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SYNOPSIS

FRESH-WATER RHIZOPODS

A CONDENSED ACCOUNT

GENERA AND SPECIES

FOUNDED UPON

PROF. JOSEPH LEIDY'S
"FRESH-WATER RHIZOPODS OF NORTH AMERICA

COMPILED BY

ROMYN HITCHCOCK, F. R. M. s.

President of the New York Microscopical Society, Editor of the American
Monthly Microscopical Journal

NEW YORK
ROMYN HITCHCOCK, PUBLISHER

Nos. 51 AND 53 MAIDEN LANE

1881

COPYRIGHT, 1881, BY ROMYN HITCHCOCK, NEW YORK.

THOMPSON & MOREAU,

PRINTERS,

51 & 53 MAIDEN LANE,
NEW YORK.

INTRODUCTION.

It is sincerely hoped that the publication of this work
will arouse an interest in the examination and study
of the simple and beautiful organisms which it describes.
It is seldom that a person can take up any study in natural
history, and follow it in a satisfactory manner without
access to many large and expensive books of reference.
Until the publication of Professor Joseph Leidji's work,
"The Fresh-water Rhizopods of North America," by
the United States Government, this was equally true of
the fresh-water Rhizopods, but now that difficulty has
been entirely removed, and the student will find all the
necessary information about the habits and forms of these
organisms in that single volume. As an introduction
to the study, this work will, it is hoped, be highly
valued by those who cannot obtain the larger one, which,
being a Government publication, will necessarily be
limited in its distribution.

There is a broad field for valuable, original investigation
in the study of the Rhizopods. We know comparative-
ly little about their modes of reproduction and propaga-

IV INTRODUCTION.

tion — so little, indeed, that any observations whatever
upon this subject will be of value, if carefully made.

The classification adopted by Professor Leidy has been
followed in this book, and in the descriptions of genera
and species the variations from the original have been
very slight, and only such as have seemed advisable to
make up for the lack of illustrative plates, or, in some cases,
for the sake of brevity. It is believed that the descrip-
tions will, in most cases, enable the student to name the
specimens that he finds without the aid of figures.

Those who possess copies of Professor Leidy's work,
and who have not made Rhizopods a special study, will
find this book a valuable adjunct — a sort of key to the
larger ome; for the schematic synopses of genera and
species will serve to lead the observer directly to the
proper genus or species with a fair degree of certainty,
by a hasty observation of the more prominent character-
istics of the forms that may be discovered.

The careful study of Professor Leidy's work, which
the preparation of this Synopsis has necessitated, has
served to increase our admiration for his ability as an
observer, and our appreciation of the great labor he has so
conscientiously performed. Apart from the pleasure which
an enthusiast always feels when engaged in his favorite
study, Professor Leidy must find his reward mainly in
his own knowledge of the lasting value of his book, and
in the satisfaction of having done his work so well.

INTRODUCTION.

GENERAL CHARACTERISTICS OF RHIZOPODS.

Rhizopods consist, essentially, of a soft mass of clear or
granular protoplasm, usually colorless, with one or more
nuclei and contractile vesicles. By far, the greater num-
ber are provided with a shell-covering, sometimes chit-
inous but frequently composed of grains of sand and
other extraneous matters cemented together.

A distinction is made between the outer protoplasmic
layer and the interior mass of the body ; the outer layer
is called the ectosarc, the inner the endosarc. The dis-
tinction between endosarc and ectosarc is not always
clear. There is no definite line of demarkation between
them, such as would make the former correspond to a
cell-wall. Dr. Wallich regards them as only temporarily
distinct portions of sarcode, mutually convertible into one
another. The ectosarc is merely a more or less thick
layer of protoplasm, which seems to have undergone
some change by contact with the surrounding medium.
The endosarc is the interior protoplasmic mass; it is
usually more coarsely granular than the ectosarc. Within
the endosarc, the nuclei and the pulsating vesicles are
found. The former are usually large, spherical, hyaline
corpuscles, in most cases situated back of the middle of
the animal. The pulsating or contractile vesicle is a
colorless, or roseate, spherical structure, which is quite

V
VI INTRODUCTION.

common in Khizopods, as well as in many forms of
Infusoria. Its true nature is not fully understood. It is
usually situated near the border of the endosarc, often
opening in the ectosarc, as in some of the Heliozoa —
the common Actinophrys, for example. The pulsat-
ing vesicles slowly enlarge until they attain a certain
size, after which they suddenly collapse and entirely
disappear ; and this operation is repeated with a degree
of regularity.

The food of Rhizopods usually consists of diatoms,
desmids, and other algae, and fragments of higher plants.
Within the body the food is usually accumulated in
spherical masses, which may be green, brownish or red ;
depending upon its nature and the changes which it
undergoes during digestion. Ehrenberg supposed that
the sperical masses indicated so many stomachs, and
therefore regarded the Rhizopods as belonging to his
Polygastrica. It is probable that the food is simply
enveloped by the protoplasm and becomes digested, after
which the hard portions may be thrown out at any part
of the surface of the body.

The most commonly observed process of multiplica-
tion is by division ; in some species the body becomes
encysted, but the entire process has not yet been fully
made out.

Rhizopods are far more common in the ordinary col-
lections of the microscopist than is generally supposed,

INTRODUCTION. VII

but since they are seldom looked for, they are often
passed by unnoticed. For their study, however, syste-
matic collections should be made, and for this purpose
the superficial ooze at the bottom of still-water should be
examined, after it has been allowed to settle for some
time in a suitable dish. They are common in the slime
of submerged rocks, stems and leaves, and especially
so in moist sphagnum, and are to be found almost
everywhere in moist situations not too much shaded,
among decaying logs, mosses, lichens, and on the bark
of trees.

In Professor Leidy's book, references to the literature
of every species are given, with the names under which
they have been described. In this book these names have
been given as synonymes, with the names of the authors
who have described them without the references. Those
who possess the older works on the Infusoria, will
doubtless find these synonymes of some assistance. The
habitats given in the texts, are only intended to indicate
where the species are likely to be found ; and too much
importance should not be attached to them in naming
specimens.

The index is arranged to serve as a check-list, so that
the student can readily keep a record of the species that
he may find.

Measurements are all given in micro-millimetres ; or, as
more conveniently named, in micras. A micra is the

VIH INTRODUCTION.

one one-thousandth part of a millimetre (0.001mm), and is
designated by the Greek letter // ; it is equal to the
0.00039 (2 g*40) of an inch. Ten micras are marked 10^,
four and a-half micras, 4.5^.

According to the old system, 10/z would be called
"one one-hundredth of a millimetre," 4.5^ would be
forty-five ten-thousandths of a millimetre. It is, there-
fore, much simpler to apply the term micra in all micro-
scopical measurements.

CLASS RHIZOPODA.

OEDEK I.— PKOTOPLASTA.

Nearly all the fresh-water Rhizopods belong to this
order. They are either naked or covered with a chitin-
oid or siliceous shell, and move by the aid of pseudo-
podal projections of the sarcode body.

ORDER II.— IIELIOZOA.

Body spherical, with many vacuoles or clear globules
which give it a foamy appearance ; usually a single nu-
cleus, but sometimes several, and distinct contractile ves-
icles. Pseudopodia delicate, granular, emanating from
all parts of the body, commonly simple and tapering,
rarely forked or anastomosing, usually straight but highly
flexible and contractile.

ORDER III.— RADIOLARIA.
Marine. Skeleton siliceous.

ORDER IV.— FORAMINIFERA.

Mostly marine. Shell usually calcareous.

ORDER V.— MOKERA.

Without organs, body free and naked, composed of
structureless sarcode.

PKOTOPLASTA

Order I.--Protoplasta.

The Protoplasta include nearly all fresh-water forms
except the Heliozoa. Naked or provided with an exterior
chitinoid, or siliceous shell. There are two sub-orders.

Sub-Order I. — Lobosa. — Pseudopods are lobose projec-
tions from the clear ectosarc, simple, often more or less
ramose, but never anastomosing, blunt or pointed.

Endosarc granular, not distinctly differentiated from
the ectosarc, containing large, colorless or yellowish, some-
times bright green, spherical corpuscles, and one or more
nuclei, and contractile vesicles. Reproduction by division.

Under certain conditions some of them become en-
cysted, and the contents of the cysts may subdivide, or
the nucleus may break up into what are apparently
spermatozoids, and the endosarc into nucleated cells like
ova.

The distinguishing characteristic of the Lobosa is the
coarse, digitate form of the pseudopodia. In the Filosa
the pseudopodia are usually much finer, and in the order
Heliozoa they are like long rays, radiating from the
centre of the spherical body of the animal.

LOBOSA.

Sub-Order II. — Filosa. — Pseudopods delicate and
thread-like, having the same general constitution and
form as in the shell-covered Lobosa, but never coarse
or lobose, acutely forking, and becoming finer as they
branch, rarely anastomosing.

Endosarc and ectosarc not distinctly differentiated, but
the entire sarcode is homogeneous and resembles the
endosarc of the Lobosa. Large, central, clear nucleus ;
several peripheral contractile vesicles just below the
nucleus. Reproductive process not fully made out.

SUB-ORDER L—PROTOPLASTA LOBOSA.

Synops'is of the Genera of Lobosa.

( Form protean, ectosarc hyaline, endosarc PAOB-

granulous, Amoeba, 4

Similar to Amoeba, but with trailing, fila-
mentous appendages, Oitramceba, 6

Similar to Amoeba, but leech-like in form,
somewhat differentiated into anterior
and posterior parts, sometimes villous
behind, Pelomyxa, 7

Similar to Amoeba, but slug-like, posterior
papillose, body bristling with cils,* often
with spicules, Dinamaeba, 9

Discoidal, endosarc distinctly colored, ec-
tosarc colorless, Hyalodiscus, 10

* Cils, a word used by Professor Leidy instead of cilia, meaning
minute linear appendages, resembling fine hairs.

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PQ

AMOZBA.

Shell composed of sand-grains or other PAOR.

material, mouth terminal or subter-

minal, Difflugia, 10

Shell compressed ovoid to pyriform,

transparent, chitinoid, Hyalosphenia, 16

Shell compressed pyriform, of thin, square

chitinoid plates, Quadrula, 19

Shell compressed pyriform, colorless, of

oval or circular or angular disks, with

incorporated extrinsic elements, mouth

oval, Nebela, 20

Shell chitinoid, reticulated, often with

sand-grains at the fundus, Heleopera, 24

Shell chitinoid, hexagonal cancellated,

usually bell-shaped ; base concavely

infundibuliform, Arcella, 25

Shell discoid, mouth eccentric, with or

without spines, never cancellated, Centropyxis, 28

Shell flexible, chitinoid, sarcode in-
timately adherent, Cochltopodium, 29

DESCRIPTION OF GENERA AND SPECIES.

GENUS I. — AMCEBA.

