materials, like the food-balls,
are often observed included in water-drops swallowed with the food, but
they also frequently appear without any such liquid investment.

Other materials related with the food, and frequently forming part of
the endosarc-jumble, consist of fragments of various vegetal tissues, such
as portions of cellular tissue of macerated leaves, vessels, ligneous fibres,
and hairs. In some fine large vigorous specimens of Amoeba proteus col-
lected from a pond in the vicinity of a saw-mill, the endosarc contained
multitudes of particles of sawdust.

In addition to the food materials and other elements of the endosarc
of Amoeba proteus, it frequently contains variable proportions of quartz-
sand in irregular angular particles.

G. A remarkable and pretty constant element of the endosarc, appa-
rently of an intrinsic character, consists of minute crystals, as seen in fig.
1 1 , pi. II. They have been observed in this and other Rhizopods by many
investigators. Though very evident, I have generally failed to determine
their exact form or the system to which they belong.

7. An important element of the endosarc is the nucleus, seen in most
of the figures of pis. I and II. It usually occupies a position posterior
to the middle of the body, but may be shifted to almost any other position
in the movements of the animal. Mostly it appears as a rather conspicuous
compressed spheroidal, or thick discoid body, with the broad surfaces some-
what convex, flat, or slightly depressed, and the border rounded. It is often
surrounded by a clear halo, apparently consisting of a globular envelope of
clear protoplasm. Tn different Amoeba? of various sizes, and from dif-

42 FRESH-WATER EHIZOPODS OF NORTH AMERICA.

ferent localities, the nucleus presents considerable range in size. In a num-
ber of characteristic individuals it measured about -^th of an inch in width
and from one half to two thirds the thickness of the width. In others it
ranged from half the size indicated to one fifth greater diameter.

The nucleus is colorless, homogeneous, indistinctly and finely granu-
lar, or more coarsely, uniformly, and distinctly granular. I did not at any
time distinguish a distinct membranous wall to the nucleus ; and a distinct
nucleolus, if present, escaped my notice.

In several instances I have seen two nuclei in the same individual, as
repi'esented in fig. 2, pi. I. More frequently I have failed to detect a single
one, though it is probable that in most cases, if not in all, it was hidden from
view by other elements of the endosarc. Occasionally, however, even in large
specimens of unusual transparency and unobscured by the presence of food
and other materials, as in the individual represented in fig. 7, pi. II, I was
unable to discover a nucleus.

8. Almost invariably there may be seen in the vicinity of the nucleus,
and approximating it in size, the clear liquid globule, which constitutes the
contractile or pulsating vesicle. It usually occupies a position just back of
the nucleus, but not unfrequently, in the movements of the endosarc, is
shifted to a position in advance. The contractile vesicle is ordinarily
observed very gradually to enlarge, and then rather abruptly to collapse,
so as to disappear altogether from view. After a brief interval it again re-
appears in the same or nearly the same position. Starting as a minute
spherule, the vesicle gradually increases as before, until it reaches its former
size, when it once more abruptly collapses. The increase, collapse, dis-
appearance, and reappearance of the contractile vesicle occur successively
and incessantly in a rhythmical manner, reminding one of the regular action
of the heart in higher animals.

The gradual expansion of the contractile vesicle is slow and more or
less variable in the time it takes to reach the full size ; the collapse ordi-
narily occupies about a second of time.

The contractile vesicle appears to be due to the accumulation or concen-
tration of water from the surrounding endosarc, which water appears then to
be expelled from the bod}- in the collapse of the vesicle. It is perfectly
clear, and of a pale, though decided roseate hue, which becomes more pro-
nounced with the expansion of the vesicle. The same hue is to be observed

GENUS AMCEBA— AMOEBA PROTEUS. 43

in the contractile vesicle, and all clear water-vacuoles of the endosarc, in
other Rhizopods and Protozoa in which these constituents occur.

Sometimes two contractile vesicles are seen in Amceba proteus, as rep-
resented in fig 6, pi. II. They occupy the usual position back of the
nucleus, or may be temporarily separated by one shifting in advance of the
latter, or indeed both ma)^ be transferred to any other position. Rarely a
greater number of contractile vesicles occur, usually in such cases smaller
and often more or less scattered.

Sometimes after the disappearance of the contractile vesicle, two or
three minute ones appear simultaneously in its place, and, as they gradually
augment in size, break into one another until all become one.

In the progressive movements of Amceba proteus, and the extension of
its pseudopods, the flow of the endosarc is accompanied with a more or
less thorough mingling of all its constituents. The smallest elements are
hurried along most briskly, while the largest exhibit more or less inertia ;
the nucleus and contractile vesicle almost always being hindmost in the race.
Occasionally, a more than ordinary impulse drives the nucleus in advance
of its habitual position, and even carries the contractile vesicle beyond it,
but in a little while they again assume their usual place.

A remarkable fact in the streaming of the endosarc, with all its varied
constituents rolling among and jostling one another, is the circumstance
that the food-balls with their liquid envelope, the water-vacuoles, the con-
tractile vesicle, and all else, retain their integrity, as if they were solid, or
contained each within a membranous sac. Never are the materials observed
to break and run together, as a result of the continued jar to which they
are subjected.

As previously intimated, Dr. Wallich expresses the opinion that the
endosarc and ectosarc of the Rhizopods are mutually convei - tible into one
another. When endosarc comes into contact with water, it undergoes a sort
of temporary coagulation, or conversion into ectosarc, and when the latter is
transferred into the interior after a time it again undergoes resolution into
the more liquid endosarc. In the taking of food he supposes that each por-
tion when swallowed becomes enveloped with a film of ectosarc, which forms
a vesicle enclosing the food and water-drop in the interior of the endosarc.
As the food undergoes digestion, and the water, altered in condition, is im-

44 FRESH- WATER RHIZOPODS OF NORTH AMERICA.

bibed from the vacuoles into the contiguous enclosarc, the vesicles of ecto-
sarc which contained the food and water undergo resolution into endosarc.

As the soft structure of Amoeba proteus is totally unprotected, even by
the thinnest membrane, one would expect to find the animal exceedingly
irritable, though such appears not to be the case in a marked degree. In
its wanderings it frequently comes into contact with more actively moving
Infusorians and mailed Rotifers without in the least being affected by their
rude shocks. On one occasion I happened to have beneath the micro-
scope a large individual of Amoeba proteus, together with a multitude of
the active ciliated Infusorian, the Coleps hirtus. The Amoeba moved about,
entirely indifferent to the frequent buffets of the Coleps. In attempting
to readjust the cover of the object-glass, a portion of the Amoeba was
crushed off; but notwithstanding the accident, the larger portion of the
creature, still retaining its nucleus and contractile vesicle, moved away,
apparently unmindful of its injury. The smaller portion of the Amoeba
was attacked by half a dozen Coleps, and the escaping granules of the
endosarc, exhibiting lively molecular movement, were greedily swallowed
by the Infusorian. One would further suppose from the structure and
semi-fluid character of the Amoeba that it must be sticky and that materials
would adhere as they came into contact with it. This is, however, so far
from being the case, that Amoeba proteus is frequently observed traversing
mud with algae and other materials, without anything adhering to its
surface even for a moment. Not unfrequently, however, various matters
are observed attached to the posterior extremity of the body, and dragged
after the animal in its movements.

Amoeba proteus, like most others of the genus and its allies, is essentially
herbivorous, though its choice of vegetal food is perhaps largely due to
the fact that it is more readily attainable than animal food. Judging from
the materials usually observed among the constituents of the endosarc, the
favorite food consists chiefly of the one-celled alga;, diatoms, desmids,
zoospores, and portions of filamentous algae, besides fragments of the
tissues of higher plants. The Amoeba evidently possesses a power of
discrimination and selection in its food, for although it appropriates with
the latter many particles of dead vegetal tissues, and even abundance of
sand-grains, it commonly rejects dead diatom shells and the empty cells of
other algae.

GENUS AMCEBA— AMCEBA PEOTEUS. 45

I have rarely bad the opportunity of directly observing Amxba proteus
swallow food, mainly from the circumstance that I did not sufficiently often
watch the animal a proper length of time for the purpose.

Mr. Duncan, in a recent publication,* intimates that the usual position
in which the Amoeba? take their food is at the posterior extremity of the
body, which I am inclined to think, from some later observations I have
made on the allied genus Dinamoeba, is correct.

On the other hand, I have repeatedly observed Amoeba proteus dis-
charge the remains of its food; the usual position being at the posterior
extremity of the body, in the vicinity of the nucleus, as represented in figs.
3, 4, pi. I. The excrementitious matters commonly consist of brownish or
colorless balls and granules, empty cells of algae, or others with the brown-
ish, shriveled remains of their contents, diatom shells, etc. The discharge
is rather sudden, and is often accompanied with the escape of some viscid
liquid. The temporary orifice abi-uptly closes, leaving no trace of its pre-
vious existence.

From the concurrent testimony of observers, it would appear that the
Amoeba? may take food at any point of the surface of the body; and the
discharge of matters may likewise occur in any position.

I have had but few opportunities of seeing Amoeba proteus capture
living animals. In one instance I saw an individual, as represented in fig.
5, pi. I, containing, within a large vacuole, an active Infusorian, a Urocen-
trum, and having a second victim of the same kind included in the fork of
a pair of pseudopods, the ends of which were brought into contact, so as
to imprison the animalcule within a circle. The latter moved restlessly
about within its prison, but after a time became motionless, and shortly
after the ends of the pseudopods which enclosed it fused together, as seen
at c in the figure just indicated. Films of ectosarc extended from the body
of the Amoeba towards the fused ends of the pseudopods, and finally the
Urocentrum was enclosed in a vacuole like that in the interior of the body
of the Amoeba. Having carefully watched the latter for some time, the
two vacuoles containing the captured Urocentrums were seen gi'adually
to diminish in size, the contents were reduced to the usual size of ordinary
food- balls of the endosarc, and all trace of the previous character of the
victims was completely lost.

* Popular Science Review, 1677, 217.

46 FRESH-WATER RHIZOPODS OF KORTH AMERICA.

The food of Amoeba villosa and other Rhizopods appears always to he
swallowed together with some water, which subsequently is commonly
observed as a clear area surrounding the food within the endosarc. Soft
food, vegetal and animal, assumes the form of spherical balls; but more
consistent food, such as diatoms, retains the original form according to its
degree of resistance. The distinctive character of soft articles of food
rapidly disappears after being swallowed. The different food materials
undergo chemical changes as a result of digestion in the endosarc, and
colors become changed in a striking manner. The bright-green chlorophyl
of algse becomes brown or yellow and shriveled within the colorless cells,
and the endochrome of diatoms becomes browner in hue and shriveled into
two narrow strings within each shell.

Some ooze gathered in the month of September from a mill-pond, in
which grows a profusion of the magnificent Nelumbo, Nehimblum lutewn,
near Woodstown, New Jersey, contained many large specimens of Amoeba
protcus, like the one represented in tig. 7, pi. I This individual occupied
a space of about one fourth of a line in length by one sixth of a line wide
in front, where three large fmger-like pseudopods diverged. The nucleus,
if present, escaped my notice. The contractile vesicle usually occupied
a position at the posterior extremity. The endosarc contained numerous
large, round or oval, yellowish, granular balls, sujjposed to consist of food,
but not visibly included in water-drops. Many of these were darkly out-
lined, and appeared to have an oil-like consistence. With them were also
mingled many clear colorless globules, granules, and crystals. When the
specimen was first noticed, it contained, just in advance of the position of
the contractile vesicle, a Brachionus, which finally assumed the appear-
ance of an ordinary food-ball, resembling the abundance of yellowish balls
with which it was associated.

In movement, the main trunk and larger pseudopods of the same
Amceba assumed more or less the appearance of being longitudinally folded.
The endosarc axially flowed as if in the interior of thick walled canals, of
which the walls appeared to be composed of finer granular matter with
scattered imbedded crystals. In the flow, all the contents did not move
with the same rapidity, and usually the smaller particles were swept quickly
by the larger ones. Other matters, including some of the largest elements,
appeared to stick to the inner surface of the extemporaneous tubes, but

GENUS AMCEBA— AMCEBA PEOTEUS. 47

successively became detached to be carried along with the rest of the con-
tents. As the posterior part of the body became exhausted of its axial
contents, it contracted, shriveled, and kept up continuously the mulberry-
like aspect of this region, as seen in the figure.

Mostly in the contraction of the posterior part of the body of Amoeba,
or of its pseudopods, as they exhaust themselves through the flux of their
endosarc, the ectosarc closes up more or less evenly with the latter. In the
Amoeba under consideration, in similar contraction of parts, the ectosarc
appeared to be slower in its closing-up, so that they became more or less
shriveled processes in their shrinkage.

Another large individual, in general form like the letter Y, measured
0.64 mm. long-, with cne of the divergent arms 0.4 mm. long by 0.04
mm. thick. The two' arms continued to diverge until they divided the
main stalk of the body, and became extended together, in nearly the
same line, so as to measure two millimetres in length. I supposed the two
limbs were about to divide, but subsequently one reversed the direction
of its motion and flowed into the other, and the animal then assumed a
palmate appearance.

Another specimen, when first observed, covered a space in both direc-
tions measuring about 0.6 mm. It appeared to be in the act of division,
consisting of two portions connected by an isthmus; but subsequently one
portion flowed into the other, while this extended three divergent pseudo-
pods. The contracted pseudopods of the former portion shriveled into
beaded cords, and then inelted-away in the progressing body-mass.

This specimen, retained under observation during two days, with
the idea that it was about to divide, finally appeared as a quiescent oval
ball 0.46 by O.o8 mm., closely covered with small round pseudopods of
clear ectosarc, looking like dew-drops, measuring 0.012 to 0.016 mm., and
occasionally containing a few granules or a minute crystal.

The largest individual observed among the Amoebae, from Woodstown
pond, extended into two arms from a posterior mulberry-like mass, which
measured 0.2 by 0.16 mm., with one arm 0.8 mm. long by 0.08 mm. thick,
and the other arm 0.6 mm. long by 0.06 mm. thick. The contractile vesicle
occupying the interior of the mulberry-like end of the body was 0.06 mm.
diameter. The crystals of the endosarc, apparently octahedral in form,
appeared to reach 0.075 mm by 0.0375 mm.

48 FRESH-WATER RHIZOPODS OF NORTH AMERICA.

Certain specimens met with from time to time, and regarded as pertain-
ing to Amoeba proteus, but presenting either more or less peculiarity, or
some point of special interest connected with the history of the animal,
may here be described.

A specimen obtained in the spring of the year from the ooze of a ditch
when first seen had the appearance represented in fig. 25, pi. IV. It was
globular, about 0.2 mm. in diameter, and projected a number of digitate pseu-
dopods in different directions. Besides the usual contents, in the vicinity of
the large contractile vescicle, there were observed half a dozen granular
balls from 0.016 to 0.024 mm. in diameter. The granules within the balls
exhibited an active swarming motion, reminding one of the rapid movements
of spermatozoids in higher animals. The nature of these granular balls I
failed to determine, but suspected they might really constitute male elements
of the Amoeba. The individual after a little while moved off in the manner
usual with Amoeba proteits, assuming a dendritic form. The nucleus was
distinctly, coarsely, and uniformly granular. The contractile vesicle ex-
panded to the extent of ^th of a millimetre in diameter, and would col-
lapse in two seconds of time. Sometimes it would reappear as two, which,
after expanding to a certain extent, would unite into a single one. After
keeping the specimen the greater part of a day, it was finally lost without
my having learned anything further in regard to the granular balls con-
tiguous to the contractile vesicle.

I have repeatedly met with Amoebae, which I have supposed to pertain
to the species under consideration, though they presented sufficient pecu-
liarity to make the reference uncertain.

A not unfrequent form is such as are represented in figs. 22, 23, and
24, pi. IV. Comparatively active, in creeping on flat surfaces, the animal
commonly presents a prolonged, somewhat triangular outline ; straight or
curved, with the broader extremity in advance, and spreading into a variable
number of conical-pointed pseudopods. These undergo frequent, but slow
change, and in their extension do not receive so much of the coarser con-
stituents of the endosarc as usual in more characteristic forms of Amccba
proteus. The posterior end of the body is narrow and blunt, simple or
papillose, and sometimes is produced into a brush or fringe of rather long
villous processes. The animal is greedy in habit, and usually contains
much food, consisting of algae, mingled with other constituents of the

GENUS AMCEBA— AMCEBA PROTEUS. 49

enclosure. The nucleus and contractile vesicle exhibit the usual charac-
ters and relative position, as in more common forms of Amoeba proteus.

An individual of the kind just described I had the opportunity of seeing
swallow and digest one of another species, the Amoeba verrucosa. The steps
of the process I have attempted to represent in figs. 13-19, pi. VII, and
they occurred as follows :

In a drop of water squeezed from mud adhering to the roots of the
plant Ludwigia, collected in a half-dried marsh, in the month of August, I
noticed an active Amoeba, as seen in fig. 13. It was of elongated triangu-
lar, snail-like form, with the anterior broader extremity extended into a
number of conical antenna-like pseudopods. The posterior end was some-
what coarsely papillose, and from the left side projected two conical pseudo-
pods like those in front. Observing an Amoeba verrucosa, fig. 12, in its usual
sluggish condition, lying almost motionless, directly in the path of the
former, I was led to watch whether the two would come into contact and
what would be the resnlt.

The A. proteus contained a number of large food- and water- vacuoles,
together with a single diatom. The contractile vesicle occupied the usual
position and exhibited the usual changes. The A. verrucosa, besides the
granular protoplasm, appeared to contain nothing but a conspicuous con-
tractile vesicle, and this remained unchanged.

The snail-like Amoeba reached the A. verrucosa, and turning with tail
end towards the right, the body shortened, and a pair of digitate pseudopods
extended from the head and embraced the latter in the manner represented
in fig. 14. The conjoined ends of the pseudopods fused together, and the
animal reversed its direction of movement, while the A. verrucosa gradually
sank deeply within its body, and assumed the appearance of a large
sphere, still retaining its contractile vesicle unchanged, as represented in fig.
15. The snail-like A. proteus assuming nearly the original shape, as first
not iced, then moved about after a while and presented the appearance
seen in fig. 16. The tail end of the body was elongated and papillose, and
the swallowed Amoeba, reduced in size, had lost its contractile vesicle
and become oval in shape. Later, the A. proteus appeared more slug-
like, while its victim had become pyriform and striate, and was then
included within a large water-vacuole, as represented in fig - . 17. Subse-
quently, the A. proteus was observed to discharge the diatom, previously

4 KHIZ

50 FRESH-WATER RHIZOPODS OF NORTH AMERICA.

noticed in the enclosure, from the side of the posterior narrow end ; and
the A. verrucosa, within its now globular water-vacuole, had become bent
upon itself, as' seen in fig. 18. Still later, the body of the A. verrucosa
appeared to have become broken up into five spherical, granular balls, as
seen in fig. 19, which rolled about among the other constituents of the
endosarc of the A. proteus. These observations were conducted through
about seven hours. What finally became of the five balls resulting
from the destruction of the A. verrucosa I did not ascertain, but sup-
posed that they were digested, to contribute to the nutrition of the Amoeba
proteus.

In my studies of Amoeba proteus I have not been so fortunate as to
trace its history from an early period, nor to discover its modes of repro-
duction. In association with the more characteristic forms, I have seen
many which I have suspected to be the young ; but it is quite as probable
that they may have pertained to other described species.

Comparatively small Amcebas are frequently to be met with, which,
though exhibiting considerable variety, are yet commonly and habitually
clavate, or more or less slug-like in shape. Similar Amoebae have been
described under the names of Amoeba Gleichenii, A. Umax, A. guttula, etc.

Some of these I have suspected to be the young of Amoeba proteus,
though with equal probability they may be considered to belong to some
other species. They are usually quite active, and glide along with the
thicker extremity in advance, with comparatively little change of form.
The posterior extremity is more or less tapering, and terminates bluntly,
and mostly without any process, though the end is apparently in some
degree prehensile, as it is occasionally observed with adherent materials
dragged after the animal in its movements.

Do

Progression commonly is due to an incessant, more or less even, or
interrupted, flow or roll of the ectosarc of the head end forward, followed
closely by an influx of the endosarc and a concurrent contraction of the
body behind. The precession of the ectosarc at the head end appears as
a clear watch-crvstal-like extension of variable thickness, into which the
endosarc flows from one side and spreads towards the other. Frequently
the onward movement of the animal is promoted by the projection of
hemispherical pseudopodal lobes, alternately and in succession, at the sides
of the head end, which are produced in the same manner as the latter itself.

GENUS AMCEBA— AMCEBA PKOTEUS. 51

The endosarc of the small Amoebae presents a basis of pale, indistinct,
granular matter, merging into the almost vanishing granular constitution
of the hyaline ectosarc. Scattered through it are coarser granules with
variable proportions of fine oil-like molecules and darkly defined particles,
which in many instances appear to be crystalline in form. A conspicuous
contractile vesicle commonly occupies a position posterior to the middle of
the body, and not unfrequently two or more of such vesicles occur. With
the more characteristic contractile vesicle, variable numbers of water-vacu-
oles frequently occur, undistinguishable from the former in appearance,
but with less regular or no evident rhythmical movements. A round
nucleus, of homogeneous granular structure, and surrounded by a clear
halo, is a common constituent.

In the smallest or youngest Amcebse, food in balls or other conspicu-
ous form is commonly absent, though occasionally an individual may be
seen containing: a single small diatom.

Examples of Amoeba}, viewed as probably pertaining to the young of
Amoeba proteus, are subjects of the following notices.

Some water scooped from a cow-track in a marshy place, in the
month of March, contained an abundance of Amoebae, together with dia-
toms. The smallest Amoeba?, as represented in figs. 21-23, pi. VIII,
were ovoid, and ranged from 0.03G to 0.048 mm. in length. They moved
actively by repeated hemispherical bulgings, first on one and then the other
side of the broader end, though at times the bulgings occurred elsewhere.

In structure, they consisted of delicate granular endosarc invested
with clear ectosarc. The endosarc contained coarser granules, among
which some appeared to be of crystalline form. There were also present a
nucleus surrounded with a faint halo, and a contractile vesicle. Often
there were two of the latter, and sometimes a greater number. None of
the specimens contained distinct food-balls.

The larger Anicebee ranged in size from the former up to 0.125 mm.
in length. These were active and slug-like in shape, as seen in fig. 29.
They moved with the thicker end forward through the agency of hemi-
spherical pseudopodal lobes, bulging alternately at the sides of the head end.
They proceeded straight forward or often curved to one side or the other.
The endosarc contained many scattered, darkly outlined granules, which
appeared indistinctly to be crystalline. It also contained many clear

52 FRESH-WATER RHIZOPODS OF NORTH AMERICA.

globules which appeared to be water-vacuoles. These larger Amoebae gen-
erally contained a considerable quantity of food, mainly consisting of
diatoms of the kind which abundantly occurred in the water with the
animals. In several instances I observed individuals in the act of dis
charging dead shells of diatoms, as represented in the figure just indicated.
The expulsion occurred at the posterior end of the body; nothing escaped
except the remains of the food, and subsequently all trace of the tempo-
rary vent disappeared.

None of these Amcebse exhibited anything like a posterior villous
process, though the end of the body appeared in some degree prehensile,
as several individuals were observed with adherent diatoms trailing after
them.

Some water with growing Nitella gathered in the autumn was pre-
served during the winter In January, the surface of the sediment contained
multitudes of minute Amcebse, such as are represented in figs. 17-20, pi.
VIII. In their movements they exhibited considerable variety of form, but
were commonly more or less ovoid or clavate, and moved with the broader
extremity forward. They were composed of pale delicate endosarc, pre-
ceded by thick watch-crystal-like extensions of clear ectosarc. The endo-
sarc contained a round or oval nucleus, two or three contractile vesicles,
and a few scattered, darkly outlined granules, but no conspicuous food.
They ranged from 0.03 to 0.04 mm. in length. The posterior extremity
was prehensile, but exhibited no clear trace of a villous process.

Some ditch-water, with ooze and portions of the root of the Arrow
Arum {Peltandra virginica), collected in autumn and examined the follow-
ing April, contained many small Amoebae in association with large and
characteristic ones of Amoeba proieus. The small Amoeba? were habitually
ovate, more or less pyriform or clavate in shape, figs. 24-2 6, and ranged from
the ^th to the jlth of a millimetre in length. They moved actively onward
in a sort of rolling manner, with the broader extremity forward ; and the
posterior tapering end was devoid of any appearance of a villous process.
The endosarc contained many fine, irregular granules, which appeared to be
starch-particles ; and among them were others which appeared indistinctly
to be crystalline. A small nucleus and a contractile vesicle were constantly
present Among the little Amoeba? a number were observed, apparently of
the same kind, but containing a large spherical, granular nucleus, reaching

GENUS AMCEBA— AMCEBA VEEEUCOSA. 53

a^th of a millimetre in diameter. The granules of the nucleus were coarse
and uniform. In some specimens, the nucleus was simple, but in others
presented a tripartite division, as represented in figs 27, 28. I failed to
trace the further history of these Auicebas.

Rarely have I had the opportunity of seeing Amoeba proteus,- or any
other species, multiplying by division. On one occasion, in the month of
February, while examining some material collected the previous autumn, I
observed a pair of small Amcebae connected by a narrow isthmus in the
manner represented in fig. 30. Each individual was of oval form, and
measured about ^th of a millimetre long by ^th of a millimetre wide. Each
contained a contractile vesicle and two large globules looking like oil, but
apparently no nucleus. The endosarc presented the usual character of
that of Amoeba proteus, and contained, besides minute crystals, a number of
alga?, some of which were green, and others, changed by digestion, were
brown. After about ten minutes from the time the Amoebae were first seen
they separated by rupture of the isthmus. Subsequently, one individual
became constricted transversely across its middle, and in the mean time,
while watching it, the other individual moved away and was lost to
view. The individual under observation became gradually more con-
stricted, and finally divided, as in the former case, into two. One division,
larsrer than the other, retained the contractile vesicle and both oil-like
globules. The smaller division, of rounded form, measured ^th of a milli-
metre ; but after a short interval a contractile vesicle appeared within it,
and the little creature assumed a clavate shape and moved out of the field
of vision. The larger division likewise assumed a clavate shape, and as it
moved away it measured ^th of a millimetre long.

AMCEBA VERRUCOSA.

Plate III.

Amccha verrucosa. Ehrenberg: Infusionsthierchen, 1838, 126, Taf. viii, Fig. xi.— Dujardin : Infueoires,
1841,236. — Perty: Kennt. kleinst. Lebensfornien, 1852, 188. — Carter: An. Mag. Nat. Hist.
1857, xx, 37, pi. i, figs. 12, 13.-Leidy : Pr. Ac. Nat. Sc. 1876, 198; 1878, 158.

Amoeba nutans. Perty: Kennt. kleinst. Lebensformen, 1852, 188, Taf. viii, Fig. 14.

Amaba quadrilineata. Carter: An. Mag. Nat.. Hist. 1856, xviii, 243, pi. v, fig. 3; 248, pi. vii, fig. 81.—
Barker: Quart. Jour. Mic. Sc. ix, 1869, 94.— Leidy: Pr. Ac. Nat. Sc. 1874, 107.

Tliecamocba quadripartita. Frouicntel: fitudes Microzoaires, 346, pi. xxviii, fig. 3.

Animal in the maturer stages, as ordinarily observed, more or less
sluggish, and often nearly motionless, commonly appearing of an irregularly
oval, round, or quadrately rounded form, with wart-like expansions and a

54 FRESH- WATER EHIZOPODS OF XORTH AMERICA.

more or less wrinkled condition of the surface; pseudopods short, broad,
blunt lobate extensions of the ectosarc; outlines of the body, wrinkles of
the surface, and pseudopodal extensions more or less sharply defined, and
.often appearing' with double lines. Endosarc pale granular, and mostly,
excepting food materials, with few or no coarse granules. Ectosarc
copious, very hyaline, and broadly extended. Contractile vesicle large and
conspicuous. Nucleus mostly distinct. Size ordinarily ranging from 0.08
by 0.072 mm. to 0.18 by 0. 1 6 mm., or from about ^th to ?tli of a millimetre.

Animal in the younger stages active and incessantly in motion; body
oval or pyriform, usually moving with the broader pole in advance; surface
comparatively smooth, but marked with four longitudinal lines or delicate
folds, sometimes with a greater or less number or none. Fore part of the
body appearing as a broad, clear pseudopodal expansion thinning away
laterally and posteriorly. Contractile vesicle posterior; nucleus in advance
of the latter. Size ranging from 0.04 by 0.02 mm to 0.12 by 0.09 mm.

Locality. — Very common, and found almost everywhere with moisture
and algae. Pennsylvania, New Jersey, Rhode Island, Connecticut, Maine,
Nova Scotia, Colorado, Wyoming, and Utah.

Ehrenberg described, in the 'Infusionsthierchen,' a species of Amoeba
with the above name as follows: "In the extended condition small, not
exceeding 1th of a line, hyaline, sluggish, with variable processes which
are very small, obtuse, and wart-like." He remarks that he never saw the
processes reach even half the extent of the body. The animal remained a
long time motionless, but appeared voracious, as it invariably contained
Oscillariae or Navicular mostly half digested. It also contained a nuclear
body and a contractile vesicle. The short, wart-like processes were always
blunt.

Dujardin refers a small Amoeba to the same species, and describes it
as globular or ovoid, with short, cylindrical, obtuse, divergent expansions
frequently appearing like warts, with very slow motion, and measuring
from 0.014 to 055 mm

Perty indicates Amoeba verrucosa, and describes a small Amoeba with
the name of Amoeba natans, which is probably the same, for he says this
is like the former, but smaller, being only the |th of a line.

An Amoeba agreeing with the description oi Amoeba verrucosa of Ehren-
berg I have frequently obtained from various localities. I have found

GEKUS AMCEBA— AMCEBA VERRUCOSA. 55

it in the ooze of ponds, ditches, and river shores, in the mud of marshes, in
wet sphagnum, among the conferva? of fountains and dripping rocks, and
in company with Rotifers, about the roots of mosses, in the yaid attached
to my house.

Amreba vea*r«Jcosa is exceedingly sluggish, and often, during the
time of its observation, remains stationary, or nearly so. In this condition
it usually appears as an irregular quadrately round or oval and more
or less wrinkled mass, with short lobate pseudopods or wave-like expan-
sions of the surface. The pseudopods are slowly projected, apparently in
a hesitating manner, and the wave-like expansions slowly but incessantly
change. In motion, the Amceba glides along with extreme slowness,
advancing by wave-like expansions, while short lobate pseudopods project
in any direction, apparently without object. The whole surface of the
Amceba often appears delicately wrinkled. See figs. 5-7, 28-36, pi. III.

A striking peculiarity of Amceba verrucosa is that the outlines of the
body, the pseudopodal expansions, and the wrinkles of the surface often
appear defined with partial or interrupted double lines, as if the animal were
invested with a delicate membrane. See figs. 1, 2, 7, 28, 29.

Amceba verrucosa is highly transparent and colorless, and it commonly
exhibits an unusual degree of extension or differentiation of the ectosarc
from the endosarc The former appears homogeneous, but under high
powers of the microscope is seen to be extremely finely granular.

The endosarc presents a diffused pale granular appearance gradually
merging into the ectosarc. It often contains but a scanty supply of food
materials, and sometimes these appear to be absent, or at least they are not
recognizable, as exemplified in figs. 5, 9-11, 35. Commonly, more or less
food is visible as pale granular, colorless or yellowish balls scattered
through the endosarc, as seen in figs. 6, 7, 28-34. Not unfrequently algae
are present, such as protococci, osc-illarias, diatoms, and desmids, as seen
in figs. 1-3, 12-14, 30-32. In several instances I observed specimens of
the Amceba containing a Trinema, or a Difflugia, or both, as seen in fig. 38.

Generally, a nucleus is included in the endosarc, but frequently I have
been unable to detect one.

A contractile vesicle is nearly always present and sometimes two or
three. In several instances I was able to satisfy myself that the Amceba

56 FRESHWATER RHIZOPODS OF NORTH AMERICA.

under observation was alive only by seeing the usual changes of the con-
tractile vesicle. Otherwise the animal appeared motionless, although close
watching would lead to the detection of an exceedingly slow change in the
wrinkling of the surface

From the inactive character of Amoeba verrucosa, and the frequent
comparative deficiency of food in the endosarc, I have suspected that the
animal might express an exhausted state of Amoeba proteus.

One of the most common and well marked amoeboid forms, represented
in figs. 12-18, pi. Ill, was originally described by Mr. Carter under the
name of Amoeba quadrilineata. Of all the varieties or species of the genus
it is that which at any time I have been able to find with most certainty.
I have frequently observed it in association with other named forms, espe-
cially Amoeba radiosa and A. verrucosa. I have also repeatedly noticed
intermediate forms, which have led me to view A. quadrilineata as the
young of A. verrucosa. It was not until after this determination, in
examining the literature of the subject, that I learned Mr. Carter had
arrived at the same conclusion from a different point of view. In an article
"On the Freshwater Infusoria of Bombay" (An. Mag. Nat. Hist. 1857, xx,
page 37), he remarks: "I have also met with another species of Amoeba
undergoing ovular development, viz. A. verrucosa, Ehr., precisely like that
which I have already described ; the Amoeba perishing as the ovules are
developed and ending in becoming a mere ovisac." He adds: "This Amoeba
appears to me — for I have watched the development of a group for many
months together — to be the adult of my A. quadrilineata, and therefore the
latter is not a new species. The formation and development of the ovules
took place in April, and the organism appears to require at least nine
months to come to maturity."

The young of Amoeba verrucosa, figs. 12-27, as ordinarily seen, appears
as a small hyaline pyriform body, usually actively moving, with the broader
extremity in advance The clear ectosarc forms a thick or broad expanse
in front, gradually thinning away posteriorly to a narrow border. It is
remarkable for retaining persistently fixed, in nearly the same relative
position, four equidistant narrow longitudinal folds or doubly contoured
lines. These extend from the back end of the animal, but do not reach its
front, ceasing shortly in advance of the visible mass of endosarc. The
latter is pale granular, and it extends from the posterior extremity ordinarily
about three-fourths to four-fifths the extent of the animal.

GENUS AMCEBA— AMCEBA VERRUCOSA. 57

The creature does not put forth distinct pseudopods; but in progression
the ectosarc rolls forward, appearing at the moment as if it were being
drained off from the endosarc, while this as incessantly streams on and
maintains the same relative position.

The contractile vesicle habitually occupies a position at the posterior
extremity of the endosarc, but is sometimes propelled forward, even to the
middle of the latter. It exhibits its peculiar movements more frequently
and expands to a proportionately greater degree than in the adult. In
collapsing it usually closes from within outwardly so as to assume at first
a reniform and then a crescentoid appearance; but in other instances it
closes so as to appear like a decreasing lens. It is very mobile, and, in the
irregular contractions of the posterior part of the animal, often assumes
an irregular outline of form. It frequently reappears in a group of from
two to half a dozen vesicles of different sizes, and these, as they expand,
become irregularly confluent until finally they form together a single large
sphere. See figs. 9, 15, 16.

The nucleus appears as a spherical or oval, faintly granular body,
often surrounded by a hyaline envelope. Occasionally two such bodies
are present. Besides the nucleus and the contractile vesicle, the endosarc
frequently exhibits nothing, except some minute oil-like molecules.

The food constituents of the endosarc commonly consist of a few
Navicular or Protococci; but often a greater number of the same are
present, and sometimes considerable portions of Oscillaria. In addition,
brownish and colorless food-balls and a few oil-like drops may be present.

Of the young of Amceba verrucosa I have observed individuals range
from the 5 ^th of a line in length by the j^th of a line in breath, up to the
size of mature forms.

The four longitudinal lines, originally supposed to be a distinctive
character of Amoeba quadriliiieata, though the usual number, are by no
means constant, for I have observed them to vary in different individuals
from a single one to half a dozen. As the animal grows they appear to
become less evident, and ultimately become obsolete or undistinguishable
from the many temporary wrinkles of the surface. See figs. 1-4, 8, 9,
12-27, 30-32, 37.

Individuals of the Amcsba terricola of Dr. Greeff* bear a near resem-

*Arch. mik. Anat. 1866, ii, 299, Taf. xviii, Fig. 1-11.

58 FRESH- WATER RHIZOPODS OF NORTH AMERICA.

blance to Amoeba verrucosa ; but others, in their larger size, ranging from
0.35 to 0.4 mm., and in the possession of a terminal villous process, remind
one more of Amoeba villosa. With the exception of the latter forms, A.
terricola and A. verrucosa agree closely in characters: the exceedingly-
sluggish habit, the indisposition to move, the great porportionate extent
and membrane-like appearance of the ectosarc, the wrinkled condition of
the surface, and the short pseudopodal extensions, are the same in both.

The Protamoeba simplex of Prof. Haeckel* likewise bears a close resem-
blance to Amoeba verrucosa ; but, according to the character assigned to the
former, a contractile vesicle and nucleus are absent, while they are present
and more or less conspicuous in the latter.

AMCEBA RADIOSA.

Plate IV, 'figs. 1-18.

Amoeba radiosa. Ehrenberg : Abh. Ak. Wis. Berlin, 1830, 39 ; 1831, 80 ; Infusionsthierchen, 1838, 128, Taf.
viii,Fig.xiii.— Dujardin: Infusoires, 1841, 23G, pi. iv, figs. 2, 3.— Perty: Kennt. kleinst. Le-
bensformen, 1852, 188.— Carter : An. Mag. Nat. Hist. 1850, 243, pi. v, figs. 10-18.

Amoeba brachiata. Dujardin : Infusoires, 1841, 238, pi. iv, fig. 4.— Fromentel : Etudes Microzoaires, 347,
pi. xxix, fig. 4.

Amoeba ramosa. Dujardin: Infusoires, 1841,239, pi. iv, fig. 5.

Comparatively small, colorless, transparent, inactive. As usually ob-
served floating, habitually stellate, with a spheroidal or oval central mass
or body, and from two or three to a dozen or more pseudopods of variable
length and form, mostly conical and acute or attenuated and thread-like,
commonly simple, straight, curved or flexuose, rarely furcate. In creep-
ing, of a less radiate character, but with the pseudopods mainly divergent
from one extremity, and that in the direction of motion of the animal.
Usually one conspicuous contractile vesicle or several smaller ones. Nu-
cleus usually distinct. Endosarc with a few oil-like molecules, sometimes
more or less replete with water-vacuoles. Food commonly scanty.

Size.— Body 0.012 mm. to 0.045 mm. diameter or rarely to 0.06 mm.;
pseudopods to 0.08 mm. long.

Locality. — In the ooze and among aquatic plants of most ponds, ditches,
and springs. Pennsylvania, New Jersey, Rhode Island, Connecticut,
Maine, Nova Scotia, and Fort Bridger and Uinta Mountains, Wyoming.

Ehrenbenr described a small form of Amoeba under the above name,

' S udien ueber Moneren u. a. Protisten, 1870, 172, Taf. vi, Fig. 12.

GENUS AMCEBA— AMCEBA RADIOSA. 59

which, he says, approximates 1 th mm., and has many variable processes in
the form of long, narrow, acute rays. Dujardin has described apparently
the same creature as pertaining to three species with the names of A. radi-
osa, A. brachiata, and A. ramosa.

A small Amoeba, of habitually radiate appearance, as usually seen, is
common in many situations. The radiate form, however, in a great meas-
ure, appears to be incidental to the animal being free and floating, for when
it is creeping upon surfaces it loses much of this specific character.

Amreba radiosa is a comparatively small inactive species, and
ordinarily is observed suspended in water almost motionless and with its
ray-like pseudopods apparently fixed as if they were rigid. It possesses
comparatively little irritability, and at times, when it comes into the vicinity
of a Stentor, a Vorticella, or a Rotifer, it may be seen whirling about in the
currents produced by these animals, with its form unchanged and its pseu-
dopods extended, as if it had no inherent power of motion. On closely
watching the Amoeba, as it remains quietly suspended in water, it is ob-
served very slowly to undergo more or less change of shape, and the
pseudopods are noticed gradually to contract or elongate, to bend from
side to side in a gentle oscillating manner, or to become twisted or bent in
an angular direction Sometimes more quickly than usual, a pseudopod
will be withdrawn in a tortuous course. While one or two pseudopods
are almost imperceptibly shortened or lengthened or entirely withdrawn,
new ones will as slowly appear and elongate.

In floating or swimming, Amoeba radiosa glides along almost imper-
ceptibly, and much in the same manner as the common Sun-animalcule.
Perty speaks of its locomotion as being very feeble. Dujardin says of
certain specimens, they lived particularly in the flocculent pellicle on the
surface of the water, and when detached they floated and were drawn into
the eddies produced by Vorticellas. Of others, described by the same
author under the name of Amoeba brachiata, he says they float in the water
when agitated; but when after a certain time they become fixed on a
surface, they apply themselves to it in extension more or less like other
Amoebae.

Characteristic specimens of Amoeba radiosa are to be found almost
everywhere, and at all times, where other Fresh-water Rhizopods occur.

60 FRESHWATER RHIZOPODS OF NORTH AMERICA.

I have observed them in the proper material, collected from pools, ponds,
ditches, springs, bogs, and other situations in all seasons of the year,
excepting when that material has been exposed to the cold of winter ; and
I have found them from the head of the Bay of Fundy to Florida, and from
near the ocean level at Cape May, N. J., to an elevation of 10,000 feet in
the Uinta Mountains of "Wyoming Territory.

Amoeba radiosa, figs. 1-18, pi. IV, as commonly observed floating or
swimming, has more or less of a stellate form, with pointed conical rays
emanating from a common centre, or it appears as a spheroidal body with
a variable number of more or less tapering pseudopods. The central sar-
code mass or body ranges from 0.01 M mm. to 0.06 mm. in diameter. The
pseudopods vary in number from one or two to a dozen or more, and consist
of extensions mainly of clear ectosarc. They vary greatly in length, — less
than the body to three or four times its diameter. Sometimes they extend
in long filaments, so as to assume almost the appearance of the rays of the
common Sun- animalcule. Usually they are moderately long, tapering,
conical, sharp-pointed, straight, bent, or somewhat tortuous. Less fre-
quently they are more cylindroid, blunt, or pointed, mostly simple, and
rarely furcate.

The eudosarc of the body consists of a fine pale granular protoplasm,
with variable proportions, though in comparatively small quantity, of darker
molecules. It usually contains one or more food-balls enclosed in water-
drops, colored or colorless, and conspicuous for their size. These may be
altogether absent, or may be replaced by simple drops of water or other
liquid, the result of digestion of food. Sometimes many water-drops or
water- vacuoles, are present, as seen in fig. 13, pi. IV, and these at times
appear to multiply or decrease, while the animal is under observation.

Among the constituents of the endosarc, a round nucleus is usually to
be detected, though sometimes it is much obscured by surrounding mate-
rials, and. occasionally cannot be distinguished without the action of
reagents upon the animal.

The contractile vesicle is constantly to be observed exhibiting all the
phenomena noticed in it in most Fresh-water Rhizopods ; but frequently,
in accordance with the general sluggish nature of this form of Amoeba, its
movements are exceedingly slow.

Occasionally a diatom or other alga may be observed among the con-

GENUS AMCEBA— AMCEBA RADIOSA. 61

stituents of the food ; but I have not seen sand particles or crystals in the
endosarc, as in other species.

Large individuals, which I have supposed to belong to Amoeba radiosa,
such as those represented in figs. 9-12, pi. IV, approach in character A.
proteus, both in shape and in greater activity, especially when creeping, as
seen in fig. 1 1 . Quiescent individuals of large size have at times appeared
to me to be undistinguishable from A. verrucosa.

In creeping on Hat surfaces, Amoeba radiosa becomes more or less dif-
ferentiated so as to appear to have an anterior and a posterior extremity,
from the former of which radiate a variable number of tapering pseudo-
pods. Sometimes these appear to emanate from one or two palmate exten-
sions, as seen in figs. 17, 18, which gradually and incessantly change their
shape as the animal slowly glides along. The pseudopods shorten and
lengthen, disappear and reappear in the usual manner, and not unfrequently
they oscillate from side to side. Sometimes I have observed individuals
drag after them adherent particles of sand or other materials, like Amoeba
proteus and A. v'dlosa, but I have never detected anything like a prehensile
process or a villous appendage. See fig. 18.

There are many organic bodies of very different character which so
closely resemble Amoeba radiosa that they might readily be mistaken for it.
Such are the colorless blood-corpuscles and primitive ova of animals.

Dr. Perty* describes aud figures bodies resembling Amoeba radiosa
which he found in the mucus of the foot of a fresh-water snail, Lymnceus.
He remarks that a small portion contained numerous bodies which he viewed
as mucus-corpuscles until he saw them exhibit the usual changes of form
of an Amoeba. He asks whether these bodies are really young Amoebse,
or whether the mucus-corpuscles of snails have the power of contracting
and of putting forth processes. The bodies, judging from the description
and accompanying figures, were evidently mucus-corpuscles which exhib-
ited the curious phenomenon now so well known as amoeboid movement.

Thirty years ago I observed similar movements and changes of form
in the blood- corpuscles of Helix albolabris and other land -snails, but I was
utterly at a loss to account for the phenomenon, and concluded that the
movements were due to endosmosis and decomposition.

In our fresh-water sponges, especially the yellow one which I formerly

•Kennt. kleinst. Lebensfomien, 185:J, p. 188, Taf. viii, Fig. 16.

62 FRESHWATER RHIZOPODS OF NORTH AMERICA.

described under the name of Spongilla fragilis* I have repeatedly observed
amoeboid corpuscles which I supposed to be parasitic, but which are now
regarded to be ova of the Spongilla. These corpuscles bear so close a
resemblance to Amoeba radiosa that it is not improbable isolated ova of
Spongilla have at times been mistaken for it.

The Spongilla amoeboids,. as represented in figs. 19, 20, pi. IV, from
sjiecimens taken from the scrapings of a Spongilla fragilis obtained from
the Schuylkill River, in July, ordinarily resemble Amoeba radiosa in the
swimming condition. They have a stellate appearance with a spheroidal
body and a variable number of pseudopods radiating in all directions.
They remain suspended, almost motionless, in the water, but feebly vary the
shape of the body, and slowly project or withdraw a pseudopod, or change
its form or direction. The body consists of a mass of pale granular pro-
toplasm with variable proportions of yellowish granular balls looking like
food. It contains a nucleus, which is often obscured by surrounding mate-
rials. It has also a contractile vesicle, which exhibits the characteristic
movements, though comparatively with exceeding slowness. Not unfre-
quently several contractile vesicles occur. The pseudopods are long,
tapering, and pointed, and are composed of ectosarc with only the finer
protoplasm of the endosarc. Associated with the amoeboids resembling'
Amoeba radiosa, are others, as represented in fig'. 21, which in their appear-
ance and slow movements resemble A. verrucosa, though they are no doubt
of the same character as the former.

AMCEBA VILLOSA.

Plate I, figs. 9, 10; II, figs. 14-16; VIII, figs. 1-16.

Amoeba. Wallich: An. Mag. Nat. Hist. 1S63, xi, 287, pi. viii.

Amoeba villom. Wallich: Ibidem, 366, pi. ix, 434, pi. x, figs. 5-9. — Duncan: Pop. Sc. Kev. 1877, 217,

pi. vi, figs. 38-40.
Amoeba prince-pa. Carter: An. Mag. Nat. Hist. 1863, xii, 30, 44, pi. iii, figs. 1-3.
Trichamceba hirta. Fromoutel: Etudes Microzoaires (no date), 345, pi. xxviii, fig. 4.

