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BULLETIN

OF THE

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buratflrji

NATURAL HISTORY,

Urbana, Illinois.

VOLUME V.

Contributions to a Knowledge of the Natural
History of Illinois.

1897-1901.

fcfcW YORfc
ttOTANICAk

Illinois State Laboratory of Natural History,

Urbana, 111.

1902.

CONTENTS.

PA9E.

Article I. — Plankton Studies. [. Methods and Appara-
tus in Use in Plankton Investigations at the
Biological Experiment Station of the University
of Illinois. By C. A. Kopoid (7 Plates.)
March, 1897 1

Article II. — A Contribution to a Knowledge of North
American Fresh- water Cyclopidce. By Ernest
B. Forbes (13 Plates.) September, 1897 27

Article III. — The North American Species ot: Diaptomus.
By Frederick William Schacht. (15 Plates.)
December, 1897 97

Article IV — The North American Centropagidce belong-
ing to the Genera Osphranticum, Limnocalanus,
and Episehura. By Frederick William
Schacht. September, "1898 225

Article V. — Plankton Studies. II. On Pleodorina illi-
noisensis, a New Species from the Plankton of
the Illinois River. By C. A. Kofoid. (12
Plates.) September, 1898 273

Article VI — A List of the Protozoa and Botifera found in
the Illinois River and Adjacent Lakes at Havana,
Illinois. By Adolph Hempel. (5 Figures.) Jan-
uary, 1899 301

Article VII. — First Supplement to the Check-List of the

Coccidce. By T. D. A. Cockerell. February,! 899. 389

Article VIII. — A Statistical Study of the Parasites of the

Unionidce. By H. M. Kelly. May, 1899 399

Article IX — Plankton Studies. III. On Plalydorina, a
New Genus of the Family Volvocidai, from the
Plankton of the Illinois River. By C. A. Ko-
foid (1 Plate.) December, 1899 419

Article X. — Notes on Species of North American Oligo-
chmta. III. List of Species found in Illinois,
and Descriptions of Illinois Tabificidcp, By
Frank Smith. (2 Plates ) March. 1900 ". 441

Article XI — Notes on Species of North American Oligo-
chceta. IV. On a New Lumbriculid Genus from
Florida, with additional Notes on the Nephridial
and Circulatory Systems of Me sopor odrilus asym-
metricus Smith. By Frank Smith. (1 Plate.)
June, 1900 459

Article XII. — The Hirudinea of Illinois. By J. Percy

Moore. (8 Plates.) February, 1901 479

BULLETIN

Illinois 3tate Laboratory

NATURAL HISTORY,

Urbana, Illinois

VOLUME V.

ARTICLE I.— PLANKTON STUDIES. I. METHODS AND
APPARATUS IN USE IN PLANKTON INVESTIGA-
TIONS AT THE BIOLOGICAL EXPERIMENT STA-
TION OE THE UNIVERSITY OF I ILL NO LS.

By C. A. KOFOID, Ph. D.

Illinois State Laboratory of Natural History,

I'RHANA, ILLINOIS.

1897.

State Laboratory of Natural History

LABORATORY STAFF.

Professor Stephen Alfred Forbes, Ph. D..
Director of State Laboratory and State Entomologist.

Charles Arthur Hart.
Systematic Entomologist and Curator of Collections.

Frank Smith, A. M..
Assistant Zoologist.

Charles Atwood Kofoid, Ph. D..
Superintendent of Biological Station.

Charles Christopher Adams, B. S.
Entomo logica I A ssis tant.

Mary .Jane Snyder.
Secretary.

Henry Clinton Forbes,
Librarian and Business Agent.

Lydia Moore Hart,
Artist.

Article I. — Plankton Studies. I. Methods and Apparatus in
Use in Plankton Investigations at the Biological Experi-
ment Station of the University of Illinois. By C. A. Kofoid.

Less than ten years ago a new field of biological science
was opened by the German investigator Hensen, namely, the
quantitative examination of the " Plankton." This term was
applied to all plants and animals floating free in the water
and incapable by their own efforts of materially changing
their position. Thus adult fish which brave the waves and
stem the current would not be included in the plankton,
while the passive eggs or the helpless fry would fall within
the limits of the definition. Practically, the content of the
term plankton as applied to fresh water is the sum total
of its minute life, both plant and animal.