When at rest, a spherical or oval mass of soft, hyaline,
colorless, granular protoplasm. When in motion, form
variable. Ectosarc hyaline and minutely granular. En-
dosarc continuous with the former, finely and coarsely
granular, with corpuscles of varied character, ingesta of
food, etc. Nuclei and one or more pulsating vacuoles.
Pseudopodia digitate, simple or branched.

Amoeba proteus. — In globular form, diameter 200^
in ovoidal form, 300// by 150//, extended in a dendroid
form, 500// in length by 400/* in breadth. This is one
of the largest species. It is nearly colorless or more or

AMCEBA. 0

less black by transmitted light, pale yellowish by re-
flected light. Pseudopodia digitate and blunt, sometimes
tapering and pointed. Nucleus usually single, discoidal,
posterior; contractile vesicle usually large and single,
generally behind the nucleus. The special charac-
teristic of this species is the digitate and blunt pseudo-
pods.

A. verrucosa. — Mature animal, rather sluggish, irregu-
larly oval, round or quadrately rounded form, with wart-
like expansions, and a more or less wrinkled surface, as
though invested with a membrane. Pseudopodia short,
broad and blunt. Endosarc pale, granular, with few or no
coarse granules. Ectosarc copious and hyaline. Con-
tractile vesicle large. Nucleus usually distinct. Size
ranging from 80^ by -72// to 180/z by 160^. Very
common.

Young animal actively moving, body oval or pyriform,
usually moving with the broader pole in advance ; sur-
face comparatively smooth, but generally marked with
four longitudinal lines or folds (Ammba quadrilineata,
Carter) ; contractile vesicle posterior. Nucleus in
front of the vesicle. Size from 40// by 20^ to 120//
by 90jw.

A. 'Padiosa. — SYN. : A. radiosa, Ehr., brachiola, Duj., ramosa,
Duj.

Comparatively small, colorless and inactive. When
floating free in the water stellate, with a spheroidal or oval
central mass with from two to three, or a dozen or more,
radiating pseudopods of variable length and form, mostly
conical and acute or attenuated and thread-like, sim-
ple, straight, apparently rigid, curved or flexuose. On

6 OUBAMCEBA.

careful watching, the form may be observed to change
very slowly, and the pseudopods to contract or elongate,
or to bend or twist.

When creeping, of a less radiate character, but with
pseudopods diverging mostly from one extremity in the
direction of the movement. Contractile vesicle single, or
several smaller ones. Nucleus usually distinct. Size,
12^ to 45/*, rarely QO/J. in diameter; pseudopods 80//
long.

A. Vlllosa. — SYN. : Amoeba, Wallich ; A. villosa, Wallich ; A.
princeps, Carter ; Trichamceba hirla, Fromentel.

Animal in motion differentiated into an anterior and
posterior region, sausage-shaped, irregularly clavate or
palmate, and commonly with few lobate, or short, thick,
digitate or conical pseudopods, mostly directed forward ;
posterior extremity commonly narrower, terminating in
a villous process of variable form, usually rounded, knob-
like or discoid. Endosarc, contractile vesicle and nucleus
as in A. proteus. Size as large as 503/*.

No positively characteristic forms of this species have
been observed in this country. The villous portions re-
semble protrusions of the endosarc.

GENUS II. — OUKAMCEBA.

Animal possessing the same essential characteristics as
the genus Amceha, but provided with fixed filamentous ap-
pendages habitually trailing from the posterior extremity
of the body. Filaments flexible, cylindrical, tubular,
inarticulate or articulate, resembling mycelial threads of
fungi, perfectly passive.

PELOMYXA. 7

VOrax. — SYN. : A. villosa, Wallich; 0. vorax, Leidy;
0. lapsa, Leidy.

Animal in all respects resembling A. proteus with the
addition of fascicles of trailing filaments. Filaments
cylindrical tubes, each fascicle emanating from * common
stalk, inarticulate, usually blunt at the ends; fascicles one
to half a dozen or more, mostly trailing in a single bunch.
Size : small form 140// long by 280 ft wide ; filaments, 40/./
to ISO// long. Bare.

0. botulicauda, Leidy. — Species comparatively small,
colorless, transparent, angular. Pseudopods short, conical,
acute, rarely digitate. Caudal appendages in one or two
tufts, each composed of two to nine acutely divergent,
segmented filaments of variable length. One or two con-
tractile vesicles and nucleus present. This may be a young
form of the preceding genus. The trailing filaments are
usually in a single tuft, but occasionally there are two.
Size : ranging from 40// by 32ft to Y6// by 20ft ; caudal
appendages, 12 ft to 4:5 ft.

GENUS III. — PELOMYXA.

SYN. : Pelobius, Greef ; Pelomyxa, Greef.

Animal like Amoeba, naked, form variable ; when
quiescent, spheroidal or ovoidal ; in motion, more or less
leech-like or slug-like in shape ; differentiated into an
anterior and a posterior region, habitually with the
broader extremity in advance and progressing by the
projection of a wave-like expansion of clear ectosarc in
front or from other parts of the body ; frequently terminat-
ing posteriorly in a conspicuous process of clear sarcode

8 PELOMYXA.

which is prehensile and often finely villous. Ecto-
sarc clear; eridosarc finely granular, containing vacuoles
and colorless globules. Nuclei numerous, scattered.
Contractile vesicles small and inconspicuous, except in
young forms. Voracious, usually gorged with vegetal
matter, with mud and sand.

villosa. — SYN. : A. sabulosa, Leidy.

Almost opaque, except when young. By transmitted
light, brown or black, with hyaline border, yellowish-
white or cream-colored, and maculated with other colors,
according to the food ; spheroidal or ovoidal in the resting
condition ; clavate or botuliform when in motion, with
a terminal, sucker-like, villous patch ; villi numerous, min-
ute, papillary or filiform, simple or ramose. Pseudopods
usually one or two broad, lobal, anterior projections, rarely
prolonged or branching, sometimes accompanied by a
few narrow, conical processes of clear ectosarc from any
part of the body. Nuclei numerous, scattered. Contrac-
tile vesicles numerous, small. This species closely resem-
bles^.. vittosa, and it is difficult sometimes to determine to
which of the two species a given form belongs. However,
the A. villosa is usually more distinctly elongated or
clavate in shape, and the pseudopods are rather more
slender than in Pelomyxa, while the villous process
is always present. In the latter the villi may be very
inconspicuous or even quite drawn in, and it is provided
with several small nuclei, not with a single large one
like A. villosa. Sand-grains are not conspicuous in
A. villosa. Size, while at rest, from 120// to 1,250/4, but
commonly from 250(« to 500/z ; when elongated, from
120/; by 60^ to 600 by 220/t, or larger.

DINAMCEBA.

GENUS IY. — DINAMCEBA.

Animal of essentially the same structure as Ammba,
spheroidal or oval when at rest, ovoid or slug-like when
in motion, with the broader extremity in advance.
Pseudopods few or many, mostly simple, subulate or long,
conical and acute, occasionally furcate. Posterior
extremity of the body papillose ; papillae variable, few or
many, simple or compound, retractile. Surface of the
body, pseudopods and papillae bristling with minute
spicules or motionless cils. Body often enveloped with
a thick layer of hyaline jelly, with minute, imbedded
spicules. Spicules of the body and of the jelly some-
times absent.

mirabilis. — SYN. : Deinamceba mirabilis, Leidy ;
A. tentaculata, Leidy; Dinamceba, Leidy.

Body round, oval, ovate or slug-like, more or less
depressed, anteriorly broad and blunt, posterior part more
narrow and more or less tapering ; spheroidal while float-
ing. Pseudopods usually numerous, and usually anterior,
moderately long, conical or fusiform. Posterior extremi-
ty of the body papillose. Surface of body, pseudopods
and papillae, thickly bristling with cils, which may be
absent in some conditions. Nucleus and contractile
vesicle usually obscured by other constituents. The large
proportion of ectosarc reminds one of A. verrucosa. In
size, form, and some other respects, it resembles Pelomyxa
villosa, but in Dinamceba the pseudopods are numerous
while they are not so in Pelomyxa. Like the latter it is
very voracious. Its favorite food seems to be desmids,
and it commonly occurs with Didimoprium and Bam-

10 HYALODI8CD8.

busina. Size : in the spheroidal form, 64/j. to 160//; creep-
ing forms, 152// by 60^ to 340^ by 220//.

GENUS Y. — HYALODISCUS.

SYN. : ffyalodiscus, H. and L. ; Plakopus, Schulze.

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

H. rubicundus. — SYN. : H. rubicundus, H. and L.; Plakopus
ruber (?) Schulze.

Endosarc brick-red, composed of line, red granules with
a few larger ones of a darker shade, or else of conspicuous,
globular, colored corpuscules mingled with fine granules.
Size : 30/* to 60/*. [If Pldkopus ruber is identical with
this, it is much larger, being 200/* to 600^.]

GENUS VI. — DIFFLUGIA.

SYN.: Difflugia, Leclerc ; Arcella, Ehr. ; Lecquereusia, Schlum.;
Homaochlamys, Heterocosmia, Exassula, Ehr.

Shell variable in shape, usually composed of angular
particles of quartz-sand, mingled with diatom frustules,
spicules, etc., sometimes of chitinoid membrane, incorpo-
rated with extraneous particles, or composed in part or
entirely of particles of a peculiar character. Mouth in-
ferior, terminal, rarely sub-terminal. Sarcode almost
filling the shell, attached by threads of ectosarc to
the interior of the fundus and sides, and by a pro-

DIFFLUGIA. 11

longation to the margin of the mouth. Nucleus single,
near the fundus of the ectosarc. Contractile vesicles
several, contiguous to the nucleus. Pseudopods, as
many as six or more, cylindrical, simple or branching,
commonly rounded at the ends, sometimes spreading
and pointed.

Synopsis of Species of Difflugia.

PAGE.

Shell spherical or oval, Globulosa, 11

Shell pyriform or pear-shaped, Pyrtformis, 12

Shell amphora-form, fundus obtuse, occasionally

with spines, neck short, mouth circular and

usually everted, terminal, Urceolata, 13

Shell goblet-shape, body spheroidal, neck wide,

cylindroid, mouth terminal, Crater a, 13

Shell amphora-form, or pyriform, fundus acumi-
nate or prolonged into a nipple, rarely with

two or three points, Acuminata, 13

Shell ovoid, or nearly spherical, composed of

sand-grains, mouth lobed, Lobostoma, 14

Shell hemispheroidal, usually yellowish chitinoid,

base inverted, mouth trilobed, Arcula, 14

Shell spherical, with hollow conical spines,

mouth crenulated, Corona, 15

Shell laterally ovoid, fundus prolonged obliquely

upward, mouth inferior; long axis of shell

oblique when animal is erect, Constricta, 15

Shell with a partition dividing neck from body,

giving it the appearance of a spiral, Sptralis, 16

Diffiugia globulosa. — SYN. : D. globulosa, Duj.; D. protei-
formis, Ehr. and Wallich ; D. globularis, Wallich ; D. acropodia, H.
and L.