Animal in motion differentiated into an anterior and a posterior region,
ordinarily more or less sausage-shape or irregularly clavate, or palmate in
shape, and commonly with few lobate, or short thick digitate, or conical
pseudopods, consisting of extensions of the sarcode preceded by more or
less thick portions of clear ectosarc, and mostly directed forward; posterior
extremity commonly somewhat narrower, and terminating in a villous area

*Proc. Acad. Nat. Sc. 1851, 278; 1874, 145.

GENUS AMCEBA— AMCEBA VILLOSA. 63

or process of variable form, but mostly rounded, knob-like, or discoid.
Endosarc as in Amoeba protcus, and containing usually nearly centrally a
single large conspicuous nucleus, and habitually posterior to this a single
large and conspicuous contractile vesicle.

Size. — To ith of an inch (Wallich).

Locality. — E n gland, France.

Amoeba villosa, a large and remarkable species, described by Dr.
Wallich, was discovered by him in England. It is cliiefly distinguished by
its habitual more or less clavate or palmate form, differentiated into an
anterior broader, and a posterior region terminating in a villous area or in a
villous knob. It commonly projects comparatively few short thick digitate
pseudopods, which are directed forward and little disposed to branch. Like
Amoeba proteus, it ordinarily possesses a single large nucleus more or less
central in position, and behind this an equally large contractile vesicle.
Besides these, the granular endosarc contains crystals, vacuoles, oil-like
corpuscles called by Dr. Wallich ' sarcoblasts,' and other bodies called
' nucleated corpuscles.' The food materials commonly observed are like
those of Amoeba proteus. Some of the specimens, according to Dr. Wallich,
attain a diameter of ith of an inch.

I have not been so fortunate as to meet with positively characteristic
specimens of Amoeba villosa, though a similar form is frequent in many of
our ponds, which appears to be a different animal, and is the subject of a
later chapter, under the name of Pelomyxa villosa.

Small Amoeba? are frequently to be met, in many positions or different
kinds of localities, which I have suspected to be the young of Amoeba
villosa, but of this view I have no certain evidence. They have the same
general form, constitution, and habits as the little Aincebse supposed to
pertain to Amoeba proteus, and differ only in the habitual possession of a
terminal villous process.

Some water, with ooze and conferva?, collected from a brick-pond, near
Swarthmore College, in the autumn, was preserved during the winter In
February, a yellowish green dust-like film covered the surface, consisting
of unicellular alga?. With these, and feeding on them, there were numer-
ous small active Amoeba?, such as are represented in figs. 4-10, pi. VIII.
They commonly exhibited a clavate shape, often modified by lateral pseu-

64 FEESH-WATEE EHIZOPODS OF NOETH AMEEICA.

dopodal lobes, and were provided with a terminal villous process of varia-
ble form. They glided along with the body straight and slightly sinuous,
or often curving to one side or the other. Frequently tbey presented little
change of form, the head alone incessantly rolling forward concurrent with
contraction of the bod)' behind; but often they projected pseudopodal lobes
on each side nearly or quite as thick as the head end itself. Though
habitually of the shape described, these little Amoebae would at times
assume a variety of forms. "When at rest, they were more or less depressed
globular or oval.

The villous process terminating the body had the appearance of a
protruding portion of the endosarc. It was often observed with adherent
algae, fig. 4, dragged about in the movements of the animal.

The ectosarc was always thickest at the head end, or in advance of the
pseudopodal lobes, and thinned away to nothing at the villous process.

The endosarc was composed of the usual pale granular matter, with
variable proportions of coarser granules and sometimes small clear globules.
Distinct crystals, likewise in variable proportions, and some of them
comparatively large, were always present. A large contractile vesicle was
another conspicuous constituent, and occasionally a second occurred. The
nucleus was globular, homogeneous, and faintly granular, and was defined
by a thin halo.

Tlje Amoebae commonly contained as food a number of the green algae
among which they lived. Frequently some of these algae within the endo-
sarc had become bright reddish brown as a result of digestion.

Occasionally individuals were observed to assume a globular shape,
and then spread out and remain quiescent, as seen in fig. 11. In this con-
dition, the body was undefined by any trace of clear ectosarc at the border,
and the contents were rendered unusually distinct. The contractile vesicle
remained unchanged

Among these Amoeba, I observed several of especial interest. While
having the same general features as the others, they contained from one
to half a dozen large nuclei, which were coarsely and uniformly granular,
as seen in figs. 12-16. When these were in greatest number, together
with the pulsating vesicle, which approximated them in size, they occupied
the greater part of the body of the animal. In its movements, both the
nuclei and the pulsating vesicle would at times exhibit the effects of mutual

GENUS AMCEBA— AMCEBA VILLOSA. 65

pressure by change of form (fig. 14), and also exhibit elasticity in the
return to the globular shape when the pressure was relieved.

The individuals with the large granular nuclei usually contained little
food, though they were quite as active as the others.

On one occasion, while observing an individual of the kind, in an ani-
malcula-cage, but not submitted to pressure, as it moved along in the usual
manner it suddenly assumed a spheroidal form. It contained two large
granular nuclei together with a large contractile vesicle and other ordinary
contents. After a brief interval, the contractile vesicle began to collapse,
when at the same moment one of the large nuclei burst, and in an instant
its coarse granular contents were expelled from the animal apparently
together with the liquid contents of the pulsating vesicle, as seen in fig. 15.
The scattered granules were minute globules, exhibiting only molecular
motion, and measuring about 0.002 mm. They were probably germs or
spores, but their destiny I failed to trace. The little Amoebae above de-
scribed, in the usual clavate form, measured from 0.08 mm. long by 0.024
mm. wide at the anterior or thicker end, to 0.14 mm. long by 0.04 mm. wide.

An individual containing three large granular nuclei was 0.1 mm. long-
by 0.01 mm. wide; the nuclei, of uniform size, were 0.028 mm. in diameter.
An individual with six large granular nuclei was of the same length as
the preceding - , by 0.028 mm. wide ; the nuclei were 002 mm. in diameter.
The granules of the nuclei were about 002 mm. in diameter.

Forms closely similar to the above, and containing the same kind of
large granular nuclei, are described and figured by Dr. Wallich in his
account of Amaba villosa*

Several weeks subsequently to making the above observations, some
Amcebaj from the same water and apparently of the same kind, instead of
the ordinary minute crystals, contained minute concretionary bodies of
varied shape, as seen in figs. 34, a-l. These bodies measured from 0.001
to 0.004 mm. Under the action of acetic acid they slowty dissolved, but
without any visible evolution of gas.

In some ooze, collected from a pond on Darby Creek, Delaware County,
Pennsylvania, in the month of March, there were a number of Amoebae
of the same character as the preceding, as seen in figs. 9, 10, pi. I. They
were usually clavate in form, reaching a length of about 0.1 mm. They

*Aii. Mag. Nat. Hist. 1863, si, 365, pi. is.

5 Rniz

66 FEESH-WATEE EHIZOPODS OF NOETH AMEEICA.

terminated behind in a conspicuous villous ball, which often exhibited in
its interior one or several contractile vesicles. The endosarc contained
many crystals and but little food, though it was abundant with the ani-
mals. The nucleus appeared unusually small, and such likewise appeared
to be the case with the contractile vesicles, of which there were commonly
several.

Some moist moss, from crevices of the pavement in the yard attached
to my house, collected in June, was placed in a dish with clear water.
After a few days a drop of water squeezed from the moss was found to con-
tain some small Amoebae, in association with the common Wheel-animalcule
{Rotifer vulgaris), etc. The Amoeba;, figs. 14, 15, 16, pi. II, were usually
clavate in shape, though modified incessantly by broad pseudopodal lobes
projecting laterally, and they mostly terminated in a minutely villous ball.
The endosarc contained the usual constituents. They moved actively, and
measured about 0.06 mm. long.

Some water with abundance of diatoms, desmids, etc., collected in
an extensive sphagnous swamp on Broad Mountain, Schuylkill County,
Pennsylvania, in September, contained many Amoebae, such as are repre-
sented in figs. 1-3, pi. VIII. Commonly they exhibited a sausage-like
shape, or an elongated clavate form, and reached the length of 0.25 mm.
They glided along with little change, or they often projected one or two,
and occasionally more, digitate pseudopods from the sides. Frequently
also smaller and narrower pseudopods were projected in a divergent manner
at the sides of the back end of the body, which terminated in a villous
process of variable form. The pseudopods contiguous to the latter would
assume in contraction the form of cylindroid villous processes. A con-
spicuous nucleus and one or more contractile vesicles were constantly
present.

OURAMCEBA.

Greek, oura, tail; amoeba.

Animal possessing the same essential characters as the genus Amoeba,
but in addition provided with fixed filamentous appendages habitually
trailing from the posterior extremity of the body. Filaments flexible,
cylindrical, tubular, inarticulate or articulate, resembling the mycelial
threads of fungi, perfectly passive, and neither retractile nor extensile.

GENUS OURAMCEBA— OUliAMCEBA VORAX. 67

OURAMCEBA VORAX.

Plate IX, figs. 1-12.

Amoeba xillosa (Wallich). Archer : Jour. Proe. Dublin Micros. Club, 1866, 56, 65 ; Quart. Jour. Mic. Sc.

vi, 1866, 190, 267 ; x, 1870, 305.
Amoeba with remarkable posterior linear processes. Archer: Jour. Proc. Dublin Micr. Club, 1873, 314;

Quart. Jour. Mic. Sc. xiv, 1874,212.
Ouramecba rorax. Leidy : Pr. Ac. Nat. Sc. Phila. 1874, 78 ; 1875, 127, 414.
Ouramaiba lapsa. Leidy: Ibidem, 1874,78.

Proposed genus Ouramecba (Leidy). Archer: Quart. Jour. Mic. Sc. xv, 1875, 202.
Amoeba form, plus a cluster of finger-Wee posterior appendages. Archer: Quart. Jour. Mic. Sc. 1876, xvi,337.

Animal in all respects resembling the ordinary forms of Amoeba proteus,
but in addition provided with a variable number of permanently fixed fas-
cicles of long filaments, appended to the habitually posterior end of the
body. Filaments permanent cylindrical tubes, in each fascicle emanating
from a common stalk, simple, or dividing only from near the root, inarticu-
late, mostly blunt at the ends ; fascicles from one to half a dozen or more,
often more or less separated, but mostly trailing in a single bunch.

Size. — Small individual in motion 0.14 mm. long by 0.028 mm. where
widest, with caudal filaments from 0.04 to 0.18 mm. long. Individual of
spheroidal form 0.14 mm. in diameter; in motion, elongated to 0.33 mm.,
with caudal filaments to 0.2 mm. long. Individual in movement, of palmate
form, 0.3 mm. long, with spread of 0.2 mm , with rays to 0.22 mm. of length.
Dendroid individuals to 0.33 mm. long, with spread of 0.14 mm.

Locality. — Rare. Found only in two localities, spring and pond, on
Darby Creek, Delaware County, Pennsylvania.

The singular amoeboid animal to which I gave the name of Oiiramreba

vovax I first noticed in May, 1874. It was obtained from the sediment of a
spring, in which grows water-cress, near Lansdowne station, on the West-
chester railroad. I found the creature the following year in the same
spring, and also in a pond, a mile distant, near Kellyville, which dried up
the succeeding summer. I have likewise observed specimens of what I
suppose to be a second species, first noticed in January, 1875, in material
collected from the same spring, and preserved since the preceding autumn.
Elsewhere I have not found Ouramoeba.

When first seen I regarded the animal as an Amoeba proteus dragging
after it a bundle of mycelial threads. The recurrence of several individuals
led me to examine the animal more attentively, when I came to the conclu-
sion that the threads were part of its structure. See figures of pi. IX.

68 FRESH-WATER RHIZOPODS OP NORTH AMERICA.

After publishing a brief notice of Ouramceba in the Proceedings of the
Academy of Natural Sciences of Philadelphia for 1874, Mr. Archer, of
Dublin, had the kindness to direct my attention to a description of the same
animal, by himself, in the Journal of Proceedings of the Dublin Micros-
copical Club for 1866, page 56, and 1873, page 314. This I was delighted
to see, as I felt that it confirmed my observation of the existence of this
curious and enigmatic variety, or species

There can be no question but that Ouramceba is the same creature as
the one which had been previously discovered and described by Mr. Archer.
This able authority, however, regarded the animal only as a remarkable
variation from ttie Amoeba villosa of Dr. Wallich, and in this light still con-
tinues to view it. as we learn from the following report of the Proceedings
of the Dublin Microscopical Club, published in the Quarterly Journal of
Microscopical Science for 1876, page 337: "Mr. Archer further presented
a preparation in Beale's carmine fluid of the curious Amoeba form, plus a
cluster of finger-like posterior appendages — Ouramceba, Leidy, which,
however, did not cause any contraction of the processes, a fact, so far
capable of being urged by Prof. Leidy in favor of his views ; but on the
other hand the gathering abounds with specimens of the ordinary character,
that is, without the faintest evidence of any linear processes — simple Amoeba
villosa (princei^s), — but, the appendages apart, quite identical with the
so-called Ouramceba "

Though none of the individuals of Ouramceba vorax which I have ob-
served equaled in size the largest ones of Amoeba proteus, in all other
respects — the possession of the caudal filamentous appendages alone ex-
cepted — I remarked no difference.

Mr. Archer speaks of the animal observed by him as a form of Amoeba
villosa of Dr. Wallich, and refers to " the presence of a large and numerous
tuft of very long prolongations commonly issuing from just beside the
villous patch."

In Ouramceba vorax I have at no time observed a villous patch, though
in several instances I have seen the posterior part of the body in its con-
traction assume a mulberry-like appearance which simulated such a patch,
as seen in fig. 9, pi. IX.

The filamentary caudal appendages of Ouramceba vorax consist of from
one to half a dozen distinct tufts, usually collected into a single bundle

GENUS OUEAMCEBA— OUKAMCEBA VOEAX. 69

trailing longitudinally behind the body, as seen in figs. 1-9, pi. IX. Each
tuft is composed of from a pair to six or more filaments emanating from a
common point or stem, from which they divide and more or less diverge.
The filaments are of variable length, not only in the same individual, but
also proportionately with the body in different individuals. Sometimes
they are few and short or long ; more frequently they are numerous and
as long as the body or longer. They are straight, curved, and often irreg-
ularly bent ; cylindrical and blunt, or sometimes acute or swollen at the
end. They are mostly simple from their point of origin, but sometimes
branch off from near the latter, and rarely elsewhere. Sometimes an indi-
vidual is seen in which the filaments appear irregularly contracted at one
or more points, and bent or twisted, as if in these positions they had been
injured and become atrophied, as represented in fig. 5.

In structure, the caudal filaments of Ouramccba vorax consist of a color-
less membranous tube with pale granular contents, mingled with a variable
proportion of oil-like molecules. The latter sometimes increase to consid-
erable drops elongated in the course of the enclosing tube. (Fig. 12.)

The mode of fixation of the caudal filaments is difficult to comprehend.
In a detached tuft, the root appeared to be continuous with a ball of homo-
geneous protoplasm, as seen in fig. 11.

In the movements of Ouramceba, the caudal filaments are entirely
passive, and are usually dragged along behind it. Sometimes in varied
movements of the animal, the tufts of filaments become more or less sepa-
rated at their root to a greater distance than usual, and widely diverge
from one another, as represented in figs 2, 3.

The caudal filaments present so much resemblance to the mycelial
threads of fungi, that I have suspected they may be of this nature, and
parasitic in character, dae to the germination of spores which had been
swallowed as food. I have repeatedly recognized, among the food of various
Amcebas, different kinds of fungus-spores, and it is not unlikely that these
lowly creatures may be infested with fungus-parasites, just as we frequently
find to be the case with insects. Even the constancy in the extension of the
filaments from a particular part of the body is no objection to the conjecture,
for in insects we observe certain species of Sphreria growing as constantly
from the head. There is, however, perhaps an important objection to this
view, and that is, the caudal filaments do not grow from a mycelium within
the protoplasmic mass of the body of the animal.

70 FRESH-WATER RHIZOPODS OF NORTH AMERICA.

According to Mr. Archer, Ouramceba, with its appendages, which he
aptty likens to "a bundle of dipt-candles," may be only a varietal form of
what I have considered to be Amoeba protens, but the solution of the ques-
tion remains for future investigation.

One of the specimens of Ouramceba vorax which earliest attracted my
attention did so on account of the unusual quantity and variety of diatoms
and other algae which it contained, rather than on account of its linear
caudal appendages. It was indeed this specimen, fairty represented in fig.
1 , that led me to adopt the specific name of the animal. The individual
was nearly a third of a millimetre in length, with the caudal appendages
one-sixth of a millimetre longer. It moved along in a flowing manner,
tongue-like in outline, with the narrower end forward, and without project-
ing any digit-like pseudopods. The caudal filaments at times trailed
behind ; at others, more or less diverged to the right and left. There were
six tufts, which would become distinctly separated, then would collect into
two bundles, and again would combine into a single one. Among the food
contents of the endosarc there were four large specimens of Navicula major,
besides several of Gomphonema, Stauroneis, and other diatoms, a Cosma-
rium, fragments of a bluish green Oscillaria, etc.

Another individual of Ouramceba, when first seen, formed a mulbeny-
like mass, as represented in fig. 3. It measured about 0.14 mm. in diameter,
and presented five tufts of filamentous appendages projecting from one half
the mass. After a little while it elongated, lost its mulberry-like appear-
ance, and projected from the sides long digitiform pseudopods, as seen in
fig. 2. The animal in this condition measured about 3 mm. long, and the
five tufts of caudal filaments were widely separated and divergent poste-
riorly. The discoid nucleus and contractile vesicle were distinctly visible,
and agreed closely in appearance and habitual relative position with those
of Amoeba proteus. Food-balls and water-vacuoles were few.

Another specimen, represented in fig. 4, had a branched appearance,
and afterward assumed a stellate form extending over a space of about
0.25 mm. It possessed but two tufts of short caudal filaments.

A specimen from a collection of the following season, represented in
fig. 5, had a palmate appearance, which, as usual with the animal, changed at
every movement. It measured 0.3 mm. in length, and had a large bundle of
filaments trailing behind, which measured up to 2 mm. in length. A large

GENUS OURAMCEBA— OURAMCEBA BOTULICAUDA. 71

Navicitla major at times extended across the back part of the body, and
then again was dragged along behind in a ponch-like extension of the same.

Another fine active specimen, observed on the same occasion, is repre-
sented in fig. 6. It was much branched, and was 0.2 mm. long. The
caudal filaments formed three tufts and ranged from 0.05 to 0.16 mm. in
length. The animal dragged after it a considerable amount of dirt, which
adhered at the point of origin of the caudal filaments.

Another specimen, with the body ramose, and 0.22 mm. long by
0.2 mm. in expanse, had but a single pair of caudal filaments. It con-
tained two large specimens of Navkula major, which at one time extended
in separate pouches of the body posteriorly like the single one of fig. 5.
A Navicula was discharged, at the posterior extremity of the body, to one
side of the insertion of the caudal filaments and the contractile vesicle.
The latter measured 0.028 mm. in diameter. The nucleus in advance was
0.02 mm. diameter.

Another specimen, with the body occupying a space of 0.26 mm. in
length by 0.2 mm. in width, had also but two caudal appendages. These,
when the animal was first seen, trailed backward from the side of a
mulberry-like mass formed of the posterior extremity of the body. The
measurements of the contractile vesicle and nucleus were the same as in
the former specimen.

Fig. 9 represents a smaller specimen, resembling the former in the
possession of a pair of short caudal filaments which project in a widely
divergent manner laterally from the posterior mulberry-like termination of
the body.

Figs. 7, 8, are two views of an individual, a small specimen, with a
single pair of long caudal filaments. The contractile vesicle was distinct,
but there appeared to be no nucleus present, and the animal was also
devoid of visible food.

OURAMCEBA BOTULICAUDA.

Plate LX, figs. 13-17.
Ouramceba hotulicauda. Leidy: Proc. Acad. Nat. Sc. Phila. 1875, 127.

Species comparatively small, colorless, transparent, irregularly angular
in outline. Pseudopods short, conical, acute, rarely digitate. Caudal
appendages in one or two tufts, each composed of from two or three up to

72 FRESH-WATER RHIZOPODS OF NORTH AMERICA.

nine acutely divergent, segmented filaments of variable length. A con-
tractile vesicle and a nucleus present.

Size. — Ranging from 0.04 mm. long by 032 mm. broad to 0.076 mm.
long by 0.02 mm. broad; the caudal appendages from 0.012 mm. to
0.045 mm. long.

Locality. — In the ooze of a broad spring, near Lansdowne station, on
the Westchester railroad, about five miles from Philadelphia.

In association with Ouramceba vorax, at Lansdowne station spring, three
years in succession, I found what I have supposed to be a different and
smaller species, for which I have proposed the name heading the present
chapter. If Ouramceba be really a distinct genus from Amoeba, it is proba-
ble that the smaller form under consideration may be the young of Oura-
mceba vorax.

Ouramceba botulicauda (figs. 13-17, pi. IX) ordinarily exhibits
an irregularly angulated outline, and often assumes a palmate shape with
short angular digit-like pseudopods. The ends of the latter present
variable proportions of clear ectosarc, and they move and retract more or
less in succession as the animal moves along. The posterior end of the
body is somewhat tapering and obtuse, and gives attachment to a variable
number of appendages. These form a single tuft divergent from a single
point: but occasionally there are two tufts. The appendages are commonly
three, but range up to nine. They are of variable length, straight, and
consist of series of elongated elliptical bodies, from one to four, also of
variable length. They resemble strings of sausages, whence the specific
name given to the animal.

The endosarc of Ouramceba botulicauda is pale granular, mingled with
a few oil-like molecules. Generally the specimens observed of the animal
contained but little food in the form of balls. One individual contained a
single diatom. One or two contractile vesicles are usually present, as
seen in the figures. A distinct nucleus was also commonly present.

PELOMYXA.

Greek, pelos, mud; mtixa, mucus.
PeloUve: Greeff, 1870. Felomyxa: Greeff, 1874.

Animal with the general character of Amoeba, naked, of variable and
inconstant form, in the quiescent condition spheroidal or ovoidal, in motion

GENUS PELOMYXA— PELOMTXA VILLOSA. 73

commonly more or less leech-like or sing-like in shape, and differentiated
into an anterior and a posterior region, habitually with the broader
extremity in advance, and progressing through the projection of a wave-
like or hemispherical expansion of clear ectosarc, in front or successively
upon either side, or from other parts of the body ; posteriorly frequently
ending in a conspicuous process of clear sarcode, which is prehensile, and
often finely villous. Body composed of a clear ectosarc with a finely
granular endosarc containing variable proportions of clear vacuoles and
other more consistent colorless globules. Nuclei numerous, scattered
through the endosarc. Contractile vesicles small and inconspicuous, except
in the young. Animal voracious and usually more or less gorged with
vegetal and animal materials, together with considerable mud and sand.

PELOMYXA VILLOSA.

Plate V, with 1he name Anuria villosa; VIII, figs. 31-33.
Amoeba sabulosa. Leidy : Proc. Acad. Nat. Sc. 1874, 87.

Animal nearly opaque, except when young, appearing, by transmitted
light, brown or black with hyaline border; by reflected light, yellowish
white and maculated with other colors dependent on the contained food;
spheroidal or ovoidal and somewhat depressed in the resting condition;
habitually clavate or botuliform when in motion; straight, curved, or
sigmoid; moving with the thicker extremity in advance; with a terminal
circular villous patch, which may be projected into a mammillary or ball-
like process; villi numerous, minute, papillary or filiform, simple or ramose.
Pseudopods usually as one or two broad lobar projections of the fore part
of the body, preceded by a thick seam of clear ectosarc, rarely prolonged or
branching, sometimes accompanied with a few narrow conical processes of
clear ectosarc projecting from any part of the body. Nuclei many,
scattered through the endosarc. Contractile vesicles man}', small and
inconspicuous, usually occupying a position in the vicinity of the villous
area. Animal exceedingly gluttonous, usually gorged with algous and
other food, dirt, and sand, which more or less obscure from view the
intrinsic elements of structure; motion sluggish, flowing, and more or less
intermittent; villous extremity prehensile, often seen clinging to fixed
objects or dragging after it adherent dirt or food materials.

Size. — In the ordinary resting or spheroidal condition from 0.12 to
1.25 mm., but commonly from 0.25 to 0.5 mm. In the elongated or clavate

74 FRESH- WATEK EHIZOPODS OF NORTH AMERICA.

form, as when in motion, from 0.12 by 0.06 mm., to 0.6 by 0.22 mm., or
rarely up to 1.75 by 1 mm. Frequently about 0.33 mm. long by 0.15
mm. at the anterior or broader end.

Locality. — The ooze of ponds, especially those of sphagnous swamps,
or of damp mossy forests. In the vicinity of Philadelphia ; Delaware
County ; mountains of Schuylkill and Monroe Counties, Pennsylvania ;
vicinity of Camden ; Hammonton, Franklinville and Absecom ponds ; and
Budd's Lake, Morris County, and vicinity of Cape May, New Jersey; China
Lake, Mount Gilbert, Uinta Mountains, Wyoming Territory.

Under the name of Pelomyxa palastris, Prof. Greeff has described one
of the largest and most remarkable of amoeboid animals, in certain respects
like Amoeba villosa, but in others of more or less peculiar character. In its
habitual shape, movements, and gluttonous nature, it resembles the latter;
but ordinarily it exhibits no posterior process, and this, when existing,
appears to be villous only in young individuals. Instead of one, it pos-
sesses many nuclei scattered through the endosarc ; and rarely is there a
conspicuous contractile vesicle present, but in its place a variable number
of small ones. The granular endosarc, besides the food materials and an
abundance of sand, contains ordinary vacuoles, and clear globules called
by the author 'Glanzkorper' or shining corpuscles. The size of the animal
commonly is about one millimetre, but reaches to two millimetres or even
more

An amoeboid form, represented in pi. V, and closely related to the
two forms above indicated, is rather frequent in the ooze of our ponds,
especially those of forest swamps. Until recently I ascribed it to Amoeba
villosa, but the weight of evidence appears to me to make it a nearer asso-
ciate of Pelomyxa palastris. I am, however, uncertain whether some of the
specimens, especially what appear to be young individuals, which I have
viewed as of the same kind or species, do not really belong to the former,
while others may pertain to Pelomyxa.

In most respects, the animal under consideration accords with the
characters assigned to Pelomyxa palastris ; but in the frequent and almost
constant possession of a posterior villous process, it best agrees with Amoeba
villosa. Under the circumstances I have named it Pelomyxa villosa, and
have the impression that all the forms may, through later investigations,
be proved to be but different stages of the same species.

GENUS PELOMYXA— PELOMYXA VILLOSA. 75

Pelomyxa villoma ordinarily ranges in its more matured forms from
0.166 to 0.33 mm, though rarely I have seen individuals reaching 1.25
mm. in diameter, or 1.75 mm. in length by 1 mm. in breadth, so that the
largest specimens are intermediate in size to the largest of those of Amoeba
villosa and Pelomyxa palustris.

Pelomyxa villosa viewed by reflected light, as seen in figs. 1, 11, 13,
14, usually appears cream-colored, yellowish white, or brownish white,
often more or less spotted with various colors, green, yellow, and brown,
due to particles of the food contents shining through. It is mostly opaque
or nearly so, and viewed by transmitted light, as seen in figs. 2-4, 6, 10, 12,
17, appears dark brown or black, with a thin hyaline border, which widens
to a more or less prominent meniscus-like thickening in advance of any
pseudopodal projection. Small or young individuals are proportionately
more and more translucent, as seen in figs. 5, 7-9, 15, 16.

When at rest the animal is somewhat depressed globular or oval, and
ordinarily when starting to move it assumes an ovoid, oblong, or clavate
shape. In progression it is commonly sausage-like in form, straight, more
or less curved or sigmoid, and habitually moves with the thicker end in
advance. The posterior — usually narrower — end mostly is more or less
finely villous ; and this portion frequently projects as a depressed ball or
disk, or as a process of variable form and extent.

The animal may move along in a slow steady roll or flow, with little
change of shape, preceded at the fore end by a continued or more or less
interrupted advance of a meniscus-like extension of clear ectosarc, pursued
closely by an incessant influx of the endosarc. Mostly the progressive
movement occurs through the alternate projection on each side of the head
of a hemispherical portion of the ectosarc followed by a rather abrupt and
quick rush of the endosarc into the pseudopodal projections.

Dr. Wallich's remarks concerning the movements of Amoeba villosa
apply equally well to those of the form under consideration. He says that
"the rush of granules of the sarcode does not follow upon a previous con-
tractile effort exercised at the posterior portion. As the animal progresses,
occasionally altering its course, there are periods during which perfect
quiescence is maintained by the granules; and the rush or flow of these
seems to take place, as it were, to fill up the vacuum engendered by the
sudden projection of a portion of the ectosarc." *

"Annals and Magazine of Natural History, 1663, xi, 369.

76 FEESH-WATEE EHIZOPODS OF 1STOETH AMEEICA.

In referring to the mutual convertibility of the endosarc and ectosarc,
Dr. Wallich exemplifies the process as it appears to occur in the movements
of Amccba villosa, and the same occurs in a manner exactly similar in Pelo-
myxa villosa. He observes that "in the projection of the ectosarc from
some area of the general surface, in the form of a hemispherical mass with
a broad base, only a very small portion of the original contour line seems
to give way at first, so as to admit the passage of the endosarc and other
granular contents into the newly projected part, but its entire floor appears
to be gradually dissolved, as it were, and free communication between the
main body and the new pseudopodal cavity is not established until the com-
pletion of this process. Whilst it is progressing the endosarc-granulesseem
to rush round a corner into the cavity, the corner gradually receding, so to
speak, and ultimately becoming altogether obliterated."*

Sometimes in the projection of a pseudopodal lobe, from the side of the
head end of the body, it will continue to be projected, and will gradually
receive the endosarc, and with it, as it were, the entire body, when, of
course, the animal changes the direction of its movement into that of the
pseudopod. This mode of movement is represented in the accompanying
woodcut outlines 1-5.

Pelomyxa villoma; mode of motion.

At times, Pelomyxa villosa will appear stationary, or nearly so, and
comparatively quiescent, and will project from any part of its surface,
slowly or more or less rapidly, a variable number of narrow, conical, or
somewhat spindle-shaped, pointed pseudopods of clear ectosarc, as seen in
figs. 3, 5, 10. These receive none of the endosarc, and are not used as
locomotive organs, but perhaps serve a tactile function.

I have not obseiwed Pelomyxa villosa assume the branching condition
of Amoeba protens, but under undue pressure I have seen it project one or
more long digitate pseudopods, as in the latter.

The villous area or appendage of the Pelomyxa under consideration
resembles that ascribed to Anuria villosa by Dr. Wallich. In the resting

* Annals ami Magazine of Natural History, 1863, xi, :S70.

GENUS PELOMYXA— PELOMYXA VILLOSA. 77

condition or spheroidal form of the animal it is not obvious, and it appears
to be capable of complete retraction and obliteration, as is the case with
the ordinary pseudopodal extensions. It is variable in appearance, though
as ordinarily seen it forms a discoid or sucker-like process defined from the
rest of the body by a constriction. When not projected, it is sometimes
visible as a circular patch terminating the posterior extremity of the body,
as represented in figs. 1,13. Sometimes the process appears as a conical
or irregularly papillary projection. The villi are very variable; sometimes
numerous, minute and crowded; sometimes fewer, thicker and widely
separated; at times short and papillary, at others more or less long and hair-
like, and occasionally branched. See figs. 1-10, 12, !3, 15-17.

The villous portion or process of the body is highly prehensile, and
serves the animal to fix its position in like manner with the sucker of a
leech. At times when I have poured off the liquid from the glass on which
I was examining a specimen of the Pelomyxa to put on it clearer water, it
would maintain its place by means of the villous end of the body. As a
temporary organ of prehension it is no doubt of importance in obtaining
food. Algas and other materials are often seen adherent to and dragged
along after it in the progressive movements of the animal', as represented
in fig 14. In structure, the villous process appears as an extension of finely
granular homogeneous endosarc without the slightest differentiation of
enclosing ectosarc, and when it is of irregular or papillary form it looks as
if it were a sort of hernial protrusion of the endosarc through an accidental
rapture of the ectosarc.

Sometimes the villous area of Pelomyxa villosa appears only as a villous
fringe to the posterior extremity of the body. Occasionally I have observed
an individual emit a multitude of minute villi near or in conjunction with
the usual villous area, or in other positions of the body. These addi-
tional or supplemental villi appeared to be less permanent than the others,
or at least after a time they were withdrawn and were no longer visible in
the same individual.

Pelomyxa villosa I have usually found to be so opaque, except in young
specimens, that the different elements of its interior structure are undis-
tinguishable without the animal is submitted to considerable pressure, or it
is actually crushed. In habit, like the Pelomyxa palustris, it is exceedingly
gluttonous, and is remarkable for the manner in which it gorges itself with

78 FRESH- WATER RHIZOPODS OF NORTH AMERICA.

food and other materials of different kinds. Usually the quantity of the
ingesta is so great as totally to obscure from view all the intrinsic consti-
tuents of the endosarc except when they rush into pseudopodal projections
of the ectosarc.

The food is mainly of vegetal character, consisting of all sorts of algae,
especially diatoms, desmids, and other unicellular forms, oscillarias and
other filamentous forms, fragments of higher plants, fibres and particles of
wood and leaves, etc., besides flocculent, apparently decaying, vegetal matter.
The food in the interior of the animal, as in other amoeboid forms, when of
soft or yielding character, appears as variously colored balls, mostly
yellowish, brownish, or green, often enclosed in water-drops, but often also
free from the latter, as indicated by the absence of the clear zone, which
usually indicates the presence of surrounding liquid. Much of the food
apparently is diffused, as fine yellowish matter, among the intrinsic granu-
lar constituents of the endosarc.

In the ordinary process of digestion in Pclomyxa villosa, as in other
amoeboid forms, green vegetal substances gradually assume a yellowish or
brownish hue. The insoluble residue of the food of all kinds is from time
to time discharged in the usual manner at the posterior extremity of the
body, but whether through or to one side of the villous process I did not
ascertain.

Quartz-sand is a frequent and abundant material mingled with the food
and other constituents of the endosarc. Not only fine but coarse particles
are swallowed, but they appear always to be directly in contact with the
granular and other matters of the endosarc, and not contained in vacuoles
or water-drops, as ordinarily is the case with most solid food. In many
individuals, the quartz-sand has appeared to predominate over everything
else in the endosarc, and such specimens, which were literally bags of sand,
I formerly described as a species, with the name of Amoeba sabulosa.

Pclomyxa palustris, as described by Prof. Greeff, also swallows a nota-
ble quantity of sand ; but this appears not to be the case, at least to any
remarkable extent, with Amoeba villosa, as described by Dr. Wallich and
Dr. Duncan.

Dr. Wallich describes crystals of rhombohedral form as a constituent
of the endosarc of Amoeba villosa; but these bodies, ordinarily so conspicu-
ous and common in Amoeba proteus, either do not exist, or they escaped my

GENUS PELOMYXA— PELOMYXA VILLOSA. 79

notice, in the more characteristic or matured specimens of Pelomyxa villosa.
In some young amoeboid forms, which I suspected to pertain to the latter,
crystals undoubtedly existed, and perhaps they are likewise abundant
enough in mature forms, but ordinarily are obscured from view by the
presence of the large proportion of sand particles. Prof. Greeff does not
mention them as an element of Pelomyxa palustris.

The basis of the endosarc of Pelomyxa villosa, as in the latter, consists
of a pale and finely granular protoplasm, mingled with more distinct fine
oil-like molecules. Besides the food materials and other ingesta, the endo-
sarc contains a variety of other elements. Among these there are variable
proportions of clear vacuoles, sometimes numerous, sometimes few, of dif-
ferent sizes.

Another element consists of clear or indistinctly granular corpuscles
of albuminoid or oleaginous appearance, mostly colorless, but sometimes
more or less feebly yellowish. They range from a small size up to 0.006
mm., though the prevailing size was about one-half this dimension. Under
the action of acetic acid they mostly remained unchanged, though many
became more distinctly granular, and less distinctly outlined. These
corpuscles probably correspond with the 'sarcoblasts' of Amosba villosa of
Dr. Wallich, and the 'Glanzkorper' or shining corpuscles of Pclomyxa palus-
tris of Prof. Greeff.

Mingled with the clearer corpuscles just indicated, there were others,
comparatively fewer, and measuring about 0.004 mm. These were more
or less homogeneous, with scattered granules superficially situated. Still
other corpuscles, about the same size as the preceding, were finely granular,
and contained a darker granular nucleolus. I am uncertain whether these
corpuscles correspond with the nuclei of Pelomyxa palustris as described by
Prof. Greeff.

In some crushed specimens of the variety of Pelomyxa villosa, origi-
nally noticed by me under the name of Amoeba sabulosa, I further noticed
a few comparatively large granular spheres reaching about 0.016 mm., and
containing each several scattered nucleoli, some of which appeared clear
and homogeneous, while others were granular.

In several instances, in crushed specimens of Pclomyxa villosa, I also
observed, as one of the constituents of the endosarc, numerous minute rods,
from 0.001 to 0.005 mm. in length, and resembling vibrios, but motionless

80 FRESH-WATER RHIZOPODS OF NORTH AMERICA.

Under the ith inch objective power of the microscope, many appeared
to be transversely striated. Similar bodies are described by Prof. Greeff as
a constituent of the endosarc of Pelomyxa palustris,

Dr. Wallich describes a conspicuous nucleus and an equally conspicu-
ous contractile vesicle as present in Amoeba villosa, having the same essential
characters and holding the same habitual position as in Amoeba proteus.
In the figures accompanying Dr. Wallich's memoir, the single large nucleus,
and the large contractile vesicle, or in its place several smaller ones, arc
among the most striking features of the creature.

In Pelomyxa villosa, except in those specimens I have regarded as
young individuals, I have at no time been able to detect a single large
nucleus like that represented in Amoeba villosa, or such as exists in A. proteus.
I have, also, at no time observed a single large and conspicuous contractile
vesicle in the more characteristic forms of the animal; but in its place there
are usually from one to half a dozen small ones, commonly occupying a
position in the vicinity of the villous area of the body, or even partly
within this area when it is produced as a process. Frequently the small
contractile vesicles are more or less obscured from view by other surround-
ing elements. They commonly remain separate and independant of one
another, and while one appears and undergoes enlargement another collapses
and disappears.

I have not been able to trace a continuation of the history of Pelomyxa
villosa.

In one instance I observed a large individual replete with quartz-sand,
apparently burst and scatter its softer granular constituents until reduced
to about one-half the original size. The remaining portion of the body
appeared unhurt, but what the phenomenon meant I did not positively
ascertain, though I suspected that it was attendant upon the expulsion of
germs.

DINAMCEBA.

Greek, deinos, terrible; amoeba.

Animal with the same essential structure of Amoeba ; when at rest,
spheroidal or oval ; when in motion, habitually ovoid or slug-like, and with
the broader extremity in advance. Pseudopods few or many, mostly sim-
ple extensions of the ectosarc, subulate, or long conical and acute, occasion-

GENUS DINAMCEBA— DINAMCEBA MIRABILIS. 81

ally furcate. Posterior extremity of the body papillose ; papillae very
variable, few or many, simple or compound, retractile. Surface of the
body, including- the pseudopods and the papilla?, bristling with minute
spicules or motionless cils.* Body of the animal often enveloped, even in
the active moving condition, with a thick layer of delicate hyaline jelly,
defined on the surface by multitudes of minute spicules. Spicules of the
surface of the body and the exterior layer of jelly with its spicules some-
times absent.

DINAMCEBA MIRABILIS.

Plate VI ; VII, figs. 1-11.

Deinamaba mirabilis. Leidy : Pr. Ac. Nat. Sc. 1874, 142, 155.
Amaba ientaculata. Leidy: Pr. Ac. Nat. Sc. 1874,167.
Dinamocba. .Leidy: Pr. Ac. Nat. Sc. 1877,288.

Body round, oval, ovate or limaciforni,f commonly more or less
depressed when moving on flat surfaces ; anterior part broad and blunt ;
posterior part narrower and more or less tapering ; sometimes broader
behind ; spheroidal when floating. Pseudopods mostly numerous, and
usually projecting from the anterior region of the body, consisting of
moderately long, conical, or somewhat fusiform, or subulate processes of
clear ectosarc. Posterior extremity of the body commonly much papillose,
with the papilla? very variable, simple or compound, rounded or elongated.
Surface of the body everywhere, including pseudopods and papilla?,, thickly
bristling with minute spicules, which are, however, in some conditions
entirely absent. Body often enveloped with a thick layer of clear proto-
plasm, which is defined by a minutely ciliated surface, and is penetrated by
the pseudopods. Endosarc mostly with abundance of oil-like molecules,
large clear globules, and multitudes of food-balls. Nucleus and contractile
vesicles commonly obscured from view by the other constituents.

Size. — Spheroidal form 0.064 to 0.16 mm. diameter. Creeping forms
152 mm. long by 0.06 mm. broad, to 0.34 mm. long by 0.22 mm. broad.

Locality. — Ponds of the cedar and sphagnous swamps of New Jersey,
commonly among the desmids Didymoprium and Bambusina, which appear
to be its favorite food.

HHBBamraba mirabilis in its quiescent condition is globular or oval,
and often appears indisposed to move. It is a sluggish animal, though much

* From the word ' cilia,' anglicized into ' cils ' — minute linear appendages, in rows reminding one of
the eyelash, whence the name.

t Shaped like a Limax, or slug.

6 KHIZ

82 FEESH-WATEE EHIZOPODS OF NOETH AMERICA.

less so than Amoeba verrucosa. When about to move, it commonly assumes an
oval and then an ovoid or a pyriform shape It slowly glides with the thicker
end in advance, usually projecting from the front a conical eminence of
hyaline ectosarc. At the same time it quickly projects from one or both
sides of the head a long subulate pseudopod. Simultaneously, or more or
less successively, a variable number of similar pseudopods may be pro-
jected from other portions of the body. The pseudopods are more fre-
quently confined to the fore part of the body. There may be but one or
two, or they may be numerous and project everywhere except at the pos-
terior extremity. The latter is covered with papillae, differing from the
pseudopods in being short and blunt. See pi. VI.

The pseudopods present considerable uniformity both in shape and
size. They are composed of the ectosarc alone, except that a few mole-
cules of the endosarc extend a little way within their base. They are elon-
gated conical, with an expanded base, slightly swollen near the middle, and
tapering to a sharp point. Occasionally one or two are forked. They make
their appearance from the ectosarc, suddenly, as short conical projections,
which run outwardly some distance with a blunt extremity, and then
rapidly extend in a tapering point, as exemplified in the group of pseudo-
pods to the right of the head in fig. 2, pi. VII. They are projected quickly
even to such a degree as to require special attention to see them produced,
and they are also as quickly retracted.

The papillae of the back end of the body are variable in number and
appearance. Sometimes they are comparatively few; at others, numerous
and thickly crowded. Not unfrequently they are themselves papillose.
Their usual form is mammillary, often enlarged at the end, or they may be
conical and pointed. They are composed of the ectosarc, but commonly
receive more of the endosarc than the pseudopods. They appear to be
retractile, like the latter, and often diminish or increase ; often and quickly
change their aspect, and frequently disappear altogether.

A remarkable feature of Dinamceba (pi. VI) is seen in every part of
the surface, including the pseudopods and posterior papillae, bristling with
exceedingly minute spicules, or rigid cils, which are directed perpendicularly
to the surface. Not unfrequently these minute cils are absent, figs. 2, 3,
5-9, pi. VII ; and in several instances in which they were abundantly
present, after some hours, on the same individuals, they had disappeared.

GENUS DINAMCEBA— DINAMCEBA MIRABILIS. 83

In several cases also I have seen minute molecules replace the spicules, as
represented in fig. 11, pi. VII.

Another character of Dinamoeba, even more remarkable than the
former, as represented in figs. 2, 7, pi. VI, is the occurrence of a thick
investment of hyaline jelly, resembling in appearance that which envelopes
certain algae, as commonly seen in the desmid Didymoprium grevillii. This
transparent cloak is borne by the active, moving animal, and is no evi-
dence of the creature being ready to pass into a quiescent or an encysted
condition. The free surface of the jelly-like cloak is defined by innumer-
able exceedingly minute rods, standing perpendicularly, which give to the
animal the appearance as if it were surrounded by a nimbus of bacteria.
Sometimes through the stratum of jelly there are to be observed variable
numbers of linear bodies resembling the former; but these have usually
appeared to me to be endowed with motion, and to be really true bacteria.

In the movements of Dinamceba, its jelly-like cloak appears to be no
obstacle, and the subulate pseudopods shoot through and beyond it as if it
did not exist.

Like the bristling spicules of the body and appendages of Dinamceba,
the jelly-like envelope with the bacteria-like cils may be absent; but, accord-
ing to my experience, it is present in the greater proportion of cases.

Dinamceba is commonly cream-white or greenish white and more or
less spotted with green and brown, or it is yellowish or brownish white
spotted with yellow and brown. The colors, with the exception of the white,
are mainly dependent on the food-balls shining through from the inte-
rior. The pseudopods, papillae, and jelly-like envelope are hyaline and
colorless.

Dinamceba mirabilis, like Pelomyxa villosa, is a gluttonous feeder, and is
commonly so gorged with food that it greatly obscures the intrinsic
elements of the endosarc and renders the animal more or less opaque.
The food-balls, mostly included in water-drops, are globular, and variable
in color according to their original nature and the changes they have
undergone in digestion.

The basis of the endosarc consists of hyaline protoplasm, with a pale,
faintly granular constitution, as in other amceboids. It is generally mingled
with a large quantity of fine oil-like molecules, which are especially well
seen where the endosarc merges in the ectosarc, and also within the roots
of the pseudopods.

84 FRESHWATER RHIZOPODS OF NORTH AMERTOA.

Occupying the central portion of the endosarc, and mingled with the
food-balls, in different individuals, there is a variable quantity of other
globular elements of different kinds. Frequently a large proportion of
these globules consist of clear oil-like drops of homogeneous liquid resem-
bling similar globules in Pelomyxa villosa. Others appear faintly granular
in structure, and may be either nuclei and food-balls, or perhaps both.
Many globules also are simple water-vacuoles, varying greatly in number
and size.

I have not been able to detect in Dinainoeba, except perhaps in a few
young individuals, a distinct nucleus, such as is usually so conspicuous in
Amoeba proteus. It is not impi-obable that a nucleus like that of the latter
may ordinarily be present, and be completely obscured by the abundant
food and other constituents of the endosarc.

A conspicuous contractile vesicle, like that habitually present in
Amoeba protens and other species, is rarely to be seen in Dinamceba. Mostly
several small clear globules, up to half a dozen, may be seen from time to
time at the posterior extremity of the animal, which appear to substitute the
usual single contractile vesicle of other amoeboid forms. These globules
remain separate, slowly enlarge, and collapse more or less successively, in
the manner of the ordinary contractile vesicle. Perhaps also as a substitute
for the more conspicuous contractile vesicle, in Dinamceba we observe the
frequent displacement, from the central mass of the endosarc, of one or more
large vacuoles, which appear within the posterior extremity, and after a
little while discharge from the body their mingled liquid and solid con-
tents, the remains of the food.

Though indefinite granular matter, apparently derived from decaying
vegetal substances, is taken with other food, Dinamceba appears not to
swallow sand or other conspicuous inorganic particles.

Crystals also appear not to be present as a constituent of the endosarc
of Dinamceba, nor did I ever detect within it minute rods or vibrio-like
bodies, such as are frequently observed in some forms attributed to Pelomyxa
villosa.