The scope of our plankton work upon the Illinois River and
its adjacent waters includes a continuous, systematic, and
exhaustive examination of the plant and animal life sus-
pended in the waters of a river system, with a view to deter-
mining its amount and seasonal changes, its local and vertical
distribution, its movement and relation to the current, the
effect upon it of floods and of drouth, of light and of tempera-
ture, the organisms which compose it, their seasonal and
cyclic changes, and their mutual interrelations. Added
interest arises from the fact that this is the first application
of this method of biological investigation to a river system
and its related waters.

It is the purpose of the present paper to describe the
methods and apparatus employed in the plankton work at the
Biological Station at Havana, Illinois, during the years 1894-
1896. Both are, as a rule, the result of mutual conference
of the various members of its staff. During the first
fifteen months of the existence of the Station the plankton
work was in the hands of Professor Frank Smith, and when,
on July 1, 1895, the writer assumed charge of this work at
the Station he found the oblique haul, described on a subse-

2 Illinois Stale Laboratory of Natural History.

quent page, already inaugurated and in successful operation.
It now devolves upon him to prepare for publication a de-
scription of this method, hut the credit for devising it and
putting it in operation belongs to those from whose hands he
received it. The apparatus was used without modification
until August 23, 1895, when the detachable bucket was
added to the net, and in October of the same year the separa-'
able carriage was introduced. In May, 1896, the pumping
method was substituted for the oblique haul in making plank-
ton collections.

Upon the opening of the Station in April, 1894, the exam-
ination of the water by the plankton method was decided
upon, and in the early part of June the first regular collections
were made. The method of plankton collection ordinarily
employed, — as, for example, by Hensen ('87 and '95) in the
Baltic and North Seas and in the Atlantic Ocean, by Apstein
('92 and '96) and Zacharias ('93-'96) in the lakes of northern
Germany, by Eeighard ('94) in Lake St. Clair, and by Ward
('96a) in Lake Michigan, — has been without exception the ver-
tical haul, in which the net is lowered to the bottom of the
body of water and then raised in a vertical line to the surface,
thus filtering a vertical column of water. Difficulties beset
the application of this method to the waters at Havana. In
the first place all the bodies of water examined at the Station
are quite shallow, the majority of the plankton collections
being made in less than three meters of water. The river itself
is the deepest water in the locality, but at its lowest stage
there are only three meters of water in the main channel,
where collections are made. This depth is increased at times
of flood, the maximum reached in the past three years being
6.1 meters. The shallowness of the water thus practically
precludes examination by means of the vertical haul.

A second difficulty exists in the unstable nature of the
bottom generally found throughout the locality to which the
operations of the Station are confined. This consists of a soft
black mud, composed largely of the detritus of decaying veg-
etation and alluvial soil deposited from the silt- charged waters
at times of flood. It is extremely unstable and upon the least

Methods in Plankton Investigations. 3

i> '

disturbance mingles with the water, rendering it impossible to
take a clean plankton collection. The soiling of the net and
the fouling of the water consequent upon dropping a large
plankton net upon the bottom further preclude the vertical
haul in the plankton work at Havana.

I. THE OBLIQUE-HAUL METHOD. (PLATES I.-III.)

The oblique haul was at first adopted as the method best
suited to the situation. This is accomplished by suspend-
ing the net to a carriage which runs upon a rope stretched
obliquely from the bottom to the surface of the water. By
this means the column of water traversed by the net is
increased to an adequate length. It also permits the employ-
ment of a net small enough to be easily operated from a row-
boat. A short description of this method of plankton collection
has been given by Professor Forbes ('94). The parts of the
apparatus used in making the oblique haul will now be de-
scribed.

1. The Quantitative Net (Plates I. and II.). — The net used
by us is the modification of the Hensen net suggested by
Apstein ('91 and '92) for fresh- water work, and more fully
described by him ('96) as the smaller model quantitative net.
It consists of three parts : (a) the filtering net proper, (/>) the
detachable bucket, and (r) the head-piece of the net.

a. The filtering net has the form of an inverted truncated
cone, whose base has a diameter of 25 cm. and whose side is
40 cm. The truncated apex, to which the bucket is attached,
is 4 cm. in outside diameter. This net is made of No. 20
silk bolting cloth, which can be obtained from wholesale
dealers in supplies for flouring mills. That used by us bears
the brand, " Especially for milling purposes. Dufour & Com-
pany." This is the same brand of cloth as that which was
used by Pieighard ('94) and Ward ('96a) in their plankton
work upon the Great Lakes. It is stated by the manufact-
urers to contain 29,929 meshes to the English square inch.
Examination under the microscope shows that this cloth
contains 32477 (— 172.75x188) meshes to the square
inch after sponging and pressing with a hot iron four times.