Shell spheroidal or oval, mouth inferior, terminal, cir-
cular, usually truncating the shell ; sometimes protruding,

12 DIFFLUGIA.

rarely inverted. Shell composed of quartz-sand, diatoms,
or of chitinoid membrane with sand and diatoms. Sar-
code, apart from food, colorless. Size : smallest, with shell
of sand, 36/j. long by 30^ broad, mouth 15 p. wide ; chiti-
noid specimens, 24// to 108/* long by 32/* to 120// broad.
Hob. — In the ooze of ditches and ponds, or on moist
earth in bogs, among mosses, etc.

pyriformis. — SYN.: Difflugia, Leclerc, Carter;
D. pyriformis, Perty, Ehr., proteiformis, Lamarck, Ehr., Wallich,
compressa, Carter, entochloris, Leidy, vets, Leidy, nodosa, Leidy,
cornuta, Leidy.

Shell pyriform, flask-shaped or ovoid, with narrow pole
prolonged into a neck of variable length, circular or
somewhat compressed ; fundus obtusely rounded or sub-
acute or produced into one to three conical processes.
Neck gradually and evenly narrowed to the oral end,
cylindroid, sometimes constricted, mouth inferior, termi-
nal, circular or oval. Shell usually composed of angular
particles of quartz-sand mingled with diatoms. Sarcode
bright green, from chlorophyll grains. Common. The
form of the shell varies greatly from pear-shaped to flask-
like, the body gradually prolonged into a cylindroid or
tapering neck. Size : 60/* to 580^ long by 40/* to 240/z
wide ; mouth 16// to 120// wide.

Hob. — Ooze of ponds, ditches and bogs.

Variety I. — D. pyriformis.

Variety II. — D. compressa, laterally compressed.
Variety III. — D. nodosa, fundus with eminences.
Variety IV. — I). cor?iitia, fundus with conical pro-
cesses.

Variety V. — D. vas* neck defined by a constriction.

DIFFLUGIA. 13

urceolata. — SYN. : D. urceo.ata, Carter, lageni-
formis, Wallich, proteifortnis, Wallich, amphora, Leidy, olla,
Leidy.

Shell amphora-form, body spheroidal, ovate or ovoid,
fundus obtusely and evenly rounded, more or less acute
or acuminate, rarely bearing blunt spines (D. olla). Neck
short, contracted, mouth large, circular, terminal, with or
without a rim, usually reflected or everted. Shell com-
monly of hyaline quartz-sand. Sarcode, colorless ; pseu-
dopods many, digitate, simple and branching. Size :
spheroidal forms, ISO// to 440/* long by 140 p. to 380/^
broad ; ovoid forms, 200// to 520// long by 140;* to 360/*
broad.

Hob. — Ditches and ponds, sphagnous swamps.

Cratera. — SYN. : D. cratera, Leidy.

Shell goblet-shaped, 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, with
particles of sand and dirt. [It is possible that these shells
pertain to the ciliated inf usorian of the genus Tintin-
nus.~\ Size : 56/* to 66/* long by 36// to 42// wide ; breadth
of neck, 28/u to 36/*.

Hob. — Among Ceratophyllum and aquatic plants.

Diffiugid acuminata. — SYN. : Dijflugia, Leclerc ; D. acumi-
nata, Ehr., Perty, bacillariarum, Perty, pyriformis, Carter, proteifortnis,
Wallich ; D. Corticella acuminata, Ehr.

Shell amphora-form or oblong, oval pyriform or cylin-
droid, with the upper part inflated ; fundus acute, acu-
minate or prolonged into a nipple-shaped process, rarely

14 DZFFLUGIA.

with two or three points ; neck long, short or none ;
mouth large, terminal, circular ; lip usually straight ;
composed of angular quartz-sand, sometimes of diatom
remains, sometimes of chitinoid membrane. Sarcode
colorless. Common. Size : smallest specimens with shell
of sand, 100 fj. long by 48/* broad ; large, pyriform speci-
mens, 400^ long by 184// broad; largest, 520// by
120/et

Hah. — Ponds and ditches.

lobostoma. — SYN. : D. proteiformis, Carter, tricus-
pis, Carter, oblonga, Fresenius, exassula tricuspis, Ehr. , lobostoma , Leidy,
cremtlata, Leidy.

Shell ovoid, oval, or nearly spherical, usually composed
of quartz-sand, rarely with diatoms, or of chitinoid mem-
brane with a few quartz particles ; mouth terminal,
usually three to six lobed, or more ; fundus obtusely
rounded. Sarcode colorless, or with green endosarc ;
pseudopods up to six or more. One of the most com-
mon species. The conjugation of two and sometimes of
three individuals has been observed. Size : ordinarily
120/* long and 100/z broad. [The shell is usually ovoid,
and closely resembles D. globulosa, for which it may
readily be mistaken unless a view of the mouth, which
is commonly tri-lobed, can be obtained.]

Diffiugia arcula.

Shell hemispheroidal ; fundus convex ; base inverted,
shallow infundibuliform ; mouth inferior, central, tri-
lobed. Shell usually of yellowish, chitinoid membrane,
mostly with more or less adherent dirt, or scattered par-
ticles of quartz-sand or diatoms, especially occupying the

DIFFLUGIA. 15

fundus. Common, perhaps an extreme variety of lobos-
toma. Size : 112/* to 144// broad, by 60/^ to 80/z high ;
mouth 28// to 40//. [This form differs from the pre-
ceding species principally by the yellowish color of the
shell]

Hob. — Sphagnous swamps.

Difflugia corona. — SYN. : D. corona, proteiformis, Wallich.

Shell spherical or spheroidal, composed of clear, angu-
lar quartz-sand ; fundus with conical spines ; mouth ter-
minal, circular, with multidentate or crenulate border.
Sarcode colorless or brownish ; pseudopods many. A
common form, but one of the most beautiful of the
genus. The denticles are thick, angular processes, usu-
ally twelve in number, ranging from six to sixteen.
The spines range from one to eleven, usually three to
seven, arranged in an eccentric circle, divergent, equidis-
tant, often a central spine is larger than the others.
Size from 140/z to 320/* in diameter ; mouth 60/z to
wide ; spines 40^ to 60// long.

Hob. — Marshes, ponds, etc.

COnstricta. — SYN. : Arcella constricta, lunata, Arr-
tiscon, guatimalensis •, Ehr. ; D. marsupiformis, proteiformis, Wallich ;
A. Homaochlamis constricta and htnata, Ehr. ; A. Heterocosmia Arctiscon
and g uatimalensis, Ehr. ; A. borealis, laticeps, Ehr.

Shell laterally ovoid, fundus more or less prolonged
obliquely upward, obtusely rounded and simple, or pro-
vided with spines. Mouth antero-inferior, large, circu-
lar or oval and inverted, with the anterior lip often
prominent. Shell as usually seen by transmitted light,
lying on the front, more or less pyriform, with the nar-

16 HYALOSPHENIA.

rower part downward, and including the mouth, which
appears as a clearer transversely oval, reniform or circu-
lar space ; composed of quartz-sand or chitinoid mem-
brane, colorless, yellowish or brown. Sarcode colorless.

A very common species. When erect, the axis, pass-
ing from the centre of the mouth to the summit of the
shell is oblique, not perpendicular as in the preceding
species. The bottom of the shell is concave, and the
mouth is inflected and situated above the plane of the
border of the base. Size: spineless forms, from 90//
long by 78// broad to 232// long by 160// broad ; spine-
bearing forms from ISO// long by 120// broad, to 340/^
long to 180^ broad.

Hob. — Ooze of ponds.

Difflugia spiralis. — SYN. : Difflugia, Leclerc ; D. spiralis,
Ehr., Bail., Fres., Pritchard, Carter, Wallich, Leidy ; Lecquereusia ju-
rassica, Schluniberger ; D. proteiformis, Wallich.

Shell retort-shaped, body usually spheroidal, laterally
compressed, with a short, wide, cylindrical neck, obtuse
fundus and circular or oval terminal mouth. Within
the shell is a partition defining the neck from the body
•and giving to the shell, by transmitted light, the appear-
ance of a single turn of a spiral. Size : length 96// to
188// ; breadth, 68// to 164^ ; thickness, 68/a to 136,«.

Hdb. — Sphagnous and cedar swamps.

GENUS VII. — HYALOSPHENIA.

SYN. : Hyalosphenia, Stein ; Difflugia, Tatem ; Catharia, Leidy.

Shell compressed, ovoid to pyriform, composed of
transparent, chitinoid membrane ; mouth terminal, infer-

HYALOSPHENIA. • 17

ior, transversely elliptical. Sarcode occupying the inte-
rior of the shell to a variable extent, attached to the in-
ner surface by threads and also to the border of the
mouth. Nucleus large and central ; contractile vesicles
several ; pseudopods digitate, few.

Synopsis of the Genera of Hyalosphenia.

Shell compressed ovoid, very delicate, colorless ; sar- PAOK.

code colorless, Cuneata, 17

Shell compressed ovoid, in narrow view oral end

notched ; sarcode green, Papilzo, 18

Shell compressed pyriform, pale yellow, with pair of

pores on border, short neck ; sarcode colorless, Tincta, 18
Shell compressed flask-shaped, long cylindroid neck ;

oral end in narrow view deeply notched, color

brownish, longitudinal rows of pits, Elegans, 19

Hyalosphenia CUneata, — SYN. : H. cuneata, Stein ; Difflugia
ligata, Tatem ; Catharia ligata, Leidy ; Hyalosphenia lata, Schulze ; H,
ligatn, Leidy.

Shell compressed ovoid, in narrow view conical and
truncate at the oral end, laterally and at the fundus con-
vex ; mouth terminal, oval ; in broader view fundus con-
vex with tapering borders, plane, convex or concave in
their descent to the mouth. Shell composed of delicate,
colorless membrane. Sarcode colorless, pyriform ; pseu-
dopods digitate, usually only one or two. The shell is so
delicate that the tension of the threads of ectosarc is suf-
ficient to bend it. Rare. Size : length 60^ to T6// ;
breadth, 44[t to 60^; thickness, 20//; mouth 16/a by
12;/.

Hob. — In ponds.

18 HYALOSPHENIA.

papilio. — SYN. : Difflugia (catharia) papilio,
Leidy ; //. papilio, Leidy.

Shell compressed oblong, ovoid, or compressed pyri-
f orm ; in the broader view the f undus transversely con-
vex, and sides gradually tapering to the slightly convex
oral end, or with a pyriform outline ; in the narrower
view the fundus angularly rounded and the oral end
notched. Mouth transversely oval, with rounded com-
missures. Shell yellowish, transparent ; endosarc bright
green from chlorophyll ; pseudopods colorless, digitate,
up to six in number. Size : length, 108// to 140/>«;
breadth, 68// to 84// ; thickness, 32^ to 40^ by 8//.

Hob. — In moist sphagnum ; not found in ponds.

Hyalosphenia tincta.