As before intimated, Dinamceba is a gluttonous animal, and, when
found under favorable circumstances, is usually observed gorged with food.
It appears mainly to feed on algse, and its favorite food consists of the
common desmids Didymoprium grevillii and Bambusina brebissonii, especially

GENUS DINAMCEBA— DINAMCEBA MIBAB1LIS. 85

the former. Where these two desniids thrive luxuriantly, in ponds of the
deep sphagnous and cedar swamps of New Jersey, I have found the
favorite haunts of Dinamoeba, Less frequently among its food contents
I have observed diatoms, closteria, and the brownish flocculent matter
common in some of the ponds indicated.

The green spots so generally observed in Dinamoeba are mostly due
to the presence of scattered cells of Didymoprium and less frequently of
Bambusina, scattered as food contents through the endosarc. As a result
of digestion, the green endochrome of the desmids loses its color, at first
becoming paler and then yellowish green, then ochreous yellow. The
discharged cells of the desmids appear with the yellow shriveled remains
of the endochrome in the centre.

The figures of pi. VI represent individuals of Dinamoeba, feeding on
Didymoprium, and containing in their interior multitudes of food-balls
mainly consisting of joints of that plant, of various shades of green, and
others rendered brown or yellow as the result of digestion.

As is intimated, by Prof. Duncan, to be the case in Amoeba, I suspect
that Dinamoeba habitually takes its food at the posterior part of the body.
I have not seen the animal in the act of seizing its food, so that I am unable
to say whether it does so through the aid of the terminal papillae. My
observations, however, lead me to believe that in swallowing the food it
first enters to either side of the papillary extremity.

In one instance in which I detected Dinamoeba in the act of swallowing,
the animal presented the appearance represented in fig. 1, pi. VI, and had
been but a few minutes previously transferred to the animalcula-cage. It
was a fine vigorous specimen, broadly oval, 0.18 mm. long by 0.16 broad,
with its characteristic subulate pseudopods projecting in every direction.
All parts bristled with spicules, and the body was enveloped in its hyaline
jelly-cloak. A long filament of Didymoprium had one end bent and
swallowed by the Dinamoeba, entering from the front, on the left side, in
advance of the middle. At the position of entrance it was enclosed for
some distance by a thick papillary protrusion of clear ectosarc, which
clasped it so tightly as to constrict the jelly-envelope of the Didymoprium
completely through to the cellular axis of the plant.

A little later the animal slowly expanded so as to measure 0.24 mm.
in length, and retaining the original breadth. At the same time, the Didy-

86 FRESHWATER RHIZOPODS OF NORTH AMERICA.

moprium was broken, the detached portion pushed off, and the retained
portion drawn in, and with this the large papilla of ectosarc. A moment
after, a large protrusion of the body occurred to the left of the posterior
extremity, followed by an abrupt discharge from it of twenty -four cells,
mostly of Didymoprium, with a few of Bambusina. The discharged cells
contained the yellow shriveled remains of the endochrome. A view of the
animal in the condition just described is represented in fig. 2.

Later, as the animal slowly glided along, it presented the appearance
seen in fig. 3. The body was depressed pyriform, with the posterior nar-
row end crowded with long papilla?. In this condition it measured 0.28
mm. long. Eight hours subsequently, the same individual measured 0.24
mm. long by 0.16 mm. broad.

In another instance I observed an active, well-fed Dinainoeba in the
act of swallowing a filament of Bambusina. The successive steps of the
process are represented in the woodcuts 1-12.

Successive changes observed in Uinamceba mirabilis while in the act of swallowing a
filament of the alga Bambusina. The arrows indicate the course of movement in the
swallowing of the alga.

When first seen, the animal was oval, 0.22 mm. long by 0.16 mm.
broad. The alga was 1.12 mm. long, and a portion of it was immersed in
the Dinamoeba, entering to the left of the posterior extremity, and extend-

GENUS DINAMCEBA— DINAMCEBA MIEABILIS. 87

ing along the left side, the fore end causing a slight protrusion of ectosarc
at the head (1). A little later the animal slightly elongated, remaining of
the same breadth (2). Gradually moving with an inclination to the
left, the relative position of the alga was changed so that it crossed in a
slant, and the anterior end protruded to the right of the head (3). The
relative position of the alga continued to change, so that it became trans-
verse (4), then gradually slanted in the opposite direction (5), and at last
assumed nearly its original position, as seen in cut 6. It next acquired a
median position, extending through the length of the animal, as seen in cut
7. The creature now extended in both directions along the alga, as repre-
sented in the succeeding woodcut (8), until it became 0.36 mm. long by
0.128 broad. The movements up to this moment had been slow and
uniform, but now the animal rather suddenly doubled upon itself, bending
the alga with it, as seen in cut 9. The two extremities of the alga were
bent more closely together until they were parallel, and their ends pro-
truded together from the same pole of the animal, as represented in cuts
10, 11. In this condition the animal measured nearly the same as origi-
nally, that is, 0.24 mm. long by 0.16 mm. broad. Subsequently the
right extremity of the alga was drawn into the animal, leaving but one
protruded, as seen in cut 12, and after a little while this also disappeared,
and the animal moved away, with the lower part, as seen in the woodcut,
in advance. As the alga was three times the length of the animal after it
was swallowed, it must have formed a coil; but this was entirely obscured
from view by the abundance of food and other constituents of the endo-
sarc. During the process of swallowing the alga, as may be noticed in
the outline figures, the number and position of the pseudopods incessantly
varied. In the beginning they were numerous ; at one time none, and
later but two or three. From the creature doubling upon itself, in the
manner represented, it would seem as if the head and papillary end of
Dinamoeba were not permanently differentiated, for both subsequently
appeared together to become the tail end, while an intermediate portion
of the body assumed the relative position of the head.

Indeed, no portions of the exterior of Dinamoeba are constant,
although they usually seem to be so Head and tail appear to be mutually
interchangeable, and such also is the case with the processes I have for
convenience distinguished as pseudopods and papillae.

88

FRESH WATER EHIZOPODS OF NORTH AMERICA.

Some hours later, on examining the same Dinamoeba, which had been
preserved in the animalcula-cage, it presented the appearance represented
in fig. 6, pi. VI. It was oval in shape, 0.272 mm. long by 0.16 mm. broad,
and sitting, as it were, on a Didymoprium. From the head projected a num-
ber of pseudopods. The posterior extremity clasped the alga by means of
a transverse cylindrical process of greater length than the breadth of the
body. The ends of the process on each side were extensions of the ectosarc
fringed with papillae. The cylinder embraced the alga so tightly as to
contract its gelatinoid sheath close to its green cellular axis

While watching the Dinamoeba, without any suspicion of what was to
follow, and with the impression that the animal was holding a resting
position, as seen in the woodcut 13, the Didymoprium suddenly broke
within its clasp, as represented in the following woodcut 1 4.

ifiitiiH~HM i iPiliiii i i ' i n r i^rtiS^QtsA ' " : '.. i l& o>. / ■'---'

j 3 " : . ,sSSS ^~~Z~C^.

W

Kit

if

Successive changes observed in Dinamoeba mirabilis while in the act of swallowing a fila-
ment of the alga Didymoprium.

The animal subsequently passed through the successive changes
seen in cuts 15-21. The Dinamoeba gradually shortened, the pseudo-
pods in front diminished to two, the two portions of the alga Avere
made to approach each other, and the right side of the body projected
in a nipple-like prominence, from which there were suddenly discharged
upward of twenty cells of Bambusina (If)). These were probably
derived from the filament swallowed, as previously described. The cells
were nearly all separated, and contained only the shriveled remains of the
endochrome.

The Dinamoeba again became elongated, all pseudopods disappeared,

GENUS DINAMCEBA— DINAMCEBA MIBABILIS. 89

and the two portions of the alga approached so as to project from the ani-
mal at an acute angle, while at the same time the right portion was observed
slowly to sink into the interior (16). The animal next turned to the
left, the two portions of the alga assumed a position at a right angle, and
the left portion broke into two (17). The animal then turned until the
head was directed backward, and the two portions of the alga remaining
in connection with the animal assumed a parallel position close together on
the left of the tail end (18). What had been the left portion of the alga
sunk gradually into the body and disappeared (19). Subsequently what
had been the head of the animal shrunk and became the tail end furnished
with pseudopods, while the previous tail end projected pseudopods and
moved in advance as the head end (20). The projecting extremity of
what had been the right portion of the alga broke off close to the animal
and was rejected (21), while the retained portion sunk out of sight.

Some days later I had the opportunity of observing another Dinamoeba
in the condition represented in fig. 4, pi. VI. It was a fine, large specimen,
of ovate form, the third of a millimetre long by the fifth of a millimetre
broad. From the left of the posterior part of the body projected two divi-
sions of a Didymoprium, which no doubt had been broken apart, as in the
former instance. The two divisions of the alga assumed a symmetrical
position at the tail end, and afterward portions of each were successively
broken off, and the retained pieces were swallowed.

Habitually Dinamoeba rejects excrementitions matters at one side of
the posterior papillary extremity; but I have repeatedly observed the animal
discharge the remains of food not only from other parts of the body, but in
two or three widely separated positions at once, as represented in fig. 7.

Though Dinamoeba mirdbilis is a more sluggish animal than Amoeba
proleus, it appears to be more irritable. Disturbance generally causes it to
withdraw its pseudopods and contract its body, though slowly. A slight
shock, I have also noticed, will frequently cause it to discharge a portion of
its food contents, and this several times and at several points at once.

An active specimen of Dinamoeba, from Atco, New Jersey, when first
noticed, was oval, 0.3 mm. in length by 0.2 mm. in breadth. After a moment,
from disturbance, it discharged a few cells of Didymoprium, at the same
time, from the right of the head and the left of the tail, and in a few
seconds afterward upward of twenty cells of the same alga from the

90 FEESH-WATEE EHIZOPODS OF NOETH AMEEICA.

former position, and a series of four cells, still connected together, from the
latter position. The animal then became globular and quiet, and measured
0.2 mm. in diameter.

On the same occasion, in the same drop of water, I observed another
fine Dinamceba, with an oval body 0.25 mm. long by 0.2 mm. broad, with
numerous subulate pseudopods projected in all directions. It exhibited a
thickly papillose tail-like appendage 12 mm. long by 0.06 mm. broad.
The tail was filled with fine granular matter, a multitude of darkly defined
oil-like molecules, clear globules, and three cells of Didymoprium. ^The
animal afterward discharged a group of cells of the latter alga from the
body to the left of the tail, and subsequently assumed a long clavate shape
0.4 mm. long by 0.18 mm. broad at the thicker end.

In one instance I observed a Dinamceba, which contained, with other
food, a desmid, the Closterium didymotocum, as represented in fig. 1, pi. VII.
"When first seen, the alga held a transverse position causing a considerable
protrusion of the body on the left side. The alga had evidently been
seized just after it had parted from another; — for one-half of the cell was
comparatively tender and doubled upon the older and more rigid half.
With the Closterium, smaller algse, and other ordinary materials, there was
an unusually large vacuole, which discharged itself several hours after first
observing it. About eight hours after seeing the Dinamceba, the minute
spicules of the surface had disappeared, and two hours later the Closterium
was discharged, but without my having seen the act. The following morn-
ing the animal presented the appearance represented in fig. 2. It was 0.21
mm. long by 0.12 mm. broad at the fore part. The pseudopods were remark-
ably long, up to 0.12 mm., and projected in every direction. The posterior
extremity ended in a number of compound papillae. The endosarc, besides
colored food-balls, contained a multitude of colorless globules. Three
smaller ones of these appeared within the tail end as contractile vesicles.
No trace of the minute spicules, usual in Dinamceba, was to be seen on
any part of the surface of the animal.

In the Proceedings of the Academy of Natural Sciences for 1874,
page 167, I described an amoeboid, under the name of Amoeba tentaculata,
as follows: Body spheroidal, oval, or limaciform, projecting a multitude of
long conical or fusiform pseudopods of clear ectosarc, into which no gran-

GENUS DINAMCEBA— DINAMCEBA MIEABILIS. 91

ules of the endosarc enter ; posteriorly finely papillate, or with a discoid
papillate subdivision. Exterior of the body colorless and transparent;
interior yellowish and spotted brown or green fr<jm the food contents.
When moving, the animal resembles a sea-slug, Eolis, in its shape and from
its many long pointed pseudopods. At the fore part of the body, in pro-
gression, a large extent of perfectly clear ectosarc precedes the endosarc,
equal to about one-sixth of the length of the body. This is blunt in front,
and with its divergent pseudopods resembles the head of a slug. When
floating, the animal looks like a large Actinophrys with thick conical rays.

This amoeboid, which I now suspect to represent only another condition
or stage of Dinamceba mirabilis, I have repeatedly found, in the autumn, in
the same localities. It agrees in habitual shape and size, in the kind of
pseudopods, and the possession of the posterior papillary organ, with the
more characteristic form. We have seen that both the minutely spiculate
condition of the surface and the gelatinoid coat of Dinamceba may be dis-
pensed with, so as to reduce it to the condition of the amoeboid form under
consideration.

This amoeboid seems as if it were Dinamceba which had passed the
actively feeding stage, as it contains but comparatively little food and the
endosarc is much reduced. The large proportion of ectosarc in relation
with the endosarc reminds one of Amoeba verrucosa.

In motion, the creature advances slug-like in manner and general
appearance. The body is composed of a central mass of granular endo-
sarc enveloped with a thick layer of clear ectosarc, of which a still thicker
portion forms the head, as seen in figs. 5, 7, and 10, pi. VII. The pseudo-
pods, usually numerous, form subulate processes of clear ectosarc occu-
pying mostly the anterior region of the body. The posterior papilla? are
variable in number and size, and in advance show more or less disposition
to merge into pseudopods.

Figs. 5-7 represent three successive views of the same individual as
observed at intervals during thirty-six hours. As first seen, fig. 5, it was
elongated elliptical with prolonged blunt poles, both of which, as well as
the exterior layer of the intermediate body portion, appeared to be com-
posed of clear ectosarc. The central mass of granular endosarc was
mingled with diffused brownish material, and contained a few clear globules
or vacuoles, various articles of food, and a large pale granular nucleus

92 FBESH-WATEB EHIZOPODS OF KOETH AMEEICA.

surrounded by a clear halo. Pointed conical pseudopods of clear ectosarc
projected everywhere from the head and body, while the tail was minutely
and profusely papillose.

When next examined, the animal appeared as in fig. 6, oval in outline,
with the anterior half covered with pseudopods, and the posterior half with
numerous short blunt papillae. The nucleus was concealed from view.

Later the body was elongated, with the posterior part most expanded,
as in fig. 7. The nucleus was nearly central and quite distinct. In the
first and last views, several small contractile vesicles were observed at the
posterior extremity of the animal.

Among the articles of food there was a long colorless thread, appar-
ently a cotton or ligneous fibre, coiled among the other constituents of the
endosarc. A bright green desmid, as seen in figs. 5, 6, finally assumed a
brown hue, as seen in fig. 7.

Fig. 8 represents an individual of the same kind as the preceding, in
the act of floating or swimming. The body of globular form, and with
numerous pointed pseudopods radiating in all directions, gave it the general
appearance of a Heliozoan, except in the character of the rays. The usual
posterior papillae did not appear in this condition, but subsequently were
seen, when the animal assumed the elongated creeping position. The size
of the central body was much reduced in its proportions, from the multi-
tude of pseudopodal rays, and measured 0.0fi5 mm. in diameter.

The endosarc cf the amoeboid under consideration is usually pale gran-
ular, and apparently mingled with brownish matter, which I have suspected
to be derived from the brown flocculent material usually so abundant in
the locality in which the creature is found. It also contains variable pro-
portions of fine oil-like molecules, water-vacuoles, brownish and colorless
granular food-balls, diatoms, and other food materials, but rarely a particle
of quartz-sand. Mostly the fine oil-like molecules are very few or are
altogether absent, and frequently also water-vacuoles appeared not to be
present except in the nature of contractile vesicles. Of these there are
apparent a variable number situated within the villous extremity of the body,
often small and comparatively numerous, at other times few and larger.

Commonly a nucleus may be detected in the movements of the animal,
as seen in figs. 5 and 7. It is of large size, pale granular, and surrounded
by a clear ring. In fig. 10, an individual is represented, in which the

GENUS DINAMCEBA— DESTAM(EBA MIBABILIS. 93

nucleus appeared to be a sphere containing large granules of uniform size.
The specimen was quiet, remained nearly stationary, and occasionally
emitted here and there a small conical pseudopod. In a similar specimen
the nucleus presented the appearance of including exceedingly delicate
coiled filaments, but the time did not permit me to investigate further the
nature of these.

Dinamoeba mirabilis, in size, habitual form, and some other characters,
approaches Pelomyxa villosa, and after recognizing Amoeba tentaculata as
representing another stage of the former, I began to suspect that it might
likewise be the same. When, however, we take into consideration the usual
abundance of pseudopods in Dinamoeba, their paucity or absence in Pelo-
myxa villosa, the difference in the character of the villous and papillary
processes, and the difference in habits, with other occasional peculiarities,
we may regard them as distinct unless further investigation shall prove
otherwise.

Dinamoeba mirabilis bears considerable resemblance to Mastigamoeba
aspera, described by Prof. Schulze.* This animal is broad, fusiform, about
0.1 mm. long, provided with many pseudopods and a general investment
of minute bacteria-like bodies, but is particularly distinguished by the
possession of a long flagellum, projecting in front, from an ovate corpuscle
enclosing a nuclear body. When I first saw the figure of Mastigamoeba, it
occurred to me that Dinamoeba was the same, and that the flagellum in the
latter had inadvertently escaped my notice. I waited rather impatiently
until the following season, that I might again have the opportunity of exam-
ining what I had described as Dinamoeba. I have since seen an abundance
of specimens in a variety of conditions ; but in none did I ever see a
flagellum.

Dinamoeba further differs from Mastigamoeba in other respects : in the
habitual form of the body ; in the pseudopods, which are digitiform in the
latter ; and in the relative position of the minute spiculate bodies investing
the animal, which in Mastigamoeba are described as generally placed
parallel with the surface.

. Dinamoeba seems also quite distinct from Dactylosphcerium vitreum of
Hertwig and Lesser,f which appears to be related with Mastigamoeba aspera,

* Archiv f. mikroskopische Anatomie, 1875, 583, Taf. xxxv.

t Archiv f. mikroskopische Anatomie, 1874, Sup. 54, Taf. ii, Fig. 1.

94 FBESH-WATEK RHIZOPODS OF NORTH AMERICA.

but, like the former, is devoid of the flagellum. Dactylosphserium is a
smaller animal than Dinamceba, of irregularly rounded form, and from
0.012 to 0.06 mm. in diameter. The pseudopods projecting in all directions
are somewhat conical and blunt. Two varieties are described, in one of
which the endosarc is occupied with multitudes of bright-yellow corpuscles;
in the other, with green corpuscles. In most examples of the variety with
green corpuscles, the body is covered with minute villi of protoplasm,
which, though simulating the minute spicules investing Dinamceba, are
clearly of a different character.

HYALODISCUS.

Greek, hualos, crystal ; discos, a quoit.
Hyalodiscus : Hertwig and Lesser, 1874. Plakopus : Schulze, 1875.

Body naked, discoidal, consisting of a colored granular endosarc, with
nucleus and vacuoles, and a clear colorless ectosarc, which in motion of the
animal extends in a broad zone beyond the colored mass of endosarc, and
projects pointed conical processes mostly few in number.

HYALODISCUS RUBICUNDUS.

Plate XLV, figs. 17, 18.

Hyalodiscus rubicundus. Hertwig and Lesser: Arch. mik. Anat. 1874, x, Supl. 49, Taf. ii, Fig. 5.
t Plakopus ruler. Schulze : Arch. mik. Auat. 1875, xi, 348, Taf. xix, Fig. 9-16.

Endosarc brick-red in color.
Size. — 0.03-0.06 mm. diameter.

In the outset of my studies of the Fresh- water Rhizopods, I met with
several specimens of what I suppose to be the curious colored amoeboid
form described by Hertwig and Lesser under the name of Hyalodiscus
rubicundus, but I have since seen no others. They were found in the
ooze of Cooper's Creek, New Jersey, in the month of May.

One of the specimens, shortly after being noticed, exhibited the appear-
ance seen in fig. 17, pi. XLV. It had an irregularly circular outline,
measured about 0.0625 mm. in breadth, and consisted of two portions.
One of these was an orange or light brick-red body with a variable number
of conical pointed processes ; the other was a thin, delicate, broad, cres-
centic band of clear colorless ectosarc embracing more than half the cir-
cumference of the former. The animal slowly glided in an amoeba-like
manner, in the direction of the pseudopodal expansion of ectosarc. In its

GENUS HYALODISCUS— HTALODISCUS RUBICUNDUS. 95

movements the red mass underwent more or less change of shape, the sur-
face at different points would rise and fall, and here and there the pointed
processes would be withdrawn and others would be projected. The band
of ectosarc also moved in a wave-like manner, extending and receding in
different positions.

The red mass of endosarc was composed of a basis of fine red granules
with a few larger ones of the same color but darker, and a few scattered
oil-like molecules. The central portion of the endosarc, from time to time,
exhibited a clearer circular spot, apparently indicating the presence of a
nucleus. There were also to be seen two or three small vacuoles, but I
failed to detect any movement in them.

Another specimen, found at the same time with the preceding, repre-
sented in fig. 18, was about half the size. It was of the same color, but
the endosarc contained a multitude of conspicuous globular colored corpus-
cles mingled with the finer granular basis. The clear colorless ectosarc
extended around the border of the colored endosarc, and projected a few
conical processes, into which none of the colored granular matter of the
latter readied. The movements of the animal were of the same character
as in the former specimen.

Plakopus ruber, described by Prof. Schulze, is probably identical with
Hyalodiscus rubicundus, as suspected by this author, though it is a very
much larger animal, and contains several nuclei. Prof. Schulze gives as
the size of the former from 0.2 to 0.6 mm.

DIFFLUGIA.

Latin, diffluo, to flow.

Difflugia : Leclerc, 1815. Arcella: Ehrenberg, 1841. Lecquereusia : Schlumberger, 1845. Bomceochlamys ;
Heterocosmia ; Exassula: Ehrenberg, 1871.

Shell very variable in shape, usually composed of extraneous angular
particles of hyaline quartz-sand, sometimes mingled with other bodies, such
as diatom-cases, sponge-spicules, etc.; the same forms sometimes composed
of chitinoid membrane incorporated with scattered extraneous particles or
composed in part or entirely of intrinsic particles of peculiar character.
Mouth inferior, usually terminal, rarely sub-terminal. Sarcodic mass com-
monly occupying the greater part of the capacity of the shell, attached by
threads of ectosarc to the interior of the fundus and sides, and by a pro-

96 FRESH- WATER RHIZOPODS OF NORTH AMERICA.

longation to the margin of the mouth. Nucleus single, situated near tne
fundus of the endosarc. Contractile vesicles several, situated at the
periphery of the latter, contiguous to the nucleus. Pseudopods usually up
to half a dozen or more, cylindrical, simple or branching, commonly
rounded at the ends, sometimes spreading and pointed.

DIFFLUGIA GLOBULOSA.

Plates XV, figs. 25-31; XVI, figs. 1-24.

Difflugia globulosa. Dujardin : An. Sc. Nat. 1837, viii, 311, pi. is, figs. 1 a, b; Hist. Nat. Infasoires, 1841,
248, pi. ii, fig. 6. Pritchard : Hist. Infusoria, 1861, 554, pi. xxi, fig. 10.

Difflugia proteiformis. Ehrenberg: Iufusionsthierchen, 1838, 131, Taf. ix, Fig. i; Micrographic Diet. 1860,
232, pi. 23, fig. 39.— Pritchard: Infusoria, 1861, 553.— Leidy: Proc. Ac. Nat. Sc. 1877,307.

Difflugia globularis. Wallich: An. Mag. Nat. Hist, xiii, 1864, 241, pi. xvi, figs. 1, 2, 17, 27. — Leidy: Proc.
Ac. Nat. Sc. 1877, 307, 321.

Difflugia proteiformis, subspecies!), globularis. Wallich: Ibidem.

Difflugia acropodia. Hertwig and Lesser: Arch. mik. Anat. 1874, x, Snpl. 107, Taf. ii, Fig. 6.

Shell spheroidal or oval, with the oral pole more or less truncated.
Mouth inferior, terminal, circular, usually truncating the shell; sometimes
more or less protruding or bordered by a short neck, rarely more or less
inverted. Shell commonly composed of quartz-sand, sometimes of diatoms,
and sometimes of chitinoid membrane usually incorporated with more or
less sand and diatoms. Sarcode, independent of the food, colorless.

Size. — Smallest specimen, with shell of sand, 0.036 mm. long by 0.03
mm. broad; with the mouth 015 mm. wide. Chitinoid specimens, with
diatoms and sand, from 0.024 mm. long by 0.032 mm. broad; with the
mouth 0.016 mm. wide, to 0.108 mm. long, 0.12 mm. broad; with the mouth
0.06 mm. wide. Largest specimens, of sand grains, 0.26 mm. long, 0.184
mm. broad, with the mouth 0.08 mm. wide.

Localities. — In the ooze of ditches and ponds frequent, in the vicinity
of Philadelphia, Pennsylvania, New Jersey, Maine, Rhode Island, Connec-
ticut, Florida, Alabama, Nova Scotia, Utah, and near Fort Bridger and
in the Uinta Mountains, Wyoming Territory. Small forms are not unfre-
quent on moist earth in bogs, meadows, and even, with algae and mosses, in
the crevices of the brick pavements of the city of Philadelphia.

Dujardin, in 1837, described a species with the name of Difflugia
globulosa, in which he says the shell is corneous, globular, and 0.1 mm.
long. Of the accompanying figures, one is ovoid, with the mouth at the
narrower end ; the other is represented as an upper view, and is oval, so

GENUS DIFFLUGIA— DIFFLUGIA GLOBULOSA. 97

that, if strictly correct, the shell would be compressed ovoid. Later, he
describes the shell as brown, globular, or ovoid and smooth; and the
accompanying figure is circular in outline, with pseudopods directed from
one pole.

Ehrenberg, in 1^38, described an oval form, the shell of which is
composed of quartz-sand, as Difflugia proteiformis, and attributes this name
to Lamarck. To the same he refers one of the three different forms
described by Leclerc as characteristic of the genus Difflugia. Lamarck,
however, applied the name of D. proteiformis to all the forms indicated by
Leclerc, without discrimination.

Of the three different forms noticed by Leclerc, one is readily recog-
nizable as Difflugia spiralis; a second, as D. acuminata; while the third,
referred to D. proteiformis by Ehrenberg, from its shape would appear
rather to associate itself with the D. piriformis of Dr Perty.

Dr. Wallich describes a more or less globular form, the shell of which
is composed of quartz-sand, or this together with diatoms, as a subspecies
of D. proteiformis, with the name of D. globularis. This name he attributes
to Dujardin, evidently in mistake for that of D. globulosa.

Difflugia globulosa, as I have supposed it to be, is not uncommon in the
ooze of ponds and ditches, and the smallest examples are frequent among
moss, algae, and other plants in damp shaded places.

The shell varies in shape from oval to ovoid and subpyriform, and to
spheroidal and oblate spheroidal, as seen in figs. 25-31, pi. XV, and figs.
1-24. pi. XVI. The oral pole of the shell is more or less truncated,
and the mouth is large, circular, entire, inferior, and commonly terminal.
Mostly it forms the truncation of the oral pole, but sometimes the latter is
more or less inflected, and the mouth becomes elevated above the level of
the bottom of the shell. Less frequently, the mouth is more or less pro-
jected, so as to produce a short neck to the shell. Oval or ovoid varieties
of the shell merge into forms which may be regarded as pertaining to
Difflugia pyriformis.

Oblate spheroidal shells, with the oral pole more or less inflected to
the mouth, resemble in shape the shell of a sea-urchin, Echinus.

In structure, the shell, as usual in other species of Difflugia, is com-
posed of particles of quartz-sand, as represented in most of the figures
above indicated. The smallest specimens frequently consist of chitinoid

7 RHIZ

98 FRESH- WATEE RHIZOPODS OF NORTH AMERICA.

membrane incorporated with variable proportions of sand grains, as
seen in figs 13-17, pi. XVI. Specimens, found in spbagnous swamps,
sometimes consist of cbitinoid membrane incorporated with variable pro-
portions of diatoms, or fragments of the same, with sand grains and other
particles of a less determinate character, as represented in figs. 9, 10, 18,
19, pi. XVI. Specimens are also found, in the same situations, composed
almost entirely of diatoms, as represented in figs. 21, 22. The larger shells
of Difflugia globulosa, composed of quartz-sand, are commonly colorless,
but may be more or less yellowish or brownish, apparently due to ferrugi-
nous staining. Occasionally specimens are seen, like those of figs. 23, 24,
in which the cementing material of the sand particles exhibits a deeper
stain of the same kind. The smallest shells are more commonly of a
yellowish hue.

In my experience it has occurred to meet with dead shells of D.
globulosa more frequently than with living specimens.

The sarcode of D. globulosa, independent of food contents, is colorless.

Difflugia globulosa through intermediate forms merges into D. pyriformis,
and I suspect also into D. lobostoma. The small oblate-spheroidal forms,
with inflected base, especially when mainly composed of chitinoid mem-
brane, are scarcely distinguishable from Arcellas. I have also seen speci-
mens in which the mouth was more or less eccentric, and I was uncertain
whether to refer them to the species under consideration, or whether to
regard them as pertaining to Difflugia constricta, or the spineless form of
Centropyxis aculeata.

The range of size is considerable. The smallest specimens, found
among moist earth, measured about 0.036 mm. long by 0.03 mm. broad,
with the mouth 0.015 mm. The largest specimens, from the ooze of a pond,
measured 0.3 mm. in diameter, with the mouth 0.16 mm.

DIFFLUGIA PYRIFORMIS.

Plates X; XI; XII, figs. 1-18; XV, figs. 32,33; XVI, fig. 38; XIX, figs. 24-26.

Difflugia. Leclerc : M6m. Mus. Hist. Nat. 1815, ii, 474, pi. 17, fig.

Difflugia pyriformis. Perty : Mittheil. Naturf. Gesells. Bern, 1848, 1G8 ; Kennt. kleinst. Lebensformen,

1852, 187, Tab. ix, Fig. 9.— Pritchard : Hist. Infusoria, 1861, pi. xxi, fig. 17.— Carter: An.

Mag. Nat. Hist, xii, 1863, 249; xiii, 1864, 21, pi. i, fig. 1.— Wallich: An. Mag. Nat. Hist.

xiii, 1864, 240, pi. xvi, figs. 9, 10, 39, 40.— Ehrenberg : Ab. Ak. Wis. Berlin, 1871, 264.—

Leidy : Pr. Ac. Nat. So. 1874, 14, 79 ; 1877,307.
Difflugia proteiformis. In part of Lamarck and Ehrenberg = Leclerc's figs. 2, 3, pi. 17, Mem. du Mus.

d'Hist. Nat. ii, 1815.

GENTTS DUTLUGIA— DIFFLUGIA PYKIFOEMIS. 99

Difflugia ? Carter : An. Mag Nat. Hist, xiii, 1864, 29, pi. i, fig. 11.

Difflugia proteiformis, subsp. D. milriformis, var. D. pyriformis. Wallicb: An. Mag. Nat. Hist, xiii, 1864,

240.
Difflugia compressa. Carter : An. Mag. Nat. Hist, xiii, 1864, 22, pi. i, figs. 5, 6. — Leidy : Proc. Ac. Nat.

Sc. 1874, 14 ; 1875, 307.
D. Corticella pyriformis. Ehrenberg: Abh.Ak. Wis. Berlin, 1871,247.
Difflugia entovhloris. Leidy: Proc. Ac. Nat. Sc. 1874,79; 1875,307.
Difflugia vas. Leidy : Pr. Ac. Nat. Sc. 1874, 155 ; 1875, 307.
Difflugia nodosa, var. of pyriformis. Leidy : see following pages.
Difflugia cornuta, var. of pyriformis. Ibidem.

Shell pyriforrn, flask-shaped, or ovoid, with the narrower pole prolonged
into a neck of variable length, of uniform transverse diameters, or more or
less compressed ; fundus obtusely rounded or subacute, or more or less ex-
panded and variably produced into from one to three conical processes; neck
gradually and evenly narrowed to the oral end, cylindroid, sometimes con-
stricted ; mouth inferior, terminal, circular, or slightly oval. Structure of
the shell usually of angular particles of quartz-sand, sometimes mingled
with diatoms ; less frequently composed of chitinoid membrane, with vari-
able proportions of diatoms and sand. Sarcode mostly with the endo-
sarc bright green, from the presence of chlorophyl grains, but often color-
less, except as modified by the presence of food.

Size. — Ranging from 0.06 to 0.58 mm. long, 0.04 to 0.24 mm. broad ;
mouth 0.016 to 0.12 mm. wide.

Locality. — rEverywhere in the ooze of ponds, ditches, and bogs.

Observed in Pennsylvania, New Jersey, Rhode Island, Connecticut,
Florida, Alabama, Nova Scotia, Colorado, Utah, Fort Bridger, and Uinta
Mountains, Wyoming.

Variety 1. — D. pyriformis ; the ordinary characteristic form, with the
opposite diameters uniform. See pi. X.

Variety 2. — D. compressa ; like the preceding, but more or less com-
pressed. See pi. XI, figs. 1-6; pi. XII, figs. 10-16.

Variety 3. — D. nodosa ; usually a large form like the latter, but with
the fundus variably produced into from one to three eminences.
See pi. XI, figs. 7-22.

Variety 4. — D. cornuta ; pyriforrn, with the fundus provided with one
or two pointed conical processes. See pi. XII, figs. 17, 18.

Variety 5. — D. vas; like the ordinary form, but with the neck defined
from the body by a constriction. See pi. XII, figs. 2-9.

100 FRESH- WATER RHIZOPODS OF NORTH AMERICA.

Difflugia pyriformis is one of the most common species, and it
presents much variety of shape and size.

The shell is ordinarily flask-like or baloon-form, or, as indicated by
the specific name, pear-shaped, with an oval or ovoid body more or less
gradually prolonged into a neck, which tapers to the mouth or is cylindroid,
and of variable proportionate length. Usually the shell is of uniform
diameters, but is sometimes more or less compressed so as to be wider in
one direction. Occasionally specimens occur exhibiting some want of
bilateral symmetry. The fundus of the shell is mostly regularly rounded,
but sometimes is more or less subacute. The mouth is inferior, terminal,
and circular or oval.

Characteristic specimens of the ordinary forms, exhibiting considerable
variety in exact shape, size, and structure, are represented in pi. X.

Specimens of Difflugia pyriformis of the ordinary kinds have a wide
range in size. Some of the smallest measure only the 4 -^th of an inch,
while large ones reach ten times that length.

Compressed forms of D. pyriformis, constituting what I have viewed as
the variety — and agreeing with Mr. Carter's species — D. compressa, are
unfrequent compared with those with more uniform diameters. Interme-
diate conditions occur, showing the gradation of one form into the other.
In D. compressa, the shell exhibits variable degrees of compression, some-
times comparatively little, at others to such an extent that the shell is twice
the breadth in one direction that it is in the other. The length usually
exceeds the greater breadth, but rarely the latter actually exceeds the
former. Specimens exhibiting various degrees of relative breadth are
represented in figs. 10-16, pi. XII.

The size of compressed specimens I have found to range as follows :
Length j|.th to ^th of an inch ; greater breadth ± th to ^th of an inch ;
lesser breadth ^th to Jgth of an inch ; with the oral end ^th to ^th of an
inch in the greater width.

A striking variety of D. pyriformis, certainly not distinct from this as a
species, I have named D. nodosa. It is not an unfrequent associate with
the more ordinary form, and is distinguished by its usually large size, its
more or less compressed form, and its broad fundus, which is produced
into from one to three knobs or conical eminences, varying greatly in
degree of development.

GENUS DIFFLUGIA— DIFFLTTGIA PYRIFORMIS. 101

In the summer of 1874, I found this variety in extraordinary profusion
in Swarthmore brick-pond, and all the specimens of pi. XI were derived
from this locality. The subsequent two seasons I could find none of the
kind in the same pond, but in 1877 it again appeared in moderate quantity.

When first discovered, the specimens were so abundant that a drop of
ooze, in which the animal lived, would often contain several dozen indi-
viduals.

They were remarkable for their large size, and the bright green color
and activity of the animal. Notwithstanding the great number of indi-
viduals, scarcely two could be found in all respects alike. The general
shape was that of the ordinary B pyriformis, usually more or less com-
pressed ; but the proportions varied considerably. Commonly the breadth
was nearly or quite double in one direction what it was in the other ; but
sometimes the compression was trifling, when the shell presented the
ordinary form of B. pyriformis. Commonly the greatest breadth occupied
the upper third or fourth of the shell.

In the view of the specimens from the narrower side, the shape was
pretty uniformly pyriform. In the view from the broader side, the lateral
border varied from an inclined plane to a concave line, while the fundus
varied exceedingly; sometimes from evenly convex to obtusely angular;
sometimes from horizontally straight to concave ; sometimes with a single
median eminence, a pair of lateral eminences, or a transverse row of three,
and all variable in their proportions. Unsymmetrical forms also occurred,
in which the knobs or eminences on one side of the shell were dispropor-
tionately produced.

The size of the knobby specimens, from Swarthmore pond, ranged as
follows: the smallest specimen was id of an inch long; ith of an inch in
the greater, and ith of an inch in the lesser breadth. A large specimen
measured jjth of an inch long ; ^th of an inch in the greater, and ^th of
an inch in the lesser breadth, with the oral end ^th of an inch wide

In my early observations on the variety B. nodosa, I was led to view
it as a species distinct from B. pyriformis, and from the bright green color
of the endosarc I named it B. entocJUoris.

Another variety of Bifflugia pyriformis, which I formerly supposed to
be a distinct species, I named B. vas. It has the shape of the more charac-
teristic specimens of B pyriformis. but has the neck defined from the body

102 FRESH- WATER RHIZOPODS OF NORTH AMERICA.

by a narrow constriction, as seen in figs. 2-9, pi. XII. I think there can
be but little doubt that this variety and the ordinary more familiar form of
D. piriformis merge into one another ; and I have met with various inter-
mediate forms. See figs. 24-26, pi. XIX.

The specimens vary greatly in size, and this is also the case in the
proportions of the body and neck of the shell. Ordinarily those from
Absecom pond range from ifh to ith of an inch in length. The smallest
specimen observed, from Swarthmore brick-pond, was ith of an inch long
and ith of an inch broad. The largest one, from Absecom pond, was
55th of an inch long by ^th of an inch broad.

Still another variety which I have occasionally seen is represented in
figs. 17, 18, pi. XII. It may be distinguished as B. cornuta, and has the
characteristic form of D. pyriformis, but has the fundus provided with one
or two conical spines. This variety I have observed to approximate by
intermediate forms the more characteristic ones of D. acuminata.

The shell of Difflugia pyriformis is commonly composed of coarse,
irregular grains of hyaline quartz-sand, and is often the roughest of its
kind; though sometimes, considering the coarseness of the materials, the
shell is wonderful for its evenness. The shell may be composed altogether
of comparatively large stones, or it may be partly constructed of these
more or less uniformly distributed, with the intervals filled in with smaller
ones. Sometimes the larger stones especially occupy the fundus or the
greater part of the body, and the neck is composed of smaller ones; some-
times the arrangement is reversed, and sometimes the largest stones are
arranged contiguous to the mouth. Not unfrequently one or several stones
greatly exceed the others, and produce conspicuous unsymmetrical projec-
tions in the shell, as seen in figs. 6-9, 12-15, pi. X; figs. 37, 38, pi. XVI.

It may not be unworthy of remark, that the coarsest and most uneven
specimens are found together in association with the smoothest, in the
same localities and apparently under the same circumstances.

Less frequently the shell of Difflugia pyriformis is constructed of an
intermixture of quartz-sand and diatoms in varying proportions, usually
the former predominating, but sometimes the latter. Large naviculas are
often conspicuous among the building materials, and occasionally spicules
of the fresh-water sponge are noticed with them. Such specimens are
represented in figs. 13, 15, 18-21, pi. X. Sometimes the shell of D. pyri-

GENUS DIFFLUGIA— DIFFLUGIA PYEIFOEMIS. 103

formis consists of chitinoid membrane, colorless or straw-colored, and
having incorporated variable quantities of diatoms and sand, as seen in figs.
22-26, pi. X. Specimens of this kind, of the smallest size, occasionally
met with, are remarkable for the great proportionate size of the adherent
diatoms, as seen in figs. 22, 23, reminding one of the cases of the basket-
worm (Thyridopteryx), often seen suspended from the branches of the arbor-
vitse and other trees.

Rarely I have seen a Difflugia, referable to D. pyriformis, in which
the shell appeared to be composed of chitinoid membrane incorporated
with flocculent black matter, apparently from the sediment of the locality
in which the creature was found. Such a specimen is represented in fig.
27, pi. X.

The shell of D. pyriformis, in all the specimens included as varieties
under the names of D. compressa, D. nodosa, D. vas, and D. comuta, as seen
in the various figures of these, in plates XI and XII, was composed exclu-
sively of angular particles of quartz-sand. Rare, indeed, is it to see a
rounded particle of quartz-sand entering into the construction of the shell
of any Difflugia ; but an example of one such shell, pertaining to D. pyri-
formis, exhibiting several rounded sand grains, is seen in fig. 15, pi. X.

The interior sarcode of Difflugia pyriformis, as usual in the genus from
the nature of the shell, is greatly obscured from view. Commonly, the
greater portion of the mass occupying the body of the shell is of a bright
green color due to the presence of an abundance of chlorophyl granules,
which appear to be an intrinsic element of structure of the endosarc.
Less frequently the sarcode appears to be in greater part or even entirely
colorless, except that the central portion may be more or less colored
by the presence of food contents.

The expressed sarcode of I). pyriformis usually exhibits a faintly
granular and colorless basis mingled with variable propoi-tions of bright
green chlorophyl granules, and others which are colorless and darkly defined
and resemble starch. Besides these, there may be seen a large and clear or
faintly granular nucleus, together with the varied constituents of the food.
In individuals with uncolored sarcode, the chlorophyl granules are absent,
and such also appears to be the case with most of the starch-like granules.
Sometimes, in the bright green specimens, the expressed nucleus exhibits a
uniform and distinct granular appearance. Mr. Carter, in an account

104 FRESHWATER RHIZOPODS OF NORTH AMERICA.

of the structuie of the sarcode of Difflugia piriformis, indicates two dif-
ferent conditions or stages as above described. The chlorophyl granules,
when present, he regards as part of the structure of the animal, as much so
as the same colored element is, in the green fresh-water polyp (Hydra
viridis). Colorless granules, in association with the green ones, he deter-
mined to be of the nature of starch, and these he also regards as part of
the structure of the animal. In the colorless stage of the latter he further
intimates the absence of the chlorophyl and a diminution in the quantity
of the starch.*

According to the same able investigator, the green condition of the
sarcode is associated with greater activity of the animal, and is especially
common in the spring season; while the colorless condition, indicative of
more passive habit, occurs in autumn. The changes in color he supposes
to be connected with changes in the nucleus, and to be related with the
reproductive process.

The Swarthmore specimens, above mentioned, found in such profusion
in the summer of 1874, were all possessed of a bright green endosarc, and
were in the most active condition. Neither before nor since have I met
with any form of Difflugia which exhibited more lively movements, and
such varied changes in the appearance of the pseudopods Extreme
extension of the latter was accompanied by an influx of more or less of the
endosarc with chlorophyl and starch-like granules. Of the many changes
presented by the pseudopods, examples are given in the figures of pi. XI.

While it has occurred to me to see multitudes of Difflugia pyriformis in
all its varieties of the ordinary form, and of D. compressa, D. nodosa, and D.
vas, with the sarcode in a bright green condition, at all temperate seasons
of the year, I have also observed them in the colorless condition in variable,
but comparatively small, proportion, at the same times and in the same
localities. The animal is also to be seen of every grade, from that in which
the body of the shell appears in greater part to be occupied by a bright
green endosarc, to that in which all color is absent except what is due to
the presence of food. Commonly, when the bright green specimens of D.
pyriformis are abundant, the uncolored ones are comparatively few. I have
further observed bright green specimens of D. pyriformis, in which the sar-
code was not only in a passive condition, but was contracted into a central

* Annals and Magazine of Natural History, xii, 18fi:i, 249.

GENUS DIFFLUGIA— DIFFLUGIA PYRIFORMIS. 105

ball occupying the body of the shell. Not unfrequently specimens appear
as if the color of the sarcode, as it is ordinarily seen, had undergone a change
into a yellowish or brownish hue.

Bifflugia pyriformis was first described with this name by Perty,* from
specimens collected in Switzerland. Two of the figures accompanying
Leclerc's original description of the characters of the genus Difflugia appear
to belong to the same.f These figures EhrenbergJ refers to his own D.
proteiformis, attributing the name to Lamarck, § who, however, applied it
without discrimination to all the forms, comprising three distinct ones, de-
scribed by Leclerc as representing the genus. Ehrenberg's figures and
description of D proteiformis,\\ as I have before intimated, appear rather
to apply to the D. ghbulosa of Dujardin.H Ehrenberg remarks of D.
oblonga, described and figured in the 'Infusionsthierchen' as a form with a
purely chitinoid shell, that if it is the same as the D. pyriformis, of Perty,
deprived of its incrusting material, as intimated by Claparede and Lach-
mann, the latter name should be disused.** This would be just, if we could
be positive of the relation of D. oblonga with D. pyriformis ; but in its shape
it appears rather to be related with D. acuminata without its point. Carterff
and WallichJJ describe Bifflugia pyriformis as occurring both in England
and India. The latter author refers the more ordinary form, as a variety,
to a subspecies which he names D. mitriformis. Figures of the latter, with
one or two points to the fundus, he refers to D. acuminata as another variety
of D. mitriformis.§§

Lang describes a form under the name of D. triangulata, the figures of
which remind me of the knobby variety of D. pyriformis. The shell is
described as triangular, flat, membranous, and reticulated. ||||

Difflugia pyriformis by gradual transition merges into D. ghbulosa, D.
acuminata, etc.

* Keant. kleinst. Lebensformen, 187.

tMem. Mus. Hist. Nat. ii, 1815, pi. 17, figs. 2,3.

t Infusionsthierchen, 131.

§ Animaux sans Vertebres.

|| Infusionsthierchen, Taf. is, Fig. i.

f An. Sc. Nat. 1837, viii, 311, pi. ix, fig. 1; Hist. Nat. Infusoires, 248, pi. ii, fig. 6.

•*Abh. Ak. Wis. Berlin, 1871,256.

tt An. Mag. Nat. Hist, xii, 1803, 249.

tt Ibid, xiii, 1864, 240.

U Ibid. pi. xvi, figs, 7, 8, 12 b.

Illl Quart. Jour. Mic. Sc. v, 1865, 285.

106 FEESH-WATEE EHIZOPODS OF NOETH AMEEICA.

DIFFLUGIA URCEOLATA.

Plates XIV; XVI, figs. 32-34; XIX, figs. 28, 29.

Difflugia urceolaia. Carter : An. Mag. Nat. Hist, xiii, 1864, 27, 37, pi. i, fig. 7.— Leidy : Pr. Ac. Nat. So.

1877, 307.
Difflugia lageniformis. Wallich: An. Mag. Nat. Hist, xiii, 1864, 240, pi. xvi, figs. 15, 16.— Leidy: Pr. Ac.