4 Illinois State Laboratory of Natural History.

The average area of the openings is reported by Reighard
('94, p. 57) to be:

.00003596 sq. cm. in the new cloth,

.00002808 sq. cm. in cloth that had been wetted and then
dried,

.00002336 sq. cm. in cloth that had been used for 40
hauls of a net.

As the new silk shrinks considerably after its first wetting,
we have followed the practice of thoroughly and repeatedly
sponging it and pressing it with a hot iron before cutting out
the net. Otherwise in a single-seam net there is sufficient
shrinkage to cause the filtering cone to take a position oblique
to the true axis of the net (See Apstein, '96, p. 34, Fig. 3).

The following directions for making a pattern for the net
are here inserted, as they may be of use to those to whom the
original descriptions given by Apstein ('91, '92, and '96) are
inaccessible.

GrlRX

Fiq.A

Fif,r, A. — Completed cone. Fig. B.— Completed pattern for the silk net.
(Both after Apstein.)

The net has the form of a truncated cone (Fig. A), whose
side (i = 40 cm.) and radii of the ends (A' 12.5 cm., and
r = 2 cm.) are known. The silk exposed in the net has the
area and dimensions of the surface of this truncated cone.

Methods in Plankton Investigations. 5

6 '

If, now, we complete the truncated cone and denote the side
of the small cone, added for completion, by x, it follows that

x : x-\-i : : r : R;

x = -j; — = 7.619 cm.
K—r

If, now, we imagine the surface of the completed cone

unrolled and spread in one plane (Fig. B), the circumferences

C ( = 2 R n ) and c ( = - 2 r n ) will form arcs subtending an

unknown angle or, and it follows that the circle described by

the radius x ( = = %xn ) is to 2 r n as 360° is to a, or

2x7i 360

2 r 7T a

360 r

a = ;

x
a= 94.5°.

This angle a being known, it is a simple matter to lay off
the pattern for the net. The pattern for the linen head-piece
is constructed in a similar manner. Allowance must be made
along the edges mr and ns (Fig. B) for the longitudinal seam.
It has been our custom to allow 4 mm. upon one margin and
8 mm. upon the other (Fig. 2, Plate I.). The two edges are
brought together and backstitched at a (Fig. 2), and the wider
margin is then turned under the other and felled at b upon
the outside of the net. Thus only a single seam 4 mm. in
width traverses the length of the net. A very fine needle is
used in the sewing, and the line of stitches can be effectually
closed with a light coat of rubber cement. Allowance must
also be made along the edge mn for attachment of the silk
between the linen cone (Plate I., Fig. \,c. b. I.) and the cover-
strip (e. s.) at the seam sm, and for the fastening of the silk,
along the margin rs, between the net clamp (n. e.) and the
head-piece {h. p.) of the bucket. In order to get the net into
the clamp it is necessary to slit the silk at several points to
within a short distance of the line rs (Fig. B).

b. The detachable bucket (Plate II., Fig. 3-5) used by us
differs in several particulars from that described by Apstein
('91, '92, and '96) and also from the one devised by Reighard
('94, p. 26, Plate II.). It copies the Reighard bucket in sub-

6 Illinois State Laboratory of Natural History.

stituting a removable plug for the turncock in the Apstein
bucket, and differs from both in the base and in the manner
of attachment of the silk in the windows.

In form it is a cylinder 7 cm. in height and 4 cm. in out-
side diameter. (Owing to the material available for construc-
tion our bucket measures 4.4 cm. in outside diameter.) It
consists of three pieces : the head-piece, the bucket proper, and
the band clamp.