Shell compressed pyriform, relation of length to
breadth variable, in transverse section compressed oval,
of pale yellow, transparent, chitinoid membrane ; mouth
transversely oval. Sarcode colorless ; pseudopods digi-
tate, two, three or more. Like II. cuneata but more
pyriform, shell colored, and lives in sphagnum instead of
in ponds. Neck very short. Shell is thicker and less
flexible than that of //. cuneata, and a pair of pores is to
be seen on the lateral borders, usually below the middle,
sometimes . another pair above. It is probable that H.
tincta merges into H, cuneata, and likewise into H. ele-
gans and H. papilio. Size : length, 76// to 92/i ; breadth,
56// to 64// ; mouth, 20 /j. by 8p.

Hob. — Sphagnous swamps and moist sphagnum.

HYALOSPHENIA. 19

elegans. — SYN. : Di^gia (catharia) elegans,
Leidy.

Shell compressed flask-shaped ; in broad side view, oval
body and long cylindroid neck, slightly widened at oral
end, which is convex downward ; narrow side long ellip-
tical, tapering to the oral end, which is deeply notched.
Shell of pale brownish, transparent, structureless, chitinoid
membrane, impressed with longitudinal rows of hemi-
spherical pits. Sarcode colorless, attached by threads to
the fundus of the shell ; pseudopods digitate, usually
three or four. This may be the same as Ehrenberg's
Difflugia spirigera. Common. Size : length, 88/1 to
108// ; breadth, 64/* to 40// ; thickness, 20// to 28//.

Hob. — Associated with H. papilio in sphagnum.

GENUS. YIII. — QUADRULA.

SYN. : Difflugia, Wallich ; Assulina, Hologlypha, Ehr. ; Quadrula,
Schulze.

Shell compressed pyriform, transparent, composed of
thin, square plates of chitinoid membrane, arranged in
transverse or more or less oblique series in consecutive
or alternating order. Mouth inferior, terminal, oval.
Sarcode colorless.

Symmetrica. - SYN. : Difflugia proteiformis, pyri-
formis, symmetrica, Wallich ; D. Assulina assulata, D. Carolinensis,
leptolepis, Ehr. ; Quadrula symmetrica, Schulze.

Shell compressed pyriform ; viewed on broad side
with fundus widely convex, and sides sloping or more or
less inflected toward the oral end, which is convex
downward ; narrower side ellipsoidal, fundus obtuse,
oval end roundly notched. Shell colorless, composed of

20 NEBELA.

square plates, arranged in transverse longitudinal or ob-
lique rows. Sarcode colorless ; pseudopods digitate, one
to three or more. Size : length, SOfi to 140;/ ; breadth,
40/* to 960/z ; thickness, 28;/ to 48;*.

Hob. — Dripping rocks, ditches, sphagnum.

GENUS IX. — NEBELA.

SYN. : Difflugia, Reticella, Allodictya, Odontodictya, Ehr. ; Nebela,
Leidy.

Shell usually compressed pyriform, transparent, color-
less, with or without appendages, composed of cancellat-
ed membrane, or of peculiar intrinsic elements of vari-
able form and size, mostly of circular or oval discs, or
narrow rectangular plates or rods, or of thin, less regular,
angular plates, sometimes of chitinoid membrane incor-
porated with extrinsic elements, and sometimes of the
latter entirely, as in Diffmgia. Mouth inferior, terminal,
oval. Sarcode colorless, same as in Difflugia, Hyalo-
sphenia, etc.

Synopsis of the Species of Nebela.

PAGE.

Shell longer than broad, without a keel, colorless, Collaris, 21

Shell broader than long, spheroidal, Flabellulum, 21

Shell shaped like N. collaris, with a keel, Carinata, 22

Shell with a keel ending in long digitate processes
projecting downward within, Hippocrepis, 22

Shell with a pair of lateral, conical spines, diverg-
ing upward from the neck, Ansata, 23

Shell bottle-form with long cylindroid neck,

covered with short, stiff cils, Barbata, 23

Shell compressed ovoid with 4-5 processes pro-
jecting from fundus, Caudata, 23

NEBELA. 21

CoUariS. — SYN. : Difflugia collaris, reticulata, canctl-
lata, carpio, binodis, annulata, laxa, D. Reticella collaris, D. R. reticul-
lata, D. R. cancellata, D. R. carpio, D. R. binodis, D. R. annulata, D.
R. laxa, D. cellulifera, Ehr. ; D. peltigeracea, Carter; D. symmetrica,
Wallich ; D. (Nebela) numata, Leidy ; Nebela numata, Leidy.

Shell compressed pyriform, longer than broad ; viewed
on broad side, fundus widely convex, sloping sides usually
slightly inflected toward the oral end, which is convex
downward ; in the narrow view oblong, fundus obtuse,
sometimes impressed on each side, gradually sloping, and
usually inflected toward the oral end, which is concavely
notched. Mouth transversely oval, entire. Shell color-
less, variable in its structural elements, generally compos-
ed of oval or circular disks, uniform or variable in size,
sometimes mingled with rod-like plates, or almost wholly
composed of them, rarely of thin, irregular, angular
plates. In some specimens the transversal section is
hexahedral, with concave sides and prominent, rounded
angles. Sarcode colorless, pseudopods digitate usually
3-6. Common. [A single specimen was observed by
Prof. Leidy, with a curved or retort-shaped shell, 150//
long by 72/4, and 36/* in section.] Size : usually 100;* to
140// in length ; average 128// long, 80^ broad, and 48,«
thick ; mouth 32// by 24//.

Hah. — Moist sphagnum ; a constant associate of Hya-
losphenia papilio and elegans.

flabettulum. — SYN. : Difflugia (Nebela) fiabelliilum,
N . flabellulum, Leidy.

Shell compressed pyriform or spheroid, usually broader
than long, sometimes not ; transverse section oval, with
rounded angular poles ; neck short or none ; mouth trans-

22 NEBELA.

versely oval, slightly convex downward, in the long
diameter. Shell, sarcode and pseudopods, like those of
N. collaris. Common. Size : length, 68// to 96^ ;
breadth, 72^ to 104// ; thickness, 32/* to 48/* ; mouth,
from 24/z by 12// to 20^ by 12//.
Hob, — Sphagnous swamps.

carinata. — SYN. : Dijflugia carinata, Archer ; N. cari-
nata, Leidy.

Shell resembling in shape and structure that of N.
cottaris, but provided with a thin keel of chitinoid mem-
brane, beginning above the neck and extending along the
lateral borders over the fundus. Sarcode like that of
N. collaris. Size : length, 144^ to 240// ; breadth, 88^
to 168// ; thickness, 40^ to 72;* ; mouth, 36// by 20 to 28//
by 28// ; carina, from 4/* to 20/* deep.

Hob. — Sphagnous swamps.

Nebela hippocrepis. — SYN. : Difflugia (Nebela) equicalceus,
N. equicalceus, Leidy.

Shell compressed pyriform, with thick, blunt, solid
carina extending around the fundus and lateral borders,
and ending in long, digitate processes projecting down-
ward into the interior of the cavity. Mouth transversely
oval, convex downward. Shell transparent, colorless,
composed of circular disks ; carina pale straw colored,
indistinctly granular. Sarcode, as in N. collaris and
carinata. Size : length, 252// to 260/* ; breadth, includ-
ing carina, 140/j to 160/* ; thickness, 68// to 72/4 ; mouth,
40// by 28// ; carina, 16^ and 8// deep.

Hob. — Sphagnum.

NEBELA. 23

Nebeld ansdta. — SYN. : Difflugia (Nebeld) ansata, N. ansata,
Leidy.

Shell compressed pyriform, with a pair of lateral, coni-
cal offsets or spurs diverging upward from the neck, but
otherwise like N. collaris. Size : length, 216/* to 260// ;
breadth, between ends of lateral horns, 132//to 164//, at
the fundus, 104// to 120/^; thickness, 60// to 64// ; mouth,
40// to 52/H by 2fyu.

Hob. — Sphagnum of cedar swamp.

Nebela barbata. — SYN. : Difflugia (Nebeld) barbata, N. barbata,
Leidy.

Shell bottle-form, slightly compressed, with cylindroid
neck about as long as the ovoidal body ; fundus obtuse,
oval end slightly expanded, convex downward in the
longer diameter ; transparent, colorless, composed of
circular disks and provided with short, stiff cils, which
apparently project from the spaces between the disks ;
mouth oval, entire. Size : length, 80^ to 120// ; breadth,
4Afjt to 56/j. ; thickness, 36// to IS/j. ; mouth, 16/* to 24// wide.

Hob. — Sphagnum of cedar swamp.

Nebela caudata.

Shell compressed ovoid, with four or five hollow, nar-
row, blunt, conical or clavate processes projecting from
the lateral borders, and summit of the fundus. Mouth
transversely oval, convex downward.

Shell transparent, colorless, in structure resembling
JIT. eollarisj but usually less distinct. Sarcode colorless.
Eare. Length, exclusive of processes, 80//; breadth,
60// ; thickness, 32// ; mouth, 20/* by 16// ; length of
processes, 16 p. to

24 HELEOPERA.

GENUS X. — HELEOPERA.

Shell compressed ovoid, composed of cancellated, chi-
tinoid membrane, presenting a reticulated appearance of
mostly dotted or interrupted lines, often incorporated with
particles of sand at the fundus. Mouth inferior, terminal,
large, transversely elliptical. Sarcode as in Hyalosphenia
and Nebela. Pseudopods numerous, digitifonn.

picta. — SYN. : Difflugia (Nebela) sphagni, Nebela
sphagni, Leidy.

Shell compressed ovoid, never pyriform, with the oral
pole narrower ; mouth terminal, forming a long, narrow
ellipse with acute commissures, convex downward, acutely
notched on the narrow sides ; composed of a yellowish,
transparent, chitinoid membrane with a reticular structure,
meshes polygonal and lines of the net dotted. Sarcode
with bright-green endosarc, owing to numerous chloro-
phyll vesicles. Pseudopods digitate, simple and branched,
large and numerous, often writhing, snake-like. Length,
92/; to 168/z ; breadth, 76/i to 136// ; thickness, 44;/ to 72// ;
mouth, Wn by 16/z to 72// by 32^.

Hob. — Sphagnous swamps.

Heleopera petricola.

Shell compressed oval ; mouth terminal, broad, ellip-
tical, convex downward, with acute commissures in the
narrow view ; fundus convex, loaded with quartz grains ;
composed of chitinoid membrane, reticular, with poly-
gonal or rounded meshes, colorless or brownish. Length,
96/; to ISO;/; breadth, 68/£ to 90/2, and 4&p to 60;*;
breadth of mouth, 52;* to 60;* by 15;/.

Hah. — Sphagnous swamps.

ARCELLA. 25

GENUS XI. — ARCELLA.

Shell composed of chitinoid membrane, never of ex-
trinsic elements, with a minutely hexagonal cancellated
structure, translucent and commonly of a brown color,
variable in shape, but usually more or less campanulate,
with a circular base, concavely infundibuliform and con-
vex 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. Pseudo-
pods few, blunt, digitate, simple or branching. Com-
monly two nuclei, one on each side. Contractile vesicles
several, occupying the periphery.