Nat. Sc. 1874, 14.
Difflugia proteiformis, subspecies D. rnitrifomiis, var. D. lageniformis. Wallich : Ibid.
Difflugia amphora. Leidy : Proc. Ac. Nat. Sc. 1874, 79.
Difflugia olla. Leidy: Proc. Ac. Nat. Sc. 1874, 156; 1877,307.

Shell amphora-form ; body spheroid, ovoid, or ovate, with the fundus
obtusely and evenly rounded, or more or less acute, or acuminate, and
rarely furnished with several usually blunt spines ; neck short, more or less
contracted ; mouth large, circular, terminal, with or without a rim of varia-
ble breadth, usually reflected and terminating in a thin delicate edge. Struc-
ture of the shell commonly of hyaline quartz-sand ; rarely of chitinoid
membrane with variable proportions of diatoms and sand. Sarcode color-
less ; pseudopods many, digitate, simple, and branching.

Size. — Of the spheroid forms, from 0.18 mm. to 0.44 mm. long by 0.14
mm. to 0.38 mm. broad; of the ovoid forms, 0.2 mm. to 0.52 mm. long by
0.14 mm. to 0.36 mm. broad.

Locality. — Ditches and ponds in the vicinity of Philadelphia ; ponds of
sphagnous swamps in New Jersey ; pools and ponds at Fort Bridger, on
Bridger Butte, and in the Uinta Mountains, to an elevation of 10,000
feet, Wyoming Territory.

Difflugia urceolata was originally described by Mr. Carter from
specimens found in England. It is represented as of oval form, slightly
prolonged to form a short neck, and with a rim slightly reflected. Its size
is stated at ±d of an inch in length and id of an inch in breadth.

The species was described the same year by Dr. Wallich, likewise from
specimens found in England, under the name of Difflugia lageniformis. It
is represented of oval form, with a short contracted neck and a strongly
reflected lip.

Difflugia urceolata is the largest species of the genus, and is common in
the ooze of ditches traversing the meadows below the city of Philadelphia,
and communicating with the Delaware and Schuylkill Rivers. It is also
frequent in the ponds of sphagnous swamps, such as those of Atco, and

GENUS DIFFLUGIA— DEvTLUGIA UECEOLATA. 107

Absecom, and Lake Hatacawanna, New Jersey; and I also found it abun-
dantly in ponds of the Uinta Mountains, Wyoming Territory.

Ordinarily the shell of Difflugia urceolata strikingly resembles the
ancient Roman amphora. The body of the shell varies from a globular
shape to a more or less ovoid form. The upper extremity, or fundus, is
obtusely rounded or more or less acute, and sometimes it is rounded and
more or less acuminate.

The neck is a short and slight cylindrical constriction from the body.
The mouth is large and circulai-, and frequently truncates the neck ; but,
mostly, it is surrounded by a lip of variable breadth, usually more or
less reflected, and terminated by a thin delicate edge. Sometimes the neck
is more or less everted, and terminates at the mouth without extending in a
circular lip or rim. PI. XIV, figs. 1-8 ; pi. XVI, figs. 33, 34.

The size of the spheroidal forms of D. urceolata ranges from about the
Jjth to the ^ th of an inch in diameter ; the ovoid forms measure from the
jith to the -^th of an inch in length.

In the ponds of sphagnous swamps of New Jersey, a variety of D.
urceolata is common, in association with the more ordinary forms, in which
the fundus of the shell is provided with usually from three to half a dozen
nipple-shaped spines. This constitutes the variety I formerly named D.
olla. The shell is commonly of the shape of the spheroidal form of D.
urceolata. The spines are mostly blunt, and often terminate in a single
stone flake of greater width than the spine at its point of attachment.
They are arranged in a circle, more or less regular, around the fundus,
usually unaccompanied by a central spine, though occasionally also there
is one in this position. They are mostly shorter, less acute, and less eccen-
tric than the conical spines in a similar position in D corona.

Examples of the variety named D. olla are rej:>resented in figs. 10-13,
pi. XIV; fig. 32, pi. XVI ; and figs. 28, 29, pi. XIX.

The shell of Difflugia urceolata is composed, as is generally the case in
other species of the genus, of colorless angular particles of quartz-sand,
mostly of larger ones scattered with some appearance of regularity, while
the intervals are occupied with smaller ones. The surface of the shell,
though often uneven, is less so commonly than in some of the smaller
species of Difflugia. Frequently larger stones occupy the neck of the shell,

108 FRESHWATER RHIZOPODS OF NORTH AMERICA.

but passing thence they gradually become smaller approaching the edge
of the rim or reflected lip.

Only in the variety with spines to the fundus, previously indicated as
D. olla, from the sphagnous ponds of New Jersey, have I seen a few speci-
mens in which the shell was composed of colorless chitinoid membrane,
incorporated with diatoms and fine sand grains, as seen in fig. 29, pi. XIX.

The interior sarcode of D. urceolata, in all its variety of forms and in
all seasons, I have found to be colorless, independently of the hues given
to the central portion of the endosarc by the varied nature of the food.
The pseudopods are ordinarily from two or three to half a dozen, and of
the usual simple digitate kind.

Difflugia urceolata by transitional forms merges into D. acuminata.

DIFFLUGIA CRATERA.

Plates XII, figs. 19-21 ; XVI, fig. 35.
Difflugia cratera. Leidy: Proc. Ac. Nat. Sc. 1877, 307.

Shell goblet-shape, with oval or spheroidal body and wide cylindroid
neck; fundus obtuse; mouth terminal, large, circular, truncating the neck,
or with a reflected rim. Composed of colorless chitinoid membrane, incor-
porated with minute particles of sand and dirt.

Size. — Length 0.056' mm. to 0.066 mm.; breadth of body 0.036 mm.
to 0.042 mm.; breadth of neck 0.028 mm. to 0.036 mm.

Locality. — Among Ceratophyllum and other aquatic plants. Canal at
Bristol, Berks County, Pennsylvania; Buffalo, New York.

Difflugia cratera is one of the smallest species of the genus, and,
though apparently rare, may be common enough, but have escaped frequent
observation from its diminutive size. I first found it among hornwort, col-
lected in the canal at Bristol, Pa., August, 1876, and noticed about a dozen
individuals. I have since met with it recently, August, 1878, in some
sediment from the water-supply of Buffalo, New York. The sediment
sent to me, on a glass slip, for examination, consisted mainly of the
curious four-spined infusorian, Ceratium longicome, and with it I detected
two individuals of Difflugia cratera. All the specimens observed appeared
to be empty shells, though it is not improbable some of them may have
contained the living sarcode, which, being contracted and transparent,
escaped notice.

GENUS DIFFLUGIA— DIFFLUGIA CRATERA. 109

Later, October, 1878, in an additional supply of sediment, received
from Buffalo, in association with Ceratium longicorne, I observed a number
of specimens of the same little Difflugia.

The Bristol specimens of Difflugia cratera varied but slightly in any
respect. The shell, as represented in figs. 19, 20, pi. XII, was goblet-
shaped, with the body and neck of nearly equal length. The body, a little
longer than the neck, was ovoid, with the narrower pole forming the
fundus of the shell. The neck was wide, cylindroid, and slightlv ex-
panded approaching the mouth, which was large, circular, and terminal.

The Buffalo specimens differed considerably from the former, as well
as among themselves, as seen in fig. 21, pi. XII, and fig. 35, pi XVI. The
beautiful goblet-shaped shells varied in the proportionate length of the body
and neck. The former was more or less oblately spheroidal, and the
latter longer or shorter than the body, and expanded in variable degrees
approaching the mouth.

In all the specimens, from both localities, the shell was composed of
colorless chitinoid membrane, which exhibited a minutely wrinkled appear-
ance, and sparsely scattered over the surface there were a few minute
sand grains and fine particles of dirt.

The Bristol specimens measured about 0.056 mm. in length ; the Buf-
falo specimens ranged from 066 mm to 0.0^2 mm. in length.

Since the above was written, it has occurred to me that the minute
shells, referred to Difflugia cratera, may perhaps pertain to a species of
ciliated infusorian, of the genus Tintinnus.

DIFFLUGIA ACUMINATA.

Plate XIII.

Difflugia. Leclerc : M<Sm. Mns. Hist. Nat. ii, 1815, 474, pi. 17, fig. 5.

Difflutjia acuminata. Ehrenberg : Infusionsthierchen, 1838, 131, Taf. ix, Fig. iii. — Perty: Kennt. kleinst.

Lebensformen, 1852, 187.— Leidy : Pr. Ac. Nat. Sc. 1874, 14, 79; 1877, 307.
Difflugia acuminata, var. acaulis. Perty : Ante, 187, Taf. ix, Fig. 6.
Difflugia bacitlariarum. Perty: Ante, 187, Taf. ix, Fig. 7.
Diffluqia piriformis. Carter: An. Mag. Nat. Hist, xii, 1863,251; xiii, 18G4, 36, " acuminated variety,"

pi. i, fig. 1 I.
Difflugia proteiformis, var. acuminata. Wallich: An. Mag. Nat. Hist, xi, 1863, 453, pi. x, fig. 13.

Difflugia ? Carter: An. Mag. Nat. Hist, xii, 1864, 29, pi. i, fig. 10.

Difflugia proteiformis, subspecies D. mitriformis, var. D. acuminata. Wallich: An. Mag. Nat. Hist, xiii,

1864, 240, pi. xvi, figs. 11, 12.
D. CorticeUa acuminata. Ehrenberg : Abh. Ak. Wis. Berlin, 1871, 247.

Shell amphora-form or oblong oval, pyriform, or cylindroid with the
upper part more or less inflated ; fundus acute, acuminate, or prolonged

110 FRESH- WATER EHIZOPODS OF NORTH AMERICA.

into a nipple- shaped process, rarely with two or three points ; neck long,
short, or none; mouth large, terminal, circular; lip usually straight. Com-
posed of angular quartz-sand, sometimes with intermingled diatoms, rarely
of the latter altogether, sometimes of chitinoid membrane with scattered
sand and diatoms. Sarcode colorless ; pseudoj:>ods as usual in the genus.

Size. — Smallest specimens with shell of sand were 0.1 mm. long,
0.048 mm. broad, and 0.032 mm. wide at the mouth; large pyriform
specimens of sand, 0.4 mm. long, 0.184 mm. broad, and 0.064 wide at the
mouth; largest cylindroid ones of stones, 0.520 mm. long, 0.12 mm. broad,
and 0.1 mm. wide at the mouth. Smallest specimens with the shell of
diatoms measured about 0.084 mm. long, 0.036 mm. broad, and 0.024 mm.
at the mouth.

Locality. — Ditches near Philadelphia, Swartkmore pond, Darby pond,
Pennsylvania ; Absecom pond, and ponds of Atco, Kirkwood, and other
spbagnous swamps of New Jersey ; ponds at Fort Bridger and Uinta
Mountains, Wyoming Territory. France, Leclerc ; Berlin, Ehrenberg ;
Switzerland, Perty ; England, Carter and Wallich.

The shell of DaSSlcayin acuminata in shape is like an ancient Roman
amphora, or is oblong oval, gradually narrowing toward the oral extrem-
ity, and acute or tapering at the summit ; or it is pyriform, with the fundus
in the latter condition ; or it is cylindroid, more or less inflated above, and
tapering at the fundus. See pi. XIII. The mouth is terminal, circular,
and large, with the lip straight or slightly contracted and rarely slightly
everted. In one instance only, as seen in fig. 12, have I seen it surrounded
by a projecting rim. The shell either narrows from the body gradually
and regularly to the mouth, or more or less abruptly, forming a neck of
variable length, sometimes short, sometimes long, and of every interme-
diate degree. The longer-necked varieties present us with the pyriform
and drop-tube-like shells.

The fundus of the shell presents various degrees of acuteness, passing
into a more or less acuminate condition or prolonged into a nipple-like pro-
cess, which may be short and thick, or long and narrow. The process is
usually straight, but is often bent to one side, and sometimes occupies
a position unsymmetrically to one side. Rarely there are two or three
processes to the fundus, as seen in figs. 25-29, pi. XII.

The amphora-like specimens of Difflugia acuminata graduate into D.

GENUS DIFFLUGIA— DIFFLTTGIA ACUMINATA. Ill

urceolata, and the pyriform varieties into D. pyriformis, while the drop-
tube-like forms are the most peculiar or characteristic.

The shell of Difflugia acuminata is ordinarily composed of clear quartz-
sand, as in D. pyriformis. Occasionally I have seen particles of garnet
mingled with the former, as represented in figs. 14, 15, pi. XIII. Some-
times the quartz-sand is mingled with variable proportions of diatoms.

Not unfrequently the shell is composed of colorless chitinoid membrane,
incorporated with quartz-sand alone or with this and intermingled diatoms.
In this kind usually the grains of sand are closely placed in juxtaposition at
and near the mouth of the shell, but are elsewhere scattered and separated
by wide intervals. In some cases, the shell is more or less covered with
large diatoms, generally adherent in the length, and diverging upward
beyond the boundary of the shell, as seen in figs. 21, 22.

Certain specimens found among sphagnum consisted entirely of dia-
toms, as seen in figs. 23-26, in most cases (which is unusual) still retaining
portions of the endochrome.

The sarcode of Difflugia acuminata is colorless, excepting the usual
coloring in the endosarc dependent on the presence of food, though I
have met with an individual, as seen in fig. 15, in which the endosarc was
bright green. In this case the color may have been due to the food, as
the specimen was obtained from among an abundance of green alga?. It
should be mentioned, however, in this relation, that most of the specimens
from which drawings were made were empty shells, chosen on account of
their comparative translucency and distinctness of structure.

The range of size of Difflugia acuminata is considerable. The smallest
ones observed are those composed of diatoms, from sphagnum. These are
about the ^th of an inch in length by the Jgth of an inch in breadth.

One of the smallest amphora-like shells, composed of sand, measured
the o J th of an inch long by the 3 ^th of an inch broad. One of the largest
amphora-like shells, composed of sand, measured the ith of an inch long
by the ^th of an inch broad ; and one of the largest pyriform shells had
nearly the same measurement. The largest drop-tube-like shell measured
nearly the ith of an inch long by the ^th of an inch in breadth.

Difflugia acuminata is one of the commonest of the genus, and is found
almost everywhere with other familiar kinds of Difflugia. It is one of
the three forms originally indicated and figured by Leclerc as character-

112 FRESH- WATER RHIZOPODS OF NORTH AMERICA.

istic of the genus. It was described and figured by Ehrenberg in the
'Infusionsthierchen,' and was first specifically named by him. It was also
figured and described under the same name by Perty, and subsequently
likewise by Carter and Wallich.

Perty represents a specimen in which the shell appeal's to be composed
of chitinoid membrane incorporated with scattered quartz grains. He
also figures and describes another under the name of Difflugia baciUariarum,
which appears to be a variety of D. acuminata in which the shell is com-
posed of diatoms.

DIFFLUGIA LOBOSTOMA.

Plate XV, figs. 1-24; XVI, figs. 25-29.

Difflugia prottiformis. Carter: An. Mag. Nat. Hist, xviii, 1856, 128.

Difflugia tricuspis. Carter: An. Mag. Nat. Hist, xviii, 1856, 221, pi. vii, fig. 80. — Ehrenberg: Ab. Ak.

Wis. Berlin, 1871, 264.
Difflugia oblonga. Fresenius: Abh. Senckenb. Naturf. Gesells. ii, 1856-8, 225, Taf. xii, Fig. 43-45.
D. Exassula tricunpis. Ehrenberg: Abb. Ak. Wissens. Berlin, 1871, 246,
Difflugia lobostoma. Leidy: Pr. Ac. Nat. Sc. Phil. 1874, 79; 1877, 307.
Difflugia cnnulata. Leidy: Pr. Ac. Nat. Sc. Phil. 1874, 79.

Shell ovoid, oval, or nearly spherical, usually composed of quartz-
sand, rarely in part or wholly of diatoms or of chitinoid membrane with a
few quartz particles; mouth terminal, usually from three- to six-lobed,
occasionally more; fundus obtusely rounded. Sarcode colorless, or with
the endosarc colored green from the presence of abundance of chlorophyl
granules; pseudopods to half a dozen or more, and exhibiting the usual
shape and changes as in other species.

Size. — Ordinarily about 0.12 mm. long and 0.1 mm. broad, with the
mouth 0.032 mm. wide. Eanging from 0.08 mm. long by 0.06 mm. broad,
with the mouth 0.024 mm. wide, to 0.14 mm. long by 0.128 mm. broad, with
the mouth 0.048 wide.

Locality. — Ponds and ditches in the vicinity of Philadelphia; Swarth-
more brick-pond, and ponds on Darby Creek, Delaware County; Morris-
ville pond, Berks County; ponds in vicinity of Easton, Northampton
County, Pennsylvania; ponds in New Jersey; Spencer pond, Maine;
vicinity of Jacksonville, Florida; Fort Bridger and Uinta Mountains,
Wyoming Territory. Bombay, Carter; Germany, Fresenius.

Difflugia lobostoma is one of the most common species, and may
be found more or less abundantly in the ooze, or among algse, in ponds and

GENUS DIFFLUGIA— DIFFLUGIA LOBOSTOMA. 113

ditches where other kinds occur. As usually observed, it is seen lying on
the side, and it often requires patient manipulation to make it turn in such
a way as to obtain a view of the mouth, on the peculiar character of which
its specific distinction mainly depends. As ordinarily seen, it bears so
close a resemblance with the corresponding views of Difflugia proteiformis,
as described and figured by Ehrenberg,* that it may not only be readily
taken for the same, but I have suspected that Ehrenberg may have actually
had this animal under observation when he described D. proteiformis.
Ehrenberg, however, makes no allusion to the character of the mouth of
the latter, and subsequently, in referring to one of the varieties of D. lobo-
stoma, described by Mr. Carter, first as D. proteiformis, and then, from the
trilobate condition of the mouth, as D. tricuspis, he does not even hint
that the latter is synonymous with his D. proteiformis. f

The name of Difflugia proteiformis is exceedingly indefinite in its
application. It was originally applied by Lamarck, J without discrimina-
tion, to all the forms figured and described by Leclerc as characteristic of
the genus Difflugia.§ Ehrenberg, attributing the name to Lamarck, applied
it to a new form, and ascribed one of the forms represented by Leclerc to
the same species. || Dr. Wallich uses the name of Difflugia proteiformis in a
sort of generic sense, and regards all other forms of the genus ordinarily
recognized as transitional subspecies and varieties.!!

As previously intimated, Mr. Carter applied the name of D. proteiformis
to a species, and subsequently, from the trilobate form of the mouth, named
it Difflugia tricuspis.**

The late Prof. Bailey, of West Point, New York, in his Microscopical
Observations made in South Carolina, Georgia, and Florida, mentions the
occurrence of D. proteiformis, but gives no clue as to the particular form
he viewed as this species.ff

Ehrenberg's description of D. proteiformis is too incomplete to deter-
mine whether it applies to what I have viewed as the D. globulosa of Dujar-
din, or the present species, which I have named, from the peculiar character
of the mouth, D. lobostoma. I was led to reject Mr. Carter's name of D.
tricuspis, evidently applied to the same, as it is objectionable, if we include

* Infusionstbierchen, 131, Taf. ix, Fig. i. || Infusionsthierchen, 131.

t Abh. Ak. Wis. Berlin, 1871, 238, 264. IT An. Mag. Nat. Hist, xiii, 1864, 215.

t Animaux sans Vertebres, ii, 1816. **Ibid. xviii, 1856, 128, 221.

$ Mem. Mus. Hist. Nat. t. ii, 474, pi. 17. ft Sinithson. Contrib. ii, 1850.

8 RHIZ

114 FEESH-WATEB EHIZOPODS OF NOETH AMEEICA.

with the species all the varieties in which the number of cusps, or rather
lobes, to the mouth, varies from three to half a dozen or more. A variety
of the same species, with a five-lobed mouth, is figured and described
by Fresenius, and referred by him to the D. oblonga of Ehrenberg.* The
reference is, however, improbable, for Ehrenberg, in speaking of the Difflu-
gia tricuspis of Carter, remarks that Fresenius regards it as D. oblonga, but
adds that he had not perceived a three-lobed mouth to the latter, f from
which it may be suspected that no lobes whatever were present, as appears
to be the case, if we may found an opinion on the figures of that form in
the ' Infusionsthierchen.'

The shell of Difflugia lobostoma is commonlv ovoid, with the mouth
situated at the narrower pole. Less frequently it is oval or nearly spherical,
or the ovoidal form may be more or less prolonged at the narrower pole, so
as to assume a sub-pyriform shape. The mouth may truncate the shell, or
it may not interfere with the curvature of the oral pole, or this may more
or less protrude so as to form a short neck or rim.

Usually the mouth is trilobed, or is bordered with three rounded lobes
or sinuses separated by angular points, and resembles the trefoil opening
employed in architectural decoration, as seen in figs. 1, 3, pi. XV. The
number of lobes of the mouth may, however, vary from that given to half
a dozen or more. Next in frequency to the trilobate mouth, according to
my experience, is the six-lobed mouth, as seen in figs. 10, 12, and after this
comes the quadrilobate mouth, as seen in figs. 5, 8, 16.

Large specimens, with a many-lobed mouth, approximate Difflugia
corona, and indeed I have observed so many of intermediate condition in
all respects, that there is little doubt that the two species merge into one
another.

The shell of Difflugia lobostoma is usually composed of angular quartz-
sand, in common with other species of the genus. Barely it is com-
posed of diatoms, or diatom-like plates, together with fragments of others,
sometimes with variable proportions of quartz-sand. Small shells occa-
sionally occur composed of chitinoid membrane with quartz particles
incorporated. Individuals in which the shell is composed wholly of quartz-
sand are represented in figs. 1-15, pi. XV.

* Abh. Senckenb. Naturf. Gesells. ii, 1856-8, 225.
1 Abh. Ak. Wis. Berlin, 1871, 238, 239.

GENUS DIFFLUGIA— DIFFLUGIA LOBOSTOMA. 115

Specimens in which the shell is composed of thin angular siliceous
plates, consisting at least in part of diatoms and fragments of others, found
usually in sphagnons swamps, are represented in figs. 18-20.

In several instances I have found specimens of large size, especially
in ponds of the Uinta Mountains, as represented in figs. 16, 17, in which
the shell was composed of rectangular and oval plates defined by interrupted
or dotted lines, the nature of which I did not determine.

Another variety, observed in a few instances, from Woodstown pond,
Gloucester County, New Jersey, had a mammillated shell, as represented
in figs. 21, 21. The mulberry appearance of the shell reminds one of the
figure of a form designated by Dr. Wallich as Bifflugia tuberculata. The
specimen had a six-lobed mouth with a short rim, but the composition of
the shell I failed to make out.

In several instances, once at Morrisville pond, Berks County, and
the other in the ditches below Philadelphia, I found peculiar translucent pale
yellowish specimens, such as are represented in figs. 25, 26, pi. XVI. The
ovoid shell, with trilobate mouth, appeared to be composed of a cancellated
membrane, as in the genus Nebela.

Rarely, also, I have seen a specimen with trilobate mouth, in which
the shell appeared to be composed of flocculent dirt, as represented in
fig. 29.

A small specimen, such as I have occasionally seen, with trilobate
mouth, and with the shell composed of chitinoid membrane, incorporated
with a few scattered quartz particles, is represented in figs. 27, 28. This
specimen, from Swarthmore brick -pond, accords with the Bifflugia tricuspis
of Mr. Carter, described as a smaller and less incrusted species than B. pro-
teiformis, with trefoil opening of the test, measuring ith of an inch, from
Bombay, Ehcenberg regards it as a distinct species, and the name has
certainly precedence of the one under which it is here included, but has
appeared to me inappropriate for adoption.

In perhaps most cases in which I have observed Difflugia lobostoma,
especially the ordinary form with trilobate mouth, the endosarc has appeared
bright green from the presence of chlorophyl corpuscles ; but in many
instances all color except that derived from the food has been absent.

Difflugia lobostoma commonly ranges in size from the ~fii to the ^ 5 th of
an inch.

116 FRESH- WATEE RHIZOPODS OF NORTH AMERICA.

A large specimen, referable to D. lobostoma, from Jacksonville, Florida,
is represented in fig. 8, pi. XVII. It had a six-lobed mouth, with deep
sinuses, separated by angular points. In all respects it closely resembled
one, of which the mouth is represented in fig. 12 of the same plate, of B.
corona, from Lake Hattacawanna, New Jersey, except that it was devoid
of spines to the summit. At the side of the latter it might be regarded as a
spineless variety of the same species.

Another specimen, from Hammonton pond, Atlantic County, New Jer-
sey, represented in figs 18, 19, pi. XV, may be regarded as a transitional
form from B. lobostoma to B. corona or B. urceolata. The shell is larger
than usual in B. lobostoma, is nearly spherical, provided with a short neck
and a feebly crenulated mouth, in which the ci'enulations are seen to be
about eleven. It is composed of thin angular plates, apparently consisting
of diatoms and fragments of others.

As before intimated, Bifflugia lobostoma is the commonest of our species,
and is found in the superficial mud and flocculent matter of most fresh-water
ponds and ditches. I have also frequently found it among the filamentous
algse and the materials adherent to aquatic plants. When first noticed after
removal to the field of the microscope, it is usually seen lying on the side.
Protruding its finger-like pseudopods, commonly about half a dozen, after
some apparent struggling it rises on end, generally with the mouth down-
ward. On tapping the slide upon which it is examined, it either firmly
maintains its position, or withdrawing the pseudopods it falls again on the
side, and usually much labor and patience are required to get the creature
in such a position as to see the mouth. From the common occurrence
of B. lobostoma, with the circumstance that, as ordinarily seen, it so much
resembles the B. proteiformis of Ehrenberg, I have been led to suppose
that it is the former, which is usually regarded as the latter by authors.

I have repeatedly seen Bifflugia lobostoma in conjugation, mostly two

individuals, but in several instances three together, so as to give a view in

outline comparable to the trefoil-shape of the mouth of the commonest

variety.

DIFFLUGIA ARCULA.

Plates XV, figs. 34-37; XVI, figs. 30, 31.

Shell hemispheroidal ; fundus convex; base inverted, shallow infun-
dibuliform; mouth inferior, central, trilobed. Structure of shell usually

GENUS DIFFLUGIA— DIFFLUGIA AltCULA. 117

of yellowish chitinoid membrane, mostly with more or less adherent dirt or
scattered particles of quartz-sand or diatoms, especially occupying the
fundus.

Size. — From 0.112 mm. to 0.144 mm. broad by 0.06 mm. to 0.08 mm.
high; mouth 0.028 mm. to 0.04 mm wide.

Locality — Sphagnum of Atco and Absecom, New Jersey; of Toby-
hanna, Pokono Mountain, Monroe County, and Broad Mountain, Schuylkill
County, Pennsylvania.

Difflugia arcula is perhaps an extreme variety of Bifflugia lobostoma.
It is not unfrequent, and appears to be confined to sphagnous swamps. In
shape, color, and material of structure, its shell resembles that of an
Arcella, as seen in figs. 34-37, pi. XV. Usually it is nearly hemisphe-
roidal; but the height is commonly a little greater than half the breadth.
The top is evenly rounded and dome-like. The bottom is a broad, shallow,
inverted funnel with reflected border. The mouth is central and trilobed;
the lobes or sinuses being variably narrowed in degree. See figs. 34-37,
pi. XV; figs. 30, 31, pi. XVI.

In structure, the shell is composed of chitinoid membrane of different
shades of straw-color, often with irregular darker spots, apparently as if
due to adherent dirt. Frequently, also, it has incorporated particles of
hyaline quartz-sand mostly scattered on the sides, or more especially
accumulated on the fundus. Sometimes a few diatoms or fragments of
these are mingled with the quartz-sand.

The specimens observed were always dead, so that I did not ascertain
the appearance of the sarcode.

The smallest specimen measured .J- 3 d of an inch broad and ^d of an
inch high ; the largest was ^d of an inch broad and 3 -i- 2 th of an inch high.

Bifflugia arcula probably merges into B. globulosa, B. lobostoma, Centro-

pyxis, and Arcella.

DIFFLUGIA CORONA.

Plate XVII.

Diffluflia corona. Wallich: Au. Mag. Nat. Hist, xiii, 1864.— Leidy : Pr. Ac. Nat. Sc. 1874, 14, 79; 1877 307.
Difflugia protciformis, subsp. L>. globularis, var. D. corona. Wallich : Ibid.

Shell spherical or spheroidal, composed of clear angular quartz-sand;
fundus with a number of conical spines of the same composition as the rest
of the shell; mouth terminal, circular, with the border multidentate or

118 FRESH- WATER RHIZOPODS OF NORTH AMERICA.

crenulate. Sarcode colorless; pseudopods many, of the usual form in the
genus.

Size. — Ranges from 0.14 mm. to 0.32 mm. in diameter; mouth 0.06
mm. to 0.18 mm. wide; spines 0.04 mm. to 0.06 mm. long.

Locality. — Ditches near Philadelphia, ponds on Darby Creek, and
Swarthmore brick-pond, Delaware County, Morrisville pond, Berks
County, Pennsylvania; Atco pond, Woodstown pond, Hammonton pond,
Absecom pond, and Lake Hattacawanna, New Jersey; Spencer pond,
Maine; Jacksonville, Florida. England, Wallich.

JDsfBugia coroisa, as represented in the figures of pi. XVII, is the

most remarkable and beautiful species of the genus. It was first indicated
by Dr. Wallich from specimens found in England It is a common Ameri-
can species, and is frequent in the vicinity of Philadelphia.

The shell of Difflitgia corona is usually nearly spherical, but frequently
is slightly prolonged approaching the mouth. It is commonly one of the
smoothest of the genus, though composed of angular particles of quartz-
sand in the usual manner. The mouth is circular, and commonly trun-
cates the spheroidal shell, or it continues its curvature, or it is somewhat
projected. The lip or border of the mouth is dentated or crenulated.
The denticles are thick, angular processes, more or less acute, sometimes
blunted, concentric, or slightly everted. They range in number from six
to sixteen; but the most frequent number is twelve, and usually a larger
rather than a smaller number prevails. The intervening notches are thick-
edged, as deep as they are wide, and rounded at bottom.

The fundus of the shell is furnished with a variable number of acute
conical spines. Generally there are from three to seven ; but they range in
number from one to eleven. Mostly they form an eccentric circle, widely
divergent, nearly equidistant, and usually occupy a position at the upper
third of the shell. Often there is a central spine, sometimes longer than
the others. Often this is absent, and sometimes it is the only one existing.
The spines are straight or slightly curved, sharp-pointed, hollow processes
of the shell, with the same composition.

The shell is composed of colorless angular quartz-sand, usually with
the larger particles scattered, with some appearance of uniformity, and
with the intervals occupied by smaller ones. Often, too, larger stones are

GENUS DIFFLTIGI A— DIFFLUGIA COEONA. 119

ranged near the mouth, and sometimes form a nearly unbroken row. The
denticles of the mouth and the spines of the fundus are likewise made up
of sand. Not unfrequently the spines end in a single sharp splinter, or
flake, which, in many instances, is of so marked a character that one can-
not avoid the impression that it has been specially selected. Mostly the
denticles and the tips of the spines are colored ferruginous brown, while the
rest of the shell is uncolored.

. As usual in Difflugias, the shell has an uneven surface, varying in this
respect mainly according to the proportionate quantity of large and small
sand grains entering into its composition. Nevertheless, the grains are
united in such a manner that, as before intimated, it is comparatively one
of the least uneven in the genus.

Irregular variations from the usual forms of D. corona are occasionally
found. In several instances I have seen specimens somewhat compressed
and unsymmetrical, probably from accident. Such a one is represented in
fig. 11, pi. XVII. In this, also, the spines were disproportionately large
compared with their ordinary condition. Sometimes the spines may be
more irregularly disposed, out of the usual proportions, more curved, much
reduced in size, and rarely nearly obsolete. I have occasionally met with
a specimen in which the mouth was more or less oblique or subterminal, and
with a single spine terminating the fundus, as seen in fig. 7.

This matter brings us to what may be viewed as transitional forms.
Fig. 12 represents the mouth of a shell of Difflugia corona, from Lake
Hattacawanna, New Jersey. In all respects, the specimen accords with the
commoner forms, but has only six denticles to the mouth. It differs only
from the large specimen of Difflugia lobostoma, of fig. 8, from Jacksonville,
Florida, in the possession of spines to the fundus. As we have seen that
the number of the spines in D. corona may be reduced from eleven to one,
we may regard the specimen of D. lobostoma, just indicated, as a spineless
form of D. corona. Thus, no positive character separates Difflugia corona
from Difflugia lobostoma as an independent species.

The interior sarcode of D. corona, as visible through its stony wall,
appears colorless, with a more or less brownish tinge and darker spots of
the same, centrally in the endosarc, dependent on the food. The pseudo-
pods present the usual appearance, digitate and palmate, or long and cylin-
drical, simple or branching, and ever changing in length and form They

120 FRESHWATER RHIZOPODS OF FORTH AMERICA.

are sometimes extended upward even to the ends of the spines projecting
from the fundus. Mostly perfectly clear, under high powers of the micro-
scope they appear uniformly and exceedingly finely granular. When
much extended, they often exhibit the entrance, along their axis, of coarser
granules from the endosarc.

Dr. Wallich, who first described B. corona, views it as a variety of what
he calls the subspecies Bifflugia globularis.

In the original notice of the latter,* as B. globulosa, Dujardin describes
the shell as corneous and nearly globular, and accompanies the account
with figures, one of which, representing a side view, is ovoid, with an oval
mouth without crenulation. In the 'Histoire Naturelle des Infusoires,' he
describes the shell as brown, globular or ovoid, and smooth.

In the 'Proceedings of the Dublin Microscopical Club,' 1866, p. 53, it
is stated that Mr. Archer, among other Rhizopods exhibited one that he
"would refer somewhat doubtfully to Bifflugia corona." He remarks, "If
this be B. corona, Dr. Wallich's figure is too regular and symmetrical, too
diagrammatic, the adherent foreign particles too accurately adapted, and too
much of one size, and the horns too short." According to my experience,
Dr. Wallich's figure is a fair representation of the species, and Mr. Archer's
criticism leads me to suppose that he had under comparison an irregular
specimen, and not one of the usual character.

Bifflugia corona ranges from the ^th to the ^th of an inch. It is one
of the most characteristic and beautiful forms, and is also common in
many localities. It is found living in the surface mud at the bottom of
ponds and ditches, or among the dirt adherent to submerged aquatic plants.
It feeds on algae and apparently also on decaying vegetal matter.

DIFFLUGIA CONSTRICTA.

Plate XVIII.

Arcella constricta. Ehrenberg: Abh. Akad. Wis. Berlin, 1841, 410, Taf. iv, i, Fig. 35, Taf. v, Fig. 1.
Arcclla hmata. Ehrenberg: Ibidem, 1841, 410; 1871, 259, Taf. iii, ii, Fig. 3, 4.

Arcella Arctiscon. Ehrenberg : Microgeologie, 1854, 108, 171 ; Abh. Ak. Wis. 1871, 258, Taf. iii, ii, Fig. 17.
Arcella guatimaletisis. Ehrenberg: Microgeologie, 1854,364; Ab. Ak. Wis. 1871, 259, Taf. iii, ii,Fig. 16;

Nordpolarfohrt, 1874, Taf. iii, Fig. 35.
Difflugia marsitpif orw is. Wallich : An. Mag. Nat. Hist, xiii, 1864, 241, 244, pi. xvi, figs. 3-5.— Leidy : Pr.

Ac. Nat. Sc. 1877, 307.
Difflugia protciformii), subspecies D. marsupiformis. Wallich: Ibidem.

Difflugia marsupiformis, variety D. cassis. Wallich: Ibidem, fig. 6. — Leidy: Pr. Ac. Nat. Sc. 1877,321.
J. Homccochlamgs constricta. Ehrenberg: Ab. Ak. Wis. 1871, 244.

* An. Sc. Nat. viii, 1837, 311, pi. 9, fig. 1.

GENUS DIFFLUGIA— DIFFLUGIA CONSTKICTA. 121

A. ffomceochlamt/8 htnala. Ehrenberg: Ibidem, 244, 274.
A. Heterocosmia Arctiscon. Ehrenberg : Ibidem, 245, 274.
A. Bclerocosmia guatimalensis. Ehrenberg: Ibidem, 245, 274.
Arcclla borealis. Ehrenberg: Nordpolarfahrt, 1874, Taf. iii, Fig. 29.
Arcella latlceps. Ehrenberg : Ibidem, Fig. 30.

Shell laterally ovoid, with the fundus posterior and more or less pro-
longed obliquely upward, obtusely rounded and simple, or in the largest
forms often provided with from one to half a dozen conical spines. Mouth
anteroinferior, large, circular or oval, and inverted, with the anterior lip
often prominent. Shell as usually seen (lying on the front, by transmitted
light) more or less pyriform, with the narrower part downward and including
the mouth, which appears as a clearer transversely oval or somewhat reni-
form or circular space ; sometimes in the shorter forms nearly circular or
even transversely oval in outline.

Shell composed of hyaline quartz-sand, or of chitinoid membrane,
usually with variable proportions of scattered mineral particles. Colorless,
yellowish, or brown. Interior sarcode transparent and colorless.

Size. — Spineless specimens range from 0.09 mm. long by 0.078 mm.
broad, to 0.232 mm. long by 0.16 mm. broad. The spine-bearing forms
range from 0.18 mm. long by 0.12 mm. broad, to 0.34 mm. long by 0.18
mm. broad.*

Locality. — The smaller spineless forms are found almost everywhere
in moist places; the larger forms, including those bearing spines, are found
commonly in the ooze of ponds. New Jersey, Pennsylvania, Maine, Flo-
rida, Alabama ; and at Fort Bridger and in the Uinta Mountains, Wyoming

Difliiigia constricta, of which many forms are represented in pi.
XVIII, is one of the most common species. It holds a slanting position in
comparison with that maintained by others ; that is to say, when the ani-
mal is erect, as in its ordinary movements, the long axis, corresponding with
a line passing from the centre of the mouth to the summit of the shell, is
oblique instead of being perpendicular. The inclination of the axis ranges
between 30° and 60°.

Commonly the shape of the shell is slightly compressed pyriform or
ovoid, with the narrower end downward and forward. It is of variable

"The length is taken from the anterior lip to the fundus, as the specimens are usually seen lying
on the object-glass of the microscope. The true length would be from the centre of the mouth in the
axis of the shell to the fundus.

122 FRESH- WATEE RHIZOPODS OF NORTH AMERICA.

length, and wider from side to side than from before backward. In the
lateral view, with the plane of the mouth or bottom of the shell on a level,
it appears obliquely ovoid, with the fundus directed backward and upward,
and with the fore part of the base or anterior lip usually more or less
prominent.

In the front or back view of the shell, as it is ordinarily seen, lying on
the object-plate of the microscope, by transmitted light, it appears pyriform,
ovoid or spheroid in outline, with a clearer transversely oval or somewhat
reniform or round space included within the lower or narrower part and
produced by the mouth. See figs. 2, 5, 7, 15, 22.

The bottom of the shell is concave, and the nearly circular or oval
mouth is inflected and situated above the level of the border of the base.
The fundus is usually obtusely rounded and simple, and viewed from
behind is transversely oval and flattened below, as seen in fig. 13.

In the largest and most elongated forms, the fundus is often provided
with from one to half a dozen acute, conical spines. A single spine pro-
duces a central, rather abruptly tapering point ; a pair surmount the sides,
and a greater number are ranged in a usually more or less regular row.

Unsymmetrical forms of Difflugia constrida are not unfrequent, espe-
cially in the larger specimens, both in the shape of the shell and in the
arrangement of the spines, when these exist.

The shell is ordinarily composed in the usual manner of other species
of the genus ; that is to say, of angular particles of quartz-sand. Sometimes
the particles have more or less uniformity ; sometimes heavier grains sur-
round the mouth, and not unfrequently also occupy the top of the fundus.
When spines are present they have the same composition as the body of
the shell ; but a remarkable circumstance is the frequent termination of these
spines with a single sharp-pointed and trenchant splinter, as if specially
selected for the purpose, and as represented in figs. 56, 57.

Rarely the shell is composed of chitinoicl membrane incorporated with
variable proportions of scattered quartz particles, in the form of minute
grains or thin plates. Occasionally minute oval pellets, and sometimes dia-
toms, enter into the constitution of the shell.

The sarcode of Difflugia constrida, independent of any food contents,
is transparent and colorless, and the animal is so very sensitive and indis-
posed to protrude its pseudopods, that in most cases it is difficult, in con-

GENUS DIFFLUGIA— DIFFLUGIA CONSTEICTA. 123

sequence of the structure of the shell obscuring the interior, to determine
whether the specimens under examination are dead or alive.

Difflugia constricta, in its various forms, is one of the most abundant of
species, and appears to be found almost everywhere where moisture and
algae are present.

Small spineless specimens, cap-like in form, of the variety named by
Dr. Wallich Difflugia cassis, such as represented in figs. 8-34, pi. XVIII,
are very common with algae, on the surface of moist earth, in marshy
places, in meadows, and in forests. I have found them constantly, in asso-
ciation with the common wheel-animalcule and several other rhizopods,
about the roots of mosses, and with algae, in the crevices of the pavements
in shaded places in the city of Philadelphia. I have even found them
among mosses and lichens high up in trees. They also occur frequently
among sphagnum.

The small spineless forms are frequently of various shades of brown,
while the larger ones are usually colorless.

The largest varieties and the spine-bearing forms are found in the ooze
of ponds. These appear to constitute the variety named by Dr. "Wallich
Difflugia marsupiformis. See figs. 35-55.

A somewhat peculiar variety, represented in figs. 37-44, I have not
unfrequently found among sphagnum. The shell is cap-like in shape,
yellowish brown in color, and composed of chitinoid membrane, usually
incorporated with variable proportions of scattered sand particles. In the
view from the front or back, the shell appears transversely oval, but flat
beneath. The mouth is deeply inflected, or forms the smaller opening of
an inverted funnel, of which the base of the shell forms the greater opening.
Sometimes the fundus of the shell is loaded with comparatively large
stones, and rarefy the shell is almost devoid of sand particles. This form
of shell approximates closely, if it does not really merge into, the spineless
variety of Centropyxis.

Either of the names Difflugia marsupiformis or D. cassis, given by Dr.
Wallich, better applies to the species than that of Arcella constricta, given
originally by Ehrenberg. The apparent constriction, often absent, is due to
the narrowing of the shell, as seen in the front view, opposite the position
of the mouth.

The form of Difflugia constricta repeats that of Trinema enclielys, but

124 FRESH-WATEE EHIZOPODS OF NORTH AMERICA.

I have not been able to ascertain whether these actually merge into
each other.

The range in size of Difflugia constricta is considerable. The smallest
measured was ith of an inch long from the anterior lip to the fundus, the
breadth was slightly less than the length, and the thickness or fore. and aft
diameter of the fundus ^th of an inch, and the mouth was ^th of an inch
wide. The largest was ^th of an inch long from anterior lip to fundus,
ith of an inch broad, ith of an inch thick, and the mouth 2 ^ th of an inch
wide. The spines of the fundus reach a length of ~\h of an inch.

DIFFLUGIA SPIRALIS.

Plate XIX, figs. 1-23.

Difflugia. Leclerc: Mem. Mus. Hist. Nat. 1815, ii, 474, pi. 17, figs. 1 and 4.

Difflugia spiralis. Ekrenberg: Monatsb. d. Berlin. Akad. d. Wissens. 1840, 199; Abhand. Akad. Wissens.
Berlin, 1871, 274, Taf. iii, Fig. 25-27.— Bailey : Micros. Obs., in Smithson. Contrib. 1850, 41.—
Fresenius : Abhand. Senckenb. Natorf. Gesells. ii, 1856-8, 224, Taf. xii, Fig. 37-42.— Pritekard :
History of Infusoria, 1861, 553.— Carter: An. Mag. Nat. Hist, xiii, 1864, 18, pi. i, fig. 9.—
Wallich: An. Mag. Nat. Hist, xiii, 1864, 215— Leidy: Pr. Ac. Nat. So. 1874,79; 1877,307.

Lcequereusia jurassiea. Schluinberger: An. Sc. Nat. 1845, 255.

Difflugia proteiformis, monstrosa. Perty : Kenntniss kleinster Lebensformen, 1852, 187, 214, Taf. viii, Fig. 22.

Difflugia Helix. Cobn : Zeitsck. f. wissens. Zoologie, 1853, 261.

Difflugia proiciformis, var. scptifera. Wallich: An. Mag. Nat. Hist. 1853, xi, 1853, 453, pi. x, fig. 12.

Difflugia proteiformis. Wallick : An. Mag. Nat. Hist. 1863, xii, 456.

Difflugia proteiformis, subspecies!), mitriformis, var. 0. D. spiralis. Wallick: An. Mag. Nat. Hist. 1864,
xiii, 1884, 240, pi. xvi, figs. 24, 25.

D. Corlicella spiralis. Ekrenberg: Abk. Ak. Wis. Berlin, 1871, 247.

Shell retort-shaped, usually with a laterally compressed spheroidal
body, and a short, wide, cylindroid neck, obtuse fundus, and terminal circu-
lar or slightly oval mouth. A partition occupying the interior of the shell,
defining the neck from the body, and giving to the shell by transmitted
light the appearance of a single turn of a spiral. Structure of the shell
variable; frequently of quartz-sand, often of peculiar elements, or of chit-
inoid membrane incorporated with various extraneous particles. Sarcode
colorless; pseudopods as usual in the genus.

Size. — Length 0.096 mm. to 0.188 mm.; breadth of body 0.068 mm.
to 0.164 mm.; thickness 0.068 mm. to 0.136 mm.

Locality. — Lakes, ponds, and ditches. Pennsylvania, New Jersey,
Rhode Island, South Carolina, Georgia, Florida, Alabama, and the Uinta
Mountains of Wyoming Territory.

Difflugia spiralis, a common and pretty species (figs. 1-23, pi. XIX),
is one of the most remarkable forms of the genus, and is also the most

GENUS DIFFLUGIA— DIFFLUGIA SPIEALIS. 125

variable in the structure of its shell. It is one of the original forms described
by Leclerc, in 1815, under the generic name alone. Though not strictly
correct to call it spiral, the construction of the shell, especially when viewed
by transmitted light, gives rise to such an impression, and thus led Ehren-
berg so to name it, and likewise Bailey after him, apparently without
knowing that the former had done so.

In Difflugia spiralis we may recognize one of the enigmatic rhizopods,
described, without illustrations, by Schlumberger, in 1845, in the 'Annales
des Sciences Naturelles.' I refer to the Lecquereusid jurassica, described as
having " a somewhat depressed ovoid-globular retort-shaped shell with a
short, wide neck and a terminal circular aperture, from which project
thick, cylindrical, blunt pseudopods."

The shell of Difflugia spiralis is retort-like or flask-shaped, with a
usually compressed spheroidal body, and a short, wide, cylindroid neck,
which is commonly produced a little more from one side than the other of
the shell. The body and neck are, however, quite variable in their exact
form and proportions. Commonly the larger specimens with a stOny
structure accord with the general form indicated. Smaller specimens
usually have a proportionately, and often absolutely, longer neck and a
more spherical, uncompressed form of body. The neck is mostly straight,
but is sometimes slightly bent or curved. Generally it is evenly expanded
where it joins the body, but is frequently inflated more to one side. The
mouth is terminal, circular, or slightly oval, and is neither contracted nor
expanded at the border.

The shell, as ordinarily viewed lying on one of the usually broader
surfaces, exhibits a dark line, indicating the presence of an interior partition,
which starts from the bottom of the neck on one side and extends in a more
or less oblique direction or curve upward toward the opposite side. In
some specimens, the partition appears to extend from one half to two thirds
way across the shell, and in others nearly or quite completely across in
a sigmoid line to the opposite side. The partition apparently continues
inwardly the curvature of one side of the body of the shell, and thus gives
rise to the impression that the latter makes a spiral turn.

