of cilia, the outer of which is largest and serves as locomotory, while
the inner set is under the control of voluntary nerves and serves simply
to bring food within the pharynx. In many cases there is really no
indication of such a distribution and the cilia seem to be merely iso-
lated clusters of hairs scattered about the oral end of the body.
Several of the rotifers are parasitic and cling to the less exposed parts
of the body of certain Amphipods, or on Annelides, or are endopara-
sitic. The muscles are often very conspicuous and, when large, show
the striated structure well. The alimentary canal, maxtax, and the
contractile water vessel have muscular tissue af another sort.
The nervous system is most difficult to study and little is certainly
known of its structure. Usually there can be made out a considera-
ble granular mass over the maxtax and in close proximity to^the eyes,
this is assumed to be the principal ganglion. From the chief or cen-
tral ganglion fine nerves pass to the muscle and organs of sense.
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OF DENISON UNIVERSITY. 45
The eyes are double or single and are sometimes supplied with a
lense ; they are always furnished with a dark red pigment and, very
generally, rest directly upon the ganglion. There are occelli at vari-
ous points in the trochal disc of some species. The sense of touch
is delicate, and there is often a special tactile tentacle, or palpus with
minute tactile rods. This may be reduced to a slight papilla or a pit,
with sensory hairs. No other sensory organs have been discovered, al-
though Huxley fancies that to be an octocyst, which the Germans call the
** Kalk-beutel," i.e. the lime-sac. This is a spheroidal sac, contain-
ing irregular grains of lime. The function is unknown, but it may
be simply a reserve supply to be used in preserving the rigidity of the
indurated parts of the body.
The mouth is more or less ventral, while the anus is dorsal. The
mouth leads by the pharynx into a roomy and expansible crop or
directly into the maxtax or masticatory organ, and this is armed with
chitinous appendages of the most various form, but referable to a sim-
ple type. Here there is a central anvil-like part called the incus and
two lateral mallei which consist of a handle (or manubrium) and a
head {uncus) which beats upon the incus and reduces the hard parts
of the food. The maxtax opens into a narrow ciliated oesophagus
which, in turn, leads to the stomach proper.
The stomach is sometimes quite distinct from the succeeding parts
of the system, but sometimes can only be distinguished by the large
size and absorbtive character of its cells. Into the stomach is poured
the secretion of a pair of glands which may be compared to the so-
called salivary glands of insects or the liver and salivary glands of ver-
tebrates. The size of the glands is dependent on the diet of the ani-
mal. In carnivorous species the glands are small, while in others
they become quite conspicuous. The intestine is clothed with long
cilia and opens into the cloaca or common receptacle of the reproduc-
tive, water vascular, and alimentary systems. In some species, how-
ever, the stomach is a coecum and has no anus. Males uniformly
lack the alimentary system and are short-lived creatures of love. In
some cases evident messentaries support the digestive tract.
The excretory system consists of a pulsating bladder, opening into
the cloaca, and two lateral vessels of various form, upon which are
flagellate chambers which contribute to keep up a circulation between
the cavity of the body and this vascular system.
Respiratory and circulatory organs, in the received sense, are absent^
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46 BULLETIN OF THE LABORATORIES
respiration taking place, as in many small entomostraca, through the
body surface, and circulation is affected by the rythmical movements
of the digestive tube and the ciliary action in the later vessels.
In mature females much of the body cavity is filled by the ovary
and the yolk masses or eggs. The ovary is disc-shaped, botryoidal
or variously contoured and in the grey substance exhibits hyaline spots
containing the nucleated ovule cells. A part of the ovary temporari-
ly secretes the yolk when the egg reaches maturity, so that the appear-
ance of the viscera differs greatly at different times. The egg, after
extrusion, is commonly carried about in a delicate external brood-sac
as in copepoda.
To add here the details of the development of the egg would lead
us too far. The male, as before said, has no functional digestive tract
and is not only much smaller than the female, but suffers a reduction in
many organs. The sensory organs are, however, well developed. The
testis is spindle-shaped or oval and opens in a, papilla, which also con-
tains the opening of the water chamber or pulsating vessel. The
spermatozoa are rod-like or thread-like and motile.
The Rotifera are found in fresh and salt water over the entire globe.
Some species may be found in damp situations on land. They exceed
even the lower Crustacea in their great adaptability to changes in out-
ward surroundings. Not only is drought not destructive to the eggs,
but the animal itself endures a long period of dissication. Other
notes upon the habits must find their place under the special descrip-
tions.