Synopsis of the Species of Arcella.

Shell hemispherical or bell-shaped, height half the PAOH.

breadth, widest at the base, Vulgaris, 25

Shell discoid or shield-shaped, height one-fourth or

one-third the breath, Discoides, 26

Shell mitriform or balloon-shaped, height exceeding

the diameter of base ; widest near the middle, Mitrata, 26
Shell viewed from above circular and dentate, from

the side crown-like ; breadth more than twice the

height, Dentata, 27

Shell basal-border everted, rising to % or % the

height of the shell, obtusely angular ; from % to

% as high as broad, Artocrea, 27

Arcella vulgaris. — SYN. : A. vulgaris, dentata, A. sticholepis
vulgaris, A. Homoeochlamis angulosa, Ehr. ; A. hemispherica, angulosa,
•uiridis, Perty ; Arcellina vulgaris, Carter.

Shell hemispherical or campanulate ; height about
half the breadth, widest across the usually slightly ex-

26 AKCELLA.

panded and circular base, which is inferior, convex at
the border, and concavely inverted infundibuliform cen-
trally 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, border rarely slightly crenulated. Sarcode
mass oblately spheroidal, colorless, except from food.
Pseudopods digitate, color of test, from colorless to
brown and deep blue. The shell sometimes appears like a
truncated pyramid, with angular outline, such forms may
be regarded as a variety angulosa. Size : breadth, 48//
to 152/x ; height, 36/* to I2p ; mouth, 12/* to 48/£. Yery
common.

Hob. — Ooze of stagnant water and on submerged
aquatic plants.

discoides. — SYN. : A. discoides, peris tic ta, Ehr. ; A.
Homoiochlamis discoides, Ehr. ; A . Heterocosmia peristicta, Ehr.

Shell circular, shield-shaped, usually with the length
from one-fourth to one-third of the breadth ; dome low,
evenly convex to the rounded, or slightly expanded and
rounded, basal-border ; base, mouth, and color of shell as
in A. vulgaris. Breadth, Y2// to 264^ ; height, 20/* to
80// ; width, 20// to 80//.

Hob. — Everywhere in association with A. vulgaris.

Arcella, mitrata.

Shell mitriform or balloon-shaped, obpyriform or poly-
hedral, higher than the breadth of the base, widest at or
near the middle, more or less contracted or sloping in-
wardly toward the base ; dome mostly inflated ; summit
and sides evenly rounded or depressed into broad, angu-

ARCELLA. 27

lar facets, bounded by prominent folds ; base rounded at
the border, inverted concavely infundibuliform ; mouth
circular, crenulated, mostly everted into the inverted
funnel. Sarcode-mass spheroidal, usually connected with
the mouth by a cylindrical neck. Pseudopods up to six
or more. Height, 80// to 180^ ; breadth at base, 72// to
168/<; at dome, 84,u to 200,u; mouth, 20^ to 80/u. Fre-
quent.

Hob. — Ponds.

Arcettd dentata. — SYN. : A. dentata, stellata, Ehr. ; A. stel-
laris, Okeni, Perty ; A. Plomceochlamis dentata, A. Heterocosmia stellata,
A. sticholepis stellaris, Ehr.

Shell, as seen from above or below, circular and more
or less dentate, resembling a wheel with pointed cogs, in
side view crown-like ; breadth more than twice the
height ; dome convex and even, or depressed at the
summit, and broadly fluted at the sides ; base centrally
inverted, concavely infundibuliform, at the periphery
more or less everted, and divided into projections of
variable length. Mouth circular, entire. Sarcode like
A. vulgaris. Shell colorless or brown. Breadth, be-
tween the points of the base, 132// to 184//; height, 44/*
to 48// ; mouth, 40// to 44//. Not common.

Hob. — Same as A. vulgcvris.

Arcetta artocrea.

Shell from one-fourth to less than half as high as
broad; dome convex and even, or mammillated or pitted;
basal-border everted and rising from one-fourth to nearly
one-half of the height of the shell, obtusely angular and
entire ; central portion of the base inverted in the usual

28 CENTROPYXIS.

manner ; mouth circular, entire, surrounded with a row
of minute tubercles. Sarcode colored from bright-green
chlorophyll corpuscles in the endosarc. Pseudopods digi-
tate. Breadth at lateral border, 144/* to 1T6// ; at base, 112//
to 136/* ; height, 40/* to GOp. ; mouth, 20// to 28^. Rare.
Hob. — Ponds.

GENUS XII. — CENTKOPYXIS.

SYN. : Arcella, Homaochlamys, Ehr. ; Difflugia, Perty ; Centropyxis,
Stein ; Echinopyxis, C. and L.

Shell discoid, circular, oval or ovoid, deepest or thick-
est and most obtuse posteriorly, with the base on a level
inferiorly and deeply inflected to the mouth, with the
dome highest posteriorly, gently curving or sloping for-
ward, more abruptly convex backward ; mouth and fun-
dus eccentric in opposite directions, the former anterior
and inferior, the latter posterior and even, or furnished
with a variable number of conical spines. Mouth circu-
lar or oval and entire, or with sinuous border, and ex-
tending into appendages within, toward the dome.
Shell usually brown, but sometimes colorless, composed
of chitinoid membrane, mostly incorporated with vari-
able proportions of sand, often in such quantity as to
resemble Difflugia, never cancellated as in Arcella.
Sarcode colorless. Pseudopods digitate.

aculeata. — SYN. : Arcella aculeata, ecornis, Dia-
dema, A, centropyxis aculeata, A. Homceochlamys ecornis, A. centropyxis,
Diadema, Ehr.; Difflugia aculeata, Perty; Centropyxis aculeata, Stein ;
Echinopyxis aculeata, C. and L., Carter, Barnard; Centropyxis, C. ecornis
Leidy.

Form exceedingly variable ; seen from above it usually
appears broadly ovoid in outline, with the mouth nearer

COCHLIOPODIUM. 29

the narrower pole and a variable number of spines diverg-
ing from the opposite pole and sides ; in the lateral view
it is cap-shaped like Difflugia constricta, but more de-
pressed ; base rests on a level at its anterior two-thirds,
and is inverted as in ArceUa. The spines range from
one to nine, or they may be absent (var. ecornis}. Length,
Sfyeto 26/*; breadth, 72/z to 220// ; height, 36// to 80/*;
mouth, 28// to 100/* ; length of spines, 20/* to 60/z.

Hob. — Common with Arcella vulgaris, among floating
confervas, or adherent to aquatic plants.

GENUS XIII. — COCHLIOPODIUM.

SYN. : Amoeba, Auerbach ; Amp hi zone lla, Archer ; Cochliopodium,
H. and L.

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, sometimes forked.

bilimbosum, — SYN. : Amceba bilimbosum, ac-
tinphora, Auerbach ; Amceba zonalis, Leidy ; Cochliopodium pellucidum,
H. and L., Schulze.

Body when at rest spheroid or ovoid ; by transmitted
light, viewed from above, appearing usually as a trans-
lucent, granular, protoplasmic mass, with coarser, darkly
outlined granules, closely invested by a transparent, color-

30 PROTOPLAST A FILOSA.

less, doubly contoured, more or less distinctly punctate
or cancellated membrane like young colorless shells of
Arcella. When moving, usually more or less completely
surrounded by a delicate, transparent zone, finely and
regularly punctate. In the lateral view usually more or
less bell-shaped, with the fundus and sides defined by a
doubly contoured dotted line, and at the mouth with a
more translucent, wide, punctate band, defined by a
scarcely perceptible dentated edge. The shell is so
closely adherent and so flexible that it accommodates
itself to the changing form of the sarcode. Pseudopods
few, conical or awl-shaped, often irregular and sometimes
furcate. In spheroidal condition diameter 24/z to 56/*.
Hah. — Springs, ponds, ditches, among algae and in ooze.

vestitum. — SYN. : Amphizonella vestita,
Archer ; C. pilosum, H. and L. ; C. vestitum, Archer.

Body as in the preceding species, but more or less cov-
ered with minute, rigid cils. Diameter, 40// to

SUB-ORDER IL— PEOTOPLASTA FILOSA.

Synopsis of the Genera of Filosa.

Body colorless, invested with a hyaline, flexible PAOK.

and elastic membrane apparently continuous

with the sarcode, Pamphagus, 31

Body covered with a thin, chitinoid shell,

usually with extrinsic particles, pseudopods

numerous and delicate, Pseudodifflugia, 33

Shell retort-shaped, chitinoid, composed of

minute, hexagonal elements in alternating

series, long axis inclined, Cyphoderza, 34

PAMPHAGU6. 31

Shell retort-shaped, but fundus with a pair of PAOK.

divergent processes, Campascus, 34

Shell ovoid, hyaline, of regular rows of oval or
hexagonal chitinoid plates, mouth serrulate ;
shell usually with spines or hairs, Euglypha, 35

Shell compressed oval, colorless, mouth ellip-
tical, with border entire and acute com-
missures, Placocista, 38

Shell compressed spherical or oval, mouth with

ragged edges, Assulina, 39

Shell hyaline, pouch-like, sometimes composed
of circular plates, long axis inclined, mouth
subterminal, Trtnema, 39

Shell globular or oval, hyaline, short, broad

neck, and subterminal or oblique mouth, Sphenoderia, 40

DESCRIPTION OF GENERA AND SPECIES.

GENUS I. — PAJMPHAGUS.

SYN. : Arcella, Homaochlamys, Ehr. ; Gromia, Schlumberger; Cory-
cie, Duj.; Difflugia, Schneider ; Pamphagus, Bailey, C. and L., Plagio-
phrys, Lecytketim, H. and L.

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 completely filling it, and appearing
to be structurally continuous with it. Nucleus large and
clear. Contractile vesicles not distinctly determined.
Mouth small, terminal. Pseudopods filamentous, long,
exceedingly delicate, branching dichotomously, not anasto-
mosing.

32 PAMPHA.GU8.

PamphaguS mutabilis. — SYN. : Corycie, Duj. ; P. mutabilis,
Bailey ; Corycia Dujardini, Gagliardi ; Plagiophrys sctitiformis, H. and L.

Animal compressed ovoid, ovate or subpyriform ;
lateral borders extending 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. Barcode pale, granular, colorless or
yellowish. Food usually one-celled algae. Animal in
movement upright, mouth downward, pseudopods diver-
gent and spreading. Length 40// to 100;^ ; greater
breadth, 2S/./ to 68^.

Hob. — Ooze of springs and ponds, and sphagnous
ponds.

PamphaguS hyalinUS. — SYN. : Arcella hyalina, A. Homao-
chlamys hyalina, Ehr. ; Gromia hyalina, Schlum. ; Difflugia tncAefys,
Schneider ; Lecytheum hyalinttm, H. and L., Archer.