Ordinarily the structure of the shell so obscures the partition from view
that a satisfactory idea of its exact form and relations cannot be obtained.
In most instances in smaller and more translucent specimens, in which the

126 FRESH- WATER EHIZOPODS OF NORTH AMERICA.

partition could be distinguished, it appeared to be a crescentoid plate, with
a large circular aperture between its upper part and the contiguous portion
of the shell. In other instances, the aperture seemed to pass through the
upper part of the partition itself.

In many specimens, the neck is more or less defined from the body of
the shell by a narrow constriction in the line of the partition, especially in
those in which the latter extends completely across.

•The structure of the shell of Difflugia spiralis is of more variable char-
acter than in any other species of the genus. Frequently it is entirely
composed of angular, colorless quartz-sand, as in the species of Difflugia
generally, and as seen in figs. 1-3, G, pi. XIX. In these specimens, also, the
usual varieties in arrangement occur, some being constructed of particles
of some uniformity of size, small or large, while others are composed of
scattered coarser particles, with the intervals filled in with smaller ones.
Sometimes there is an accumulation, especially of larger stones, centrally
on the broader surfaces of the shell, as seen in figs. 4, 5.

• The former figure represents a large specimen, in which the shell was
mainly composed of thin, narrow, rectangular plates, mingled with some
diatoms, and the central portion of the broader surfaces of the body was
occupied by large particles of quartz-sand.

A singular variety is that in which the shell is composed of short vermic-
ular bodies closely laid together, as represented in figs. 7, 9-11. The same
form is described by Dr. Wallich as occurring in England. The vermicular
bodies are transparent and colorless, but when viewed by reflected light
present a silvery white lustre. Dr. Wallich calls them chitinous pellets.

Occasionally I have found specimens composed of similar bodies sepa-
rated by marked intervals, and apparently imbedded in a homogeneous
membrane, as represented in fig. 8.

Other varieties of shells, related with those last indicated, consisted of
a net-work of apparently the same nature as the vermicular bodies, as seen
in fig. 12, or of minute scattered corpuscles, as seen in fig. 13. With these
shells, as represented in the two figures just referred to, there were incor-
porated scattered particles of quartz-sand.

Another interesting variety observed is one in which the shell was
mainly constituted in the usual way of a stone-work masonry, but had the
neck composed of vermicular bodies, as seen in fig. 5.

GENUS DIFFLUGIA— DIFFLUGIA SPIEALIS. 127

A singular variety is represented in figs. 14, 15, in which the shell is
composed of narrow plates or rods mostly in small parallel groups of twos
and threes or more, and laid closely together in every direction. This is
probably the kind to which Schlumberger refers in his account of Lecque-
reusia jurassica, in which he says the shell is composed of a paste of minute
bacillar bodies.

Small forms of Difflugia spiralis are not uncommon in which the shell
is composed of transparent chitinoid membrane incorporated with variable
proportions of linear bodies, diatoms, and sand particles, as represented
in figs. 16-22.

A curious specimen, of large size, represented in fig. 23, was composed
of irregularly rounded or oval bodies containing a central nucleus. The
nature of these bodies I did not determine.

The sarcode of Difflugia spiralis is colorless, independently of the color
given to the endosarc from the presence of food. In the more translucent
specimens it can often be detected as a spheroidal mass of variable size
occupying the body of the shell, with a narrow neck passing off from
one side, in a retort-like manner, and extending through the aperture of
the partition, and thence gradually widening to the mouth. The food
usually gives to the endosarc a yellowish or pale brownish hue, which is
sometimes mingled with green and other colors. The pseudopods in num-
ber, form, and changes, are of the same character as in other species of
the genus.

The size of Difflugia spiralis ranges from the ^th to the ^th of an
inch.

Difflugia spiralis may be regarded as the oldest known species, and, as
previously intimated, was described and figured by Leclerc in 1815. He
represents two varieties ; one in which the shell is composed of quartz-sand,
the other in which it appears to be composed of chitinoid membrane. He
also represents two individuals united, mouth to mouth, in the condition
usually indicated as that of conjugation.

Perty describes and figures the same species, but regards it as a mon-
strosity of Difflugia piriformis, in which view he is sustained by Dr. Wallich.
I can see no reason why Difflugia spiralis should be considered a monstrosity
any more than any other recognized form of the genus.

Difflugia spiralis is a common species, but I have found it especially

128 FRESH- WATER RHIZCXPODS OF NORTH AMERICA.

abundant in the ponds of sphagnous and cedar swamps in New Jersey,
where it is also to be obtained, in the greatest variety of form, in association
with D. piriformis, D. urceolata, etc. The habits and food are the s^me as
in other species generally.

I have occasionally observed two individuals of Difflugia spiralis
applied together, mouth to mouth, in the manner first described and figured
by Leclerc, and as represented in fig. 3, pi. XIX. This condition I have
not been able to discover leading to any important result, and I may say
the same of other species of Difflugia seen in conjugation.

In one instance I saw two small individuals applied to the mouth of a
third and larger individual, and in another instance I saw three small
individuals in like manner applied to a larger one.

In the instance represented in the figure, on focusing the conjugating
pair so as to see the contents, they were observed to flow from one to the
other and back again. After about half a dozen repetitions of the flow and
ebb, the contents, apparently equally divided in the two shells, remained
quiescent for a time, and then the two individuals separated and moved
away in the usual manner. The construction of the shell prevented the
determination of any change within, even if such had taken place.

HYALOSPHENIA.

Greek, hualos, crystal; sphen, a -wedge.
Hyalosphenia: Stein, 1857. Difflugia: Tatem, 1870. Catharia : Leidy, 1874.

Shell compressed ovoid to pyriform, composed of transparent structure-
less chitinoid membrane; mouth terminal, inferior, transversely elliptical.
Sarcode mass occupying the interior of the shell to a variable extent,
attached to its inner surface by divergent threads and also connected to the
border of the mouth; composed of pale granular protoplasm mingled with
colorless or colored corpuscles, or both together. Nucleus large, and cen-
trally situated in the fundus of the sarcode. Contractile vesicles several,
occupying a position between the former and the periphery of the fundus.
Pseudopods few, digitate.

GENUS HYALOSPHENIA— HYALOSPHENIA CUNEATA. 129

HYALOSPHENIA CUNEATA.

Plate XX, figs. 1-10.

Hyalosphcnia cuneata. Stein: Sitzungsb. Biihm. Akad. Wisseus. 1857.

Difflugia ligata. Tat era : Month. Micros. Jonr. iv, 1870, 313, pi. lxviii, fig. 1.

Caiharia ligata. Leidy : Proc. Ac. Nat. Sc. 1874, 79.

Hyalosphenia Jala. Schulze: ArcLiv niikr. Anat. xi, 1875, 335, Taf. xviii, Fig. 15, 18. — Archer: Quart.

Jour. Mic. Sc. 1877, 110.
Eijalosplimia ligata. Leidy: Pr. Ac. Nat. Sc. 1875, 415; 1876,197.

Shell compressed ovoid, with the narrower part conical and truncate
at the oral end, laterally and at the fundus convex ; mouth terminal, oval.
Shell composed of delicate, transparent, colorless, and structureless chiti-
noid membrane. Sarcode mass colorless, pyriform, and attached by threads
of ectosarc to the interior of the shell ; j)seudopods digitate, usually not
more than one or two.

Size. — Length 0.06 mm. to 0.076 mm. ; breadth 0.044 mm. to 0.06 mm.;
thickness 0.02 mm ; breadth of mouth 0.016 mm. by 0.012 mm.

Locality. — Lansdowne station spring, on Westchester railway, five
miles from Philadelphia.

Hyalosphcroiia ciBiaeata, figs. 1-10, pi. XX, is compressed ovoid, and
in the view of the broader side presents a transversely convex fundus and
more or less tapering lateral borders, which may be plane, convex, or con-
cave in their descent to the mouth. The narrower view of the shell is also
obtusely rounded at the fundus and tapering at the sides. The mouth is
terminal and oval, with obtusely rounded commissures.

The shell of H. cuneata consists of delicate, transparent, colorless
chitinoid membrane without trace of definite structure. It is sometimes
sufficiently delicate to be bent by the tension of the threads of ectosarc
attached to it within. In one specimen, the broad sides of the fundus
appeared to be bent inward by the tension of these threads, as seen in the
lateral view, fig. 5. In another specimen, the tension of the threads
appeared to indent every point of attachment, as seen along the border
in fig. 1.

The size of the shell in several specimens ranged from ^th to ^th of
an inch in length, by ith to i.th of an inch in breadth, and about ,-^r,th of

o ' J 4ho 410 1 1250

an inch in thickness. The mouth measured about the * th of an inch wide.

IliUO

9 EHIZ

130 FI1ESH-WATEE EHIZOPODS OF NORTH AMEEICA.

The sarcode in the few specimens observed occupied about one half
of the interior capacity of the shell. It was inverted vase-like in shape,
attached at the border of the mouth, gradually contracting and then
expanding again within the body. It was attached by long diverging
threads of the ectosarc to the sides and fundus of the shell.

The sarcode is colorless, and its basis consists of a pale, finely granular
protoplasm. Imbedded in the body, toward the fundus of the shell, it
contains a large, faintly granular and globular nucleus, from ^th to ~fh
of an inch in diameter. At the periphery of the body, contiguous to the
nucleus, two or three contractile vesicles may be visible at once.

Around, but especially below, the position of the nucleus, the endosarc
contained a multitude of darkly outlined granules, and a variable number
of larger, clear, well-defined globules, oil-like in appearance. A few pale
vacuoles and small brown food masses were likewise visible.

Usually H. cuneata puts forth but a single digitate pseudopod, but
occasionally two and less rarely three are emitted. They present the com-
mon form and the scarcely perceptible granular character observed in
related animals.

H. cuneata, from its great transparency, would be admirably adapted
for the study of the various life phenomena of its kind, but unfortunately
the creature appears to be exceedingly rare. In four years I found only
half a dozen individuals, and all these were obtained from the same locality,
a spring, in which grew water-cress, near Lansdowne station, on the West-
chester railway, a few miles from Philadelphia.

In one instance two individuals were found in conjugation, and when
first observed they presented the appearance seen in fig. 6. The sarcode
of both was continuous at the mouth of the shells ; but in one of these it
was less than a fourth of the quantity in the other. A moment after, the sar-
code was observed to flow from the larger to the smaller portion until the
two became equal in size, and assumed each a trilobate form, as seen in
fig. 7. A fourth lobe was produced in one portion of the sarcode, and then
the lobes became extended in both so as to form an attachment to the sides
and fundus of the shell, as seen in fig. 8. Shortly after, one portion of the
sarcode narrowed its connection with the other at the mouth of the shell,
then detached itself and shrunk away, as represented in fig. 9. At this time
the specimens were accidentally lost ; but several hours later, one of the

GENUS HYALOSPHENIA— HYALOSPHENIA PAPILIO. 131

individuals was found again, and presented the appearance seen in fig. 10,
with the sarcode contracted into the fundus of the shell.

From first to last a nucleus appeared to be absent in the sarcode. The
endosarc contained fine granular matter, coarser, darkly defined granules,
oil-like globules, clear vacuoles, and a few brown food particles.

Hyalosplienia cuneata, with this name, was first described by Stein.
What appears to be the same was afterward described by Tatem, in Eng-
land, under the name of Difflugia ligata. Schulze subsequently described
what he regards as a distinct species from that of Stein under the name of
Hyalosplienia lata I have not access to the description of the latter author;
but from its quotation by Schulze I cannot detect sufficient difference to
distinguish two species.

Stein remarks that in H. cuneata the animal can abruptly and quickly
separate from the mouth of the shell and retract to the bottom. Schulze
remarks that in H. lata he never observed such a sudden contraction as
this. That this apparent difference of habit has no specific value is shown
in the fact, that most lobose rhizopods, when disturbed, may retract their
pseudopods, but retain the connection of the sarcode mass with the mouth
of the shell, notwithstanding the rudest shaking, while at other times any
of them may and will sever the connection and quickly retreat to the
fundus of the shell.

The specific names of cuneata, ligata, and lata are expressive of charac-
ters common to any or all the examples described by Stein, Tatem, Schulze,
and myself.

HYALOSPHENIA PAPILIO.

Plate XXI.

Difflugia (Catharia) papilio. Leidy: Pr. Ac. Nat. Sc. 1874, 156.
Hijalosphmia papilio. Leidy: Pr. Ac. Nat. Sc. 1875, 415; 1876, 197.

Shell compressed oblong ovoid, or occasionally compressed pyriform;
in the broader view, with the fundus transversely convex and the sides
gradually tapering to the slightly convex oral end, or with a pyriform out-
line; in the narrower view, with the fundus angularly rounded and the
oral end notched. Mouth transversely oval, with rounded commissures.
Shell composed of transijarent, yellowish chitinoid membrane. Sarcode
with bright green endosarc from the presence of chlorophyl; the mass

132 FRESH- WATER EHIZOPODS OF NORTH AMERICA.

attached by divergent threads to the summit and sides of the shell; pseu-
dopods colorless, digitate, up to half a dozen in number.

Size. — From 0.1 OS mm. to 0.14 mm. long, 0.068 mm. to 0.084 mm.
broad, 0.032 mm. to 0.04 mm. thick; and the mouth end from 0.032 mm. to
0.04 mm. broad and 0.008 mm. in the opposite diameter.

Locality. — Abundant in the moist sphagnum of sphagnous swamps
of Pennsylvania and New Jersey. Tobyhanna, Pokono Mountain, Monroe
County; Broad Mountain, Schuylkill County, Swarthmore, Delaware
County, Pennyslvania ; Absecom, Atlantic County, Longacoming, Ham-
monton, Atco, Malaga, Vineland, etc., New Jersey.

SiyaEospheiiia papilio is common and at times exceedingly abundant
in moist bog-moss or sphagnum, in sphagnous swamps, but is not found in
ponds except accidentally. No other lobose rhizopod has more impressed
me with its beauty than this one. From its delicacy and transparency,
its bright colors and form, as it moves among the leaves of sphagnum,
desmids, and diatoms, I have associated it with the idea of a butterfly
hovering among flowers. From its comparative abundance, the readiness
and certainty with which it may be obtained and preserved, and from its
transparency, which allows its structure to be well seen, it is peculiarly
well adapted for the study of the life-history of its order. I have collected
it from early spring to late autumn, and have retained it olive in sphagnum,
in a glass case, through the winter. During the Christmas holidays, I have
repeatedly exhibited it, in the living condition, to the admiration of friends.*

* This interesting Khizopod, found together with a profusion of other remarkable microscopic
forms of both animal and vegetal life, of which many are novel and yet undescribed, recalls pleasing
recollections of excursions into the sphagnous bogs, cedar swamps, and pine barrens in the southern
region of New Jersey. These localities have special charms for the botanical student on account of the
diversity of beautiful and interesting plants they produce. In proper season, in most places, they are
redolent with the rich perfume of the Magnolia glauca and the fragrance of the Clethra alnifolia. In
early spring, the ground is adorned with bright patches of the little Pyxie, ryxidanthera barbulata, and
Sand-Myrtle, Leiophyllum buxifolium. Later, the swamps display an abundance of Helonias bullata, and
still later, many other liliaceous plants, as Zygadenus Umanthoidcs, Nartkedum americanum, besides more
common ones. Rich are the woods and swamps in Orchids of the genera Cypripcdium, Goodyera,
Spiranthes, Liparis, Habrnarla, Calopogon, Pogonia, and drethvsa. On dry banks, amidst a host of
Vacciniums and other ericaceous plants, are conspicuously seen the spikes of white flowers of the
grassy-looking Xerophyllum asphodeloides ; while the bogs below are as conspicuously dotted with the
curious green and purple Pitcher-plant, Sarracenia purpurea, nestling among sphagnum, and entangled
among Cranberry and Sundews, Drosera filiformis, etc. In many places occurs the singular grass, with
its underground fruit, the AmphioarpumPurshii; and in more restricted localities appears the rare little
fern, the Schizcea pusiUa.

Upward of thirty years ago, while examining the structure of sphagnum, my attention was
distracted by the movements of a singular animal, whose character and affinities I did not then recog-
nize. Soptember 9th, 1873, the fiftieth anniversary of my birth, a friend, Clarence S. Benient, presented

GENTTS HYALOSPHENIA— HYALOSPHENIA PAPILIO. 133

The shell of H. papilio, pi. XXI, is usually compressed oblong ovoid,
but occasionally is compressed pyriform. The compression is about equal
to one half the greater diameter. The transverse section, figs. 14, 15, is
elliptical, with rounded angular poles. Viewed on the broader surface,
figs. 1, 3-5, 7, 11-13, the outline is broadly convex at the fundus, from
which the sides slant in a straight or nearly straight line close to the
mouth, where they are commonly slightly everted. The lower extremity
or line of the mouth is transversely slightly convex. In a comparatively
few specimens, in the view of the broad surface of the shell the outline
is decidedly pyriform, as seen in fig. 10. In the view of the narrower side
of the shell, the outline is flask-shaped, with the fundus rounded, obtusely
angular, or slightly prolonged; and the oral end appears as a concave
notch. See figs. 2, 6, 8, 9.

The mouth is inferior, terminal, and transversely elliptical, with rounded
commissures, and is convex in the wider and concave in the narrower direction.

The shell is buff- or straw-colored, of lighter or darker shade, and rarely
nearly colorless. Among thousands of specimens from different localities,
I do not recollect meeting with one in which at least a trace of yellow
could not be detected. As in other species of the genus, it is perfectly
transparent and structureless, nor did I ever find a specimen with adherent
extraneous bodies of any kind. The thickness of the shell is pretty uniform,
but is slightly greater around the mouth.

In the view of the broader side of the shell, along the border of the
fundus, there may be detected from two to half a dozen minute apertures,
around which the shell is slightly thickened. These appear to serve for the
ingress and egress of water accompanying the protrusion and retraction of
the pseudopods. See figs. 1, 3-5, 7, 10-13.

The shell of Hyalosphenia papilio exhibits but little variation in size.
It ranges from ^th to 2 ^th of an inch in length by ^th to ~t\\ of an inch
in breadth, and ^th to ith of an inch in thickness. The mouth ranges
from ^th to 5 -J- th of an inch in breadth.

me with a small Hartnack microscope, which, from its convenient size and form, I kept on my study
tabic From time to time I was led to make observations on Fresh-water Ehizopods detected in sedi-
ments collected in the vicinity of Philadelphia. A year later, in examining water squeezed from sphag-
num obtained at Absecom, I observed many individuals of the same singular animal above indicated,
but now, understanding its nature, I described it as Difflugia papilio. It was the rediscovery of this beau-
tiful form which impelled me to pursue the investigations which constitute the material of the present
work.

134 FEESH-WATEE EHIZOFODS OF NOETH AMEEICA.

The sarcode of Hyalosphenia papilio I have never seen entirely filling
the shell. Its proportionate size with the capacity of the latter varies very
much, the difference apparently being more or less dependent upon the
amount of nutriment taken by the animal. Thus I have observed, in the
summer months, when apparently the conditions of life were most favor-
able to the animal, that the sarcode mass was largest, and most nearly filled
the shell, as seen in fig. 1. Under less favorable circumstances the sarcode
was smaller ; and sometimes the animal would impress me with the idea of
being starved, when the sarcode mass would occupy less than half the
capacity of the shell, as seen in fig. 4.

In the view of the broad surface of H. papilio, the sarcode mass usually
appears pouch-like in outline. The upper part is ovoid; the lower part is
as wide as the shell contiguous to the mouth, and the intermediate part is
contracted. In the view of the narrow side of the animal, the sarcode
mass touches the shell laterally, and appears therefore to fill it more in the
less than in the greater breadth.

Diverging processes of the ectosarc fix the sarcode mass to the sides
and fundus of the shell. These processes, of course, vary in length in
proportion as the sarcode mass diminishes or increases. They are conical
extensions of the ectosarc, more or less tapering to filaments, and are
usually simple, but sometimes furcate at their outer connection. They are
of the nature of pseudopods, and may be detached from the shell and
withdrawn into the sarcode mass, while new ones may be projected and
extended to become attached to the shell.

The sarcode of H. papilio is remarkable for the quantity of chlorophyl
which enters into its constitution. I have never met with a living speci-
men of the animal in which this material was absent. It is of a bright
green color, like that of the green fresh-water polyp Hydra viridis, and
occurs in spherical corpuscles ranging from ^th to the -^- th of an inch in
diameter. They are usually so numerous as to obscure all the other con-
stituents of the sarcode; but almost invariably this is free from them in
the vicinity of the mouth.

The basis of the sarcode is the usual faintly granular colorless proto-
plasm mingled with larger and more distinct granules. The ectosarc every-
where appears colorless and clear or faintly granular.

The interior of the sarcode mass near the upper part is occupied cen-

GENUS HYALOSPHENIA— HYALOSPHENIA PAPILIO. 135

trally by a large, spherical, clear or pale granular nucleus ; in different
specimens ranging- from about -^th to r J 00 th of an inch in diameter.

In the vicinity of the nucleus, at the periphery of the sarcode mass,
there may be detected several contractile vesicles. From two to four are
frequently seen at the same time together. They generally expand to
about ^th of an inch in diameter before collapsing.

Below the position of the nucleus, between it and the clear sarcode
contiguous to the mouth, the endosarc is occupied by variable quantities
of brownish food-balls, vacuoles, and occasionally distinct algous forms,
intermingled with the constituent elements.

Green algae swallowed as food, unless of comparatively large size and
more peculiar shape, are not usually distinguishable among the materials
of the endosarc in consequence of their being obscured by the abundance
of constituent chlorophyl corpuscles. Among them there may occasionally
be seen a diatom, a desmid, or a fragment of an oscillaria. The endo-
chrome of the algse, as a result of digestion, appears to become shriveled
and assumes a decidedly yellowish or reddish-brown hue.

The brownish food-balls vary in quantity and size. They are mostly
granular, but sometimes have an oleaginous appearance, and lie free in the
endosarc or are contained in vacuoles. They appear to be accumulations
of food in the process of digestion, or the remains of food which have
undergone digestion and are ready to be discharged.

The vacuoles vary in number and size, sometimes few, sometimes many,
and ranging from .^th to ^th of an inch They appear as globules of
clear colorless liquid, of pale colorless granular matter, or of colored food-
balls surrounded by a stratum of either or both of the former.

At times one or more of the vacuoles may be seen slowly approaching
the mouth of the shell, on reaching which their contents are discharged.
Food-balls, in like manner, without being enclosed in vacuoles, may be
seen pursuing the same course.

In the vicinity of the mouth not unfrequently vacuoles may be seen
to appear, to gradually enlarge, and then collapse, in the manner of the con-
tractile vesicles so constantly occupying a position at the upper part of the
sarcode mass.

With the other materials of the endosarc there are numerous colorless
well-defined granules which resemble starch, also many small pale globules

136 FRESHWATER RHIZOPODS OF NORTH AMERICA.

resembling vacuoles, and in addition oil-like globules of various sizes,
sometimes colorless and sometimes yellowish in hue. These latter mate-
rials especially are obscured by the chlorophyl corpuscles.

The pseudopods are digitiform and from two or three to half a dozen or
more in number. They sometimes extend to a length of —th of an inch
with a thickness of gith of an inch. They are usually simple, but occa-
sionally branch, and are blunt at the end. They are colorless, and with
high powers can be seen to be finely but faintly granular throughout. The
coarser granules of the endosarc do not enter them.

As the pseudopods protrude, the mass of the sarcode in the interior of
the shell proportionately diminishes, and the threads of attachment are put
to a greater stretch. When the animal is disturbed, the pseudopods are
retracted, but the sarcode mass commonly retains its attachment to the
mouth of the shell. Occasionally, however, when the animal is suddenly
or rudely disturbed, the sarcode mass retreats far into the shell, as repre-
sented in fig. 5. In proportion as the sarcode retracts or extends, the
attaching threads shorten or lengthen.

Not unfrequently, but especially in October and November, and also
in the winter months, in sphagnum preserved in a moderate temperature,
specimens of H. papilio are to be seen in which the sarcode mass forms
a compressed spheroidal ball lying completely quiescent within the shell,
as represented in figs. 7-11. The ball, in the narrower view of the latter,
is seen to touch the sides, but in the broader view does not extend to
the lateral borders. The ball ranges from ith of an inch to 3 J th of an
inch in breadth, and ^th to ^ th of an inch in thickness. Generally it is a
little greater in its longitudinal than in its broader transverse diameter.
The constitution of the ball appears to be nearly the same as the sarcode
mass in the active animal, but is devoid of the materials recognized as food,
and also presents no vacuoles nor contractile vesicles. It is bright green
from the presence of abundance of chlorophyl corpuscles, which exist in
the same proportion as usually observed in the active condition of the animal.
A central clearer spot would appear to indicate the retention of the nucleus.
The exterior of the ball is composed of a layer, of variable thickness, of
colorless, faintly granular ectosarc, not defined from the granular endosarc
extending into the mass of chlorophyl corpuscles. Occasionally the green
sarcode ball is invested by a more distinct and colorless membrane.

GENUS HYALOSPHENIA— HYALOSPHENIA PAPILIO. 137

Not unfrequently specimens of the kind just described are seen with
one or more globular masses of granular matter, colorless or colored yel-
lowish or brownish, lying between the green sarcode ball and the mouth
of the shell, as represented in fig. 10, which I have supposed to be excre-
mentitious. In several instances I have seen an animal withdraw its pseu-
dopods, retreat deeply into the shell, retract its threads of attachment, and
assume the form of an oval or spheroidal ball. This would subsequently
discharge several masses of excrementitious matter of the kind indicated,
and become proportionately reduced in size.

In many specimens with the sarcode in the condition of a quiescent
ball, the mouth of the shell appears to remain open ; in others it is closed
by a sort of gelatinoid operculum, as seen in fig. 11. In one instance
observed, as seen in fig. 9, the lips at the mouth of the shell were in
close apposition, and cemented together by the material of the oper-
culum.

I have repeatedly met with specimens of H. papilio, as represented in
fig. 12, in which the shell contained nothing excepting a quantity of scat-
tered bright green chlorophyl corpuscles, in all respects like those ordinarily
observed in the sarcode mass of the animal.

I have further repeatedly observed specimens in which the shell con-
tained a variable number of globular, granular, colorless corpuscles, of
nearly uniform size in the same specimen, but of different sizes in different
ones, as represented in fig. 13. The nature of these bodies I have not
determined, nor whether they actually pertain to the Hyalosphenia or
belong to some parasite, but I have suspected them to be spores of the
former.

H. papilio in comparison with many other rhizopods is of remarkable
uniformity in size, shape, and constitution. Though I have seen thousands
of specimens, from different localities, in mountainous regions, and nearly
at the sea-level, I have observed but trifling variation. I never have seen
anything like decided transitional forms, never any with the shell positively
colorless, and not one in any condition, whether of activit} T or quiescence,
in which the sarcode was devoid of the chlorophyl corpuscles.

As previously intimated, and for the reasons given, I have considered
Hyalosphenia papilio peculiarly well adapted for study, and I have looked
hopefully forward to it as a means of throwing light upon the modes of

138 FRESH-WATER EHIZOPODS OF NORTH AMERICA.

reproduction of the shell-covered rhizopods in general, but up to the pres-
ent time I have been disappointed. Among the multitude of specimens
I have seen I never observed a pair in the position which is commonly
viewed as that of conjugation, and regarded as having some relation with
reproduction.

HYALOSPHENIA TINCTA.

Plate XX, figs. 11-18.

Shell compressed pyriform, variable in the relation of breadth to
length ; in transverse section compressed oval ; composed of pale yellow,
transparent, structureless, chitinoid membrane ; mouth transversely oval.
Sarcode colorless ; pseudopods digitate, usually two, three, or more.

Size — Smallest specimen, 0.076 mm. long, 0.056 mm. broad, 0.028
mm. thick, with the mouth 0.02 mm. by 0.008 mm. ; second specimen
broader than long, 0.06 mm. long, 0.08 mm. broad, with the mouth as in
the former ; third specimen, 0.08 mm. long and broad, 0.036 mm. thick,
and mouth same as in former; largest specimen, 0.092 mm. long, 0.064
broad, and mouth as in the others.

Locality. — Abundant in the sphagnous swamps of Tobyhanna, Pocono
Mountain, Monroe County, Pennsylvania ; found also in the sphagnum
near Kirkwood station, on the Camden and Atlantic railway, New Jersey.

Hyalosphenia tincta, figs. 11-18, pi. XX, is closely related with
H. cuneata, but from its more pyriform shape, pale tinted shell, and living
in sphagnum instead of ponds, I have regarded it as distinct.

The shell is compressed pyriform, with a very short neck, usually with
little difference between the length and breadth. It is composed of pale
yellow or straw-colored transparent chitinoid membrane, without trace of
definite structure. It is thicker than in H. cuneata, and is therefore less
flexible. At the lateral borders, usually below the middle, it presents a
pair of minute pores for the ingress and egress of water. Sometimes
another pair of similar pores are found along the same border above the
middle. See figs. 11, 12, 14, 16, 18.

In transverse section, the shell is laterally compressed oval, with
obtusely rounded poles. The mouth has the same form, and is slightly
directed upwardly toward the commissures.

The size of the shell differs but little, though there is considerable

GENUS HYALOSPHENIA— HTALOSPHENIA TESTCTA. 139

variety in the relation of the greater breadth to the length. Most frequently
the specimens observed were quite or nearly equal in length and breadth.
Specimens of usual size ranged from ith to ^th of an inch in length and
breadth, with rather less than half the thickness. The mouth is about
ji- th of an inch in breadth and ^th of an inch in the short diameter.

The sarcode is colorless and finely granular, and usually contains a
multitude of large colorless globules, which are scarcely distinguishable
as vacuoles, food-balls, or contractile vesicles. The latter were only to be
recognized by looking for them in the usual position, along the border at
the fundus of the sarcode mass. A nucleus is present, but is obscured by
the surrounding granules and globules. .

Viewed laterally, or from the extremities, the sarcode mass was
observed to touch the broader sides of the shell; but more or less vacancy
was left between it and the narrower sides. The lateral borders and fun-
dus of the mass are attached in the ordinary manner to the inner surface of
the shell by threads of the ectosarc.

The pseudopods are commonly two or three in number, thick, digitate
and simple, but sometimes are more numerous and branching.

Some individuals of this species appeared to be particularly irritable,
and tapping the glass upon which they were placed would not only cause
them to retract their preudopods, but also to separate from the mouth of the
shell and retreat into its fundus. In the contraction of the sarcode mass
it would assume a spheroidal form, but not withdraw the threads of attach-
ment to the sides and fundus of the shell. After a few moments of rest,
the sarcode would again descend and establish an attachment to the mouth
of the shell, and once more protrude its pseudopods. In one individual,
the sarcode mass actually protruded its pseudopods before the body was
extended to the mouth of the shell, as represented in fig. 12.

Hyalosphenia tincta I found abundantly in moist sphagnum, of the large
sphagnous swamps, at Tobyhanna, on the Pokono Mountain, Monroe County,
Pennsylvania, in July, 1876. Later I found it, though rarely, in sphagnum,
near Kirkwood station, on the Camden and Atlantic railroad, New Jersey.

I was at first disposed to view Hyalosphenia tincta as being the same as
H. cuneata. They have nearly the same size and form ; but the difference in
color of the shell and the difference in the character of the locality they
inhabit have led me to regard them as distinct.

140 FRESHWATER RHIZOPODS OF NORTH AMERICA.

Associated with Hyalosplienia tincta, I observed a number of speci-
mens, of the same sizes, variations in form, and color, but in which the shell
exhibited more or less evidence of areolation. In some, the appearance
was exceedingly indistinct; in others, it was quite positive, and these latter
had then all the characters of a species of another genus, which I have
named Nebela flabellulum. Those with the indistinct appearance of areola-
tion weie evidently transitional varieties toward the latter.

I have observed sufficient variation in specimens to suspect it probable
that Hyalosphenia tincta merges into H. cuneata, and likewise into H. elegans
and H. papilio.

HYALOSPHENIA ELEGANS.

Plate XX, figs. 19-29.
Difflugia (Catharia) elegans. Leidy: Proc. Ac. Nat. Sc. 1874, 156; 1875, 415.

Shell compressed flask-shaped; in the view of the broader side, with
an oval body and long cylindroid neck, slightly widened at the oral end,
which is convex downward; in the view of the narrower side, long elliptical,
and tapering to the oral end, which is deeply notched. Shell composed
of pale brownish, transparent, structureless, chitinoid membrane, which is
impressed with longitudinal rows of hemispherical pits. Sarcode colorless,
attached by threads to the sides and fundus of the shell; pseudopods digi-
tate, usually three or four in number.

Size.— Length from 0.088 mm. to 0.108 mm.; breadth of body 0.064 to
0.04 mm.; thickness of the same 0.02 to 0.028 mm.; breadth of neck and
oral end 0.016 to 0.02 mm.; short diameter of oral end 0.008 mm.

Locality. — Abundant, in association with Hyalosphenia papilio, in sphag-
num in the same localities.

Hyalosphenia eSegans, figs. 19-29, pi. XX, a common and graceful
form, living among sphagnum, appears to be quite distinct from the pre-
ceding species. The shell is compressed flask-shaped. Viewed on the
broader side, the outline of the body is oval and more or less tapering into
a rather long cylindroid neck The fundus is convex, and the oral end is
slightly expanded and convex downward. In the view of the narrower
side, the shell presents a long elliptical outline, tapering to the oral end,

GENUS HYALOSPHENIA— HYALOSPHENIA ELEGANS. 141

which appears deeply notched from the turning upward laterally of the
oral commissures.

The shell is composed of transparent chitinoid membrane, of a pale
chocolate-brownish hue, without a trace of definite structure. It is of
uniform thickness, except that it forms a thicker border to the mouth.
The sides of the shell exhibit a more or less symmetrically corrugated
appearance, due to series of hemispherical inflections, which are remarkably
constant and persistent.

The mouth is oval, and is convex in its wider diameter.

The size and form of the shell vary but little. Commonly, specimens
range from ith to ~th of an inch in length, ^>th to i th of an inch in
breadth, and ^th to * th of an inch thick, with the mouth -i-th of an inch
in the greater and ^th of an inch in the less diameter.

The sarcode of H. elegans is colorless, though sometimes the endosarc
appears more or less yellowish from the quantity of food it contains.
Usually, the endosarc contains many vacuoles and food-balls, mostly of a
yellowish or brownish hue, besides which it contains the usual constituents
found in allied forms.

The nucleus is usually more or less obscixred or may be completely
hidden from view by the surrounding materials. It is pale granular and
globular, and measures from ..^th to j^th of an inch in diameter.

From two to four contractile vesicles are frequently visible together in
the vicinity of the nucleus at the periphery of the sarcode mass They
measure about the ^th of an inch previous to their collapse.

The mass of sarcode occupies more or less of the interior space of the
shell, according as the animal has been well or poorly supplied with nourish-
ment. Sometimes it nearly fills the shell; at others, it barely occupies half
its capacity. Extensible threads of ectosarc diverge from the sarcode
mass to the sides and fundus of the shell, varying in length in proportion
as the mass enlarges or diminishes

The pseudopods are digitate, usually three or four in number, mostly
simple, sometimes forking or branching, and finely granular in constitution.

Specimens of H. elegans are frequently found with the sarcode in an
encysted condition in the form of a compressed ovoid or spheroid ball, of
variable size, as seen in figs. 27-29. These specimens also often exhibit a
number of pale granular spheres, of variable size, occupying the neck of

142 FRESH- WATER RHIZOPODS OF NORTH AMERICA.

the shell, as represented in figs. 24, 29. They probably consist of excre-
mentitious matters discharged from the sarcode ball as it assumed the
resting condition. Sometimes specimens are met in which the position
of the sarcode ball is occupied by a number of pale granular spheres, as
represented in fig 25. They are of more uniform size and more definite
granular structure than in the spheres of supposed excrementitious matter.
Their nature I have not determined, but have suspected them to be spores
or reproductive bodies, though they may be entirely foreign to the rhizo-
pod. They measure about the ^th of an inch in diameter.

I have found no specimens referable to H. elegans which exhibited
any clearly transitional disposition toward H. papilio or other forms.

The thing previously described which appears most to resemble H.
elegans is the Difflugia spirigera, of Ehrenberg-, from the Bavarian Alps.*
If what I have described as series of hemispherical inflections of the shell
correspond with his four internal longitudinal spiral lines, the animals are
probably the same, though the size he gives is a third less than the smallest
of those I have observed.

QUADRULA.

Latin, quadrula, a little square.
Difflugia: Wallich, 1863. Assulina ; Hologlypha: Ehrenberg, 1871. Quadrula: Schulze, 1875.

Shell compressed pyriform, transparent, colorless, composed of thin
square plates of chitinoid membrane, arranged in transverse or more or less
oblique series, in consecutive or alternating order. Mouth inferior, termi-
nal, oval. Sarcode colorless, having the characters of that of Difflugia, etc.

QUADRULA SYMMETRICA.

Plate XXTV, figs. 20-25.

Difflugia proteiformis, \a,r. symmetrica. Wallich: An. Mag. Nat. Hist, xii, 1863, 458, pi. x, fig. 16.
Difflugia pyriformis, var. symmetrica. Wallich : An. Mag. Nat. Hist, xii, 1863, 467 ; xiii, 1864, 232, pi.

xvi, fig. 26.
Difflugia symmetrica. Wallich : Ibidem, 245.

Difflugia assulata. Ehrenberg: Abh. Ak. Wis. Berlin, 1871,249, Taf. ii, Fig. 4,5.
D. Assulina asmlata. Ehrenberg: Ibidem, 246.
Difflugia carolinensis. Ehrenberg : Ibidem, 250, Taf. iii, Fig. 14.
D. Assulina carolinensis. Ehrenberg: Ibidem, 246, 274.
Difflugia Leptolepis. Ehrenberg : Ibidem, 254, Taf. iii, Fig. 15.
D. Assulina Leptolepis. Ehrenberg : Ibidem, 246, 274.
Quadrula symmetrica. Schulze: Arch. inik. Anat. 1875, 329, Taf. xviii, Fig. 1-6. — Leidy: Pr. Ac. Nat.

Sc. 1875, 415.— Archer : Quart. Jour. Mic. Sc. 1877, 122.

"Monatsb. Berl. Ak. Wissens. 1853,526; Abhand. 1871, Taf. iii, Fig. 4.

GENUS QUADRULA— QTJADRULA SYMMETRICA. 143

Shell compressed pyriform : viewed on the broader sides, with the
fundus widely convex, and the sides sloping or moi'e or less inflected
toward the oral end, which is convex downward ; viewed on the narrower
side, ellipsoidal, with the fundus obtuse and the oral end roundly notched.
Mouth transversely oval and convex downward. Shell colorless, trans-
parent, composed of square plates arranged in transverse longitudinal or
more or less oblique rows. Sarcode colorless ; pseudopods digitate, from
one to three or more.

Sue. — Length 0.08 mm. to 0.14 mm. ; breadth 0.04 mm. to 0.96 mm. ;
thickness 0.028 mm. to 0.048 mm. ; mouth from 0.02 mm. by 0.008 mm. to
0.032 mm. by 0.016 mm.

Locality. — Dripping rocks with Fegatella, in Fairmount Park ; ditch
at the side of the Norristown railroad above Manayunk, Philadelphia;
sphagnum of the sphagnous swamps of Absecom, Vineland, and other
places in New Jersey.

Quadrula symmetrica, figs. 20-25, pi. XXIV, the only representa-
tive of its genus, is remarkable for the peculiar construction of its shell,
which is compressed pyriform. Viewed on the broader surfaces, the out-
line is pyriform, or ovoid, with the sides sloping or more or less inflected, eo
as to produce a neck of variable length. The oral end is transversely
convex. Viewed on the narrower sides, the outline of the shell forms a
long ellipse, tapering to the oral end, which appears notched. The mouth
is transversely oval and entire.

The shell is perfectly colorless and transparent, and is composed of
square, structureless, chitinoid plates. These are arranged, with some gen-
eral degree of regularity, in transverse, more or less oblique, or longitudi-
nal rows. Longitudinally for the most part they successively increase in
size from the vicinity of the mouth toward the fundus. Frequently the
row surrounding the mouth is larger than the next, and those on the sum-
mit of the fundus are smaller than the preceding ones. The general
arrangement is like that of tiling with variable regularity. Mostly their
order is consecutive, but sometimes somewhat alternating. They are not
entirely disposed with the symmetry expressed b} r their name, for frequently
smaller plates break the regular succession of larger ones, and sometimes
one angle of a plate replaces that of a contiguous one.

144

ERESH-WATER RH1ZOPODS OF NORTH AMERICA.

Besides figs. 20-25, pi. XXIV, the accompanying figures, in the
arrangement of the plates of the shell, represent the more important varieties
which I have observed.

The size of the shell ranges
from about the ^th to the ,4th of an
inch in length by ^.th to ^th of an
inch broad.

The sarcode is colorless, and
in all its characters resembles that
of Hy alosphenia. The food- vacuoles
often appear yellowish. The nu-
cleus when visible measures about
the j^th of an inch or more. The
pseudopods are digitate and usu-

Quadrula symmetrica. Opposite sides of the same shell.

ally two or three in number.

In several instances I have found specimens, late in the season, with
the sarcode in a quiescent or encysted condition. Fig. 25 represents such
a specimen obtained from sphagnum in November. It was of the largest
size, about the ~th of an inch in length. The plates were arranged ob-
liquely aci'oss the shell, and were pretty uniform in size. The neck was
occupied by a laminated diaphragm as thick as one third the length of the
shell. The sarcode mass formed a compressed oval ball occupying a cen-
tral position in the body of the latter The ball was nearly colorless or
faintly yellowish, and granular, and contained several large oil-like glob-
ules. A central clearer space appeared to indicate the presence of a nucleus.

Dead shells are sometimes found containing in the interior a number
of scattered plates, or the same in one or more little packets, like those
composing the wall of the shell.

Quadrula symmetrica was first described by Dr. Wallich, under the
name of Diffluyia symmetrica, from specimens found in England. It was
more recently described, and referred to a new genus, by Prof. Schulze,
from specimens found near Dresden.

Ehrenberg described the same as pertaining to three different species,
under the names of Diffluyia assulata, D. carolinensis, and D. leptolcjns. These,
in 1871, with a number of other forms, he referred to a subdivision of
Diffiugia with the names of Assulina and Holoylyplia. As, however, the

GENUS NEBELA— NEBELA COLLAEIS. 1 15

latter would apply to the first members of the subdivision indicated, which
appear to be only varieties or at most two species of Cyphoderia, neither
of the names could be considered as properly taking precedence of
Quadrula distinctly applied to Assulina assulata, the fourth member of
Ehrenberg's list.*

NEBELA.

Greek, ncbel, a bottle.
Diffiugia: Ehrenberg, 1848. EeticeUa; AUodictya ; Odontodictya : Ehrenberg, 1871. Nebela : Leidy, 1874.

Shell usually compressed pyriform, transparent, colorless, with or
without appendages,, composed of cancellated membrane or of peculiar
intrinsic structural elements of variable form and size, mostly of circular
or oval disks, of narrow rectangular plates or rods, or of thin, less regular,
angular plates, often almost exclusively of one or the other, sometimes of
two or more intermingled in variable proportions, sometimes of chitinoid
membrane incorporated with more or less extrinsic elements, and sometimes
of these entirely, as in Diffiugia. Mouth inferior, terminal, oval. Sarcode
colorless; in form, constitution, and arrangement as in Diffiugia, Hyalo-
sphenia, etc.

NEBELA COLLARIS.

Plates XXII; XXIII, tigs. 1-7; XXIV, figs. 11, 12.

Diffiugia collaris. Ehrenberg: Monatsb. Ak. Wis. Berlin, 1848, 218; Microgeologie. 1854, 331; Abh. Ak.

Wis. Berlin, 1871, 143, Taf. ii, Fig. 27; Taf. iii, Fig. 21.
Diffiugia reticulata. Ehrenberg: Monatsb. Ak. Wis. 1848, 218; Microg. 1854, 331; Ab. Ak. Wis. 1871, 143,

Taf. ii, Fig. 26.
Diffiugia cancellata. Ehrenberg : Monatsb. Ak. Wis. 1848, 379 ; Microg. 1854, 331 ; Ab. Ak. Wis. 1871, 145,

Taf. ii, Fig. 3.
Diffiugia Carpio. Ehrenberg: Microg. 1854, 115.

D. Lagena fi. Carpio. Ehrenberg: Microg. 1854, 331; Abh. Ak. Wis. 1871, 251, Taf. ii, Fig. 22, 27.
Diffiugia binodis. Ehrenberg : Microg. 1854, 331 ; Abh. Ak. Wis. 250, Taf. ii, Fig. 22, 23.
Diffiugia annulata. Ehrenberg: Microg. 1854, — ; Ab. Ak. Wis. 1871, 249, Taf. iii, Fig. 19.
Diffiugia laxa. Ehrenberg: Microg. 18j4, — ; Ab. Ak. Wis. 1871, 254, Taf. iii, Fig. 22.
Diffiugia peltigeracea. Carter: An. Mag. Nat. Hist, xiii, 1864, pi. i, fig. 12.
Diffiugia symmetrica. Wallieh: An. Mag. Nat. Hist, xiii, 1864, pi. xvi, figs. 27-33.
D. EeticeUa collaris (AUodictya). Ehrenberg: Ab. Ak. Wis. 1871, 247.
D. IieticeUa reticulata (Odontodictya). Ehrenberg: Ibidem.
D. IieticeUa cancrllata (Odontodictya). Ehrenberg: Ibidem.
D. EeticeUa Carpio (AUodictya). Ehrenberg: Ibidem.
D. IieticeUa binodis (Odontodictya). Ehrenberg: Ibidem.
D. EeticeUa annulata (AUodictya). Ehrenberg: Ibidem.
D. EeticeUa laxa (AUodictya). Ehrenberg: Ibidem.

Diffiugia cellulifcra. Ehreuberg: Deutsche Nordpolarfahrt, 1874, 460, 466, Taf. iii, Fig. 24.
Diffiugia (Kebela) numata. Leidy: Proc. Ac. Nat. Sc. 1874, 157.
Nebela numata. Leidy: Proc. Ac. Nat. Sc. 1876, 116, figs. 1-5; 1877, 264.

•Abhand. Akad. Wissens. Berlin, 1871, 246.
10 RUIZ

*•

#»

146 FEESH-WATEE EHIZOPODS OF NOETH AMERICA.

Shell compressed pyriform, longer than broad; in the broader view,
with the fundus widely convex, the sides sloping downward and generally
slightly inflected toward the oral end, which is convex downward; in the
narrow view, oblong, with the fundus obtuse, sometimes impressed on each
side, gradually sloping, and usually slightly inflected toward the oral end,
which is notched Mouth transversely oval, entire. Shell colorless,
exceedingly variable in its structural elements, generally composed of oval
or circular disks, sometimes nearly exclusively of one or the other, or inter-
mingled in various proportions, more or less uniform or variable in size,
sometimes mingled with rod-like or narrow rectangular plates, and some-
times almost wholly composed of these, rarely composed of thin, irregular,
angular plates. Sarcode colorless, resembling in general constitution and
arrangement that of Hy alosphenia, etc. ; pseudopods digitate, usually from
three to half a dozen.