Descriptive Part. — As above stated, the following descriptions are
given without attempt at orderly arrangement, with the expectation of
ultimately attempting a systematic review. In cases where lack of
literary aids make positive identification impossible, the description
alone will be given, awaiting future identification.
GENUS FLOSCULARIA, Oken,
The head is margined by five oval processes bearing exceedingly long setae of
excessive fineness. The mouth is central, with a funnel-form opening. There is
a crop-like vestibule, separated by a partition from the pharynx, except in the cen-
tre, which is perforate, the opening being margined by several pendulous cilia.
The adult is attached by a long, jointed foot, but the young is motile and possesses
eyes, which are aborted after the metamorphosis.
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OP DENISON UNIVERSITY. 47
FlOSCULARIA or NAT a, Ehr,
is not a rare inhabitant of the pools of Minnesota. The very full de-
scriptions of this species, given by various authors, would seem to have
exhausted the subject, but we do not even yet feel sure that the so-
called species are not local or age variations. The other species are
F, appendiculata, F. proboscidea, F. complanata, F. longiloba, and F,
trifolium.
Of Rotifer and Callidina we find a number of species, but reserve
the consideration of the group for another occasion.
Notommata furnishes several species which are very abundant and
striking, but a large number of works are necessary for their study.
GENUS EUCHLANIS, Ehr.
The lorica is oval and composed of an arched dorsal shield and a plane ven-
tral one. The lorica in front is broad and presents a large opening for the head.
The shell often has a carina above, while the dorsal shield is movable upon the
ventral. The trochal disc is strongly ciliate and bears two terminal sensory or-
gans with clumps of tactile hairs. There is a single cervical eye and the viscera
are highly differentiated. The foot has four short segments and two terminal
lanceolate claws.
EucHLANis (dilatata) hipposideros, Gossc,
{Plate III, Fig, 2.]
The identification of our species with the above is made in spite of
minor points of disagreement which may be looked upon as the result
of faults in the descriptions or slight variations in structure. Eckstein
gives the length at .45 mm., while Eyferth says .23 mm. Our spe-
cies varies only between . 22 and . 24 mm. and is quite uniform, so far
as observed. The form is oval, the lorica being excavated before and
behind, as vshown in the figure, although it is not often seen as clearly
as drawn.
The trochal disc has two broken circlets of cilia, and on either side
the head is a pit densely ciliated within. The drawing given by Eck-
stein shows the arrangement well. Two curious sensory organs oc-
cupy the very front of the head. The ganglion is very large and
quadrate, the eye being near its anterior part and quite large. The
maxtax is quadrate, showing the component parts well. The stomach
is ob-pyriform and there are two accessory glands. . The ovary has
very large nuclei and the egg is of great size. The contractile vessel
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.22 N
0. 3.
.24
.14
.15
.06
.07
.072
.06
.048
48 BULLETIN OF THE LABORATORIES
is clearly seen and all the details of the water vascular system may be
made out with ease. The lateral vessels are tortuous canals, while
upon them are seated beaker cells, the flask-shaped base of which con-
nects directly, by means of a curved tube of less diameter, with the
main can^l. The mouth of the flask is directed downwards and
has a small opening near which is the point of insertion of a long
cilium which extends upward into the flask, where it is constantly in
motion. There seems to be no reason to doubt that by means of
these beaker-cells the vascular system is in communication with the
perivisceral cavity. The foot is comparatively slender and has, aside
from distinctly cross-striate muscles, two large foot glands which open
in the ends of the rather long dagger-shaped claws. A pair of fine
bristles springs from the dorsal surface of the last segment of the foot.
The following measurements were taken :
No. I. lorica .22 mm. long. No.
** .14 mm. wide.
foot .06 mm. long.
claws .07 mm. long.
jaw capsule .06 mm. long.
Found in Minnesota during the whole summer among water plants.
EUCHLANIS AMPULIFORMIS, Sp. tl,
[Plate II, Fig. 3.]
This species, which deviates toward Salpina, is smaller than the
above and, in outline, is somewhat flask-shaped. The back is cari-
nate and the flat ventral plate is excavated posteriorly with a cordate
opening. The head is produced and densely hairy below. The
maxtax is small, but the cervical eye is very large. The nuclei of the
ovary are very conspicuous, although the egg is not as large in propor-
tion as in the above. The foot is four-jointed and the claws are elon-
gated and somewhat curved. The lorica is .16 mm. long, the claws
.08 mm. Another individual measured .20 mm. and the claws were
.12 mm. long. This species was seen but twice, June i8th, 1884,
in Minnesota.