The head-piece of the bucket (Plate II., Fig. 3, h. p.) is a
cylinder 2 cm. in height, whose upper edge is rounded upon
the inner face. The lower edge is threaded at m (Fig. 3) so
as to screw into the top of the bucket proper, which is corre-
spondingly threaded at n (Fig. 4). The screw is so con-
structed that the inner surface is uninterrupted when the bucket
proper is fully screwed on. The head-piece also bears three
equidistant eyes (Fig. 3, e.), in which are tied the three stay-
lines (s. I.) which pass up to the large, and then to the small,
rings of the net, and finally unite with the draw-line (Plate
III., Fig. 6, d. /.). The position and manner of attachment
of these stay-lines can be seen in Plate II., Fig. 3, and in Plate
III., Fig. 6. The net is clamped on the head-piece by the
circular net clamp (Plate II., Fig. 3, n. c), which is a band
of brass 1 cm. in width. To the ends of the band are attached
wings (w. n. c), which are approximated by means of a
thumb-screw (/. s.). By this operation the silk beyond the
line rs (Fig. B.) is firmly clamped between the brass band of
the net clamp and the head-piece of the bucket.

The bucket proper (Plate II., Fig. 4 and 5) is a brass cylin-
der 5 cm. in height, and of the same diameter inside and
out as the head-piece. In the side of the bucket at a height
of 2 cm. are cut three windows 2.5 X 3.5 cm. These windows
are closed by a band of No. 20 silk held in place by a band
clamp, in which are windows similar to those in the wall of
the bucket. The bucket was constructed from a heavy piece
of brass tubing, the bottom (Fig. 4, b.) being inserted in the
following manner. The tube is turned out to the shoulder
(Fig. 3, sh.) and heated in a jet of steam, and while still hot
the piece of brass from which the bottom (b.) is finished, is

Methods in Plankton Investigations.

«i> '

inserted upon the shoulder. The shrinking of the tube as it
cools holds the bottom firmly in place, and it can then be
completed as shown in Fig. 3. At the center of the bottom
is the outlet of the bucket, which is reamed to hold the taper-
ing plug {p.). Both the plug and the bottom are finished
obliquely to a drip-point (d. p.) at one side. This facilitates
the removal of the last few drops of the catch from the bucket.
The bucket below the bottom of the windows holds about
7 cu. cm. The base (ba.) retains the original thickness
(.5 cm.) and its weight adds to the stability of the bucket.
Since the drip-point does not project below the base the
bucket can be set down, and, owing to the fact that its center
of gravity is low, it is not easily overturned. This is a dis-
tinct advantage where the work must be done in a small row-
boat at the mercy of the waves.

The band clamp (Plate II., Fig. 4 and 5, b. c.) is a sheet
of brass 4.5x15.3 cm., and about .1 cm. in thickness. At
a distance of .75 cm. from the ends the sheet is bent out at
right angles, and a brass bar 4.5 X. 75 X. 25 cm. is soldered
in the angle thus formed (Plate II., Fig. 4 and 5, pi. and//.').
The band is now bent around the bucket and the ends brought
together by means of two screws (sc.) which pass through
the one bar and screw into the other (Plate II., Fig. 5, pi.
and //.')• The windows (Fig. 4, w.) can now be cut through
both the band and the walls of the bucket. The pillar (Fig.
5, pi.) between the windows adjacent to the ends of the clamp
is .5 cm. wider than the other pillars, whose width is about
1 cm. The inner edges of the windows are carefully rounded
so as to afford no lodgment for the plankton. It is also a
convenience to attach the band of silk (Fig. 4, s.) which closes
the windows to the side of the bucket by means of a thin
coat of King's waterproof cement. The band clamp can then
be slipped over the bucket and the silk bound firmly in place
by tightening the two screws (Fig. 4 and 5, sc). The base
also bears an eye (e.) for the line which fastens the bucket to
the carriage at z (Plate III., Fig. 6).

The above-described detachable bucket, devised by the
writer, has certain obvious advantages over the Apstein and

8 Illinois State Laboratory of Natural History.

Eeighard buckets after which it is very largely modeled. Its
advantages are its stability, the drip-point, and the band
clamp, the latter permitting readily the renewal of the silk in
the bucket.