Size. — In fifty specimens two thirds ranged between 0.1 mm. and 0.14
mm. in length. The smallest of the series was 0.064 mm. long, 0.036 mm.
broad, 0.02 mm. thick, with the oral end 0.016 mm. broad and 0.008 mm.
thick. The largest was 208 mm. long, 0.12 mm. broad, 0.06 mm. thick,
with the oral end U.048 mm. broad and 0.032 mm. thick. An average-sized
specimen was 0.128 mm. long, 0.08 mm. broad, 048 mm. thick, with the
mouth 0.032 mm broad and 0.024 mm. thick.

Locality. — Moist sphagnum, of the sphagnous swamps of New Jersey,
Pennsylvania, Maine, Florida, Alabama; rarely in moss at the edge of a
pond in the Uinta Mountains, Wyoming Territory.

Wefoela collaris (pi. XXII ; pi. XXIII, figs. 1-7), a remarkable and
beautiful rhizopod, is common and abundant, living in the moist sphag-
num of the sjmagnous swamps of New Jersey and Pennsylvania. It is a
constant associate of Hy alosphenia papilio and H. elegans. Sometimes the
sphagnum in certain localities actually swarms with the animal, and a
drop of water squeezed from the plant contains a multitude of them. At
other times and in other localities, apparently under equally favorable
circumstances, the sphagnum contains few or none of the animals, though
it is rare not to find traces, such as a few dead shells, in the sphagnum of
most localities.

The shell is compressed pyriform, longer than broad, though varying

GENUS NEBELA— NEBELA COLLARIS. 147

considerably in the proportion of the different measurements. Viewed on
the broad surface, the outline is pyriform, with the oral end convex down-
ward. The sides slope downward to the mouth, sometimes nearly in a
straight line, sometimes with more or less inflection, giving rise to a neck
of variable length, though generally short. In the view of the narrower
surface, the outline is elliptical or more or less narrowly pyriform, with the
oral end concavely notched, and with the fundus obtuse, and sometimes
impressed at the sides.

The transverse section of the shell is oval and evenly rounded at the
poles, but occasionally is narrowed gradually, or somewhat abruptly
approaching the latter.

In some specimens, the section has a hexahedral outline, with concave
sides and prominent rounded angles, as seen in fig. 6, pi. XXIII.

Sometimes the shell is impressed laterally and at the fundus, so as to
produce obtusely angular borders and a somewhat carinated appearance,
as seen in fig. 4, pi. XXII, representing a transverse section.

Sometimes the narrower forms present at the lower third, at each lateral
border, a slight conical prominence, at the apex of which the shell appears
to be perforated by a minute pore, as seen in figs. 1, 2, 4, 7, pi XXIII.

The mouth is transversely oval and entire, and has rounded com-
missures, as seen in fig. 4, pi. XXII.

In composition, the shell is of extraordinary character, from the variety
in form and arrangement of its elements. Most frequently it is composed
of oval or circular disks, as represented in figs. 1-12, 15-17. The disks
usually hold no relationship in size with that of the shell : the smallest
specimens may have the largest disks, and the largest ones may be com-
posed of those of the smallest size. Sometimes the shell is almost entirely
composed of circular disks, sometimes of oval disks, and frequently the
two kinds are intermingled. Sometimes they are of pretty uniform size ;
at others, they are intermingled, of different sizes. Most frequently the
larger disks occupy the fundus and body and the smaller ones the lower
part or neck of the shell. Sometimes the larger disks are more or less scat-
tered, with some approach to uniformity, and the intervals are occupied by
smaller ones. Indeed, there exists almost any conceivable arrangement of
the round and oval disks in the construction of the shell.

Another variety of the shell, not uncommon, though less frequent than

148 FEESH-WATEE EHIZOPODS OF NOETH AMEEICA.

the former, is composed of narrow rectangular plates, intermingled with a
comparatively few round or oval disks, as seen in figs. 13, 18, pi. XXII.
The narrow plates are usually placed parallel, in close juxtaposition, in small
patches, which are arranged in different directions, while the round or oval
plates occupy intervals here and there, singly or two or three together.
The general appearance gives the impression of certain kinds of tessellated
pavement.

Some shells are mainly composed of round and oval disks, of the
variety first described, intermingled with a few narrow rectangular plates
or rods, of various lengths, as represented in fig. 7.

Occasionally I have seen specimens with extraneous matters, such as
quartz particles and diatoms, incorporated with the shell. A specimen
represented in fig. 8 appears to have a few sponge spicules added to the
ordinary intrinsic elements of composition.

Not unfrequently there are found, in association with the usual more
characteristic varieties of Nebela collaris, individuals which have the same
form of shell, but with its structure rather related with that of the ordinary
forms of Difflugia, In some specimens the shell is composed of thin and
irregularly angular silicious plates, as represented in fig. 12, pi. XXIV. The
intervals of the plates appear as dark or clear outlines, according to the
focus, and the margin of the mouth of the shell is uneven, as it is formed
by the bordering plates. Mostly the intervals of the silicious plates are
conspicuous, and appear to be occupied by a clear cementing substance,
or the shell appears to be composed of clear chitinoid membrane paved with
the silicious plates, as seen in fig. 11.

The specimens vary greatly in the forms of the component silicious
plates, which consist of variable proportions of the kind just described,
with others which are more regularly rectangular, or in the form of rods,
and sometimes with diatoms, and round or oval plates like those which
ordinarily compose the shell of Nebela collaris. Through such specimens the
latter would appear by transition forms to merge into Difflugia compressa.

The sarcode of Nebela collaris is colorless, but frequently the endosarc
appears more or less yellowish or brown, from the abundance of mingled
food in balls and as diffused granular matter. It is a remarkable fact that
rarely green food or food of any other color than those just mentioned is
seen in this animal.

GENUS NEBELA— NEBELA COLLARIS. 149

The general appearance, extent, arrangement, and constituents of the
sarcocle are the same as in Hyalosphenia. The nucleus is usually obscured
from view by the accumulation of food and other matters. The contractile
vesicles are seen, two or three in number, between the position of the
nucleus and the periphery of the sarcode mass. Among the yellowish
contents of the endosarc, the balls often have the appearance of oleaginous
globules

The pseudopods are digitate, mostly simple, and usually from two or
three to half a dozen in number. They extend to the ^th of an inch in
length or more, and commonly are about the j^th of an inch thick.

The range of size and the proportionate diameters of Nebela collaris
vary considerably. Average-sized specimens are about ^th of an inch
long, gj- th broad, ^th thick, with the mouth about ^th broad and j^- th in
the short diameter. A common-sized specimen was the ^th of an inch
long, ^th broad, ^th thick, with the oral end ^th by ^th of an inch.
The smallest specimen, of a large number, was ^th of an inch long,
^th of an inch broad,- ^th of an inch thick, with the mouth end ~\h by
gigth of an inch. The lai-gest specimen, from moss, on the borders of a
lake high up in the Uinta Mountains, Wyoming Territory, was ^th of an
inch long, ith of an inch broad, and g- 6 th of an inch thick, with the oral
end ith by ^ th of an inch.

Nebela collaris may frequently be observed with the sarcode in the
condition of a quiescent ball, or in an encysted state, occupying the central
portion of the body of the shell, as represented in figs. 7, 8, 1 0, pi. XXII.
The ball is compressed spherical, and varies in size in different individuals.
At an early stage it contains a quantity of the yellowish food, but this is
gradually discharged, and contributes to the formation of the epiphragm
usually found occupying the mouth and neck of the shell. In its later
condition, the sarcode ball is pale yellowish or nearly colorless, of granular
constitution, mingled with coarser and more defined granules and oleagi-
nous-looking globules, small and large.

The epiphragm (fig. 7) is laminated, and often contains globular
bodies, apparently remains of the food discharged or purged from the
sarcode ball.

Occasionally specimens occur in which the sarcode is substituted by
a variable number of granular spheres, of nearly uniform size, which,

150 FRESH- WATER EHIZOPODS OF NORTH AMERICA.

as in other similar cases, I have suspected to be spores or reproductive
germs; though they may not belong to the animal, and may be of parasitic
nature.

Nebela collaris was originally described by me under the name of Nehela
numata; but on studying the literature relating to the Fresh-water Ehizo-
pods, I have been led to the conclusion that the same had been repeatedly
described by Ehrenberg with different names, of which Difflugia collaris is
one of the earliest-
All the forms described and figured by Ehrenberg with the names of
Difflugia collaris, D. reticulata, D. cancellata, D. Carpio, D. binodis, D. annulata,
D. laxa, and D cellulifera, I suspect to pertain to the same animal, and this
I suppose to be the same as that I first described as Nebela numata.

In a systematic arrangement of the Arcellinse,* Ehrenberg has placed
the above-named forms, except the last one, in a group he calls Difflugia
Reticella Of this he makes an edentate subgroup, — Allodictya, and a dentate
group, — Odontodictya.

If the names of Reticella, Allodictya, and Odontodictya are to be regarded
of generic or subgeneric value, they would apply to the first-named species
of the group or subgroups.

D. Reticella asteropliora is the first species of the first subgroup, and D.
Reticella binodis that of the second subgroup. The character of the former
is obscure; but, judging from the imperfect figure, it is not generically the
same as Nebela, and therefore the names of Reticella and Allodictya would
not supplant Nebela Nor would Odontodictya correctly replace Nebela; for,
although Difflugia binodis with little doubt refers to what I have considered
a variety of Nebela collaris, the term is erroneous, for no species of Nebela
is dentated.

I think it probable that several other forms described and named by
Ehrenberg likewise pertain to Nebela collaris, but they are so doubtful that
I think it unnecessary to mention them.

The series of specimens represented by Dr. Wallich in figs. 27 to 33,
pi. XVI, of the thirteenth volume of the Annals and Magazine of Natural
History for 1 864, and described as transition forms of Difflugia symmetrica,
appear to me to pertain to the same animal as Nebela collaris. Dr. Wallich
remarks that the shell is sometimes compressed, but frequently is not so.

"Abhand. Akad. Wissens. Berlin, 1871, 244.

GENTJS NEBELA— NEBELA COLLAEIS. 151

In all other respects, the forms agree with the varieties of N. coliaris, but I
have never met with specimens in which the shell was otherwise than com-
pressed.

Mr. Carter, in the same work, described a form under the name of
Difflugia peltigeracea, which probably also belongs to the same animal as
Nebela coliaris.

The nature of the singularly varied shell of Nebela coliaris I have not
been able to determine with any satisfaction. In the characteristic forms,
the elements of structure, the disks and plates, appear to be intrinsic,
and not of a foreign character. They appear to be cemented together or
conjoined at the borders, and not implanted upon or incorporated with a
distinct chitinoid membrane. In breaking the shell, the line of rupture
follows the outlines or intervals of the disks and plates. The shell appears
to be silicious, as it remains unchanged when exposed to the action of
heated sulphuric and nitric acids.

Dr. Wallich, in referring to the structure of the shell of the transitional
forms of Difflugia symmetrica, which, as previously intimated, I suspect to
belong to Nebela coliaris, calls the peculiar elements colloid disks and plates.
He remarks of them that they are derived from the animal, and not directly
from the medium in which it lives. He supposes, however, that they are
formed through the coalescence of diatoms and other mineral elements
with the chitinoid basal substance of the shell,
which then undergo metamorphosis into all the
colloid forms that occur.* Of this process I have
been unable to satisfy myself; but the exceed-
ingly varied specimens which have come under
my notice, of shells composed of elements appar-
ently intrinsic and of regular but widely different
forms, of others apparently of extrinsic elements
regular and irregular, with many others of a transi-
tional character, would appear to justify the con-
clusion of Dr. Wallich.

. . Curved variety of Nebela coliaris.

bince the foregoing went to press, in sphag-
num from the cedar swamp of Malaga, Gloucester County, New Jersey,
among multitudes of characteristic specimens of Nebela coliaris, together

* Annals and Mag. of Nat. Hist. 1864, xviii, p. 234, pi. xvi, figs. 27-33.

1 52 FRESH-WATER RHIZOPODS OF NORTH AMERICA.

with many other rhizopods, I observed a Nebela, agreeing with the former,
except that it had a curved or retort-shaped shell, as represented in the ad-
joining woodcut. It was a living, active individual, and the only one of
the kind detected. The shell was composed mainly of circular plates of
variable size. Its length was 0.15 mm. ; its greater breadth 0.072 mm.,
and its less breadth 0.036 mm.

NEBELA FLABELLULUM.

Plate XXIII, figs. 8-19.

Difflugia (Nebela) fldbelUlum. Leiily: Proc. Ac. Nat. Sc. 1874,157.

Nebela fldbelMwm. Leidy : Proc. Ac. Nat. Sc. 1876, 118, figs. 6,7; 1877,264.

Shell compressed pyriform or spheroid, usually broader than long,
sometimes as long as or longer than the greater breadth ; transverse section
oval, with rounded angular poles ; neck short or none ; mouth transversely
oval, slightly convex downward in the long diameter. Shell in color and
structure like that of Nebela collaris. Sarcode and pseudopods like those of
the latter.

Size.— Length 0.068 mm. to 0.096 mm.; breadth 0.072 mm. to 0.104
mm.; thickness 0.032 mm. to 0.048 mm.; mouth from 0.024 mm. by
0.012 mm. to 0.02 mm. by 0.012 mm.

Locality. — Sphagnous swamps of Pennsylvania and New Jersey.
Toby ban na, Pocono Mountain, Monroe County ; Broad Mountain, Schuyl-
kill County; Swarthmore, Delaware County, Pennsylvania; Absecom,
Longacoming, Kirkwood, and other places in New Jersey.

Nebela flabelluaitm, represented in figs. 8-19, pi. XXIII, may be

regarded as a variety of N. collaris in which the breadth in one direc-
tion is greater than the opposite one, and approaches nearly or exceeds
the length. It is not so common as the characteristic varieties of the
latter, but in some localities occurs abundantly. It is a beautiful object
as ordinarily seen, and reminded me of a delicate lace-covered fan. Usually,
as it lies in the field of the microscope, it presents a broad pyriform outline,
with convex fundus, and the sides more or less inflected, so as to produce
a neck of moderate length. Sometimes the sides slope in straight lines, so
as to leave no distinction of body and neck. Occasionally, also, specimens
occur in which there is no prolongation of the oral pole, so that the shell
is slightly oblate spheroidal in outline, as seen in fig. 15.

GENUS NEBELA— NEBELA FLABELLULUM. 153

The transverse section of the shell is broadly oval, with the poles
angularly rounded, as seen in fig. 1 0.

In the narrower lateral view of the shell it is elliptical, with the oral
pole tapering at the sides. The month is transversely oval. In the
bi'oader view of the shell it is slightly convex downward, but in the narrow
view it appears as a concave notch.

The shell of Nebela flabellulum has the same constitution and variety
of elements as in N. collar is. It is most frequently composed of oval or
circular disks, as seen in figs. 8, 12, 17, or of the two together intermingled
in different proportions. Sometimes the larger circular or oval disks are
more or less regularly distributed, and the intervals filled in with small
disks, as seen in fig. 1G.

Sometimes narrow rectangular plates in different proportions are inter-
mingled with the disks, and occasionally the former greatly predominate,
as seen in fig. 14.

Occasionally I have found specimens in which quadrate plates, like
those of Quadrula symmetrica, were mingled with the more usual structural
elements, as seen in fig. 1 i).

The size and proportions of the shell of Nebela flabellulum vary but little,
compared with N. collaris. Commonly the length is less than the breadth,
and this is nearly twice in one direction what it is in the other. Often the
length and breadth are about equal, or the former measurement is a little
greater than the latter. Through varieties which are longer than broad, N.
flabellulum merges into N. collaris; but the former is sufficiently distinct and
prevalent in some localities to make it convenient to name it as a separate form.

Of the pyriform variety, or that with a more or less distinct, neck, the
size ranges from ijth to ^th of an inch in length, the ^th to ^th of an inch
in breadth, ith to ± th of an inch in thickness, with the mouth j^th by ^th
to JLth by 2 4th of an inch.

The oblate spheroidal forms range from „4th to 4\th of an inch lon^,

1 O 370 3j0 ~ 7

3 4 th to 3 J th of an inch broad, ith to 7 | th of an inch thick, with the mouth
the same as in the former.

The sarcode has the same conformation, kind of attachments, and con-
stitution as in Nebela collaris. The endosarc ordinarily contains a multi-
tude of yellowish and brownish food-balls, many of which often have a
highly oleaginous appearance.

154 FRESH-WATER RHIZOPODS OF NORTH AMERICA

In a specimen from the great sphagnous swamp of Longacoming,
Camden County, New Jersey, represented in fig. 14, the sarcode mass was
encysted, and the mouth of the shell closed with a laminated epiphragm.
The shell was composed mainly of short, narrow, rectangular plates laid
together in small patches, and arranged in diagonals, with intervals occupied
by round and oval disks. The sarcode ball, about the g- th of an inch in
breadth, contained a large and uniformly granular sphere, occupying about
three fourths of its capacity, and measuring the ±Ah of an inch in diameter.
The material of the ball exterior to the granular sphere appeared to consist
of a portion of the original sarcode, retaining a numbei of the brownish
food-balls.

Nebela fldbeUalum I have found most abundantly in the extensive
sphagnous swamps of Tobyhanna, Pocono Mountain, Monroe County,
Pennsylvania. Here especially I found the oblate spheroidal or neckless
variety. The species was associated with N. collaris, Hyalosphenia papilio,
H. elegans, etc. In the same swamp grew profusely, at the margin of ponds,
the Water Arum, Calla palustris.

NEBELA CAFJNATA.

Plate XXIV, figs. 1-10.

Difflugia carinata. Archer : Proc. Dub. Mic. Club, Dec. 1866, 122. Quart. Jour. Mic. Sc. vi, 1867, 178 ;

ix, 1869, pi. xx, fig. 12 ; xii, 1872, 195.
Nelela carinata. Leidy: Proc. Ac. Nat. Sc. 1876, 118, figs. 10, 11.

Shell resembling in shape and structure that of Nebela collaris, but
provided with a thin keel of chitinoid membrane, commencing above the
neck and extending along the lateral borders of the body over the fundus.
Sarcode also resembling that of N. collaris in color, arrangement, and con-
stitution.

Size. — Length from 0.144 mm. to 0.24 mm.; breadth from 0.l88 mm.
to 0.168 mm.; thickness 0.04 mm. to 0.072 mm.; mouth 0.036 mm. by
0.02 mm. to 0.028 mm. by 0.028 mm. ; carina from 0.004 mm. to 0.02 mm.
deep.

Locality. — Moderately frequent in the sphagnous swamp of Absecom,
Atlantic County, New Jersey ; occasionally elsewhere in sphagnum.

Wehela carinata, represented in figs. 1-10, pi. XXIV, is a beautiful
species, first discovered by Mr. Archer in Ireland. It is frequent in the

GENUS NEBELA— NEBELA CAKINATA. 155

moist sphagnum of the cedar swamp of Absecom, New Jersey, and I have
obtained it from sphagnum bordering a spring in the vicinity of Swarth-
more College, Delaware County, Pennsylvania, but have rarely found it
elsewhere. It is usually larger than Nebela coUaris, with which it is found
associated, and which it closely resembles in shape and constitution.

The shell is transparent and colorless, and is compressed pyriform,
usually being provided with a more or less distinct neck of variable length.
From that of Nebela collaris it differs in the possession of a well-marked
keel, extending from the lateral borders and fundus, and usually commenc-
ing about one third the length of the shell above the mouth. The keel is
commonly of considerable depth, but is not proportioned in extent to the
size of the shell. It is a thin membrane terminating by a sharp free edge,
and by transmitted light is defined from the cavity of the shell by the
double contour-line of the wall of the latter. It usually presents a more or
less indistinctly granular aspect, but not the defined elements of structure
of the shell, of which it is an expansion, excepting occasionally obscure
traces of the same may be detected. In the transverse section of the shell,
which is oval, the keel appears as acuminate points to the poles.

The mouth of the shell is transversely oval and convex downward,
as in N collaris.

The structure of the shell exhibits the same form, variety, and arrange-
ment of elements — round and oval disks, narrow rectangular plates, and
broader angular plates, as in Nebela collaris.

In a single instance, I obseiwed a specimen, represented in fig. 4, in
which some comparatively large quartz particles adhered to the shell, scat-
tered on the fundus, and especially along the border from which emanated
the carina.

As before mentioned, Nebela carinata is larger than N collaris, and its
range of size is not so great as in this. In twenty specimens measured at
different times, six were ~th of an inch long, five were longer, and nine
shorter. The smallest specimen measured the ^.th of an inch long, ^th of
an inch broad, ±Ah of an inch thick, with the oral end ^th of an inch by
i2 y th of an inch. The largest specimen was r J- th of an inch long, ^th of an
inch broad, ^ th of an inch thick, with the oral end 5 * 6 th by g g th of an inch.
The carina ranges from ^th of an inch to p^th of an inch deep.

The sarcode of Nebela carinata exhibits the same characters as that of

156 FEESH WATER RETIZOPODS OF NOETH AMEEICA.

Nebela collaris. It is colorless, except that the endosarc is more or less
brownish or yellowish, from the usual abundance of food-balls and dif-
fused material of the same nature.

I have also observed N. carinata with the sarcode mass in an encysted
condition and the shell closed with an epiphragm. A specimen of this kind
is represented in fig. 5.

NEBELA HIPPOCREPIS.

Plate XXV, figs. 9-14.

Difflugia (Nebela) cqvicalceus. Leidy : Proc. Ac. Nat. Sc. 1874, 156.
Nebela equicahciis. Leidy: Proc. Ac. Nat. Sc. 1876, 118, fig. 12.

Shell compressed pyriform, witli a thick, blunt, solid carina extending
around the body at the fundus and lateral borders, and ending in long
digitate processes projecting downward into the interior of the cavity.
Mouth transversely oval, convex downward. Shell transparent, colorless,
composed of circular disks; the carina pale straw-colored, homogeneous,
indistinctly granular. Sarcode, in color, structure, and arrangement, as in
N collaris and N. carinata.

Size. — Length 0.252 mm. to 0.26 mm.; breadth, including carina,
0.14 mm. to 0. 16 mm.; thickness 0.068 mm. to 0.072 mm., with the
mouth 0.04 mm. by 0.028 mm., and the carina 0.016 mm. deep and 0.008
mm. thick.

Locality. — Wet sphagnum at the borders of Absecom pond, New-
Jersey.

Nebela hippocrepis, a remarkable species, represented in figs. 9-14,
pi. XXV, is related to Nebela carinata, which it resembles in shape, but is
larger. It is rare, as I have observed but six specimens in four years,
and these were found only in the wet sphagnum at the edge of Absecom
pond, New Jersey.

The shell is compressed pyriform and variable in the proportions of
breadth to length, and a longer specimen may be of less breadth than a
shorter one.

The top of the fundus and lateral borders of the body of the shell are
occupied by a thick horseshoe-like keel, the ends of which project down-

GENUS NEBELA— NEBELA HIPPOCEEPIS. 157

ward and inward into the cavity. The whole extent of this peculiar
appendage to the shell occupies about two-thirds its length. Its projecting,
digit-like ends divide off from the general cavity of the shell a pair of
elongated conical recesses extending upward and outward along the lateral
border. At the fundus, the keel is about half the thickness of its depth,
but becomes thinner to its termination. It is pale straw-color and indis-
tinctly granular.

The structure of the shell, independent of the keel, is the same as in
the other species of Nebela; but, in the few specimens observed, it was in
all composed of circular disks of nearly uniform size

The sarcode has the same color, relations, kind of attachment, and
structure as in N. collaris. A clearer space in the centre of the endosarc
indicates the presence of the usual nucleus.

When Nebela liippocrcpis was disturbed, ordinarily it would withdraw
the pseudopods, but the sarcode mass would remain connected with the
mouth of the shell. When obliged to leave the latter in receding, it would
sometimes retain a connection with the ends of the horseshoe-like appendage
of the shell, as seen in fig. 14.

The smallest specimen observed was ~\h. of an inch long, ith of an
inch broad, 3 ' 7 th of an inch thick, and had the mouth 67u th by -^th of an
inch. The carina was ^ 8 th of an inch deep at the fundus, and had the
digit-like ends ~ th of an inch long.

The largest specimen was ^th of an inch long, ^th of an inch broad,
~\\i of an inch thick, with the mouth ^.th by ~th of an inch, and the carina
was f5 y th of an inch deep and ^th of an inch thick.

In two instances I found specimens of empty shells of a Nebela,
evidently related with that described, though they did not possess the
horseshoe appendage. The shells had the same shape and structure as N.
liippocrcpis, but were smaller In one, represented in fig. 13, pi. XXIV,
two long conical horn-like recesses, or hollow processes, extended from the
lateral borders of the fundus downward into the cavity of the shell. In
the other specimen, the horn-like recesses were interrupted in their course, so
that the lower third was separated from the upper portion. If these horn-
like recesses were solid and continuous by a horseshoe appendage in the
interval around the fundus of the shell, we would have the condition
ordinarily presented by Nebela liippocrepis.

158 FRESH- WATER RHLZOPODS OF NORTH AMERICA.

NEBELA ANSATA.

Plate XXV, figs. 1-8.

Difflugia (Nebela) ansata. Leidy: Pr. Ac. Nat. Sc. 1874, 156.
Nebela ansata. Leidy: Pr. Ac. Nat. Sc. 1876, 118, fig. 14.

Shell compressed pyriform, with a pair of lateral conical offsets diverg-
ent upwardly from the neck, but in other respects, in structure, color, and
in the shape of the mouth, as in Nebela collaris. Sarcode likewise as in the
latter.

Size. — Smallest, 0.216 mm. long, 0.132 mm. broad between the ends
of the lateral horns, 0.104 mm. broad at the fundus, 0.06 mm. thick, with
the mouth 0.04 mm. by 0.028 mm.; largest, 0.26 mm. long, 0.164 mm.
broad at the ends of the lateral horns, 0.12 mm. broad at the fundus, 0.064
mm. thick, with the mouth 0.052 mm. by 0.028 mm.

Locality. — Moderately frequent in the sphagnum of the cedar swamp
of Absecom, New Jersey.

Itfebela ansata, represented in figs. 1-8, pi. XXV, another remarkable
form, is distinguished by the spur-shaped appendages projecting from the
sides of the neck. It gives the impression of Nebela hippocrepis devoid
of the horseshoe-liko body, which is the striking peculiarity of the latter.
The general shape of the shell is like that of N. hippocrepis, and it is also
about the same size. The lateral horns diverge upwardly at the conjunction
of the neck and body of the shell. They are hollow, acute, conical offsets
of the latter, and are usually more or less incurved, but are sometimes
nearly straight or slightly recurved.

The structure of the shell is like that of the other species of Nebela,
and, like that of N. collaris, presents great variety. Usually it is composed
of circular disks nearly uniform or of more or less variability in size.
Frequently the disks appear to overlap one another at the contiguous
borders, a condition also observed in the other species, though compara-
tively rarely.

Occasionally specimens occur, as represented in fig. 1, in which a
number of partially detached disks are seen projecting along the inner mar-
gin of the lateral horns and on the opposite border of the body of the shell.

The sarcode in all respects is like that in the previously described

GENUS NEBELA— NEBELA ANSATA. 159

species of Nebela. Usixally it presents the ordinary form, but sometimes
individuals are observed in which processes of it extend into the lateral
horns. These processes are, however, not persistent, and the animal may
retract them entirely into the sarcodic mass, as it does the pseudopods, or
the threads of attachment to the fundus of the shell.

Nebela ansata is a large species, and its shell measures from ^th of an
inch to -jth of an inch in length, f J th inch to ^th inch in breadth at the
points of the lateral horns, and ^th inch to ^th inch in breadth at the fun-
dus, with the thickness ^th inch. The mouth averages about ^ th of an
inch by ith of an inch.

I have found Nebela ansata in the moist sphagnum of the cedar swamp
of Absecom every year since my first notice of it in 1874. It is about as
frequent as Nebela carinata, with which it is found in association, as well as
with the other species described.

In September, 1874, I observed a specimen in which the mouth of the
shell was closed by a doubly convex epiphragm, the sarcode was contracted
into a mass nearly filling the body of the shell above the position of the
lateral horns, and the interval was nearly filled with yellowish dirt, appa-
rently the food remains discharged from the sarcode mass. The following
morning the sarcode had extended itself so as to compress the dirt within a
smaller space against the epiphragm. The third day the specimen was
found, as seen in fig. 4, with the sarcode contracted into a compressed
spheroidal ball, and with the dirt occupying a still smaller space than pre-
viously within the neck of the shell.

NEBELA BARBATA.

Plate XXIV, figs. 14-17.

Difflugia (Nebela) barbata. Leitly : Proc. Ac. Nat. Sc. 1874, 157.
Nebela barbata. Leidy : Proc. Ac. Nat. Sc. 1876, 119, fig. 18.

Shell bottle-form, slightly compressed, with the neck cylindroid, and
about as long as the ovoidal body ; fundus obtuse, oral end slightly expand-
ed, and in the longer diameter convex downward; mouth oval, entire.
Shell transparent, colorless, composed of circular disks, and furnished with
short stiff cilia.

Size. — Length 0.08 mm. to 0.12 mm.; breadth of body 0.044 mm. to

160 FEESH-WATEE EHIZOPODS OF NOETH AMEEICA.

0.056 mm.; thickness of the same 0.036 mm. to 0.048 mm.; breadth of neck
0.014 mm. to 0.024 mm.; thickness of the same 0.012 mm. to 0.02 mm.;
mouth 0.016 mm. to 0.024 mm. wide.

Locality. — Wet sphagnum of the cedar swamp of Absecom, and similar
localities, New Jersey.

IVeheBa barbata, represented in figs. 14-17, pi. XXIV, has a slightly-
compressed bottle-shaped shell, with a cylindroid neck, which is about, as
long as the ovoidal body. In the view of the broader sides, the neck is
more abruptly defined from the body, the fundus is broadly convex, and
the oral end is slightly expanded and convex downward. In the narrower
view, the neck is more gradually produced from the body, the fundus is
more sloping from an obtusely angular summit, and the oral end is con-
cave downward.

In composition, the shell accords with that of other species, being
colorless and transparent, but I have observed it only composed of circular
disks. The surface of the shell is furnished with short rigid cils, projecting
straight outwardlj r , apparently from the intervals of the disks. The cils
usually cease within a short distance of the mouth.

The sarcode and its habits in all respects are like those of Nebela col-
laris and other species.

Nebela barbata approximates in size average specimens of N. collaris.
The shell measures from ^th to „-^th of an inch in length, with the body
ith to ,4-,th of an inch in breadth and — th to .4,th of an inch in thickness.

Nebela barbata is not of unfrequent occurrence in wet sphagnum of
the cedar swamp of Absecom and similar places in New Jersey.

Rarely, I have found specimens of Nebela, in the same locality, which
have the form and constitution of N barbata, but are entirely devoid of the
cils. They may be regarded as a transitional variety toward Nebela collaris.

NEBELA CAUDATA.

Nebela caudata. Leidy : Pioc. Ac. Nat. Sc. 1876, 58.

Shell compressed ovoid, with from four to five narrow, blunt, conical or
clavate processes projecting from the lateral borders and summit of the fun-

GENUS NEBELA— NEBELA CAUD ATA. ]61

dus. Mouth transversely oval. Shell transparent, colorless, with the
structure resembling that of Nebela collaris, bu£ usually less distinct. Sar-
code colorless.

Size. — Length of the shell, exclusive of processes, 0.08 mm. ; breadth
0.06 mm.; thickness 0.032 mm.; breadth of mouth 0.02 mm. by 0.016 mm.
Length of processes 0.016 mm. to 0.024 mm.

Locality. — Rare, in sphagnum of the cedar swamps of Absecom and
Malaga, New Jersey.

WebcSa caudata, represented in figs. 21-24, pi. XXVI, is compara-
tively rare, as I have not seen more than half a dozen specimens, and none
of these were in an active condition. It was found in association with the
more common forms in the sphagnum of the cedar swamps of Absecom
and Malaga, New Jersey.

The shell is compressed ovoid, but in the narrower view appears more
pyriform. From the lateral borders and summit, as seen in the broad view
of the shell, there projects an unsymmetrical row of four or five long cau-
date appendages. These are narrow conical or clavate, hollow prolonga-
tions of the shell, straight or curved and blunt. Gradually expanding at
the base, they give a somewhat polyhedral outline to the shell. The mouth
of the latter is transversely oval and convex downward.

The shell is colorless and transparent, and appears to have the same
structure as in Nebela collaris, but usually less distinct.

In one of the specimens observed, of N. caudata, the shell was com-
posed of comparatively large circular disks overlapping at their contigu-
ous borders. Another specimen, an empty shell, was made up of circular
and oval disks mingled with nari-ow rectangular plates. In a third specimen,
the shell was composed of chitinoid membrane indistinctly granular and
with no decided appearance of disks or rectangular plates. The caudate
processes are chitinoid extensions of the shell.

In the specimens observed which were not dead, the sarcode was in an
encysted condition, appearing as a compressed spherical ball, occupying
the central part of the body of the shell, while the mouth of the latter was
closed with a thick epiphragm. The sarcode ball was colorless, and filled
with fine granules and clear globules.

Four specimens measured the same length, ^th of an inch; two

11 KHIZ

162 FRESH-WATER RHIZOPODS OF NORTH AMERICA.

measured .-^th of an inch in the greater breadth, and two .^,th of an
inch; the less breadth was ith of an inch. The mouth was j^- th by j^th
of an inch.

HELEOPEKA.

Greek, helos, a bog; pera, a bag.

Shell compressed ovoid, composed of cancellated, chitinoid membrane
presenting a reticulated appearance of mostly dotted or interrupted lines,
often at the fundus incorporated with particles of sand. Mouth inferior,
terminal, large, transversely elliptical. Sarcode and its constituents as
usual in Hyalosphenia and Nebela. Pseudopods numerous, digitiform.

HELEOPERA PICTA.

Plate XXVI, figs. 1-11.

Difflugia (Xebela) splwgni. Leidy: Proc. Ac. Nat. Sc. 1874, 157.
Nebela sjphagni. Leidy: Proc. Ac. Nat. Sc. 187(5, 119, figs. 16,17.

Shell compressed ovoid, with the oral pole narrower; mouth terminal,
forming a broad narrow ellipse with acute commissures, convex downward
in the length, and appearing as an acute notch from the narrow sides.
Shell composed of a yellowish, transparent chitinoid membrane with a
reticular structure; the meshes of the net being polygonal and the lines of
the net dotted. Sarcode with bright-green endosarc from the multitude of
chlorophyl corpuscles entering into its constitution. Pseudopods numerous,
long, digitate, simple, and branched.

Sue —Length 0.092 mm. to 0.168 mm.; breadth 0.076 mm. to 0.136
mm.; thickness 0.044 mm. to 0.072 mm.; mouth 0.036 mm. by 0.016 mm.
to 0.072 mm. by 0.032 mm.

Locality. — Frequent and abundant in the sphagnous swamps of Penn-
sylvania and New Jersey.

Heleopera picta, represented in figs. 1—11, pi. XXVI, I formerly
included in the genus Nebela as Nebela sphagni, but now regard it as
sufficiently peculiar to consider it as the type of another genus.

The animal is found abundantly in almost every extensive sphagnous
swamp in association with various species of Hyalosphenia, Nebela, and
other rhizopods. It has the same bright coloring as Hyalosphenia pap'lio,
but has appeared to me of less graceful proportions and beauty.

GENUS HELEOPERA— HELEOPEEA PICTA. 163

The shell of Ileleopera picta is compressed ovoid, and never presents
the pyriform shape so common in Nebela. In the broad view of the shell,
it has an egg-like outline, the narrow end forming the convex line of the
mouth. In the narrower view of the shell, the outline is elliptical, and the
mouth appears as a deep angular notch. The mouth is transversely ellip-
tical, with angular commissures, as represented in fig. 11.

The shell is composed of chitinoid membrane, and is transparent and
of a yellowish or pale raw sienna color. It presents a reticulated struc-
ture with polygonal meshes. Under higher powers, the lines of the reticu-
lation appear to be composed of rows of granules, or they have a beaded
arrangement. The surface of the shell is not perfectly even, but is slightly
undulating, apparently from elevation of the reticulation above the level of
the intervening meshes.

Occasionally irregular particles of hyaline quartz are incorporated
with the shell at the summit of the fundus, as seen in figs. G, 7, 1 0.

The sarcode of Ileleopera picta has a bright green endosarc from the
abundance of chlorophyl which enters into its composition. The chloro-
phyl corpuscles usually measure from ^th to ^th of an inch in diameter;
but in different specimens and conditions of these, they range from j^th to
^th of an inch in diameter.

A large clear nucleus occupies the centre of the sarcode, but is usually
more or less obscured from view by the surrounding chlorophyl corpuscles
and other, uncolored, elements.

The sarcode occupies the greater part of the interior of the shell,
usually leaving but a small interval at the sides and fundus, as seen in
the view of the broad surfaces of the animal. It has the same means of
attachment to the fundus by threads of ectosarc as in Nebela and other
genera.

Contractile vesicles, three or four at the same time, occupy the ordinary
position, at the periphery of the sarcode contiguous to the nucleus, as in
Hyalosphenia, etc.

The pseudopods are large and numerous, and may be seen extending,
and often writhing snake-like, in all directions, from the capacious mouth.
They are commonly simple and cylindrical, with blunt ends, but they fre-
quently branch, and at times present pointed ends. They not unfrequently
extend the length of the shell, with a thickness of about -^th of an inch.

1(34 FRESH-WATER RHIZOPODS OF NORTH AMERICA.

Commonly the size of Heleopera picta varies but little, a frequent size
being about ^th of an inch in length by ^th of an inch in breadth ; but
individuals are met widely differing at different places and seasons. It ranges
from 4-th to ith of an inch in length : ~th to Mh of an inch in the greater

270 lot) " ' ooU lot *->

breadth, and Mh to i-,th of an inch in the less breadth. The mouth varies

* 57U aou

from ith by JLth of an inch to ith by 7 -f- th of an inch.

Heleopera picta is frequently found in the encysted condition, in which
state the aperture of the shell is closed by a double convex laminated
epiphragm of a yellowish or brown color, as seen in figs. 2, 4-7. The
encysted sarcode is compressed spherical, occupying the centre of the
shell, as seen in the view of the broader surfaces, and in contact with
them, as seen in the view of the narrower surfaces. The encysted ball
retains unchanged the profusion of chlorophyl corpuscles, which ordinarily
obscure from view almost everything else. Commonly a clearer central
spot of the ball betrays the presence of a nucleus

Generally the chlorophyl corpuscles, mingled with colorless granules,
form a closely agglomerated mass enveloped with a stratum of colorless
granular protoplasm of variable thickness. Most of the chlorophyl cor-
puscles appear of nearly uniform size, and in different specimens commonly
range from J^th to ^th of an inch in diameter.

On the 9th of April, 1877, I observed an individual of H. picta, ob-
tained from sphagnum preserved all winter in a glass case, with the
appearance represented in fig. 2. The interior encysted ball was about
j^th of an inch in breadth, and contained the usual agglomeration of chlo-
rophyl corpuscles, of comparatively uniform size, including a nucleus.
The agglomeration was capped on one side by a large accumulation of fine
molecules, which by reflected light appeared milk-white.

Individuals of H. picta are found, as represented in fig. 8, in which the
mouth of the shell is closed by an epiphragm ; but the usual sarcode mass
is replaced by a multitude of more or less scattered chlorophyl corpuscles,
like those which ordinarily occur within the sarcode. These are probably
spoi-es or germs derived from the breaking-up of the latter.

Sometimes, also, individuals are seen in which the shell, with the
aperture open or closed, contains a multitude of yellowish bodies, as seen
in fig. 10, which resemble the chlorophyl corpuscles deprived of their
bright green hue.

GENUS HELEOPERA— HELEOPERA PETRICOLA. 165

In the encysted condition of H. picta, the compressed globular ball is
more or less proportionate in size with that of the capacity of the shell ; in
different individuals it ordinarily ranges from ^ th to „* th of an inch in
breadth.

The mouth of the shell in the encysted condition of the animal is not
only closed by an epiphragm, but is more or less narrowed by the approx-
imation of the lips, and sometimes these appear closely glued together.

HELEOPERA PETRICOLA.

Plate XXVI, figs. 12-20.

Shell compressed oval ; mouth terminal, broad, elliptical, convex down-
ward, with acute commissures ; fundus convex, loaded with quartz-sand.
Structure of shell of chitinoid membrane, reticular, with polygonal or
rounded meshes, transparent and colorless, but sometimes brownish. Sar-
code colorless ; pseudopods numerous.

Size. — Length from 0.096 mm. to 0.15 mm.; greater breadth 0.068 mm.
to 0.09 mm.; less breadth 0.048 mm. to 0.06 mm. ; breadth of mouth 0.052
mm. to 0.06 mm. by 0.015 mm.

Locality. — Sphagnous swamps of Pennsylvania and New Jersey. Ab-
secom, Hammonton, and Longacoming, New Jersey; Broad Mountain,
Schuylkill County, Pennsylvania.

Heleopera petricola, represented in figs. 12-20, pi. XXVI, is found
in sphagnum in association with the former species, but is comparatively
rare. A few individuals I have met with every year since 1874, in
large swamps of New Jersey and Pennsylvania. In most cases I have
observed the animal in the quiescent or encysted condition, and rarely have
I seen it in an active state.

The shell is compressed oval, with a very wide terminal mouth, the
line of which, in the broad view of the shell, is convex downward. The
fundus is convex, and is invariably more or less loaded with large, hyaline,
angular quartz-sand.

In structure the shell appears to be composed of chitinoid membrane,
with a reticular arrangement, sometimes well marked, at others rather
indistinct. It is usually colorless, but is sometimes of a pale ferruginous
brown, probably due to the infiltration of iron oxyd, which is not unfre-
quent in sphagnous swamps.

166 FRESH-WATER RHIZOPODS OF NORTH AMERICA.

The sarcode is colorless, except that the endosarc may be more or less
colored by the presence of food, as seen in fig. 12. The form, arrange-
ment, and mode of attachment of the sarcode mass are the same as in the
species of Nebela, etc. The pseudopods are many, and variable like those
of H. picta.

In the encysted state of H. petricola, the sarcode forms a compressed
oval or spherical body, nearly colorless or pale yellowish, with a granular
constitution, often mingled with globules of various sizes of an oleaginous
appearance. The mouth of the shell is closed by a laminated epiphragm.

The shell of Heleopera petricola ranges from 2 -i- th to ^th of an inch in
length, ith to ^th of an inch in the greater breadth, and 5 -^th to ^th of an
inch in the less breadth. The mouth is from ^-.th to i.th of an inch broad

480 41b

by j^gth of an inch in the opposite diameter.

ARCELLA.

Diminutive of the Latin, area, an ark.

Shell composed of chitinoid membrane, with a minutely hexagonal
cancellated structure, translucent and commonly of a brown color, variable
in shape, but usually more or less carnpanulate, with a circular base con-
cavely mfundibuliform and convex at the border, and with the mouth
central. Sarcode occupying the central portion of the shell, connected
with the mouth by a cylindrical neck, and by means of threads of ectosarc
with the dome of the shell. Pseudopods few, digitate, blunt, simple or
branching. Commonly two nuclei, situated one on each side of the sar-
code mass. Contractile vesicles several, occupying the periphery of the
upper part of the latter.

The genus Arcella was discovered and first described by Ehrenberg
in 1830. In its varied forms, it is among the commonest of the shell-bearing
fresh-water rhizopods. Ehrenberg and others have described, figured, and
named a number of varieties as so many different species, which, however,
appear to graduate into one another by those of intermediate or transi-
tional character. Claparede and Lachmann say they have proved that an
Arcella, of the form described by Ehrenberg as A. vulgaris, sometimes con-
structs for itself a new shell of one of the forms to which Perty gives the
names of A. angulosa, A. dentata, and A. Okeni. They add, that there can

GENUS AECELLA. 167

therefore be no doubt as to the specific identity of these different forms.
Hertwig and Lesser further remark, that they were able to distinguish only
a single species to the genus.

It has, nevertheless, appeared to me convenient to designate those
which are widely different by separate names, as is done with other organic
forms more positively regarded as distinct species. In this view I have
described the more conspicuous forms, and have adopted the names applied
to them, grouping with each those of intermediate characters which most
nearly approximate them.

The shell of Arcella is usually more or less campanulate, and varies
greatly in the proportion of height and breadth, — sometimes being so low as
to appear shield-like, sometimes so high and expanded as to be balloon-like.
Usually it is widest at the circular base, but often is widest near or at the
middle. It has an even, convex dome, or this may be divided into facets
defined by more or less prominent folds, or else it is impressed with rows of
concave pits. The base is convex at the border, and forms an inverted
concave funnel, with the circular mouth in the centre.

The shell is usually of some shade of brown : pale or darker raw
sienna, to burnt sienna or deep brown, or even almost black. The younger
the shell apparently the paler it is, and in the earliest condition is colorless
and transparent.

The shell is composed of a more or less translucent or transparent
chitinoid membrane, with a minutely hexagonal cancellated structure. It
is intrinsic to the animal, and never has incorporated with it quartz-sand,
diatom shells, or other extraneous matters.

The hexagonal cancelli are about g^th °f an mca m diameter.
According to Hertwig and Lesser they are hollow. This was proved by
an ingenious experiment. The shell, after treatment with sodium carbonate,
was treated with acetic acid, when the cancelli became filled with minute
bubbles of gas.

The sarcode mass occupies the interior of the dome of the shell cen-
trally, and is ordinarily attached to the mouth by a short neck. The
periphery of the mass is attached by divergent threads of ectosarc to the
interior of the dome and base of the shell.

The pseudopods are usually few, simple, cylindrical, and rounded at
the end.

168 FEESH WATER EHIZOPODS OF NOETH AMEEICA.

Auerbach* states that he has found in a single Arcella as many as
forty nuclei. Claparede and Lachmannf remark that individuals are fre-
quently found with a single nucleus ; but it is not rare to see as many as
twelve or fifteen. Hertwig and Lesser J confirm the statements of these
observers, and state that under favorable circumstances they observed a very
variable number of nuclei, mostly more than five. Carter § says that there
are but two nuclei, one on each side of the sarcode mass, and this accords
with my own observations. Usually I have been able to detect two nuclei,
occasionally one only, and rarely three. Perhaps, however, in some of the
larger specimens, what I have casually assumed to be food-balls or contrac-
tile vesicles, may have been in part rather of the nature of nuclei.

In the usual views of Arcella from above or from beneath, two or three
to half a dozen or more contractile vesicles are seen along the circular
border of the sarcode mass, some slowly enlarging, one or more collapsing,
and several reappearing. The Arcellas feed on various algse and decaying
vegetal matters, but I have not been able to determine whether they
feed on infusoria. They are found in all standing waters, in the superficial
sediment, and also on the surface of submerged plants. A favorite resort
is the under surface of floating leaves of aquatic plants.

A singular condition not unfrequently occurring in Arcella is the pro-
duction of one or more conspicuous air-bubbles within the sarcode mass.
These I have observed gradually to enlarge, and then slowly to diminish
and disappear without the evident escape of anything. In a single indi-
vidual I have observed as many as six bubbles at once. They appear to
be due to the development of gas, and their disappearance to its absorption.
From experiments of Biitschli, he suspects the gas to be carbonic dioxide.||

Claparede and Lachmann declare that Arcella changes its shell several
times during the course of its life. When the animal becomes too large
for the shell, it constructs a new one. In this condition, the Arcella almost
entirely passes out of its old shell, and at the aperture forms a large mass,
which secretes upon its surface a new shell. In such a case, two shells
are observed applied to one another, mouth to mouth, the one thick and
dark, the other delicate, and at first perfectly colorless, but later pale

*Zeitschrift f. vrissens. Zoologie, vii, 425.
tfitudea sar lea Iufusoires ct lcs Rhizopodes, i, 444.
tArchiv f. mik. Anatomie, x, Sup. 97.
$An. Mag. Nat. Hist, xviii, 1864, 221.
|| Archiv f. mik. Anat. xi, 1875, 459.