POLYARTHRAEA.
The family includes the two genera, Triarthra and Polyarthra, In both
genera the foot is wanting and appendages of the sides of the body take its place.
The body is not segmented except anteriorly and the form is not definite. The
genus first mentioned has two lateral and a ventral appendage, while in Polyarthra
the appendages are collected in groups upop the opposite §i4es. In bpth genera
the egg is carried about as in Amirece^
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OF DENISON UNIVERSITY. 49
GENUS POLYARTHRA, Ehr.
A single species has so far been encountered and I am able, with
the works at hand, to discover no reason to doubt its identity with P.
platyptera of Ehrenberg.
When swimming freely this animal seems to consist of two quad-
rilateral segments, the first, or head segment being considerable shorter
than wide in outline, while the body is a third longer than wide. The
trochal ciliation is slight. Two sensory organs are conspicuous upon
the front of the head and the eye occupies the middle of the first
segment near its posterior margin. The maxtax is very large and the
stomach is short, with a tubular intestine. There are two prominences
on either side of the body near the front, each bearing three lanceolate
spines. The egg is very large and is perhaps half as bulky as the
whole body. The contractile vessel is small and little could be seen
of the lateral vessels. The length is .10 mm. ; width, .08 mm.; setae,
.088 mm. long. This species seems rare and was found among plauts
in standing water during June and July of 1884 and 1885 near Min-
neapolis.
The group of genera termed Macrodactylea or Longiseta includes
such animals as have a more or less elongate and frequently cylindrical
body, often strongly curved, and possess the following characters.
The cuticle is considerably indurated ; the terminal segment of the foot
is long ; there is usually a lack of symmetry exhibited by the claws or
maxtax; and the cilia are sparse upon the trochal disc.
The following genera are at present included in the family :
Scaridium, Monura, Furculaiia^ Distemma^ Monocerca^Mastigo-
cerca, Diurella^ Heterognathus^ Ratiulus.
GENUS DIURELLA, Borv de St. V.
The body is more or less perfectly cylindrical, and curved either ventrally or
dorsally. The claws are rather long and frequently seem united, and are curved
ventrally, The eye is cervical and single. There is a sensory tube upon the
upper (dorsal) part of the disc. Three species are described, although doubt ex-
ists as to the specific value of one of these; they are D. iigrisy Ehr., D. RaMulus^
Eyferth, and D. stylata, Eyferth, to which a species is added below under the name
D. insignis. The common species in America is
DiURELLA TIGRIS, {Ehr. ) Bory.
The descriptions and figures of European authors vary remarkably
in this instance, but from them all we are abl^ to gather 5\iffici^;jt tQ
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50 BULLETIN OF THE LABORATORIES
make it reasonably sure that pur species is really D, tigris. It is
quite variable in size and form. The cylindrical body is strongly
curved ventrally. The head is distinctly set off from the body by a
suture as represented by Eyferth but not by Eckstein. The sides of
the neck extend into a sharp spine on either side, which, however, may
be easily overlooked. There is a sensory cylinder which forms a third
prominence upon the front. The foot consists of but a single evident
segment which is quite short. The appendages assume a variety of
appearances. Usually they seem to form a flattened triangular plate
curved in the same plane as the body. This appearance is figured by
Eckstein, though he describes the appendages as consisting of two pairs,
the outer half as long as the inner, both being united at the tips into
one plate. Eyferth says, on the other hand, that the foot bears two
unequal, bristle-like, curved claws, but his drawing shows two equal
claws. Our experience confirms Eyferth' s account. Like Rattulus,
this species moves in circles or arcs of circles when lashing its tail, but
has the power of moving in a straight line by the use of the cilia alone.
The maxtax is nearly as drawn by Eckstein. The chief organs are
two anchor -like indurated processes which are unlike in length and
form. The walls of the maxtax are furnished with ring-muscles.