Previous to the adoption of the bucket just described, the
net in which the collections at Havana were made was closed
by a circular piece of silk clamped on the end of a brass
cylinder screwing into the head-piece (Plate I., Fig. 1, h. p.).
The clamp used for this purpose is similar to that
employed to fasten the net to the head-piece. (See Plate
I., Fig. 1, and Plate II., Fig. 3, n. c.) When a collection
had been made the silk circle was removed and, with the plank-
ton condensed upon it, transferred to the killing fluid. This
form of plankton bucket was used by Apstein ('92) on his
qualitative plankton net, and was afterwards described by
Borgert ('96) for a net to be towed behind steam- vessels.

c. The head of the net (Plate I., Fig. 1) is a truncated
cone, at whose upper and lower ends are rings 10 and 25 cm.
in diameter respectively (u. r. and /. ;-.). These rings are
made of No. 5 (American Standard Gauge) brass wire. The
side of the cone (e. b. I.) is made of heavy linen, known in the
trade as " butchers' linen." Its lower edge is joined to the
silk net at the seam (Plate I., Fig. 1, sm.), where it also
meets the cover-strip (e. s.) — a narrow band, made of the
same cloth — which extends over the lower ring (/. r.). In the
upper edge of the cone is bound a heavy cord (cd.) which, in
turn, is fastened to the upper ring (u. r.) bj a series of loops
of strong thread (th.). The upper ring and the cone are sup-
ported by three equidistant wire stays (w. s.). These are
made of No. 8 brass wire and are provided with an eye at
each end. The lower eye (/. e.) embraces the lower ring and
is held in place by small hips soldered upon each side. The
upper eye {u. e.) is attached to the cord (cd.) by a small cloth
strap (st.) and also serves as a point of attachment for a stay-
line (s. I.) which runs from the bucket to the lower end of
the wire stay (w. s.) to which it is fastened, passing from
this to the upper eye (;/. e.) and then to the draw-line (Plate
III., Fig. (J, d. /.).

Methods in Plankton Investigations. 9

& '

2. The Carriage (Plate III., Fig. 6 and 7). — The carriage
for the plankton net is a wooden bar, 100x5x2 cm. It
hears upon one edge two ceiling pulleys (Fig. 6, /. and p.'),
through which passes the carriage rope (c. r.). In order that
there may he no tendency on the part of the carriage to float,
two bars of lead (/.) are inserted in its lower edge, so that it
naturally assumes a position upon the lower side of the rope.
The carriage is so constructed that it may be separated along
the line a b c, thus freeing the net from the fixed carriage
rope. Its two parts are held together by two flat brass hooks
(k.) which enter the staples (s.). The net and the lines per-
taining thereto are attached to the removable part of the
-carriage at four points (w, x, y, a) at which screw-eyes are
inserted, the attachment being made by means of small metal
snaps (sn.). At the anterior end of the carriage a stay-line
(s. I. 4), coming from the end of the draw line (d. /.), is fast-
ened to the screw-eye w. Upon this line comes the main
stress when the carriage is drawn along the rope. The upper-
most of the three stay-lines of the net (s. I. 1) bears a snap
which is fastened to the screw-eye x at the lower anterior
corner of the carriage. This makes it certain that the plane
of the mouth of the net will be kept perpendicular to the line
of progress of the carriage. A snap at y binds the net to the
carriage and another at z supports the bucket.

3. Accessory Apparatus (Plate III.). — The stay- and draw-
lines are of braided linen. The latter is about thirty-five meters
in length and is carried on a hand-reel. It is knotted at inter-
vals of one meter to a point thirty meters from the opening
of the plankton net. The carriage rope is a five-sixteenths
inch braided rope known in the trade as " sash cord." It
does not kink in handling, and if once thoroughly seasoned
is subject to little change when wet and cannot easily be
stretched. This rope is about forty meters in length and is
marked by colored threads at a point exactly thirty meters
(Plate III., Fig. 7, m.) from the opening of the net. The
location of the end knot (Fig. 6, k.) is marked in a similar
manner.

Three sharpened stakes (Fig. 7, b. s., m. s., and e. s.), the

10 Illinois State Laboratory of Natural History.

brace-, main-, and end-stakes, respectively three, four and one
half, and five meters in length, complete the apparatus nec-
essary for making an oblique haul.