GENUS AECELLA. 1G9

yellowish. The former is the old shell; the latter, the new one. The
Arcella passes alternately from one shell to the other, leaving always,
however, a part of its body within the old shell. Finally, when the new
shell has assumed. due consistence, the Arcella passes entirely into it, and in
the violent separation which occurs at the moment between the two shells,
the old one is split.*

Individuals of Arcella, are often met with in pairs applied base to base,
and, in common with other rhizopods in a similar position, are generally
supposed to be in conjugation, that is to say, in a condition akin to sexual
intercourse. Sometimes the two individuals present the same appearance
of form, size, and color, but frequently exhibit marked ditference in color,
while the size and shape are the same or very nearly so. Often the one
shell is colorless or faintly yellowish, while the other exhibits a more or less
decided yellow or brown color. Between these extremes, couples are met
with exhibiting differences of color of every shade of those just mentioned.
Frequently the sarcode of the conjoined Arcellas may be observed to form a
single mass, rapidly streaming to and fro between the shells Subsequently
the mass separates into two portions, which retire into their respective shells.
These finally separate, and the animals move away without showing any-
thing conspicuously different from what is ordinarily observed in them.

Many of the instances of paired Arcellas I have looked upon as prob-
able cases of conjugation ; but others, especially those presenting wide
differences in the color of the shells, I have suspected to be cases of repro-
duction, in which the individual with the colorless or nearly colorless shell
was the offspring derived by division from the sarcode mass of the individual
with the colored shell. This view accords with that of Hertwig and Lesser, f
as I understand them, in relation to the same kind of cases. I have never
observed the final result in the manner described by Claparede and Lach-
mann, that is to say, the occupation of the apparently new shell by all the
sarcode mass of the old one, and the rupture of this. The new shell, instead
of being larger than the parent shell, is often slightly smaller, but is more
delicate and flexible, and perhaps, therefore, also more capable of expansion.
It assumes color and becomes darker and stronger with age. At first, the
cancellated structure is barely visible, but soon becomes more distinct.

* fitudes sur les Infusoires et les Rhizopoiles, i, 445.

t Archiv f. mikroskopisehe Anatomie, x, 1874, Supplement, p. 97,

170 FRESH-WATER RHIZOPODS OF NORTH AMERICA.

Biitschli,* after observing 1 three individuals together, of Arcella vulgaris,
in conjugation, saw them separate without evident change, but later noticed
in one of them a number of cell-like bodies which occupied the space
between the sarcode mass and the shell The cell-like bodies afterward
assumed the appearance and movements of Amcebas, and escaped from the
mouth of the shell. He suspected them to be the young brood of the
Arcella, but their subsequent fate he did not determine.

ARCELLA VULGARIS.

Plates XXVII; XXVIII, figs. 1-7.

Arcella vulgaris. Ehrenberg: Abh. Ak. Wis. Berlin. 1830, 40, 53, 61, 69, 70, 75, Taf. i, Fig. vi; 1831, 90;
1871, 234. Infusionsthierehen, 1838, 133, Taf. ix, Fig. v.— Dujardin: Infusoires, 1841, 247,
pi. ii, figs. 3-5.— Perty : Kermt. kleinst. Lebensformen. 1852, 183, 186, Taf. ix, Fig. 1-3— Carter:
An. Mag. Nat. Hist, xviii, 1856, 128, 221, pi. vii, fig. 79; xiii, 1864, 30, pi. ii, fig. 14.— Claparede
and Lacluuann: Etudes Infus. Rhizop. 1858, 9, i, 444. — Pritchard: Hist. Infusoria, 1801,555,
pi. xxi, figs. 7-9.— W allien: An. Mag. Nat. Hist, xiii, 1864, pi. xvi, figs. 34-37.— Hertwig and
Lesser : Arch. mik. Anat. 1874, 96.— Leidy : Pr. Ac. Nat. Se. 1874, 14 ; 1876, 55.— Biitschli : Arch,
mik. Anat. 1875, 459, Taf. xxv.

Arcella dentata. Ehrenberg : Ab. Ak. Wis. Berlin, 1830, 40 ; 1831,90. Infusionsthierchen, 1838, 134, Taf.
ix, Fig. 7, except a. — Perty: Kennt. kleinst. Lobensforruen, 1852, 186.

Arcella liemispherica. Perty : Kennt. kleinst. Lebensformen, 1852, 186, pi. ix, fig. 5.

Arcella angulosa. Perty: Ibidem, 186.

Arcella viridis. Perty ? : Ibidem.

Arcellina vulgaris. Carter : An. Mag. Nat. Hist, xviii, 1856, 247.

A. Sticholepis vulgaris. Ehrenberg: Abh. Ak. Wis. Berlin, 1871,244.

A. Eomaochlamys angulosa. Ehrenberg: Ibidem.

Shell hemispherical or campanulate; height about half the breadth
and more or less, widest across the usually slightly expanded and circular
base, which is inferior, convex at the border, and concavely inverted infun-
dibuliform centrally to the mouth. Dome evenly convex or angularly
faceted or concavely pitted at the summit and sides; the facets or pits
variable in number, bounded by prominent folds and ranged in two or
three circles. Mouth circular, mostly entire, rarely slightly crenulated at
the border. Sarcode mass oblately spheroid, colorless independently of
the color of the endosarc derived from the food, connected with the mouth
by a short cylindroid neck, and attached by divergent threads of ectosarc
to the inner surface of the dome. Pseudopods digitate. Color of the test
passing from completely colorless in the earliest condition, through various
shades of brown, to the deepest hue.

Size.— Breadth 0.048 mm. to 0.152 mm.; height 0.036 mm. to 0.072
mm.; breadth of mouth 0.012 mm. to 0.048 mm.; elevation of mouth 0.006
mm. to 0016 mm.

"Archiv f. mik. Anat. si, 1875, 459.

GENUS ARCELLA— ARCELLA VULGARIS. 171

Locality. — Common in the ooze of almost all standing fresh waters,
and on submerged portions of aquatic plants. Nova Scotia, Maine, New
Jersey, Pennsylvania, Alabama, Florida, and in the Uinta Mountains and
valley of Fort Bridger, "Wyoming Territory.

Arcella vulgaris, represented in pi. XXVII, and figs. 1-7, pi.
XXVIII, is one of the most common of the shell-bearing Fresh-water
Rhizopods, and is found in almost every pond, ditch, or long-standing pool
in boggy places, creeping in the soft ooze of the bottom or in the floc-
culent matter adherent to submerged plants.

As ordinarily seen (fig. 2, pi. XXVII) beneath the microscope, it
appears as a brown circular disk, with a paler circular central spot corre-
sponding with the mouth. In a side view (fig. 1 ), the outline is usually
low bell-shaped or hemispherical, with the basal border rounded or slightly
prominent and rounded. The height is about half the breadth of the shell,
but is often more or less, and the greatest width is at or just above the base.
The latter is mostly circular, convex downward at the periphery, and
concave centrally, so as to appear like an inverted funnel. The mouth
is central, circular, and situated at the top of the inverted funnel-like
base. The border of the mouth is entire (fig. 2), but sometimes is more
or less crenulated, as seen in fig 9.

The dome of the shell may be evenly convex to the rounded or
slightly prominent base. Often its summit and sides are depressed into
a variable number of shallow concavities or more or less angular facets
defined by folds of the shell. The depressions are ranged into two or
three series, usually one on the dome and one or two at the sides, or
there may be a single depression on the dome and one or two series at
the sides.

Sometimes the shell appears like a truncated pyramid, or a tent sup-
ported by poles, as represented in figs. 8-13, pi. XXVIII. Such a form is
indicated by Ehrenberg as one of the varieties described under the name
of Arcella dentata, and referred to a particular species by Perty with the
name of A. ar,gidosa. Varieties occasionally occur with a transversely
oval or quadrately oval outline, with depressed summit and sides, as seen
in figs. 4-7 of the same plate.

The shell of Arcella vulgaris is usually of some shade of ochre-yellow

172 FEESH-WATEB EHIZOPODS OF NOETH AMEEIOA.

or brown, but is found from a colorless transparent condition through every
tint of raw and burnt sienna to dark umber brown, and so opaque as to
obscure the contents from view.

The sarcode of Arcella vulgaris is colorless, independently of the color
imparted to the endosarc by the presence of food. In the side view of
the animal, it usually appears as an oblate spheroidal ball resting on the
inverted funnel of the mouth, and attached by a variable number of diver-
gent threads of ectosarc to the inside of the dome of the shell.

Generally I have been able to detect two nuclei, and only two, in the
sarcode, one situated on each side. A number of contractile vesicles
also are visible at the periphery of the sarcode mass. Among the food
contents of the endosarc, yellowish-brown and green food-balls are to be
detected, and sometimes with these small diatoms and desmids.

Sometimes individuals are seen with the sarcode detached from the
mouth and retracted to the top or to one side of the fundus of the shell.
Sometimes the sarcode mass assumes an irregular form, as represented in
fig. 1 4, pi. XXVII. In this individual, the sarcode subsequently assumed
the ordinary appearance, as seen in most of the accompanying figures. Its
shell was so delicate and flexible, that the summit would become depressed
with the protrusion of the pseudopods, and would again assume an even
convex condition on their retraction.

Occasionally I have found Arcella vulgaris with the sarcode in an
encysted condition, presenting the appearance of a spheroid ball, resting
upon the position of the mouth, as seen in fig. 33. In this individual, the
ball was surrounded with a flocculent granular matter, probably excrement
discharged from the sarcode as it assumed the quiescent state. The ball
was white and granular, and enclosed in a membrane.

Sometimes I have observed the encysted ball of sarcode so large that
it produced a complete eversion of the base of the shell, as represented in
fig. 3, pi. XXVIII.

Frequently I have observed pairs of individuals of Arcella vulgaris
applied with their bases together, and with the shells alike in form, though
often differing in color, and sometimes slightly in size. The couples have
exhibited various degrees of difference in hue, and sometimes, while one
shell is colored, the other is completely colorless, or presents only the
faintest straw-yellow tint. See figs. 17, 24, pi. XXVII; fig. 1, pi. XXVIII.

GENUS AECELLA— AECELLA DISCOIDES. 173

The shell of Arcella vulgaris ranges from ^- th to ~$h. of an inch in
breadth, ^th to ^th of an inch in height, with the mouth ^ th to ^th of
an inch in breadth, and elevated ^th to ^th of an inch.

ARCELLA DISCOIDES.

Plate XXVIII, figs. 14-38.

Arcella discoides. Ehrenberg : Monatsb. Ak. Wis. Berlin, 1843, 139 ; Abh. Ak. Wis. Berlin, 1871, 259,

Taf. iii, Fig. 1.— Leidy : Proc. Ac. Nat. Sc. 1876, 56.
A. Hvmaochlamys discoides. Ehrenberg: Ab. Ak. Wis. 1871, 244.

Arcella pcristicta. Ehrenberg : Microgeologie, 1854, 331 ; Ab. Ak. Wis. 1871, 260, Taf. iii, Fig. 11, 12.
A. Heterocosmia pcristicta. Ehrenberg: Ab. Ak. Wis. 1871, 245.

Shell mostly circular, shield-shaped, usually with the height from one
fourth to one third of the breadth ; dome low, evenly convex to the rounded
or slightly expanded and rounded basal border ; base and mouth, and like-
wise color of the shell, as in Arcella vulgaris. Sarcode as in the latter.

Size. — Breadth from 0.072 mm. to 0.264 mm.; height from 0.02 mm. to
0.08 mm. ; width 0.02 mm. to 0.08 mm. ; elevation of mouth 0.108 mm. to
0.02 mm.

Locality. — Everywhere in association with Arcella vulgaris. Pennsyl-
vania, New Jersey, Florida, Alabama, and Fort Bridger and Uinta Mount-
ains, Wyoming Territory.

Arcella discoides (pi. XXVIII, figs. 14-38) I view as the variety
of A. vulgaris in which the shell presents a greater proportionate reduction
in height compared with the breadth; but the one graduates into the other.
Usually with the height from a little less than a fourth to little more than a
third of the breadth, the shell appears shield-shaped, with an even convex
surface, neither faceted nor pitted. The base has the same character as in
A. vulgaris. The mouth varies greatly in its size in proportion to that of
the shell, ranging from one fourth to one half the corresponding diameter
of the latter.

From the comparative shallowness of depth of the shell, especially in
the colorless condition, Arcella discoides is especially well adapted for the
investigation of its contents.

The description and figure of A. discoides of Ehrenberg appear to
apply to a large-mouthed colorless individual.

The sarcode mass usually forms a disk, convex above, with rounded
or obtusely angular border, and impressed below, where it rests on the

.174 FRESH-WATER RHIZOPODS OP NORTH AMERICA.

inverted funnel of the mouth. As many as a dozen contractile vesicles may
sometimes be detected. Commonly I observed two nuclei, sometimes one,
and sometimes three.

The size of the shell of Arcella discoides usually ranges from about
g^th to ^th of an inch in breadth, ^th to ^th of an inch in height, with
the mouth ^th to ith of an inch wide, and elevated above the base from
s^-th to .^.th of an inch.

olJ5 1J00

Among some Utricularia from Jacksonville, Florida, I found a num-
ber of specimens, viewed as pertaining to A. discoides, in which the base of
the shell was more widely and deeply concave than usual, as represented
in figs. 33, 36. In some of the individuals, the shell was circular; but, in
others, it was oval or quadrately oval. The mouth, also, was oval, but with
the long diameter crossing that of the shell, as seen in fig. 35.

I have also occasionally met with Arcella discoides having an oval shell
in Absecom pond, New Jersey, as represented in fig. 34. From the same
locality I obtained several specimens, in which the shell had a somewhat
trilobate outline, as seen in fig. 38.

In empty shells of Arcella discoides I have generally noticed a circle
of bright dots surrounding the mouth, as seen in figs. 34-38. Whether
these dots are pores or minute tubercles I have not ascertained. When
present in living specimens, they are entirely obscured from view by the
granular sarcode within the shell. Similar dots I have likewise noticed
in some of the specimens attributed to Arcella vulgaris, as represented in
figs. 4, 6.

Occasionally I have observed small discoid Arcellas, measuring about
ji- th of an inch in diameter, such as ai*e represented in figs. 30, 31, which
I have supposed to be the young of Arcella discoides. The shell is trans-
parent, has a pale yellowish tinge, and is so delicate that traction of the
threads of attachment of the sarcode draws parts of the shell out of shape,
or at times bends the two sides toward each other. The mouth is indis-
tinctly seen ; a cancellated structure, if existing, is not evident ; and even
the shell itself, at times, requires attention to perceive it.

The sarcode is colorless and granular, and usually exhibits two or
three contractile vesicles at a time. Mostly I detected no nucleus ; but
in several specimens I observed what I supposed to be one, measuring
3~th of an inch. The pseudopods are few and digitate. Specimens of

GENUS AECELLA— AECELLA MITEATA. 175

the kind just described appear to me to resemble the Pseudochlamys patella
of Claparede and Laehmann,* and I have suspected that they may be the
same.

ARCELLA M1TRATA.

Plate XXIX.
Arcella milrata. Leidy : Proc. Ac. Nat. Sci. 1876, 56.

Shell mitriform or baloon-shaped, obpyriform or polyhedral, higher
than the breadth of the base, widest at or near the middle, more or less
contracted or sloping inwardly toward the base ; dome mostly inflated ;
summit and sides evenly rounded or depressed into broad angular facets,
bounded by prominent folds ; base rounded at the border, inverted con-
cavely infundibuliform ; mouth circular, crenulated, mostly everted into
the inverted funnel. Sarcode mass spheroidal, usually connected with
the mouth by a cylindrical neck, and attached by threads of ectosarc
to the interior of the shell. Pseuclopods up to half a dozen or more.

Size. — Height from 0.08 mm. to 0.18 mm. ; breadth at base 0.072 mm.
to 0.168 mm. ; breadth at dome 0.084 mm. to 0.2 mm. ; width of mouth 0.02
mm. to 0.08 mm. ; elevation of mouth from base 0.02 mm. to 0.024 mm.

Locality. — Abundant in Absecom pond ; also found in ponds at Atco,
Malaga, and other places, New Jersey; Tobyhanna, Pocono Mountain,
Pennsylvania; and ponds in the Uinta Mountains, Wyoming Territory.

Arcella mitrala, though by no means so common as the forms
which have been viewed as characteristic of A. vulgaris and A. discoides,
is rather frequent in the ponds of sphagnous and cedar swamps of New
Jersey. I have found it especially abundant in Absecom pond, so rich in
other rhizopods. I found it also in a pond in which grew a profusion of
the Yellow Pond-lily, Nuphar advena, at an altitude of about 10,000 feet,
in the Uinta Mountains, Wyoming.

Arcella mitrata, as represented in the figures of pi. XXIX, departs
from the form of A. vulgaris in a direction opposite to that of A. discoides.
Viewed from above or below (figs. 1, 3, 5, 7, 10), it is commonly circular,
though often more or less modified by angular projections of the base or

* Etudes s. 1. Iiifus. et Rhizopodes, 1858, 9, 443, pi. xxii, fig. 5. Hertwig and Lesser: Archiv
f. mikr. Anat. 1874, 100, Taf. iii, Fig. 1.

17G FRESHWATER RHIZOPODS OF NORTH AMERICA.

prominent sides of the body of the shell. Viewed from the side (figs. 2, 4,
6, 8, 9, 11), it is variable in shape, though ordinarily it is more or less
balloon-like or rounded mitriform, commonly of greater height than the
breadth, and narrowed at or near the base.

The dome is mostly inflated, and is round and even, or both it and the
sides may be depressed into a variable number of faces defined by folds.
The base is circular, and sometimes irregularly and widely dentate in out-
line, and it is more or less deeply inverted in a funnel-like manner toward
the mouth. The latter is circular, with a variably crenulated border, and
is everted into the top of the inverted funnel-like base of the shell.

The color of the shell of A. mitrata presents all the shades of difference
occurring in A. vulgaris.

The sarcode, as in the latter, is colorless. It usually forms an oblate
spheroidal mass connected with the mouth by a cylindroid neck of variable
length. Sometimes the sarcode mass is prolate spheroidal, and often demi-
spheroidal or demioval, in which case the base mostly rests upon the posi-
tion of the mouth of the shell. The body of the sarcode is ordinarily
attached by a multitude of diverging threads of ectosarc to all parts of the
interior of the shell.

Pseudopods appear commonly to be more numerous in A. mitrata than
in the other forms, but in other respects do not differ.

Generally, the size of A. mitrata exceeds that of Arcella vulgaris. It
ranges in height from about ^th to ^th of an in(h; in breadth at base
from i,th to ^.th of an inch; in breadth near the middle from ~t\\ to r J r th

SoO 150 300 1J5

of an inch. The mouth ranges in width from ^- th to ^ th of an inch, and
its elevation above the base, exclusivo of the eversicn, is from ^th to j^th
of an inch.

I am uncertain whether a form like that of Arcella mitrata has been
previously recognized. I had suspected that it might be the same as
Arcella costata of Ehrenberg, but this is doubtful from the absence of ribs,
and its being more than three times the size. Since first describing it, in
looking up the literature of the rhizopods, I met with Mr. Archer's descrip-
tion of Arcella globosa, with which it appears best to agree, and perhaps it
may be the same.

GENUS ARCELLA— ARCELLA DENTATA. J 77

ARCELLA DENTATA.

Plate XXX, figs. 10-19.

Arcella dentata. Ehrenberg: Ab.Ak. Wis. Berlin, 1800,40; 1831,90; 1871,2(54. Infusionsthierchen, 1838,
134, Taf. ix, Fig. vii (the first figure only of the series). — Leidy: Proc. Ac. Nat. Sc. 1874, 14 ;
1876, 56.

Arcella stellaris. Perty : Mittheil. Naturf. Gesells. Bern. 1849, 126.

Arcella Okaii. Perty : Kennt. kleinst. Lebensfonnen, 1852, 182, 186, Taf, ix, Fig. 4.

Arcella stellata. Ehrenberg : Microgeologie, 1854, 192. Ab. Ak. Wis. 1871, 261, Taf. iii, Fig. 10.

A. Homaoelilamijs dentata. Ehrenberg: Ab. Ak. Wis. 1871,244.

A. Heterocosmia stellata. Ehrenberg: Ibidem, 245.

A. Sticholepis stellaris. Ehrenberg: Ibidem, 244.

Shell, as seen from above or below, circular and more or less dentated;
in the side view, crown-like ; breadth more than twice the height; dome
convex and even, or depressed at summit and broadly fluted at the sides;
base centrally inverted, concavely infundibuliform, at the periphery more
or less everted, and divided into points of variable length. Mouth circular,
entire. Sarcode resembling that of Arcella vulgaris.

Size. — Breadth between points of base from 0.132 mm. to 0.184 mm. ;
breadth of base to position of eversion 0.10 1 mm. to 0. 14 mm.; height from
0.44 mm. to 0.048 mm.; width of mouth from 0.04 mm. to 0.044 mm.;
elevation of mouth above the base 0.01 mm. to 0.016 mm.

Locality. — Same as for Arcella vulgaris, but comparatively rare. The
most characteristic found at Lake Hattacawanna, Morris County, New
Jersey. Obtained also in Pennsylvania.

The dentated form (figs. 10-19, pi. XXX) only of the Arcella dentata
of Ehrenberg I have regarded as characteristic, while the others I have
viewed as subordinate forms of Arcella vulgaris. While the latter appear
to me as comparatively slight modifications from the evenly convex form
of A. vulgaris, perhaps produced by unequal traction of the threads of the
sarcode mass on the shell, the former could only be produced from the
same form of A. vulgaris by evolution or growth of the dentate processes.

Perty has figured and described the same form from Bern, Switzer-
land, under the name of Arcella Okeni and A. stellaris.

Arcella dentata, represented in figs. 10-19, pi. XXX, occurs in the
same localities as A. vulgaris, but is comparatively rare I have found it
in the ditches below Philadelphia, and sparingly in a number of other
places. The most extreme forms I found, in considerable numbers, in
Lake Hattacawanna, Monroe County, New Jersey.

12 RHIZ

178 FRESHWATER RHIZOPODS OF NORTH AMERICA.

The shell, as in other named forms, occurs colorless, and of every
shade of brown, from the palest to the deepest.

Viewed from above or beneath (figs. 10, 12, 14, 16), the shell resem-
bles a wheel with pointed cogs. Viewed from the side (figs. 11, 13, 15, 17,
18), it resembles a crown, sometimes with evenly rounded top and turned-
up rim edged with conical points, sometimes with the top depressed and a
series of radiating ridges curving to the points of the rim. The latter is
formed by an eversion of the border of the base prolonged into points of
variable length. Sometimes these are quite short, sometimes so long that
they even reach as high as the top of the shell. They vary in number,
usually from nine to a dozen.

The base of the shell from a level forms an inverted concave funnel, at
the top of which is situated the circular, entire mouth.

The sarcode of Arcella dentata is in all respects like that of Arcella
vulgaris, except that it has a more depressed or more oblate spheroid form,
due to the greater shallowness of the shell.

Usually the shell of Arcella dentata is more than three times the breadth
of the height, and in this respect is more like A. discoides than A. vulgaris,
as I have distinguished them.

The size of the shell of A. dentata presents but little variation. It
usually ranges from ^- th to ^.th of an inch in breadth between the points
of the rim, ith to ith of an inch at the level of the base, ^ th to ^th of
an inch in height, with the mouth 6 -|.th to ^th of an inch wide, and elevated

fro m i>A to m t]l of au inch -

ARCELLA ARTOCREA.

Plate XXX, figs. 1-9.
Arcella artocrea. Leidy: Proc. Ac. Nat. Sc. 1876, 57.

Shell from a fourth to less than half the height of the breadth; dome
convex and even, or mammillated or pitted; basal border everted and
rising from a fourth to nearly half the height of the shell, obtusely angular
and entire; central portion of the base inverted in the usual concavely
infundibuliform manner; mouth circular, entire, surrounded with a circle of
minute tubercles. Sarcode having the same general form and relationships as
in other Arcellas, but rendered bright green from the presence of abundance
of chlorophyl corpuscles in the endosarc. Pseudopods colorless, digitate

GENUS AECELLA— ARCELLA ARTOCREA. 179

Size. — Breadth at lateral border 0.144 mm. to 0.176 mm.; breadth at
base 0.1 12 mm. to 0.136 mm.; height 0.04 mm. to 0.06 mm.; width of mouth
0.02 mm. to 0.028 mm.; elevation of the same 0.012 mm. to 0.024 mm.

Locality. — Absecom pond, New Jersey.

Arcella artoerea (pi. XXX, figs. 1-9) is most nearly related to
A. discoides, but the sarcode mass is of a bright-green color from the
presence of an abundance of chlorophyl corpuscles entering into the com-
position of the endosarc. It is rare, as I have found it only in Absecom
pond, and in the wet sphagnum skirting the same, and here seldom.

The shell is comparable in shape to an ordinary pie, a turban, or to a
low and round-crowned hat, and is of a bright raw sienna-brown color of
varied shades.

The shell is commonly between a fourth and a third of the height
of the breadth, but also occurs of greater or less proportionate height.
Viewed from above or below (figs 1, 3, 5, 7), the outline is mostly cir-
cular, but is sometimes oval, quadrately oval, or more or less constricted,
so as to be biscuit-shaped. The lateral, prominent, more or less angular
border is elevated from a fourth to neai'ly half the height of the shell.
The dome is evenly convex, or it is mammillated or conversely pitted.
The base is centrally inverted in a concave funnel-like manner. The
mouth is circular, or sometimes oval, and is entire. It is elevated from a
fourth to nearly half the height of the shell, and sometimes appears slightly
everted into the funnel formed by the base of the shell. Around the
mouth there is a circular row of bright points which appear to be minute
tubercles.

The sarcode forms a lenticular mass of variable proportionate size,
occupying the central portion of the shell (fig. 1). It is attached in
the usual manner by threads of ectosarc, and the pseudopods are like
those of other forms of Arcella. The endosarc is bright green, from the
presence of chlorophyl corpuscles measuring about g^th of an inch in
diameter.

Arcella artoerea is a comparatively large form, in this respect also
related to A. discoides. It ranges in breadth from ^- th to —th of an inch,
and in height from ^th to — th of an inch.

180 FRESH-WATER RHIZOPODS OF NORTH AMERICA.

CENTROPYXIS.

Greek, Iccntron, a prickle; intxis, a box.

Arcella: Ehrenberg. Difflugia: Party. Ceniropyxis: Steiu, 1857.

Eehinopyxis: Claparede and Lachmann, 1859. HomceocMamys : Ebrenberg, 1871.

Shell discoid, circular, oval, or ovoid, deepest or thickest and most
obtuse posteriorly, with the base on a level interiorly and deeply inflected
to the mouth, with the dome highest posteriorly, gently curving or sloping
forward, more abruptly convex backward; mouth and fundus eccentric
in opposite directions, the former anterior and inferior, the latter posterior
and even, or furnished with a variable number of conical spines. Mouth
circular or oval and entire, or with the border more or less deeply sinuous,
and extending into appendages within the shell toward the dome. Shell
usually of various shades of brown, but sometimes colorless, composed of
chitinoid membrane mostly incorporated with variable proportions of
quartz-sand, and often to such an extent as to assume the structure common
in Difflugia. Sarcode colorless; pseudopods digitate.

Centropyxis, according to my experience, always appears distinctly
separated from Arcella, while, on the other hand, it appears more closely
related with Difflugia through D. constricta. The shell of Centropyxis, as
in the latter, has the mouth and fundus eccentric in opposite directions,
while in Arcella they are both central in the same longitudinal axis. The
shell of Arcella is chitinoid, with a distinct hexagonal cancellated structure,
and is always free from extraneous particles, whereas in Centropyxis the
shell, though often membranous or chitinoid, does not exhibit a cancellous
structure, and is mostly incorporated with more or less extraneous matters.

CENTROPYXIS ACULEATA.

Plates XXX, tigs. 20-34; XXXI; XXXII, figs. 29-37.

Arcella aculeata. Ehrenberg : Ab. Ak. Wis. Berlin, 1830, 40 ; 1841, 368, Taf. iii, Fig. 5. Infusionsthieroben,

1838, 133, Taf. ix, Fig. vi.
Arcella ecornis. Ebrenberg: Ab. Ak. Wis. Berlin, 1841, 368, Taf. i, Fig. 9; Taf. iii, Fig. 46. Mierogeologie,

1854, Taf. xxxiv, ii, Fig. 1.
Difflugia aculeata. Petty : Kennt. kleinst. Lebensformen, 1852, 186.
Centropyxis aculeata. Stein: Sitz. Biibm. Gesells. Wis. ? 1857.
Echinopyxis aculeata. Claparede and Laebmann: Etudes Infus. 1859, 447. — Carter: An. Mag. Nat. Hist.

xiii, 1864, 29, pi. i, fig. 8.— Barnard : Proc. Am. As. Adv. So. xxiv, 1875, 241. Am. Quart.

Mic. Jour. 1879, 83, pi. viii, fig. 3.
A. Centropyxis aculeata. Ebrenberg: Ab. Ak. Wis. Berlin, 1871, 245.
A. HomceocMamys ecornis. Ehrenberg: Ibidem, 244.
A. Centropyxis Diadema. Ehrenberg: Ibidem, 245.
Arcella Diadema. Ehrenberg: Ibidem, 259, Taf. iii, Fig. 7, 8.
Centropyxis. Leidy: Pr. Ac. Nat. Sc. 1876, 57.
Centropyxis ecornis, variety. Leidy.

GENUS CENTEOPYXIS— CENTEOPYXIS ACULEATA. 181

Centropyxis aculeata (pi. XXX, figs. 20-34; pi. XXXI; pi. XXXII,
figs. 29-37) is one of the most common of the Lobose Protoplasts, and is
found everywhere in the usual localities of Arcella vulgaris It is exceed-
ingly variable in character, but I have not been able to distinguish more
than the one species. This is to be sure not alwaj^s aculeate, as expressed
by the name; but the spineless form is evidently a mere variety.

The spinous forms may be regarded as the more characteristic, as
represented in the figures of pi. XXXI, except the last two of the series,
and as seen also in figs. 29-34 and 37 of pi. XXXII. The spineless forms,
constituting the Arcella ecornis of Ehrenberg, represented in figs. 20-34, pi.
XXX, figs. 33, 34, pi. XXXI, and figs. 35, 36, pi. XXXII, may be regarded
as a variety with the name of Centropyxis ecornis.

Size. — Length of shell transversely from 0.088 mm. to 0.26 mm.;
breadth 0.072 mm. to 0.22 mm. ; height 0.036 mm. to 0.08 mm. ; diameter
of mouth 0.028 mm. to 1 mm ; length of spines 0.02 mm. to 0.06 mm.

Locality. — Everywhere in association with Arcella vulgaris and quite as
common. Abundant in ditches and ponds in Pennsylvania, New Jersey,
Rhode Island, Massachusetts, Florida, Louisiana, Colorado, Wyoming
Territory, Utah, and Nova Scotia.

The shell of Centropyxis aculeata as commonly observed reminds
one of an Arcella with the fundus pressed to one side, so as to render the
mouth eccentric. As usually seen beneath the microscope, from above or
below, it appears with a more or less broadly ovoid outline, with the
mouth nearer the narrower pole and a variable number of spines diverging
from the opposite pole and sides.

In the lateral view, the shell is cap-shaped, like the shell of Difflugia con-
stricta, but commonly more depressed. The mouth and fundus being eccen-
tric in opposite directions, the former is anterior and inferior, and the latter
posterior and more elevated than the fore part of the shell. The greatest
perpendicular depth of the shell is back of its middle, and its shallowest
portion forms the anterior border, which often is somewhat depressed below
the general cui-vature of the front of the dome. The base of the shell
rests on a level at its anterior two-thirds, and is inverted funnel-like as in
Arcella. The fundus of the shell is obtusely rounded, and is usually
furnished with a variable number of divergent spines arranged in a single,

182 FEESH-WATEE EHIZOPODS OF NOETH AMEEICA.

somewhat regular row, along the summit posteriorly and at the sides. The
spines range from one to nine, but, as previously indicated, may be
altogether absent. They are straight or curved, awl-shaped, hollow pro-
cesses of the shell. In one instance, as represented in fig. 35, pi. XXXI,
a curved spine projected from the front of the shell.

The shell of Centropyxis aculeata is commonly composed of a yellowish
or brown chitinoid membrane, incorporated with variable proportions of
quartz-sand. Often finer particles of this material are scattered over the
shell, while usually the largest grains accumulate in variable quantity along
the position of the spines on the fundus. Barely, the shell is entirely
devoid of adherent or incorporated sand or other particles, as seen in the
specimens of figs '29-33, pi. XXXII. Often the shell appears composed of
sand particles, as is ordiuarily the case in Difflugias, and as represented in
figs. 1 7-30, pi. XXXI. Sometimes the sand is substituted by thin plates,
probably diatom fragments, as seen in fig. 3, and sometimes by more dis-
tinctly marked diatoms, as seen in figs. 31-34, pi. XXXI, and fig. 34, pi.
XXXII.

Especially in the Centropyxis ecornis is the shell composed of quartz-
sand, as seen in the figures of that variety in pi. XXX.

The spines of Centropyxis aculeata are almost always composed of chit-
inoid membrane, even when the body of the shell consists of sand, but
sometimes these processes have particles incorporated, and not unfrequently
they are terminated by a sharp quartz flake.

Mostly the shell of Centropyxis is of some shade of brown or dull
yellow, but may also be colorless. Not unfrequently the specimens com-
posed of sand appear to have the cementing substance stained while the
sand is colorless, or the former may be of a darker hue than the latter.
Such specimens appear as if invested by a colored net with lighter meshes.

The construction of the mouth, of Centropyxis aculeata appears to be
of more complex character than in most other Lobose Protoplasts, and its
condition seems to have escaped the notice of previous investigators. This
has no doubt been due to the fact that the orifice of the mouth is so deeply
inverted, and is commonly more or less obscured from view by the "sand
composing or incorporated with the walls of the shell.

In many specimens, the mouth, as seen through the shell, from beneath
or above, appears large, and simply circular, as represented in figs. 21, 25,

GENUS CENTEOPYXIS— CENTEOPYXIS ACULEATA. 183

pi. XXX, figs. 17-33, pi. XXXI, and figs. 34, 37, pi. XXXII. Commonly,
in the same view, the mouth is more or less sinuous, as represented in most
of the remaining figures of Centropyxis in the same plates. The bordering
sinuses of the mouth have seemed to me to be variable in number — ranging
from two to eight.

When the shell is composed of chitinoid membrane, and is sufficiently
translucent and clear of sand, in the lateral view, as represented in figs. 7,
10, pi. XXXI, figs. 29, 31, 32, 36, pi. XXXII, the mouth is seen to com-
municate with the cavity of the shell at the upper extremity of the inverted
funnel-like base of the latter.

The borders of the orifice of the mouth appear to be extended in broad
bands, corresponding in position with the sinuses of the mouth above indi-
cated. From the difficulty of getting and maintaining the shell of Cen-
tropyxis in a favorable position for the purpose, I could not satisfactorily
determine the exact arrangement of the ascending bands; but they seemed
to me to expand at the upper extremity, in some cases to remain free, in
others to come into contact with the interior of the roof of the shell. Mostly
the upper ends of the bands appeared to be notched.

At times, in examining specimens, and causing them to roll about in
the animalcula-cage, from the mouth beneath, a glimpse could be caught of
one or two of the notched ends of the bands, as seen in fig. 5, pi. XXXI.
Rarely, a specimen would occur in which a pair of the bands would be
distinctly visible, through the mouth from below, as seen in fig. 30, pi.

XXX, and fig. 35, pi. XXXIII.

While spineless specimens of Centropyxis, composed of chitinoid mem-
brane, approximate Arcella in character, I never could satisfy myself that
the shell of the former exhibited the cancellated structure of the latter. In
some chitinoid shells of Centropyxis, as those represented in figs. G, 14, pi.

XXXI, I observed a punctated appearance of some uniformity, but it did
not display the clear cancellated arrangement so characteristic of the shell
of Arcella.

Centropyxis seems a decidedly more shy creature than Arcella, and is
very much less disposed to put forth its pseudopods. The sarcode is color-
less and transparent, and its constituents are usually much less evident
than in other ordinary Lobose Protoplasts. Abundant as the animal is, I
rarely have had the opportunity of observing it under favorable conditions,

184 FEESH-WATEE EHIZOPODS OF NOETH AMEEICA.

. to see the sarcode so as to distinguish its different elements. Mostly, the
structure of the shell was such as to obscure the interior soft structure,
and generally it has so happened that in specimens in which the shell was
transparent, it was almost invariably empty.

Centropyxis is frequently found among floating confervas, or among
the flocculent materials, with desmids, diatoms, and other algae, adherent to
aquatic plants. The spines of the shell would appear to enable it to main-
tain its position. . According to Claparede and Lachmann, delicate pseudo-
pods are transmitted by the spines ; but this fact I have not observed. The
ordinary pseudopods are protruded usually a few at a time, and they
present the same appearance as in Difflugia and Arcella.

Smaller specimens of the variety Centropyxis ecornis, so far as the
shell is concerned, become undistinguishable from the smaller, spineless
kinds of Difflugia constricta.

Forms recently described by Professor Barnard, under the names of
Echinopyxis tentorium and E. hemisplierica (Am. Quart. Micros. Jour. 1879,
84, pi. viii, figs. 1, 2), found in association with Centropyxis aculeata, in
creeks and ponds of New York, I have not observed. The figures of the
former, ~E. tentorium, remind me of the single-spined variety of Difflugia con-
stricta, as represented in fig. 51, pi. XVIII.

COCHLIOPODIUM.

Greek, cochlis, a shell ; pons, a foot.
Amoeba: Auerbach. Amphizonella : Archer. Cochliopodium : Hert wig and Lesser.

Animal minute, provided with a flexible, chitinoid shell thinning away
to the broadly expansive mouth, and exhibiting a minutely cancellated
structure. Sarcode intimately adherent to every part of the interior of the
shell, pale granular, mingled with variable proportions of highly refractive
corpuscles, often crystals and other elements, together with a large central
nucleus and one or more contractile vesicles. Pseudopods delicate, hya-
line, conical, pointed, and sometimes forking.

COCHLIOPODIUM BILIMBOSUM.

Plate XXXII, figs. 1-25.

Amoeba bilhnbosa. Auerbach : Zcits. wis. Zool. vii, 1856, 374, Taf. xix, Fig. 1-13.
Amaba aciinopliora. Auerbach : Ibidem, 392, Taf. xx.
Amoeba sonalis. Leidy: Proc. Acad. Nat. Sc. 1874, 87.

Cochliopodium pellucidum. Hertwig and Lesser: Arch. mikr. Anat. x, 1874, Suppl. 66, Taf. ii, Fig. 7. —
Schulze : Ibidem, xi, 1875, 337, Taf. xix, Fig. 1-5.

GENUS COCHLIOPODIUM— COCHLIOPODIUM BILIMBOSUM. 185

Body when at rest spheroid or ovoid ; by transmitted light, viewed
from above, appearing as a usually translucent, granular, protoplasmic
mass, with coarser, darkly outlined granules, closely invested by a trans-
parent, colorless, doubly contoured, more or less distinctly punctate or
cancellated membrane, like the young colorless shell of Arcella. When
in movement, and viewed in the same direction, usually appearing more or
less completely surrounded by a delicate transparent zone of variable
width, and finely and regularly punctate. In the lateral view, usually
appearing more or less widely bell-sliaped in outline, with the fundus and
sides defined by a doubly contoured dotted line, and at the mouth with a
wide, more translucent, and more or less delicately punctate band defined
by a scarcel}' perceptible dentated edge. Interior protoplasm with a large
round nucleus toward the fundus, with variable proportions of highly
refractive corpuscles, crystals, vacuoles, and usually one or more contrac-
tile vesicles. Pseudopods mostly few, hyaline, of variable proportions,
conical, often irregular and sometimes furcate.

Size. — In the spheroidal condition from 0.024 mm. to 0.056 mm. in
diameter.

Locality. — In springs, ponds, ditches, and other quiet bodies of clear
fresh water, among algae and in ooze. Pennsylvania, New Jersey, Florida,
Fort Bridger, Wyoming Territory, and New Brunswick.

The genus Cochliopodium was first clearly characterized, and its often
enigmatic appearances satisfactorily interpreted by those able investigators
of the Rhizopods, Drs. Hertwig and Lesser. The species under considera-
tion was named by them C. pellucidum ; but, as the same appears to have
been previously described by Auerbach under the name of Amoeba bilim-
bosa, according to the rules of scientific nomenclature I have felt it obliga-
tory to adopt the latter specific name.

Cochliopodium bilintbosuni, represented in figs. 1-25, pi. XXXII,
is common among algae floating in the water of ditches and ponds, espe-
cially with Zygnema, Spirogyra, etc. From its minuteness it is easily
overlooked ; and in the younger condition, from the transparency and
undeveloped structural character of the shell, it is apt to be mistaken for
an Amoeba.

At rest the animal may appear as a spheroidal or ovoidal, translucent,

186 FRESH-WATEE EHIZOFODS OF NOETH AMERICA.

pale granular, colorless, or faintly yellowish ball, invested with a colorless
membrane seen at the border as a distinctly double contour-line. When
the creature begins to move, a clear, delicate, transparent zone is seen to
extend from the body on one or another side or all around

An attentive study of Cochliopodium in its various movements indi-
cates the animal to be bell-shaped, with a flexible shell, which it is capable
of widely expanding at the mouth. At the fundus and sides, the membrane
is comparatively thick, and is observed at the borders as a double contour-
line. The lower part of the shell is exceedingly thin and delicate, and
may be inflected or more or less widely reflected, the mouth contracting
or enlarging proportionately with the inflection and reflection of the part
of the shell surrounding it. The interior sarcode is continuous with its
chitinoid membranous investment, and at no time appears to become
separated so as to leave spaces filled with water, as in Hyalosphenia
or Euglypha.

Cochliopodium in form may be compared with an Arcella, and the
shell of this would be like that of the former, if its basal portion were very
thin and capable of reflection beyond the border of the base.

The broad zone surrounding Cochliopodium, as seen in figs. 1, 16, 17,
21-23, in the upper or under view of specimens, or the broad crescentic
band spreading more or less on one side in corresponding views, as seen in
figs. 2-4, 12, In, 19, are due to the reflection or turning outwardly of the
thin basal band of the shell surrounding the mouth. In the lateral view of
specimens, the same band may be likewise observed more or less reflected,
as seen in figs. 5-9, 11, 18, 20. When the thin basal band is closed or
completely inflected, specimens appear as in figs. 13, 14.

In the maturer specimens of Cochliopodium, the shell exhibits a punc-
tate appearance, due to a minutely cancellated structure, probably like that
of the shell of Arcella. The structure is especially to be detected in the
double contour-line seen bordering the body, and in the basal band of the
shell. In the intermediate position it is obscured by the granular structure
of the sarcode. The punctated structure is sometimes exceedingly indis-
tinct, and can be detected only under the best defining power of the micro-
scope, together with the most favorable disposition of light. In young
specimens, as in those represented in figs. 21-23, I could detect no evi-
dence of the cancellated structure, and infer that it is developed only at a
later period.

GENUS COCHLIOPODIUM— COCHLIOPODIUM BILIMBOSUM. 187

The sarcode of Cochliopodium is so closely adherent to the flexible
and elastic investing shell that in all its changes of form, the shell accommo-
dates itself to those changes. It consists of a pale, finely granular proto-
plasm, having scattered through the mass variable proportions of clear and
darkly outlined round and oval corpuscles, which have an oleaginous or a
starch-like appearance. Mingled with these there are commonly a few
liquid globules or vacuoles, of which one or two may from time to time be
recognized as contractile vesicles. Among the coarser elements of the
sarcode, crystals are often present. The usual food contents consist of
diatoms and one-celled algoe, together with some sand grains.

A large round nucleus with a large pale granular nucleolus occupies
the sarcode toward the fundus of the shell.

The more conspicuously granular portion of the sarcode ordinarily
remains confined within the thicker portion of the shell, while only a clearer
portion spreads outwardly within the thin basal band of the shell.

The pseudopods of Cochliopodium are usually seen as hyaline awl-
shaped extensions of the sarcode, of variable proportions, generally simple,
but not unfrequently forking or moderately branching at the end. They
often appear as delicate conical or more acuminate extensions from beneath
the expanded border of the shell, and look as if they were actually processes
of the latter. They also appear as more granular or darker extensions
from the chief mass of the sarcode, seen through the basal band of the
shell and projecting beyond it, as represented in figs. 5, 7, 15-17, 21-23.

Individuals are frequently observed in which the pseudopodal exten-
sions seem to perforate the shell, as represented in figs. 10, 12. Auerbach,
in describing the animal as Amoeba bUimbosa, supposed that it actually had
the power of forcing its pseudopods through the investing membrane; and
this view appears to have been held by Greeff and Archer in Amphizonella.
Hertwig and Lesser, and afterward Schulze, explained the true nature of
this appearance, which seems to be due to the pseudopodal extensions pro-
truding from between narrow folds of the bottom of the investing shell.

Cochliopodium bilimbosum is commonly observed gliding slowly over
the surface of objects, as a round or oval granular body, included by a
delicate zone or crescentic band of variable extent. The body is often so
minute and transparent as readily to escape notice. The zone or band is
of such extreme transparency and tenuity as scarcely to be visible with-

188 FRESH-WATER EHIZOPODS OF NORTH AMERICA.

out a favorable ttght. It is usually widest in the direction of movement of
the animal, and often is seen only on the side of movement. It is inces-
santly changing, seems defined by a more or less irregularly dentated
edge, and gives the impression of being a thin pseudopodal expansion
of the sarcode. The true pseudopods, projecting from beneath the edge
of the disk, are so little differentiated as to appear like pointed processes of
the disk itself.

Cochliopodium seems to be a hungry animal, and is not unfrequently
observed in the attempt to swallow diatoms or other algas too large for its
capacity, as represented in figs. 18, IP. The discharge of matters from the
body occurs as in other rhizopods. In one instance, as represented in fig.
4, I observed a mass of matter discharged, looking like a portion of the
sarcode itself, in which was contained a diatom.

COCHLIOPODIUM VESTITUM.

Plate XXXII. figs. 26-28.

Amphizonella vestita. Archer: Quart. Jour. Mic. Sc. 1871, xi, 112, 135, pi. vi, figs. 1-6.
Cochliopodium pilosum. Hertwig and Lesser: Arch. mik. Anat. x, 1874, Suppl. 78.

Cochliopodium vestitum. Archer: Quart. Jour. Mic. Sc. 1877, 334. In part, including only the hirsute
form, mostly with interior chlorophyl-like granules.

Body constructed as in the preceding species, but more or less covered
with minute rigid cils or fine hair-like appendages. Sarcode containing
variable proportions of chlorophyl granules, which, however, may be absent.

Size. — From 0.04 mm. to 0.06 mm. in diameter.

Locality — Absecom mill-pond, New Jersey; China Lake, Uinta Mount-
ains, Wyoming Territory. Ireland, Mr. Archer.

Cocliliopodium vestitum (figs. 26-2>>, pi. XXXII), discovered by
Mr. Archer, was at first attributed to the genus Amphizonella of Professor
Greeff; but subsequently, recognizing its difference, he accepted the posi-
tion given to it in the former genus by Hertwig and Lesser. These authori-
ties, without evident reason, substituted for it the name of Cochliopodium
pilosum. Mr. Archer regards both this and the more common form described
in the preceding article as varieties of the same species, and includes both
under the name of Cocliliopodium vestitum. While admitting that this view
may be correct, and certainly it is so in the light that the so-called species
of rhizopods merge into one another, yet, according to the plan adopted, I
think it desirable to consider the two forms as distinct.