The stomach is glandular and its cells contain large globules of fatty
matter. The intestine is pear-shaped and furnished with numer-
ous cilia. The contracting vessel is large but the lateral vessels
are not easily seen and I can add no details. The single cervical eye
is large and seated on a large elongate ganglion. The ovary is small
and the egg, when present, occupies the left side of the body on its
ventral aspect. The total length is about .20 mm. of which the body
forms .16 mm. The longer claw measures, in large specimens, .048
mm. and the shorter only .036 mm. Sometimes I fancied that I saw
two lateral spines as described by Eckstein. The width of the lorica
is about .65 mm. This species was encountered in Ohio and Minne-
sota in all situations and seasons.
DiURELLA INSIGNIS, Sp. fl.
{Plate J V. Fig. 6.)
A larger species than the above is found in Minnesota. The
length, exclusive of the claws, is from .17 to .20 mm. The claws
are .06 mm. long, one being much longer than the other. There are
spines in the cervigal region similar XQ those described in in the above.
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OF DENISON UNIVERSITY. 5 1
The body is much more slender, while the viscera do not differ essen-
tially from D, tigris,
GENUS MONOCERCA, Ehr.
This genus includes elongated, nearly cylindrical or conical forms, having a
single greatly elongated claw and more or fewer accessory spines on the last seg-
ment of the foot, The maxtax is elongate, with unequal indurated ridges. The
stomach is oval and the intestine cylindrical.
The only specimens of this genus as yet seen resemble very closely
M. rattus of Ehrenberg but are somewhat longer. The lorica is .30
mm. long while the claw is .22 mm. The foot consists of two seg-
ments, both of which are very short, while the last carries four or more
unequal spines. The pulsating vessel is elongate oval but the details
were not studied. This rotifer it quite rare.
GENUS DINOCHARIS, Ehr.
The lorica is cylindrical or prismatic, with a wide opening in front. The
head is distinct and feebly ciliated. The eye is cervical. The foot is long, rigid,
and three jointed. The claws are long and the foot bears, beside these, long
spines anteriorly and behind. The whole shell is densely covered with granula-
tions or spinules.
DiNOCHARIS POCILLUM, Erhr, (?)
(Plate II. Fig. I.)
The most abundant form of this genus in America varies so greatly
in both size and details of structure that one is tempted to identify it
with the most frequent species of Europe in spite of variations from
the descriptions of authors. The outline of the lorica is cup-shape
and its symmetry is broken by two ridges near the posterior edge, pass-
ing transversely. It is 1 1-5 times as long as wide. The first segment
of the foot is short and bears two long curved spines above. The
middle joint is twice as long and nearly cylindrical. The third seg-
ment is about as long as the first and bears two curved claws four
times as long as the segment and also a short spine about as long as
the segment.
The whole body is about . 24 mm long, including the claws, which
measure . 08 mm. The eye is large and is seated on an ovoid ganglion.
The ovary is large and the nuclei are quite distinct. The egg is
obliquely placed and nearly as long as the width of the lorica. Two
curved elliptical glands lie in front of the stomach. The lateral ves-
sels of the vascular system are large. Encountered only in Minnesota.
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52 BULLETIN OF THE LABORATORIES
A somewhat larger form, also found in Minnesota, has more slender
claws and seems to lack the spine on the last joint of the foot. The
shape is otherwise the same.
The cast-off shell of still a different form, in which there is an in-
dication of segmentation near the anterior of the lorica,was once seen.
GENUS SALPINA, Ehr.
Somewhat resembling Euchlanis^ but having spines upon the front and posterior
margins of the laterally compressed lorica. There is a median area above, which
is less perfectly indurated than the sides, giving rise to two ridges. The foot is
short, three-jointed, and bears two lanceolate claws. The eye is single and the
ciliation of the trochal disc rather strong. The maxtax is large and the digestive
tract well differentiated. Water- vascular system with two or three beaker-cells on
either side. The ^%'g is carried about with the parent after extrusion.
Salpina affinis, sp, n.
{Plate 11. , Fig. 4,)
This species is so allied to S. mucronata, Ehr. that it is with some
hesitation that a new name is proposed. While agreeing in most
characters, it differs from that species in having the upper pair of
anterior spines much longer than the lower and curved downward and
in having the lower pair of posterior spines much longer than the
single upper one and curved upward. S. mucronata is said to
measure but .15 to .16 mm., while our form is .22 to .24 mm. long and
.10 mm. wide. The anterior spines measure .045, length of claws, .06
mm. The whole shell is granulated and there is a band in front, set
off by a distinct line. There is a sensory tube which bears a bundle
of cilia at its end, and which usually projects from between the two
dorsal spines of the lorica. The eye is lunate and seated on a very
large, almost spherical ganglion. The maxtax is very large and opens
into a slender oesophagus. The stomach is glandular and saccate.