Animal spheroidal and slightly produced at the lower
pole into a short, broad neck, terminating in a circular
mouth. Shell membranous, transparent, colorless, struc-
tureless and elastic. Pseudopods filamentous and fur-
cate. From 32/* in diameter to 48/* in length, and 44^ in
breadth.

Hob. — Superficial ooze of ponds, ditches and lakes.

Pamphayus curvus.

Animal retort-shaped or ovoid, with the prolonged
narrower pole curved, and with the body in transverse
section circular. Mouth inferior, terminal, circular.
Shell colorless or pale yellowish, structureless. Nucleus
and pseudopods as in P. mutabilis. From 4A/u in length
by 28//, to 60^ by 36//.

PSEUDODIFFLUGIA. 33

Pamphagus avidus. — Body oval or ovoid, in transverse
section circular, wider at the oral pole ; mouth small,
circular, contractile. Length, 148^ to 220 fj. ; breadth,
120//.

Hob. — Cedar swamp.

GENUS II. — PSEUDODIFFLUGIA.

SYN. : Pseudodifflugia, Schlum. ; Pleurophrys, C. and L.

Animal provided with a thin, chitinoid shell, usually
incorporated with variable proportions of fine quartz
sand or other extrinsic material. Mouth terminal, infe-
rior. Sarcode usually colorless, with a large, clear nu-
cleus, but obscured by the nature of the shell. Pseudo-
pods numerous, exceedingly delicate, filamentous and
forking at acute angles.

gradlis. — SYN. : P. gradlis, Schlum. ;
Pleurophrys spharica, C. andL., H. and L., Schulze; Pleurophrys (?) am-
phitremoides, Archer, Schulze ; Pleurophrys (?) fnlva, Archer ; Pleuro-
phrys compressa, lageniformis, Schulze ; Pleztrophrys angulata, Meresch-
kowsky.

Shell of variable form, usually spheroidal, ovoidal or
oblong oval, and of uniform transverse diameters and
straight, but rarely compressed and slightly curved.
Mouth terminal, circular ; structure obscurely granular,
often with fine sand, and frequently almost entirely com-
posed of coarser sand, colorless or brownish. Length,
40// to 160/* ; breadth, 20/; to 1(%.

Hob. — Ooze of ponds, ditches, &c.

34 CYPHODEKIA.

GENUS III. — CYPHODERIA.

SYN. : Dijftugia, Assulina, Ampullaria, Hologlypha, Ehr. ; Cypho-
deria, Schlum. ; Euglypha, Perty ; Lagynis, Schulze.

Shell retort-shaped, mouth downward, long axis in-
clined ; chitinoid, transparent, colored or colorless, com-
posed of minute, hexagonal elements of uniform size,
arranged in alternating series in parallel, spiral rows.
Mouth minutely beaded. Sarcode pale, granular, usually
nearly filling the shell. Nucleus large, clear, usually
homogeneous. Contractile vesicles present. Pseudo-
pods numerous, forking, mostly radiating in a horizontal
plane.

Cyphoderia ampulla. — SYN. : Difflugia ampulla, lagena,
Seelandica, adunca, alabamensis, uncinata, hologlypha, D. Assulina
adunca, D. A. alabamensis, D. A. ampulla, D. A. margaritacea, D. A,
uncinata, Ehr. ; Cyphoderia margaritacea, Schlum., Stein, Fresenius,
Carter, H. and L., Leidy, Schulze ; Euglypha curuata, Perty ; Lagynis
baltica, Schulze ; Euglypha margaritacea, Difflugia margaritacea, Eugly-
pha baltica, Wallich ; Cyphoderia ampulla, Leidy.

Shell retort-shaped, neck short, cylindrical, curving
downward and truncated by a circular mouth ; body
oblong oval, longitudinal axis inclined but nearly hori-
zontal ; fundus obtusely rounded, sometimes flattened,
frequently prolonged into a nipple at the summit ; color
yellowish or colorless. Length, from 112/i to 176// ;
breadth, from 40/j. to 80// ; mouth, 16// to 28//.

Hob. — Ooze of ponds, lakes and ditches.

GENUS IV. — CAMPASCUS.

Shell shaped like Cyphoderia, but fundus provided
with a pair of divergent, chitinoid processes.

EUGLYPHA. 35

Campaseus cornutus.

Shell retort-shaped, neck short and curved, obtuse
fundus directed backward and upward, with a divergent
conical prolongation on each side ; composed of trans-
lucent, yellowish, chitinoid membrane incorporated with
scattered particles of sand ; mouth circular, bordered by
a delicate, colorless, annular expansion. Pseudopods fur-
cate and very delicate. Length, 112;* to 140;t ; breadth,
180;* ; mouth, 24// to 28^.

Hob. — Ooze of China Lake, Wyoming Territory, at
an altitude of 10,000 feet.

GENUS Y. — EUGLYPHA.

SYN. : Euglypha, Duj. ; Difflugia ; Assulina ; Setigerella, Ehr.

Shell hyaline, ovoid, of uniform diameter or com-
pressed, composed of regular rows of oval or hexagonal
chitinoid plates, arranged in longitudinal series, the
plates alternating with one another in the different rows.
Mouth terminal, circular or elliptical, the marginal plates
forming a series of minutely serrulate, angular points.
Shell usually provided with spines or hairs. Sarcode
colorless, with a large nucleus and contractile vesicles.
Pseudopods filamentous, exceedingly delicate, dichoto-
mously branching, not anastomosing, with no evident
circulation of granules, more or less horizontally diver-
gent.

ia alveolata - SYN. : E. alveolata, Duj., Ehr., Pritch-
ard and others ; E. tuberculata, Duj., C. arid L., Pritchard, Perty ; Di-
fflugia areolata, aca.nthoph.ora> levigata, striolata, Ehr. ; E. lizvis, setigera,

36 EUGLTPHA.

Perty ; Difflugia floridce, pilosa, moluccensis, amphora, rectangularis,
D. Roberti^ Mutter, D. seriata, striata, Assulina alveolata, amphora, etc.,
SetigereUa acanthophora, setigera, Difflugia Shannoniana, Dijjflugia
subacuta, Ehr.

Shell transparent, colorless, usually regularly ovoid,
often oblong ovoid, sometimes flask-shaped ; in transverse
section circular, rarely compressed ; fundus broad, obtusely
rounded, rarely sub-acute ; oral end narrowest, often more
or less tapering. Mouth circular, surrounded with 4 to
12 (?) angular, denticulate points. Plates of the shell
usually oval, ovate or cordate (?), arranged in alternating
longitudinal rows, overlapping at the contiguous borders
so as to produce hexagonal areas included in zones of
minute, elliptical areolae. Fundus with 4 to 6 spines,
usually straight and equidistant, divergent or convergent,
sometimes irregular — in smaller, less well-developed
forms, spines are absent. Length, 30/* to 152/* ; breadth
18 ft to 88/z.

Hob. — Among algae, mosses, etc., in bogs and in moist
situations, and in ooze of ponds.

ciliatO,. — SYN. : Difflugia ciliata, pilosa, strigosa,
D. SetigereUa strigosa, Ehr. ; Euglypha compressa, Carter, Leidy,
Schulze ; E. strigosa, Leidy.

Shell compressed ovoid, with the oral pole usually
more or less tapering and truncated by the transversely
oval mouth ; transverse section oval, with rounded, more
or less sub-acute poles. Fundus and lateral borders
mostly fringed with spines or bristles, variable in number
and robustness, sometimes absent, sometimes numerous.
Plates mostly elongated hexahedral, closely fitting at the
margins. Mouth bordered with from 6 to 14 or more (?)

EUGLYPHA. 3T

t

blunt, angular, crenulated teeth, composed of the lowest
plates of the shell, which are usually thicker than the
others. Length, 56//to 100 ju ; greater breadth, 24// to 60^ ;
less-breadth, 16^ to 32//.

Hob. — Common in wet sphagnum, of sphagnous
swamps.

Euglypha cristata.

Shell tubular, flask-shaped, moderately inflated toward
the fundus, and tapering gradually to the slightly con-
tracted mouth ; circular in transverse section, hyaline,
colorless, composed of overlapping oval plates, appear-
ing as hexahedral areas, sometimes resembling hexa-
gonal plates joined at the edges. Mouth round, 4 to
6 angular serrulated teeth. Fundus with a tuft of
curved, radiating spines. Length, 40^ to 72^ ; breadth,
10// to 20/z.

Hob. — Sphagnous swamps.

Euglypha mucronata.

Shell like E. cristata, but with a conical, acute dome,
prolonged into a long, mucronate spine, sometimes two.
Length, 108/4 to 140// ; breadth, 32/i to 44// ; mucro, 20//
to 44// long.

Hob. — Wet sphagnum.

Euglypha brachiata.

Shell like E. cristata, but with a tuft of spines
to the fundus, and with 2 to 4 to 6 long spines springing
from the neck and diverging or curving upward and
outward. Length, 104/* to 128// ; breadth, 28;^ to 40/;.

Hdb. — Wet sphagnum and ooze.

38 PLACOCISTA.

GENUS VI. — PLACOCISTA.

SYN. : Euglypha, Carter.

Shell compressed oval, hyaline, colorless, with acute
border and terminal, elliptical mouth, the border of the
latter entire, with acute commissures; plates of the lon-
gitudinal alternating rows oval, overlapping, so as to
produce hexahedral areas limited by zones of minute
ellipses. Lateral borders and fundus furnished with
acuminate spines, articulated with the shell. Sarcode as
in Euglypha. This genus differ from Euglypha by its
entire mouth without dentate scales, and by its articulated
spines.

Placodsta Spinosa. — SYN. : Euglypha spinosa, Carter, Archer,
Leidy.

Shell transparent, colorless, compressed oval, with
acute, lateral borders, sometimes slightly tapering toward
the oral pole ; mouth large, transversely elliptical, with
acute commissures and entire, edentulous border ; com-
posed of oval, imbricating plates, in alternating longitu-
dinal series, the overlapping borders producing hexahe-
dral areas limited by zones of minute ellipses ; oral row
of plates like the others, and not forming angular teeth
as in Euglypha. The lateral, acute border of the shell
fringed with movable subulate spines articulated with
the shell by a minute knob, usually in pairs, sometimes
single and rarely triple. Length, 100// to 136 /JL ; breadth,
80// to 96^, and 36// to 60/z ; mouth, 40/* to 60/z ; spines,
to 40// long.

Hob. — Moist sphagnum of cedar swamps.

TKINEMA. 39

GENUS VII. — ASSULINA.

SYN. : Diffliigia, Euglypha, Assulina, Ehr.

Shell compressed spherical or oval ; neck almost obso-
lete, terminating in a transversely elliptical mouth, with
nneven or ragged edges, composed of minute, oval or
hexagonal plates in alternating rows. Sarcode and pseu-
dopods as in EuqlypJia.