PROTOPLASTA FILOSA. 189

CochUopodkim vestitum is comparatively rare. Mr. Archer found it in
pools, both in the green and colorless state, in two localities in Ireland;
but Hertwig and Lesser, and Schulze, who describe the more common form,
C. peUucidum, do not appear to have met with this one. I have found it
only in two localities, and these very remote from each other: — in light
ooze, in Absecom pond, New Jersey, September, 1874; and in the same
kind of material, in China Lake, Uinta Mountains, Wyoming Territory,
August, 1877.

Several specimens obtained at the former locality were of a bright-
green color from the large quantity of chlorophyl diffused throughout the
sarcode, as represented in fig. 26, pi. XXXII. Others, associated with the
bright green ones, were much less colored from the less proportion of
chlorophyl; and some had no color whatever, as represented in fig. 27.
The investing shell or membrane was more or less thickly covered with
short, delicate, rigid cils; but in all other respects, excepting the green
color of the sarcode when present, these specimens were like those of C.
hiUmbosum.

The specimens from the Uinta Mountains, as seen in fig. 28, had the
same character as the colorless ones of Absecom pond, but the shell had a
yellowish tinge.

PROTOPLAST A FILOSA.

The Filose Protoplasts, or the Protoplasts with extremely delicate
thread-like pseudopods, have the same general constitution and form as the
shell-covered Lobose Protoplasts.

The sarcode or protoplasmic mass never exhibits so clear a differen-
tiation of ectosarc and endosarc as that of the Lobose Protoplasts, but
appears generally of more homogeneous character and exclusively like
the endosarc of the latter. The pseudopods never occur as coarse lobate
or digit-like extensions of the sarcode, but invariably as exceedingly deli-
cate threads, acutely forking, and becoming finer and finer as they branch.
They rarely or do not at all anastomose, and only at times become more
or less confluent through the entanglement of portions of food. In compo-
sition, the pseudopods appear as filaments of the finely granular protoplas-
mic basis of the sarcode, and are commonly devoid of conspicuous granules
or fine oil-like molecules.

Like in most shell-covered Lobose Protoplasts, the sarcode contains a

190 FRESH- WATER EHIZOPODS OP NORTH AMEBIC A.

large clear nucleus, which occupies a central position of the fundus. Mostly
several contractile vesicles occupy a position peripherally in the intermedi-
ate part of the sarcode mass, just below the position of the nucleus.

The Filose Protoplasts are usually more sensitive or shy than the
Lobose forms, and it is often difficult to induce the animals to project their
delicate pseudopods. These are more numerous than in the Lobose Proto-
plasts, and are possessed of all the power and capabilities of movement and
change of the digitate pseudopods.

Ordinarily the sarcode of the Filose Protoplasts occupies a greater
proportion of the interior of the shell than in the Lobose forms ; and when
retracted from the interior surface they remain attached by much fewer
threads, and oftener appear separated altogether.

The shell of the Filose Protoplasts exhibits similar varieties of construc-
tion and chemical composition as in the Lobose forms.

I have learned almost nothing in relation to the modes of reproduction
of the Filose Protoplasts. I have many times seen pairs of individuals
conjoined by the mouth in the so-called condition of conjugation, but ascer-
tained nothing of the results. Besides observing certain genera and species
in the encysted condition, — that is to say, the sarcode contracted into a ball
within the shell and enclosed in one or a pair of additional egg-shaped
shells, — I have from time to time seen individuals containing, instead of the
ordinary mass of active sarcode, a variable number of globular spore-like
bodies, which I have suspected to have resulted from the breaking-up of
the sarcode mass.

PAMPHAGUS.

Greek, pampliagos, all-devouring.

Arcella: Elirenberg, 1838. Gromia: Schluinberger, 1845. Corycie: Dujardiu, 1852. Pamphagm : Bai-
ley, 1853. Difflugia: Schneider, 1854. Corycia (Dujardin) : Claparede and Lachinann,
1858. Momocochlamys .- Elirenberg, 1871. Plagiophrys ; Lecyihium: Hertwig and Lesser, 1874.

Animal colorless, transparent, invested with a hyaline, structureless
membrane, which is flexible and elastic and concurs strictly with any
changes of form of the body, but ordinarily restricts such changes, and is
not voluntarily extensible. Sarcode always completely occupying the
investing membrane, and appearing to be structurally continuous. A large,
clear nucleus. Contractile vesicles not distinctly determined. Mouth small,
terminal. Pseudopods filamentous, long, exceedingly delicate, branching
dichotomously, not anastomosing.

GEMJS PAMPHAGUS— PAMPHAGUS MUTABILIS. 191

PAMPHAGUS MUTABILIS.

Plate XXXIII, figs. 1-9.

Corycie. Dujardin: An. Sc.Nat. 1852, xviii,240.

Pamphagus mutabilis. Bailey: Am. Jour. Sci. Arts, 1853, xv, 341. — Archer: Quart. Jour. Mic. Sc. 1871,

xi, 101; 1872, xii, 195,423.— Leidy: Pr. Ac. Nat. Sc. 1878, 172.
Corycia (Dujardin). Claparede and Lachmauu : Etudes Infus. et Rhiz. 1858-59, i, 453. — Pritchard : Hist.

Infos. 1861, 550.— Leidy : Pr. Ac. Nat. Sc. 1874, 227.
Pamphagus (Bailey). Pritchard : Ibidem, 551.
Corycia Dujanlini. Gagliardi: Quart. Jour. Mic. Sc. 1871, xi, 80.
Plagiophrys souiiformis, Hertwig aud Lesser: Archiv mile. Anat. 1874, x, Suppl. 115, Taf. 3, Fig. 2.

Animal compressed ovoid, ovate, or sub-pyriform ; lateral borders ex-
tending to the fundus, acute ; fundus in the greater breadth obtusely rounded,
more or less acute or even acuminate; mouth small, transversely oval, with
a thickened border. Sarcode pale granular, colorless, or faintly yellowish,
with diffused minute oil molecules, often with darkly defined oil-like glob-
ules in the upper region, and frequently water vacuoles in the lower region.
Nucleus large, clear, compressed spherical. Food usually of various one-
celled algae. Animal in movement upright, with the mouth downward,
and the pseudopods divergent and spreading horizontally ; at rest, lying
upon the broader sides.

Size. — Ranging from 0.04 mm. long by 0.028 mm. in the greater breadth
to 0.1 mm. long by 0.068 mm. in the greater breadth.

Locality — The ooze of springs and ponds, and pools in sphagnous
swamps. Observed in Pennsylvania, New Jersey, and Fort Bridger, Wyo-
ming Territory.

Dujardin described a rhizopod under the name of 'Corycie,' in 1852,
from specimens found in rain-water, expressed from Jungermannia, collected
in November and December. He observes that it is a .very remarkable
Amoeba, on account of its membranous integument, which folds in various
directions, according to the movements and contractions of the animal, and
frequently presents the appearance of being twisted when it turns on itself.
The membranous envelope is perfectly extensible and elastic. The size of
the animal is from 0.08 mm. to 0.2 mm.

The following year, Professor Bailey described what seems to be the
same animal under the name of Pamphagus mutabilis. It was found in great
number in an aquarium which had been supplied with material from pools
and streams in the vicinity of West Point, New York. Bailey adds : " I

192 FRESHWATER RHIZOPODS OF NORTH AMERICA.

have thousands of these animals now living in midwinter." The description
is accompanied with many woodcuts representing various changes of form
and conditions of the animal.

Professor Bailey remarks: "If the reader will imagine a bag made of
some soft extensible material so thin as to be transparent like glass, so soft as
to yield readily by extension when subjected to internal pressure, and so
small as to be microscopic ; this bag filled with particles of sand, shells of
diatoms, portions of alga? or desmids, and with fragments of variously
colored cotton, woolen, and linen fibres, will give a picture of the animal ;
to complete which it is only necessary to add a few loose strings to the bag,
to represent the variable radiant processes which it possesses around the
mouth."

In the normal condition the animal appears to be compressed obcordate
or pyriform, with the filamentous branching pseudopods projecting from the
broader extremity. The animals observed by Professor Bailey were in a
very active condition, and they are described and figured as gorged with a
variety of food. Many are represented in different states of distortion due
to the materials swallowed being so much longer than the usual length of
the animal. A number of the figures further represent the creature either
in the state of conjugation or of division, in which process from a pair to
as many as five individuals are engaged together. Professor Bailey refers
to the condition as probably being one of spontaneous fission, though he
says he did not see it actually occur. Single undistorted individuals appear
to have been about 0.1 mm. in length. One is represented extended on a
swallowed fibre reaching the length of 0.25 mm. Another is represented
in which a swallowed fibre, in the extension of the animal, has perforated
the fundus.

Hertwig and Lesser, in their recent admirable researches, have de-
scribed, as it seems to me, the same animal as the Pamphagus mutabilis, under
the name of Plagiophrys scutiformis.

I have repeatedly, though rarely, observed specimens of what I have
considered to be the Pamphagus mutabilis of Professor Bailey, but usually iso-
lated, and never in anything like the number and variety described by the
latter. Those I have met with presented some variety in size, proportions,
and shape, but I have viewed them as pertaining to the same. I have
adopted Professor Bailey's name of Pamphagus mutabilis, as this was pre-

GENUS PAMPEAGUS— PAMPHAGUS MUTABILIS. 193

ceded only by the vernacular one of ' Corycie,' and not until several years
later was that of Corycia employed.

Famphagus miitabilis is a remarkable creature, comparable to an
Amosba in which the ectosarc had become coagulated, and retained its
elasticity, but lost its voluntary power of extension. The investing mem-
brane or shell is so thin, transparent, and elastic, and yet so intimately
adherent or continuous with the interior fluent sarcode, that it appears
scarcely more differentiated than the limiting ectosarc in Amoeba verrucosa.

The animal is commonly of a compressed oval or ovate form (figs. 1, 3,5,
7, 8, 9, pi. XXXIII), and in transverse section lenticular (figs. 2, 6). The
fundus is mostly more or less acute, and sometimes acuminate, but is also in
a variable degree obtusely rounded. The lateral borders are acute, extend-
ing to the fundus. The oral pole is usually the narrower ; and the mouth
is terminal, small, transversely oval, and bounded by a thickened border.
At times this has appeared continuous ; at others, interrupted on one side,
as represented in fig. 3. Above the mouth, at a variable distance, the
membrane often exhibits a circular line, apparently due to a temporary
folding, as seen in figs. 7-9. The animal moves slowly in an upright posi-
tion, with the mouth downward, and the delicate, long, filamentous pseudo-
pods radiating in any and all directions, but mostly on a plane at right
angles to the mouth. In movement the body of the animal is sometimes
bent, curved, or twisted, and the investing membrane becomes variously
inflected and wrinkled. The pseudopods usually diverge in straight lines,
acutely branching, and often extend to a length even greater than that of
the body. The angles of the forked branches often appear webbed from
expansions of the protoplasm ; and the terminal branches become more and
more delicate. Occasionally the pseudopods assume a tortuous appearance,
as seen in figs. 1, 2, and sometimes one or more are seen suddenly and
abruptly to bend in a geniculate manner, as seen in figs. 5, 7. When the
pseudopods are entirely withdrawn, the animal falls, and lies upon one of its
broader sides, as usual with most of the shell-covered protoplasts of com-
pressed form.

The interior sarcode of Pamphagus mutabilis always completely fills
and is continuous with the delicate investing integument, never leaving any
vacant space, such as is frequently observed in Euglypha and most shell-

13 EHIZ

194 FEESH- WATER EHIZOPODS OF NOETH AMERICA,

covered Protoplasts. The sarcode is formed of a basis of pale, granular,
colorless protoplasm, not unfrequently presenting a feeble yellowish hue.
Diffused through the protoplasm there are numerous fine oil-like molecules,
and often an accumulation of these occupies an intermediate zone. The
fundus of the sarcode mass is occupied centrally by a large, clear, homo-
geneous nucleus, as seen in figs. 1-6. Rarely, as in fig. 7, I have seen the
nucleus occupy a lateral position.

Contiguous to the nucleus frequently the sarcode is mingled with
variable proportions of scattered oil-like globules, as represented in figs. 5,
7, 9, but these are often absent or minute and inconspicuous, as seen in
figs. 1-4, 8.

The lower region of .the sarcode, intermediate to the nucleus and the
mouth, is commonly occupied with more or less food materials, consisting
of green one-celled algae, diatoms, etc. The green algse turn red, as a
result of digestion. With the food there are often mingled colorless
globules of various sizes. Some of these appear to consist of water ; and
occasionally I have seen one or more enlarge and collapse. In one instance
I observed such a globule approach the mouth (fig. 3) and have its liquid
contents expelled. Independently of these water globules, not always
present, I detected no distinct contractile vesicle.

The pseudopods of Pamphagus mutabilis appear as filamentous exten-
sions of the protoplasmic basis of the sarcode, finely and obscurely granu-
lar in constitution, and without oil molecules. I could never detect any
appearance of circulation of granules in the pseudopods.

The investing membrane or shell of Pamphagus mutabilis is colorless,
transparent, and structureless. It is highly elastic, so that it yields to the
extension of rigid food, and returns to its normal condition when the extend-
ing force is removed.

PAMPHAGUS HYALINUS.

Plate XXXIII, figs. 13-17.

Areella t hyalina. Ehrenherg: Infusionsthierchen, 1838, 134, Taf. ix, Fig. viii. Abh. Ak. Wis. Berlin.

1871, 235, 264.— Fresenius : Abh. Senek. Gesells. 1856-58, ii, 219, Taf. xii, Fig. 1-24.
Oromia hyalina. Sehlumberger : An. Sc. Nat. 1845, iii, 255.
Difflugia Enchelys. Schneider: Miiller's Arcbiv, 1854, 204, Taf. ix, Fig. 16-24.
A. Homceochlamys hyalina. Ehrenberg: Abh. Ak. Wis. Berlin, 1871, 244.
Lecythium hyalinum. Herfrwig and Lesser: Arch. mik. Anat. 1874, x, Snppl. 177, Taf. iii, Fig. 8. — Archer:

Quart. Jour. Mic. Sc. 1877, xvii, 197, pi. xiii, figs. 1,2.

Animal spheroidal, and feebly produced at the lower pole into a short,

GENUS PAMPHAGUS— PAMPHAGUS HYALINUS. 195

broad neck, terminating in a circular mouth. Shell membranous, trans-
parent, colorless, structureless, and elastic. Sarcode intimately adherent
to the interior of the shell, finely granular, with variable proportions of
oil-like molecules, usually more or less accumulated in a median zone, and
with more or less vacuoles at the lower part. Nucleus large, and commonly
with a large and distinct nucleolus. Pseudopods filamentous, delicate, and
furcate.

Size — From 0.032 mm. in diameter to 0.048 mm. in length and 0.044
mm. in breadth.

Locality. — In the superficial ooze of ponds, ditches, and lakes. Ob-
served in Pennsylvania, New Jersey, and Wyoming Territory.

In his great work, the 'Infusionsthierchen,' Ehrenberg describes a
small rhizopod under the name Arcella hyalina, almost spherical, and with
a smooth hyaline membranous shell. It ranges from ith to ith of a line.
It exhibited within many vesicles, and possessed many filamentous pseudo-
pods. Later what appears to be the same animal was described by
Schlurnberger with the name of Gromia hyalina, and by Schneider with
that of Difflugia hyalina. Recently Hertwig and Lesser have also described
the creature, and have referred it to a new genus, with the name of Lecy-
thium hyalinum. In what respect this genus differs from Pamphagus I am
unable to see, and therefore have considered it as pertaining to the same.

Paniphngtis lit alinus, as I take it to be, I have occasionally found,
though I suspect it is not uncommon, but on account of its inconspicuous
character is readily overlooked It is a minute, spheroidal, translucent,
colorless creature, represented in the magnified views of figs. 13-17, pi.
XXXIII. The shape is nearly spherical, or it is slightly tapering at the
oral pole, or feebly prolonged so as to be sub-pyriform. The mouth is
inferior, terminal, comparatively large, circular, and dilatable, and its
margin is entire and thin. The shell or membranous investment is struc-
tureless and elastic, but not voluntarily extensible or contractile.

The sarcode is like that of Pamphagus mutabilis, but usually contains a
greater proportion of oil molecules collected in the intermediate zone, and
a greater number of clear vacuoles in the lower portion. Sometimes the
large nucleus is clear and homogeneous, as seen in fig. 14, but in others it
has appeared of pale granular constitution, and contained a large distinct
nucleolus, as represented in figs. 15-17.

196 FRESH- WATER EHIZOPODS OF NORTH AMERICA.

Pamphagus hyalinus is a peculiarly delicate and sensitive creature, and
readily undergoes decomposition. In repeated instances, I have observed
the animal project from the mouth of the shell portions of the sarcode, which
would gradually swell up and become more or less filled with different-sized
vacuoles, as seen in figs. 15-17. The projected protoplasm would sometimes
increase to more than half the bulk of the animal in its normal condition.
Suspecting that this condition was a preparatory step to segmentation, I
was led to watch patiently several individuals for some hours to learn the
result, which however, in each case, proved to be decomposition or death.

PAMPHAGUS CURVUS.

Plate XXXIII, figs. 11, 12. ■

Animal retort-shaped, or ovoid with the prolonged narrower pole
curved, and with the body in transverse section circular. Mouth inferior,
terminal, circular. Shell transparent, colorless or pale 3 r ellowish, structure-
less. Sarcode continuous with the interior of the shell, and having the
nucleus as in P. mutabilis. Pseudopods likewise as in the latter.

Size. — Froni 0.044 mm. in length by 0.028 mm. in breadth to 0.06 mm.
in length by 0.036 mm. in breadth.

Locality. — Vicinity of Philadelphia, in the superficial ooze of ponds.

In a few instances I have met with a small rhizopod resembling in
structure and habit the Pamphagus mutabilis, but with a shape like that of
Cyphoderia. The shell is structureless and closely adherent to every part
of the surface of the interior sarcode, from which it appears to be as insep-
arable as in Pamphagus mutabilis. Figs. 11, 12, pi. XXXIII, represent two
such specimens.

PAMPHAGUS AVIDUS.

Plate XXXIII, fig. 10.

Body oval or ovoid, in transverse section circular, wider at the oral
pole; mouth small, circular, expansile and contractile. Nucleus, etc., as in
P. mutabilis.

Size. — From 0.148 mm. to 0.22 mm. in length by 0.12 mm in breadth.

Locality. — Cedar swamp of Atco, New Jersey.

In September, 1877, in some material collected in pools in the cedar

GENUS PSETJDODIFFLUGIA. 197

and sphagnous swamp of Atco, New Jersey, I found several individuals
of a species of Pamphagus, larger and apparently different from any of the
preceding. Its size accords with that given for 'Corycie' by Dujardin, and
perhaps the animal may be the same.

One of the individuals observed, represented in fig. 10, pi. XXXIII,
was so replete with food as greatly to obscure from view the nucleus and
other usual constituents of the sarcode. Among the food contents were two
considerable portions of the alga Didymoprium, which were so long as to
cause some distortion of the animal, making it project beyond the normal
outline both in front and behind. Among the contents of the sarcode,
besides the ordinary pale granular basis and fine oil-like molecules, there
were noticed many clear globules or water vacuoles.

The pseudopods were like those of P. mutahilis. In the distorted con-
dition of the animal, as represented in the figure, the creature measured
0.22 mm. in length by 0.12 mm. in breadth. The longest pseudopod
measured 0.2 mm. in breadth. The following morning, after first seeing the
specimen, it had discharged the two long portions of Didymoprium, and in
this condition presented a cordiform outline, with the mouth depressed and
puckered, and it measured 0.16 mm. in length by 0.1 12 mm. in breadth.

Another individual, of ovoid form, had the mouth in the centre of the
broader pole. It was 0.148 mm. long by 0.12 mm. broad. It contained
many clear globules or water vacuoles from 0.004 mm. to 0.008 mm.,
together with oil-like globules up to 0.01 mm. in diameter. The abundant
food consisted of indistinct yellowish granular material and a number of
round, one-celled, bright green algae. A clear nucleus in the fundus of the
sarcode measured 028 mm. in diameter.

This large form of Pamphagus may perhaps be the same animal as
the Plagiophrys cylindrka of Claparede and Lachmann, which approximates
it in size.

PSETJDODIFFLUGIA.

Greek, pseudos, false; Latiu, diffluo, to flow.
Pseiidodifflugia : Schlumberger, 1845. Pleurophrys: Claparede and Lachmann, 1859.

Animal provided with a thin chitinoid shell mostly incorporated with
variable proportions of fine quartz-sand, or other extrinsic material, of inde-
terminate character, commonly distinguished as 'dirt.' Mouth terminal,

198 FEESH-WATEE EHLZOPODS OF NOETH AMEBICA.

inferior. Sarcode mostly colorless, with a large clear nucleus, but usually

with other constituents of the former obscured by the nature of the shell.

Pseudopods numerous, exceedingly delicate, filamentous, and forking at

acute angles.

PSEUDODIFFLUGIA GRACILIS.

Plate XXXIII, figs. 18-28.

Pseudodifflugia gracilis. Schlunibeiger : An. Sc. Nat. 1845, iii, 254.

Pleurophrys sphawica. Claparede and Lachmann: Etudes Infnsoires et Rhizopodes, 1859, i, 455, pi. xxii,
fig. 3. — Archer : Quart. Jour. Mic. Sc. 1869, pi. xx, fig. 1, 1870, 121. — Hertwig and Lesser :
Arch. mik. Anat. 1874, x, Suppl. 135, Taf. iii, Fig. 4.— Schulze : Ibidem, 1875, xi, 122.

Pleurophrys? amphilremoides. Archer: Quart. Jour. Mic. Sc. 1870, 121, pi. xx, fig. 2. — Schulze: Arch,
mik. Anat. 1875, xi, 123, Taf. vii, Fig. 1.

Pleurophrys? fulva. Archer: Ibidem, 1870, 122, pi. xx, fig. 3.— Schulze: Ibidem, 124, figs. 2, 3.

Pleurophrys compressa. Schulze : Arch. mik. Anat. 1875, xi, 125, Taf. vii, Fig. 4, 5.

Plcurophnjs lagcniformis. Schulze: Ibidem, Fig. 6-8.

Pleurophrys angulata. Mereschkowsky : Arch. mik. Anat. 1878, 192, Taf. x, Fig. 14.

Shell of variable form, mostly spheroidal, ovoidal, or oblong oval, and
of uniform transverse diameters, but rarely somewhat compressed, usually
straight, occasionally slightly curved. Mouth terminal, circular. Structure
of the shell mostly obscurely granular, often with fine sand, and frequently
almost or quite entirely composed of coarser sand ; colorless or brownish.

Size. — Length from 0.04 mm. to 0.16 mm.; breadth 0.02 mm. to 0.1 mm.

Locality. — Frequent in the ooze of ponds, ditches, etc. Vicinity of
Philadelphia and other places in Pennsylvania; New Jersey; Uinta Mount-
ains, Wyoming Territory.

The genus Pseudodifflugia is one of those described by Schlumber-
ger,*and not usually recognized by succeeding observers. It is character-
ized as having a membranous shell, ovoid or ovo-globular, smooth or rolled,
with a wide round aperture, from which project very long fine filaments,
simple and branched. The author remarks that the genus approaches
nearly to Difflugia, but differs in the character of its pseudopods.

The species Pseudodifflugia gracilis is described as having an ovoid,
bluish brown shell, of variable length, and encrusted as it were with minute
grains of sand. The size is 0.035 mm. to 0.056 mm in length by 0.029 mm.
to 0.035 mm. in breadth.

The characters assigned to Pleurophrys by Claparede and Lachmann
lead me to suspect that it is not different from Pseudodifflugia. They
observe that it is related with the Actinophryans as Difflugia is with the

* Annales des Sciences Naturelles, 1845, 254.

GENUS PSEUDODIFFLUGIA— PSEUDODIFFLUGIA GRACILIS. 199

Arncebas. They further remark that the animal is covered with a shell
composed of foreign substances cemented together, and having a single
aperture. The species indicated by them under the name of Pleuroplmjs
spliccrica* is described as possessing a spherical shell composed of silicious
particles, and measuring 0.02 mm. The figure accompanying their descrip-
tion represents a nearly globular shell of coarse sand, with granular fila-
mentous pseudopods extending like the rays of an Actinophrys.

I have many times met with inconspicuous rhizopods with a shell
approximating in character that of the Difflugias, but with delicate filament-
ous pseudopods. I have suspected them to belong to the genus Pseudo-
difflugia of Schlumberger or of Pleurophrys of Claparede and Lachmann.
They occur in the ooze of ponds, and are of such obscure character, that
unless attention is directed to them, they are liable to be overlooked or mis-
taken for the excrement of worms or other masses of dirt They present
considerable variety in form, size, color, and exact composition of the shell,
and such intermediate gradations that 1 have been disposed to view most
of them as pertaining to the same species.

Pseudodifflugia gracilis, as I have supposed it to be, is of quite
variable form, proportions, and size. Commonly it is ovoid, with the mouth
at the narrower pole, but sometimes is ovate, oval, oblong, or sub-pyriform.
See figs. 18-21, pi. XXXIII. The mouth is circular, and appears to be
contractile or dilatable, so that it varies in size according to its condition.
Sometimes it is oblique or sub-terminal, as seen in fig. 22, and occasionally
I have found individuals with the shell somewhat curved and the mouth
oblique, as represented in fig. 24. Usually the shell is of uniform trans-
verse diameters, but sometimes is more or less compressed, as represented
in the specimen of figs. 26, 27. The fundus of the shell is broad and
mostly evenly convex, but sometimes rather flattened.

The color of the shell is variable, usually some shade of brown, but
often colorless. In composition it often appears membranous, and incorpo-
rated with variable proportions of fine dirt and sand. Sometimes the dis-
tinctly visible sand grains are minute and scattered, and sometimes they are
larger and closely cemented together, as is ordinarily the case in most
species of Difflugia, and as seen in the figures last referred to.

* fitudes Infusoires, 455, pi. xxii, fig. 3.

200 FRESH- WATER RHIZOPODS OF NORTH AMERICA.

In several instances I found individuals which I viewed as pertaining
to the same animal, in which the shell was mainly granular and translucent,
but had large sand grains accumulated at the extremities, as seen in fig. 25.

In those specimens in which the shell is not too thoroughly incorporated
with dirt or sand, the interior sarcode becomes more or less visible, and is
seen to be of variable extent in relation to the capacity of the shell. A
large clear spot in the fundus of the sarcode indicates the presence of a
nucleus, and a darker intermediate zone the accumulation there of fine oil
molecules. The lower region is likewise observed to contain vacuoles and
portions of food.

The pseudopods of Pseudodifflugia gracilis are numerous, finely fila-
mentous and branching. They are sometimes observed diverging from the
mouth in profuse bunches ; at other times in a few filaments. See figs. 18-
28. On one occasion I observed a number of pseudopods run together into
a broad patch of protoplasm, which involved, within a vacuole, two greer
algous cells, as seen in fig. 22.

The movements of the animal are exceedingly slow, and it often
requires long watching to observe it project the pseudopods.

Pseudodifflugia is more closely related with Pamphagus and Cypho-
deria than with the Heliozoa. Subsequently to Claparede and Lachmann,
other investigators have described Pthizopods which they refer to species
of Pleurophrys, but which I suppose to pertain to Pseudodifflugia, and
most of them to P. gracilis.

Mr. Archer* described a form which he refers to Pleurophrys spliccrica,
though of larger size and otherwise different from that of the former
authors. Schulze considers the determination incorrectf The shell is
represented as spheroidal, brown, and composed of granular matter, with
a size of n 4„th of an inch.

150

Fig. 19 represents an individual of nearly the size and constitution
of that just indicated, as described and figured by Mr. Archer. It is,
however, of ovoid shape, and measures 0.16 mm. long by 0.1 mm. broad.
Both forms I view as pertaining to Pseudodifflugia gracilis.

In the same memoir, Mr. Archer indicated two Other forms as pertain-
ing to Pleurophrys, with the names of P. amphitremoides and P. fulva.%

* Quart. Jour. Micr. Sc. 1809, fig. 1, pi. xx ; 1870, 121.
t Archiv f. niikr. Anatomic, 1875, xi, 122.
% Quart, Jour. Micr. Sc. 1870, 121, 122.

GENUS CYPHODERIA. 201

Both have ovoid shells, in one incorporated with diatoms, in the other with
sand and of a yellow color. Schulze admits these as species, and describes
others he regards as the Fame,* but I would regard all as varieties of
Pseudodifflugia gracilis.

The latter author has described two other forms with the names of
Pleurophrys compressa and P. lageniformis, but these also I incline to believe
belong to the Pseudodifflugia gracilis as mere varieties.

Hertwig and Lesserf have described a rhizopod which they regard as
Pleurophrys sphcerica, to which they also consider the large form pertains
described by Mr. Archer. The specimens indicated by the former have an
ovoid, brown, granular shell, ranging from 0.03 mm. to 0.05 mm. In struc-
ture, form, and size they sufficiently accord with Schlumberger's description
to belong to Pseudodifflugia gracilis.

Quite recently, since the present work went to press, MereschkowskyJ
has described a form under the name of Pleurophrys angulata, which ap-
pears to me not to differ from the former.

Fig. 28, pi. XXXIII, represents a remarkable variety obtained from
ooze in a lake of the Uinta Mountains, Wyoming Territory, but the only
specimen of the kind seen, though ordinary forms were common enough.
The shell was amphora-shaped, with a nipple-like process to the fundus
and a rim to the mouth, and was composed of comparatively coarse sand
grains. Its length was 0.06 mm.; its breadth 0.036 mm. The pseudopods
extended in a dense bundle. As a conspicuous variety, this might be
appropriately distinguished as Pseudodifflugia amphora.

CYPHODERIA.

Greek, kuphos, curved; deros, the neck.

Diffiugia : Ehrenberg, 1840. Cyphoderia : Sehluinberger, 1845. Euglypha : Perty, 1852. Lagynis : Schultze,
1854. Ampullaria; Hologlypha ; Assulina : Ehrenberg, 1871.

Animal provided with a retort-shaped shell, the mouth directed down-
ward, and the long axis of the body inclined. Structure of the shell
chitinoid, transparent, colored or colorless, composed of minute hexagonal
elements of uniform size arranged in alternating series in parallel spiral
rows. Mouth minutely beaded. Sarcode pale, granular, usually nearly

* Arehiv mik. Anatomie, 1875, xi, 122.

t Arehiv mik. Anatomie, 1874, 135, Taf. iii, Fig. 4.

t Ibidem, 192, Taf. x, Fig. 14.

202 FEESH-WATEE EHIZOPODS OF NOETH AMEEICA.

filling the shell or slightly contracted from its sides ; when shorter than the
cavity of the shell, mostly adherent to the fundus by a pair of pseudopodal
threads. Nucleus large, clear, and usually homogeneous. Contractile
vesicles occupying an intermediate zone of the sarcode. Pseudopods nu-
merous, forking, radiating in any direction from the mouth, but mostly on
a horizontal plane, susceptible of a great variety of movement and change

of form.

CYPHODERIA AMPULLA.

Plate XXXIV, figs. 1-16.

Difflugia Ampulla. Ehrenberg: Bericht Preus. Ak. Wis. 1840, 199; Abb. Ak. Wis. 1871, Taf. iii, Fig. 11.

f Difflugia Lagena. Ebrenberg : Abb. Ak. Wis. 1841, 413, Taf. iv, Fig. 11 ; 1871, Taf. ii, Fig. 2.

Cyphoderia margaritaeea. Scblumberger: An. Sc. Nat. 1845, iii, 255. — Presenilis : Abb. Senck. Naturf.
Ges. 1856-58, ii, 225, Taf. xii, Fig. 28-36.— Stein : Sitzungsb. Bobm. Akad. 1857 (fid".
Schulze). — Carter: An. Mag. Nat. Hist. 1864, xiii, 33, pi. ii, fig. 18. — Hertwig and Lesser:
Arcb. mik. Anat. 1874, x, Sup. 132— Leidy: Pr. Ac. Nat. Sc. 1874, 227 ; 1877, 294— Scbulze :
Arcb. mik. Anat. 1875, xi, 106, Taf. v, Fig. 12-20.

Euglypha curvata. Perty : Kennt. kleinst. Lebensfonnen, 1852, 187, pi. viii, fig. 21.

Lagynia baltica. Scbultze : Organ. Polytbalamien, 1854, 56, Taf. i, Fig. 7,8.

Euglypha margaritaeea. Wallicb : An. Mag. Nat. Hist. 1804, xiii, 240,244,245, pi. xvi, fig. 48.

Difflugia margaritaeea. Wallicb : Ibidem, 245.

Euglypha baltica. Wallicb: Ibidem.

Difflugia Seelandica. Ebrenberg : Abh. Ak. Wis. 1869, Taf. ii, Fig. 23.

Ampullaria (Werneck). Ebrenberg: Ibidem, 1871, 234.

Difflugia adunca. Ebrenberg : Ibidem, 1871, 248, Taf. iii, Fig. 8, 9.

? Difflugia alabamensis. Ebrenberg: Ibidem, Fig. 10.

Difflugia uncinata. Ebrenberg: Ibidem, Fig. 13.

Hologlypha, seu D. Assulina adunca, D. A. alabamensis, D. A. Ampulla, D. A. margaritaeea, D. A. unci-
nata. Ehrenberg : Abb. 1871, 246.

Euglypha, seu D. Assulina Seelandica. Ebrenberg: Abb. 1871, 246.

Cyphoderia ampulla. Leidy : Pr. Ac. Nat. Sc. 1878, 173.

Shell retort-shaped, with a short cylindrical neck curving downward,
and truncated by a circular mouth ; body of the shell oblong oval, with the
longitudinal axis, in the active or moving condition of the animal, more or
less inclined, but nearly horizontal ; fundus obtusely rounded, sometimes
flattened, frequently more or less prolonged or narrowed at the summit
into a nipple-like process. Color of the shell mostly yellowish, less fre-
quently colorless.

Size. — Ranging from 0.112 mm. to 0.176 mm. long by 0.04 mm. to
08 mm. broad, with the mouth 0.016 mm. to 0.02S mm. wide.

Locality. — The superficial ooze of springs, ponds, lakes, and ditches.
Pennsylvania, New Jersey, Rhode Island, Florida, Wyoming Territory,
and Nova Scotia.

Cyphoderia ampulla has an oval oblong, retort-shaped shell, with a
short cylindroid neck curving downward to the mouth. See figs. 1-15, pi.

GENUS CYPHODEEIA— CTPHODERIA AMPULLA. 203

XXXIV. The long axis of the shell forms a line curving upwardly and
backward from the mouth. In the ordinary position of movement of the
animal, the mouth is directed downward on a horizontal plane, while the
body of the shell is directed backward, with but slight inclination from the
same plane.

The sides of the shell are commonly eventy convex, but occasionally
somewhat flattened or slight^ tapering toward both poles. The fundus is
usually evenly convex, but sometimes flattened, and frequently more or less
prolonged and narrowed at the summit into a nipple-shaped process, as seen

in figs. 4-8.

The mouth of the shell is circular, and exhibits a beaded margin more
or less distinct. Schulze describes it as possessing a delicate and structure-
less membranous expansion or zone;* but this, if it exists, escaped my
attention, or was taken for an expansion of sarcode at the root of the
pseudopods.

The shell is straw-colored or pale yellowish, and often entirely color-
less. It is transparent, and apparently composed of chitinoid membrane,
as in Arcella. It exhibits a structure of variable distinctness, consisting
of exceedingly minute hexagonal elements, alternating with one another,
and arranged in spiral rows. Ordinarily the shell has a more or less
uniform punctate appearance; but when the structure is more than usually
distinct, the arrangement of hexagons is very obvious. The outlines of
the hexagons will appear single and dark, or double and clear, as seen in
fig. 16, according to the focus in which they are viewed. In several
instances it has seemed to me as if the hexagons were externally faceted
in inclined triangular planes from common centres.

The soft contents of the shell of Cyphoderia occupies its capacity in
varying extent, as in the case of Euglypha. Sometimes it entirely fills the
shell, sometimes it is more or less contracted in an intermediate position
from the sides, and it is not unfrequently more or less contracted from the
fundus. In the last condition, the mass is usually attached to the dome of
the shell by a pair or more of fine thread-like extensions of the sarcode, as
is so conspicuously observed in Hyalosphenia, and as represented in figs.
13, 14.

A large clear nucleus occupies the fundus of the body, and generally

• Archiv f. mik. Anatomie, 1875, 111, Taf. v, 20.

204 FRESH-WATER EHIZOPODS OP NORTH AMERICA.

below it there is an accumulation of oil-like molecules. Between the
latter and the mouth of the shell, the sarcode contains variable propor-
tions of food materials, water vacuoles, and commonly several contractile
vesicles.

The pseudopods radiate from the mouth, often to a distance consider-
ably more than the length of the shell. They are exceedingly delicate,
and branch usually at very acute angles, but do not anastomose. Some-
times, in movement, they abruptly bend, and occasionally suddenly con-
tract in a tortuous manner.

Ordinarily, the shell of Cyphoderia measures about 0.125 mm. in length
by 0.05 mm. in breadth, but specimens range from about 0.11 mm. to 0.2
mm. in length.

Cyplwderia ampulla is common in the ooze of springs, ponds, and lakes,
though I have never found it very abundantly at any one time. I have
obtained it from springs and ponds in the vicinity of Philadelphia. The
largest specimens I found at Lake Hattacawanna, New Jersey. I also
found it in China Lake, in the Uinta Mountains, at an altitude of 10,000
feet, and likewise at the base of the mountains, at Fort Bridger, in Wyoming
Territory. The Wyoming specimens were remarkable from their commonly
having the shell with a nipple-shaped prolongation at the fundus.

The genus Cyphoderia was characterized by Schlumberger in 1845,
and the species described under the name of Cyphoderia margaritacea from
specimens obtained in the mud of brooks of the Vosges and Jura. The
same was, however, described by Ehrenberg, five years earlier, in the
'Bericht' of the Academy of Sciences of Berlin, under the name of Difflugia
ampulla* This is confirmed by figures of the species published in the
'Abhandlungen' of the same society in 1871. Recent authorities adopt the
specific name of Schlumberger ; but there is no good reason for retaining
it, and, according to the usual rule, I have employed the earlier name.

CAMPASCUS.

Greek, kampe, bent ; askos, a bottle.

Animal provided with a shell having the form like that of Cyphoderia,
but provided with a pair of lateral divergent processes to the fundus, and
composed of homogeneous chitinoid membrane. The soft part together
with pseudopods as in Cyphoderia.

"The original description is as follows: " Lorica oblonga clavata, punctorum seriebus obliquis
eleganter notata, hyalina, ostiolo ovato. Mag. ^'"."

GENUS CAMPASCUS— CAMPASCUS COENUTUS. 205

CAMPASCUS CORNUTUS.

Plate XXXIV, figs. 17-24.
Campascus cornutus. Leidy : Proc. Acad. Nat. Sci. 1877, 294.

Shell retort-form, with a short curved neck, and with the obtuse fundus
directed backward and upward, and provided on each side with a divergent
conical prolongation; composed of translucent, yellowish, homogeneous,
chitinoid membrane, incorporated with scattered sand particles. Mouth
circular, directed downward, bordered by a delicate, colorless, annular-
expansion. The interior soft part resembling that of Cyphoderia; a large
nucleus at the fundus; pseudopods filamentous, furcate, exceedingly deli-
cate.

Size. — Ranging from 0.112 mm. to 0.14 mm. long by 0.18 mm. broad,
or between the lateral processes of the fundus from 0.08 mm. to 0.-112 mm.
broad; mouth 0.024 mm. to 0.028 mm. wide.

Locality. — The ooze of China Lake, Uinta Mountains, 10,000 feet
altitude, Wyoming Territory.

Campascus cornutus is intermediate in character to Centropyxis
aculeata and Cyphoderia ampulla. The shell has the structure and horn-like
processes of the former ; but the shape and the structure of the animal, with
the pseudopods, have the character of the latter.

This animal I discovered in August, 1877, in ooze collected in China
Lake, in the Uinta Mountains, about 25 miles from Fort Bridger, Wyo-
ming Territory. I have not found it elsewhere. I at first took it for a new
species of Cyphoderia; but I failed to detect the hexagonal structure char-
acteristic of the shell of this genus.

In the side view of Campascus, as seen in fig. 21, pi. XXXIV, the
shell has the exact form of that of Cyphoderia ampulla, the lateral processes
being concealed. Either in the under or the upper view, as seen in figs.
17, 20, the lateral prolongations backward of the shell give it a triangular
outline, in which the mouth forms the apex, the processes form the basal
angles, and the intermediate portion of the base forms the rounded fundus.
The lateral processes are conical and curved, and are on the ventral rather
than on the dorsal aspect of the fundus. In some specimens, as seen in that
of fig. 22, it is rudimental, and in this particular one also the summit of the
fundus was somewhat pointed.

206 FRESH- WATER RHIZOPODS OP NORTH AMERICA.

The mouth is circular, and surrounded with a delicate, structureless,
membranous zone, as represented in figs. 20, 21.

The shell of Campascus is dull yellowish or straw-colored, and is com-
posed of homogeneous chitinoid membrane incorporated with scattei'ed
sand particles. Even with high microscopic power I could detect no trace
of hexagonal structure, such as exists in the shell of Cyphoderia and Arcella.

The soft part of the animal is like that of Cyphoderia or Euglypha. A
large, clear nucleus occupies the fundus of the sarcode mass, and in con-
tiguity with it, especially accumulated just beneath, there is a quantity of
oil-like molecules. The adherent sand particles to the shell prevented me
from detecting contractile vesicles, which no doubt exist in a corresponding
position to that in Cyphoderia or Euglypha. The pseudopods are like
those of the latter animals The shell of Campascus is commonly about
0.125 mm. in length.

EUGLYPHA.

Greek, eu, well; gluplie, sculptured.
Eughjplia: Dujardin, 1841. Difflugia : Ehrenberg, 1841. Assulina; Setigerclla : Ehrenberg, 1871.

Animal provided with a hyaline, ovoid shell, of uniform diameter,
or compressed, composed of regular, oval or hexagonal plates of chitinoid
membrane, arranged in alternating longitudinal series. Mouth terminal,
circular or elliptical, with the marginal plates forming a series of minutely
serrulate angular points. Shell mostly provided with spines or hairs, though
sometimes absent. Sarcode colorless, with a large nucleus in the fundus,
and usually several contractile vesicles occupying an intermediate position
of the mass. Pseudopods filamentous, exceedingly delicate, dichotomously
branching, not anastomosing, and with no evident circulation of granules.
Animal when in motion with the shell erect or jDerpendicular, with the
mouth downward, and with the pseudopods more or less horizontally
divergent.

The genus Euglypha contains a number of distinct or well-marked
forms which are conveniently considered to be so many species; but, through
a multitude of intermediate conditions, the species appear to graduate into
one another. They are the most elegant and complex in the structure of
their shell of any of the Protoplasts provided with such a covering.

The shell of Euglypha is composed of plates, mostly of uniform size,

GEXUS EUGLYPHA— euglypha alveolata. 207

and arranged with great regularity in longitudinal rows, alternating with
one another in the different rows. Commonly the plates appear of longitu-
dinally oval shape, and overlap at the contiguous borders so as to include
hexagonal areas enclosed by circles of minute elliptical areas, or they
appear of hexahedral shape, and are closely adapted together at the borders.
Ehrenberg describes and figures in his various communications a number
of forms in which the shell is represented as being composed of longitudi-
nal rows of alternating rectangular plates.* Of this kind I have seen
none, and incline to think, from my experience, that the shape of the plates
as thus described is illusory. The shell of the ordinary forms of Euglypha,
viewed with unfavorable light, or when the structure is not distinct, will
appear to be composed in this way, when clearer definition will prove them
to exhibit the structure as above described.

EUGLYPHA ALVEOLATA.

Plate XXXV, figs. 1-18.

Euglypha alveolata. Dnjardin: Iufusoires, 1841, 252, pi. ii, figs. 9, 10. — Perty : Kennt. kleinst. Lebensfor-
men, 1852. 187.— Pritchard: Hist. Iufus. 18G1, £56, pi. xxi, fig. 11.— Carter: An. Mag. Nat.
Hist. 1856, xviii, 221, pi. v, figs. 25-36; 1864,xiii,33,pl.ii,fig. 17.— Wallich: An. Mag. Nat.
Hist. 1864, xiii, 240, pi. xvi, ligs. 41-45. — Hertwig and Lesser : Arch. mik. Anat. Suppl. 1874,
124, Taf. iii, Fig. 5.— Sclmlzo: Arch. mik. Anat. 1875, 97, Taf. v, Fig. 1, 2.— Micro-graphic
Dictionary, pi. 23, fig. 54.— Leidy : Pr. Ac. Nat. Sc. 1874, 225; 1877,262,321; 1S78, 171.

Euglypha tuberculata. Dujardin: Infusoires, 1841, 251, pi. ii, figs. 7,8.— Perty : Kennt. kl. Lebensformen,
1852, 187.— Claparede and Lachmann: Etudes Infus. et Ebizopodes, 1858-9, i, 456.— Pritch-
ard: Hist. Iufus. 1861,556. — Micrographic Dictionary, pi. 23, fig. 53.

Difflugia areolata. Ehrenberg: Abb. Ak. Wis. Berlin, 1841,413, Taf. i,Fig. 8; Taf. ii.Fig. 4,5; Taf. iv,
Fig. 2; 1871,264. Mouatsb. Ak. Wis. 1845, 319 ; 1848,215; 1849,89, 98, 191, 228, 321; 1853,
182, 236, 322. Mikrogeologie, 1*54, Taf. xxxii, Fig. 2 ; xxxviii, Fig. 2 ; xxxix, Fig. 25. Zweite
deutsche Nordpolarfahrt, 1S74, Taf. iii, Fig. 23.

Difflugia acanthophora. Ehrenberg : Ab. Ak. Wis. 1841, 413, Taf. iv, Fig. 36 ; 1871, 264.— Pritchard: Hist.
Iufus. 1861, 553, pi. xii, Fig. 64.

Difflugia lasmgata. Ehrenberg : Ab. Ak. Wis. 1841, 413, Taf. ii, Fig. 43.

Difflugia striolata. Ehrenberg : Ibidem, Fig. 44. Monatsb. 1851, 321 ; 1853, 182. Mikrogeologie, 1854, Taf.
xxxiii, Fig. 3.

Euglypha la-vis. Perty : Kennt. kleinst. Lebensformen, 1852, 187, Taf. viii, Fig. 18.

Euglypha setigera. Perty : Ibidem, fig. 19.

Difflugia Florida. Ehrenberg: Monatsb. Ak, Wis. 1853, 366. Mikrogeologie, 1854, Taf. xxxiv, Fig. 3. Abh.
Ak. Wis. 1871,252.

Difflugia pilosa. Ehrenberg : Mikrogeologie, 1854, Taf. xxxiv, B. v, Fig. 6. Abh. Ak. Wis. 1871, 256.

Difflugia moluccensis. Ehrenberg : Abh. Ak. Wis. 1869, 48, Taf. ii, Fig. 12.

Difflugia amphora. Ehrenberg : Ibidem, 1871, 248, Taf. iii, Fig. 17.

Difflugia rectangularis. Ehrenberg : Ibidem, 256, Taf. iii, Fig. 16. Zweite deut