The very large egg is ventral. No careful study was made of the
viscera. Minneapolis, May.
The species of the genus, aside from those mentioned, are S.
spinigera^ Ehr., S. brevispina, Ehr., S. ventralis, Ehr., S. bicarinata,
Ehr, 5. redunca, Ehr., S. dentatus, Duj., and S, polyodonta, Schm.
There is reason to suppose that several of these are but varietal forms.
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OF DENISON UNIVERSITY. S3
GENUS MONOSTYLA, Ehr.
Shell depressed, oval ; head opening large, notched before and behind. The
foot has two short basal segments and a long terminal one ending in a small spine,
hence appearing as though bearing one long spine. The eye is single and situ-
ated at the base of a large ganglion. The maxtax is large and quadrate. The
viscera are simple.
MoNOSTYLA (quadridentata, Ehr, ?)
Two species of MonostYla have been thus far encountered, one of
which may be identical with M. quadridentata of Ehrenberg. The
body is bell-shaped or inverted pear-shaped, the oral margin being
produced into two sickle-shaped spines turned outward, which are dis-
tinct from the acute margins of the shell itself. The body is com-
posed of two segments or apparent segments, the second being small
and conical. The terminal joint of the foot is slender and elongate,
f)earing a thorn-like spine. The ganglion is very large. The maxtax
is also large and opens into a sack-like alimentary canal not evidently
subdivided. The shell in this species is ornamented with granules.
Length of lorica, .15 mm., width, .11 mm., terminal caudal joint, with
spine, .08 mm. Found in June, in Minnesota.
A second species is smaller, measuring from .11 to .12 mm. , foot
.04 to .08 mm., width, .11 mm. The shell is smooth and the curved
spines are absent.
The following species are known : —
Monostyla lunar is, Ehr., M, cornuta, Ehr., M. closterocerca,
Schm., M, oophthalma, Schm., and M. macrognatha, Schm.
GENUS DISTYLA, Eckstein.
Shell ovate conical, closed behind, except for the small opening admitting the
foot. In front, the opening is wide and guarded on either side by projecting an-
gles. The foot is one-jointed and bears two equal, divaricated spines. The
shell may be smooth or ornamented with raised lines and serrations. The eye is
single and seated upon a considerable ganglion. Two species are described by
Eckstein from Europe {D. gissensis and D. ludwigii) and two additional ones occur
in America.
DiSTYLA MINNESOTENSIS, Sp. U.
This is a large species, .25 mm. long, with a pear-shaped body of
two segments, the first being .20 mm. long and of equal width. The
second segment is .05 mm. long and has an oval slit behind for the in-
sertion of the foot and permitting its free lateral motion. The claws
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54 BULLETIN OF THE LABORATORIES
are .13 long and slender, the terminal third being attenuated. The
ganglion is small and bears a single red eye. The trochal disc is
retracted by four powerful muscular bands. The stomach is globular
and glandular. The short segment of the foot is moved by pairs of
evident muscles. This species was but once seen in July.
DiSTYLA OHIOENSIS, Sp. H.
The lorica is . 1 2 mm. long and its form is much as in the previous
species. Width of lorica .084 mm., length of claws .028 mm. The
sides of the lorica project in front to form a tooth on either side of the
head. The lorica is sculptured into regular areas upon the first seg-
ment. There is a quadrate plate projecting over the base of the
claws. The latter are attenuated toward the end. The details of struc-
ture are not known.
GENUS SQUAMELLA, Ehr.
The three genera Squamella^ Metopidia^2ind. Lepadella agree closely together, be-
ing characterized by the presence of four, t>vo, or no eyes respectively. The or-
ganization is much as in Euchlanis. The lorica consists of an oval, arching, scale-
like shield above, and a flattened plate below. The foot consists of three short
joints terminating in two acute claws The head terminates above in an oval scale-
like appendage.
They only species belonging to this group as yet seen was hastily
identified with Squamella bractea and, in absence of further informa-
tion, we will simply give measurements in addition to the figure, in
which, by the way, but one pair of eyes is represented, leaving us to
infer that the animal is Metopidia rather than Squamella.
Length .08 mm. — .14 mm. Width (in the latter case) .12 mm.