Assulina Seminulum. — SYN. : Dijftngia seminulum, Ettgtypka
seminulum, Difflugia semen, Ehr. ; Euglypha brunnsa, Leidy ; E. tinc-
ta, Archer ; E. seminulum, Leidy.

Shell nearly as broad as long, compressed, spheroidal
or oval ; breadth nearly equal to the length ; thickness
half or less than half the breadth ; dome and lateral bor-
ders rounded or sub-acute. Mouth transversely oval,
and abruptly truncating the pole of the shell, or the latter
may be prolonged into a short neck. Shell chocolate
brown, sometimes quite light, and in young individuals
colorless, usually lighter in color at the mouth ; com-
posed of minute, oval or hexagonal plates, arranged in
alternating longitudinal or obliquely parallel, spiral rows ;
oral plates, lighter in color than the others, end in irregu-
lar processes. Sarcode usually occupies but little more
than half the capacity of the shell, arranged about the
axis. Pseudopods few and extremely delicate. Length,
50/j. to 83// ; breadth, 40/z to 71//, and 16^ to 33// thick.

Hob. — Sphagnum, often very abundant.

GENUS VIII. — TKINEMA.

Shell hyaline, pouch-like, with its long axis inclined or
oblique, with the mouth sub-terminal. Dome obtusely

40 SPHENODERIA.

rounded ; mouth inverted, circular, minutely beaded at
the border. Structure of the shell in the smallest forms
apparently homogeneous, but in the larger ones composed
of circular plates arranged in alternating series, and often
appearing with a beaded margin. Sarcode and pseudo-
pods as in Euglypha. When moving, the body is in-
clined, mouth downward, fundus directed upward and
backward.

enchellS. — SYN. : Trineme, Trinema, Duj. ; Diflngia
enchelis, Arcella hyalina, constricta, A. Nidus pendulus, A. disphara,
caudicicola, enchelys, megastoma, rosirata, reticulata, seriata, pyrum ;
Homceochlamys constricta, etc., Sticholepus caudicicola, etc., Heterocosmia
Pyrum, Ehr. ; Trinema acinus, Duj. ; T. enchelis, Leidy.

The only species. One of the commonest shell-bear-
ing rhizopods. Length, 16// to 100/^; breadth, 10// to
60 ; mouth, 5// to 24/*.

Hob. — Ooze of pools and in moist places.

GENUS IX. — SPHENODERIA.

Shell globular or oval, sometimes slightly compressed,
hyaline, membranous, with a short, broad neck, and a
wide, elliptical, subterminal, or oblique (?) mouth ; body
with circular, oval or hexagonal plates or cancelli, ar-
ranged in alternating series. Sarcode and pseudopods as
in Euglypha.

Sphenoderia lenta. — SYN. : S. lenta, Schlum., Ehr. ; Euglypha
globosa, Carter, H. and L., Schulze, Leidy; Assulina lenta, Ehr.

Shell delicate, membranous, colorless, transparent,
globular, oval or oblong ; sometimes slightly compressed,

8FHENODEEIA. 41

with a short, broad, compressed neck, widening toward
the narrow, elliptical mouth, which is oblique or subter-
minal (?). Border of mouth thin, delicate, entire. Bod y
of shell composed of circular or oval plates, overlapping
at their contiguous borders and arranged in alternating
series, apparently not extending to the neck. Sarcode as
in Euglypha and Trinema. Sphenoderia is closely re-
lated to Trinema; and a variety with a denticulated
mouth is nearly related to Assulina seminulum. Glo-
bose forms : length, 32^ to 56// ; breadth, 28// to 52// or
to 56fji in diameter ; oval forms : from 28^ to 56^ long,
and 20// to 44// broad.

Hob. — Common in moist sphagnum and in bogs.

Sphenoderia macrolepis.

Shell pyriform, compressed, with a broad neck gradu-
ally extending from the body, and terminating in an
oblique, elliptical mouth, and with the broader surfaces
composed mainly of a pair of hexahedral plates, from
which the neck is extended below. Length, 20/* to

ju.

Hob. — Sphagnous swamp.

42 HELIOZOA.

Order II. — Heliozoa.

The Heliozoa or sun-animalcules are usually of a
spherical form, with pseudopodal filaments radiating from
them in every direction, rarely forking or anastomosing.
They usually multiply by division. While the Lobosa
and the Filosa are essentially creeping animals, the
Heliozoa, or sun animalcules, are swimmers.

Synopsis of the Genera of Heliozoa.

Body spherical, colorless, single contractile PAOB.

vesicle, pseudopods simple, Actinophrys, 43

Body like Actinophrys, form variable, with
an envelope of protoplasm with a villous
surface, Heterophrys, 44

Body like Actinophrys, single or in connect-
ed groups, invested with a layer of proto-
plasm with spicules, rays simple, Raphidiophrys, 44

Body soft, spheroidal, amoeboid, colored ;
pseudopods Actinophryan, pin-like, and
digitate, Vampyrella, 45

Body spheroidal, with delicate, membranous

covering, with two oral orifices, Diplophrys, 46

Body spherical, like Actinophrys, but the
outer vesicular portion distinct from the
inner mass, rays with an axis, Actinosphcsrium, 47

Body Actinophryan, rays silicious, simple or
furcate ; also soft rays, and an investment
of protoplasm, Acanthocystis, 48

AOTINOPHEYS. 43

Body sphencai, invested with silicious glo- PAaB.

bules ; pseudopods few, not granular, Hyalolampe, 49
Body within a spherical, latticed capsule, with

a stem, Clathrultna, 50

DESCRIPTION OF GENERA AND SPECIES.
GENUS I. — ACTINOPHRYS.

Body soft, spherical, composed of hyaline, colorless,
pale and finely granular protoplasm, with mingled coarser
granules and minute oil-like molecules, more or less
crowded with large, clear vesicles or vacuoles. Nucleus
central, ordinarily obscured. A large contractile vesicle
at the periphery. Pseudopods numerous, projecting as
exceedingly delicate, tapering rays, or finely granular
extensions of the protoplasm of the surface ; not branch-
ing.

Sol. — SYN. : Trichoda sol, Muller, Schrank ; Peri-
tricha sol, Bory ; Actinophrys sol, Ehr., Pritchard and others ; A. diffor-
mis, Ehr. ; A. Eichornii, Claperide ; A. oculata, Stein.

Spherical, translucent, vesicular or foamy, vesicles usu-
ally uniform ; contractile vesicle single, large, active.
Nucleus commonly obscured. Rays numerous, straight ;
length 1, 3 or 4 times the diameter of the body. Diameter
of body, 40/i to 120^ ; pseudopods, commonly 80^ to 160/z.

Hob. — In quiet waters with aquatic plants.

A ctinophrys picta.

Similar to A. sol, but of a bright-green color, owing
to the presence of chlorophyll mingled with the proto-
plasm. Diameter, 56// to 105//. Not common.

Hob. — Sphagnous swamps.

44 RAPHIDIOPHRYS.

GENUS II. — HETEROPHRYS.

Animal resembling Actinophrys, but the body ordi-
narily enveloped with a thick stratum of protoplasm, de-
fined by a granulated or thickly villous surface, and pene-
trated by pseudopodal rays.

HeterophryS myriapoda. — SYN. : H. myriapoda. Archer,
Greeff : (?) H. varians, Schulze ; (?) H. variabilis, Greeff .

Body composed of a soft, usually spherical, granular
mass of protoplasm, colorless at the surface, commonly
bright-green within, due to chlorophyll corpuscules ; in
some conditions with little or no color except such as is
imparted by the food ; containing clear, colorless cor-
puscles, vacuoles, nuclei, and one or more contractile
vesicles. With or without an exterior envelope of proto-
plasm. Pseudopods simple, granular rays. Diameter,
g-^j- to -3-^5- of an inch (Archer). [The range of this
species does not seem to be well established, and it may
include forms that are very variable in shape and appear-
ance.]

GENUS III. — RAPHIDIOPHRYS.

Animals ordinarily associated in groups of variable
number, closely aggregated or conjoined by isthmus-like
bars. Individuals of Actinophryan form, consisting of a
soft, spheroidal body of granular protoplasm, with oil-like
molecules and variable proportions of clear, colorless or
bright-green corpuscles, and a large, central nucleus.
Exterior of the body invested with a thick layer of deli-
cate, colorless protoplasm, extending in tapering processes

VAMPYKELLA. 4:5

on the pseudopodal rays, and densely pervaded with
minute spicules, tangentially arranged. Pseudopodal
rays very long, numerous, straight, simple, finely
granulated.

Raphidiophrys viridis.

Single, or more frequently in closely aggregated groups
of variable number. Individuals green or colorless.
Spicules thickly distributed, tangentially arranged, ex-
tending outwardly on the bases of the pseudopodal rays,
comparatively coarse and slightly bent. Diameter about
•g-J^ of an inch (Archer), 90//, Leidy.

Hob. — Ditches, rivers.

jRdphidiophryS degans. — SYN. : A. oculata, sol, Carter; £.
elegans, H. and L., Leidy, Archer; Sephcerastrum conglobatum, Greeff.

Single, or usually in groups of two or three dozen or
more, united by narrow bands. Individuals bright-green
from the presence of chlorophyll corpuscles, or colorless.
Spicules delicate, in the form of semicircles, tangentially
arranged, with their convexity directed toward the body
and the pseudopodals rays. Contractile vesicle changes
its position. Diameter, 32// to 40//; rays, 240//; length
of semicircular spicules, 6/*.

Hal). — Springs and ponds among aquatic plants.

GENUS IY. — VAMPYKELLA.

SYN. : Amceba, Fresenius ; Vampyrella, Cienkowski.

Animal usually Actinophrys-like, with a soft, sphe-
roidal body, capable of amoeboid variations of form ;

4:5 DIPLOPHRYS.

composed of pale, colorless, granular protoplasm, with
abundance of coloring matter, oil-like molecules, and
vacuoles. Pseudopods as Actinophrys-like rays, Acineta-
like rays, and digit-like, lobate, or wave-like expan-
sions.

lateritia. — SYN. : Amceba lateritia, Fres., Cienk.;
V. spirogyrcz, Cienk., Hackel, H. and L., Archer.

Body brick or orange-red, with hyaline periphery,
commonly spherical, but capable of much change of
shape. Pseudopods Actinophrys-like rays, and also lobate
extensions, together with Acin eta-like rays [rays with
heads, pin-like]. The pin-like rays are incessantly pro-
jected and withdrawn. The specimens observed by
Prof. Leidy did not greatly change their shape. Dia-
meter, 28. 5// to

GENUS Y. — DIPLOPHRYS.

SYN. : Diplophrys, Barker ; Acanthocystis, Eltzorhanis, Greeff ; Cys-
tophrys, Archer.

Animal minute, spheroidal, with a delicate homoge-
neous membranous investment, and a pair of oral orifices
slightly lateral to the opposite poles. The interior, transpa-
rent, slightly granular protoplasm with a central nucleus,
several pulsating vesicles, and usually a single, bright-
yellow or red, oil-like globule. Pseudopods delicate,
filamentous, and radiant in a tuft from both oral orifices.
The young associated in groups, often of many indivi-
duals.

47

Archeri. — SYN. : Diplophrys Arckeri, Barker, H.
andL., Archer, Greeff, Schulze ; Acanthocystis spinifera (?) Greeff ; Cysto-
phrys oculea, Archer ; Elaorhanis cincta, Greeff.

The only species ; not observed by Prof. Leidy in
the mature form. Diameter, 10// to 20// (Schulze). Those
observed by Prof. Leidy, and placed by him in this
group measured only 4/^ to 5//. They were trans-
parent and each contained a bright, cherry-red, oil-like
corpuscle.

GENUS YI. — ACTINOSPH^ERIUM.

Body spherical or oval, composed of finely granular
protoplasm, enclosing a mass of delicate, polyhedral vesi-
cles or vacuoles occupied by a clearer, hyaline proto-
plasm. The outer one or two layers of vacuoles more or
less distinctly defined from the interior by greater size,
translucency, and apparently by the intervention of a
thicker film of granular protoplasm. Nuclei numerous
and imbedded in the latter beneath the peripheral vacu-
oles. Contractile vesicles two, commonly opposite, in
the peripheral layer. Rays numerous, tapering exten-
sions of the granular protoplasm, including an axis-
thread, which starts beneath the peripheral vacuole
layer.

Actinosphcerium EicJiornii — SYN. : Actinopfays EichoniH,

Ehr., Pritchard, and others; Actinophrys sol, Kolliker ; Actinosphce-
liwn Eichomii, Stein, Greeff, H. and L., Schulze, Leidy.

Body transparent, colorless, usually with a single pe-
ripheral layer of the large vacuoles, which are deeper
than broad ; or, in large and old individuals, sometimes

48 ACANTHOCYSTIS.

two peripheral layers of vacuoles of more uniform diame-
ters. The well-marked distinction between the outer
layer of vesicles and the inner mass, distinguishes this
from Actinophrys. Diameter, SS// to 400/^ ; rays,

Hah. — Ponds, ditches, lakes, among aquatic plants.

GENUS YIL — ACANTHOCYSTIS.

•

SYN. : Trichoda, Schrank ; Actinophrys, Ehr. ; Acanthocysti:,, Carter.

Animal Actinophrys-like in appearance. Body sphe-
rical, soft, composed of finely granular protoplasm
mingled with bright-green and colorless corpuscles ;
the former absent at times, also containing diffused
oil-globules, a central nucleus, vacuoles, and food in
balls. Invested with numerous delicate, silicious rays,
implanted by minute basal disks and ending in a simple,
pointed or furcate extremity ; also giving off numerous
delicate, soft rays like Actinophrys • further enveloped
by a layer of protoplasm, rising in pointed processes on
the rays, and pervaded by many exceedingly minute,
linear particles ; the enveloping layer sometimes absent.

Chcetophora. - SYN. : Trichoda ch^iophora,
Schrank; Actinophrys viridis, Duj., Perty, Pritchard, Mic. Diet.;
Acanthocystis turfacea, Carter, H. and L., Archer, Greeff ; A. viridis,
Greeff, Greenacher, Schneider, Leidy ; A. pallida, Greeff.

Body spherical, bright-green or colorless. Nucleus
central, commonly obscured. Silicious, or spiny, rays of
two kinds ; one long, strong, and acutely furcate ; the
other short, delicate, and widely furcate, sometimes ab-
sent. Soft rays simple, granular, as long as, or longer

HYALOLAMPE. 49

than the spirious rays. Exterior envelope of the body
appearing like an atmosphere of exceedingly minute
bacterium-like particles, sometimes absent. Diameter,
48/j. to 100// ; length of furcate spines, 20/* to 60//.
Hah. — Same as Actinophrys and Actinosphcerium.

Acanthocystis f

Spinous rays numerous, exceedingly delicate ; emanat-
ing from lenticular disks at the surface of the body, and
sharply pointed at the distal end. Enveloping layer of
protoplasm finely granular, sometimes absent. Pseudo-
podal rays longer than the former. Diameter, 36^ to
48/e.

Hob. — Among aquatic plants in ponds and ditches.

A canthocystis f

Body spherical, composed of a basis of granular proto-
plasm with a central nucleus, with green and colorless
corpuscles, or colorless ones only. Spinous rays numer-
ous, short, pin-like. Diameter, 39^ to

Hob. — Among floating algae.

GENUS VIII. — HYALOLAMPE.

SYN. : ffyalolampe, Greeff ; Pompholyxophrys, Archer.

Animal spherical, composed of a finely granular proto-
plasmic mass, mingled with variable proportions of
colored granules and vacuoles, with a central nucleus.
Body invested with a thick layer of loosely coherent,
minute, clear, silicious globules. Pseudopods few,
radiant, exceedingly delicate, filamentous, not granular.

50 CLATHEULINA.

. — SYN. : H. fenestrata, Greeff, H. and
L. ; Pompholyxophrys punicea, Archer ; H. exigua, H. and L.

Body more or less yellowish, brownish, or reddish.
Investing silicious globules commonly in three layers.
Diameter, 40/* to 80// ; silicious globules, 4//.

GENUS JX. — CLATHRULINA.

SYN. : Clathrulina, Cienk. ; Podosphcera, Archer.

Animal provided with a spherical, latticed, silicious
capsule, attached by a long, filiform stem to aquatic
plants or other objects. Contents of the capsule a soft,
Actinophrys-like body, with the same kind of pseudo-
podal rays which project through the openings of the
capsule.

Clathrulina elegans. — SYN. : C. elegans, Cienk., Archer, Greeff,
H. and L. , Leidy ; Podosphccra Hackeliana, Archer.

Capsule colorless, becoming yellow or brown with age ;
openings circular, or polygonal with rounded angles.
When near maturity the sarcode contracts from the cap-
sule. Body consists of soft, colorless, granular proto-
plasm, with scattered, oil-like molecules, numerous vacu-
oles and a central nucleus. Rays straight, mostly simple,
somewhat furcate, long and numerous. Pedicle of vari-
able length, attached by an expanded, lobate disk. While
young the capsule is not obvious, and the pedicle is much
thicker in proportion. Diameter of capsule, 30// to 44//
[and more] ; length of pedicle, 60/7 to 260// ; thickness,
2/*, to 4r//.

Hob. — Ponds, ditches, swamps.

FOKAMINIFERA. 51

Order III. — Foraminifera.

The Foraminifera are almost exclusively marine, only
a single well-defined genus, ffromia, is found in fresh-
water.

GENUS GKOMIA.

Animal spherical or oval, composed of granular proto-
plasm, with a large, central nucleus, and invested with a
homogeneous, chitinoid membrane. Mouth terminal,
and emitting copious streams of protoplasm, which flow
around the body and extend into numerous pseudo-
podal rays, freely branching and anastomosing, so as to
form an intricate net which exhibits an incessant flow of
granules along the filaments both outward and inward.

Gromia terricola.

Body spherical or oval, pale-yellowish or cream-colored,
more or less translucent. Shell chitinoid, thin, transpa-
rent, colorless or yellowish, with adhering sand and dirt.
Interior protoplasm white by reflected light, pale-yellow
by transmitted, granular, with fine oil-molecules, usually a
few clear vacuoles, and a large, clear or pale, granular
nucleus. Mouth obscure, emitting fine, granular proto-
plasm which breaks up into diverging and anastomosing
streams. An incessant circulation of granules is to be ob-
served along the filaments. Diameter, 112/4 to 120// ;
oval variety, 112/* long by 100// broad.

Hob. — With moss, and in crevices of pavements in
shaded places, in the City of Philadelphia

52 BIOMYXA.

GENUS BIOMYXA.

Animal without a shell ; initial form spherical, but in-
cessantly changing, consisting of a glary, colorless, finely
granular protoplasm, which has the power of expanding
and extending itself in any direction, and of projecting
pseudopodal filaments, which freely branch and anasto-
mose. Granules circulate along the body and pseudopods ;
contractile vesicles numerous and minute, occurring in
both the body and in the pseudopods. Nucleus present
or absent. It is uncertain whether the animal which is
described under this genus is a Rhizopod, or the plas-
modium of a fungus, or whether it should be classed
among the Monera. It may be one of the naked Rhizo-
pods, and in some cases looks like detached portions of
the sarcode of Gromia. A nucleated form has been
observed.

INDEX AND CHECK-LIST.

PAGE.

Foraminifera 51

Biomyxa, 52

Gromia, 51

terricola 51

Heliozoa 42

Acanthocystis, 48

chaetophora, 48

? 49

? 49

Actinophrys, 43

picta, 43

sol, 43

Actinosphasrium, 47

Eichornii -. . . 47

Clathrulina 50

elegans, 50

Diplophrys, 46

Archeri 47

Heterophrys 44

myriapoda 44

Hyalolampe, 49

fenestrata 50

54 INDEX AND CHECK-LIST.

PAOE.

Raphidiophrys, 44

elegans, 45

viridis 45

Vampyrella, . s 45

lateritia, . , 46

Protoplasta,

FlLOSA, ................. 3, 30

Assulina, ................. 39

seminulum, ............ 39

Campascus, ............... 34

cornutus ............. 35

Cyphoderia, ...............

ampulla, ............. 34

Euglypha, ............... 35

alveolata, ............ 35

brachiata, ............ 37

ciliata, ............. 36

cristata, ............. 37

mucronata, ............ 37

Pamphagus ................ 31

avidus, ............. 33

curvus, ............. 32

hyalinus, ............. 32

mutabilis, ............ 32

Placocysta, ............... 38

spinosa, ............. 38

Pseudodifflugia, ............. 33

gracilis, ............. 33

INDEX AND CHECK-LIST. 55

PAGE.

Sphenoderia 40

lenta 40

macrolepis, 41

Trinema 39

enchelis, .' 40

LOBOSA, 2

Amoeba 4

proteus 4

radiosa, 5

verrucosa, 5

villosa, '. . . . 6

Arcella, 25

artocrea 27

dentata 27

discoides, • ... 26

mitrata 26

vulgaris, 25

Centropyxis 28

aculeata, 28

Cochliopodium 29

bilimbosum 29

vestitum ' ... 30

Difflugia, 10

acuminata, 13

arcula • .... 14

constricta, 15

corona, 15

cratera 13

globulosa 11

lobostoma 14

pyriformis, 12

spiralis 16

urceolata 13

56 INDEX AND CHECK-LIST.

PAQB.

Dinamoeba, 9

mirabilis, 9

Heleopera, 24

petricola 24

picta, 24

Hyalodiscus 10

rubicundus, 10

Hyalosphenia, 16

cuneata, 17

elegans, 19

papilio, 18

tincta 18

Nebela, 20

ansata, 23

barbata 23

carinata 22

caudata 23

collaris, 21

flabellulum 21

hippocrepis 22

Ouramoeba 6

botulicauda 7

vorax, 7

Pelomyxa, 7

villosa 8