4. Operation of the Oblique Haul (Plate III.). — In this
operation two persons are required, an oarsman to handle the
skiff and an operator for the apparatus. The method of pro-
cedure is as follows. The brace rope (Fig. 7, b. r.) is fastened
near the lower end of the brace stake (b. s.) and the latter is then
set as firmly as desired. The main stake (;;/. s.) is then put in
place and the brace rope is tied to it. Next, the carriage rope
(e. ;-.) is fastened. to the main stake (m. s.) at a point 5 to 8 meters
distant from the thirty-meter knot (;;/). The boat is then
rowed away in line with the two stakes and the carriage rope
is unreeled until the end is reached, when it is run through the
pulleys (Fig. 6,/. and p.') of the upper part of the carriage.
The end knot (k.) is then tied and fastened to the rear pulley
(p.') by the release thread (///.). The carriage rope is next
tied to the lower part of the end stake (Fig. 7, e. s.), and at a
point just in front of the anterior pulley (p.) it is bound to
the end stake by the release line (r. I.). The lower part of
the carriage with the suspended plankton net can now be
attached to the upper part, and the end stake is ready to be
placed. When the end stake is set, the carriage line (Fig.
7, e. r.) runs obliquely from the release line to the surface of
the water at the main stake. The net occupies the position n.
(Fig. 7), and having been lowered vertically does not strain
any water in its descent. After placing the end stake the
skiff is rowed to the main stake as the draw-line (Fig. 7, d. I.) of
the carriage is unreeled. A quick jerk upon the carriage rope
snaps the release line (/-. /.) on the end stake, and the slack
in the carriage rope can be taken up at the main stake. The
carriage rope and nee now take the position c. r.' and ;/.'
(Fig. 7), and the thirty-meter knot ;;/ is at the surface of the
water. Everything is now in readiness for making the catch.
At the signal the release thread (th.) which binds the rear
pulley to the end knot is broken by a quick pull upon the
draw-line. The carriage bearing the plankton net is drawn
up the oblique rope the distance of thirty meters in one minute

Method's in Plankton Investigations. 11

5

by the operator, who regulates the speed by the meter knots
on the draw-line and the counting of the oarsman, one count
being given every other second by the watch. By this method
a uniform velocity for the plankton net at all parts of its
ascent and in different hauls is assured, and a very important
source of error in the vertical haul, as it is usually made, is
avoided. The oblique haul is not so complicated as it may
perhaps seem to the reader. With a little practice the whole
operation may be completed in less than twenty minutes.

Whenever a current is present in the body of water exam-
ined, it has been our custom to make the oblique haul across
the current, thus eliminating, so far as may be, its effect upon
the coefficient or straining capacity of the net. In water in
which there is little or no current it is of advantage, in work-
ing in a skiff, to set the apparatus "with the wind." In
waters abounding in vegetation, channels of the length and
width requisite for making the oblique haul were opened from
time to time by cutting out and removing the rank growth of
aquatic plants.

5. Difficulties encountered. — Certain difficulties attended
the operation of the oblique haul. Owing to the turbidity of
the water, in many situations it was practically impossible to
place the apparatus so as to avoid vegetation. Whenever the
plankton net or the ropes strike a submerged plant, a cloud
of flocculent debris is set free in the water and the collection
is fouled. It was only with the greatest labor that channels
could be kept open in the vegetation, for its rapid growth and
its shifting by the wind soon closed any opening that had
been made. Again, the manipulation of the apparatus in
rough weather is somewhat difficult, the waves at times tear-
ing loose the stakes before the completion of the collection.
At periods of high water the strong current and the increased
depth made it impossible to set the apparatus or keep it in
place. This necessitated the substitution of a series of ver-
tical hauls from a floating boat for the customary oblique
method of collection.

The plankton at Havana is subject to extreme local and
seasonal variations, not only in volume but also in composi-

12 Illinois State Laboratory of Natural History.

tion. For example, at one time Cladocera predominate and
at another diatoms are present in vast numbers, and at still
another rotifers constitute practically the whole of the plank-
ton. Observations upon the operation of the net in the midst
of these fluctuations awakened the suspicion that the amount
of water actually strained was subject to considerable varia-
tion, dependent, among other causes, upon the amount and,
more especially, the composition of the plankton. If the
plankton were constant in quantity, kind, and distribution,
the error arising from the progressive clogging of the net as it
traverses the thirty meters would be distributed alike in all of
the catches, and they would still be comparable ; but the exist-
ence of the fluctuations in the plankton just noted and the
consequent variation in the amount of water strained, con-
stitute an important source of error in any deductions based
upon comparisons of catches made under these variable con-
ditions. This source of error is present in the vertical as
well as in the oblique haul. Furthermore, change in the silk
itself consequent upon use adds to the errors due to the fact
that the collection is made by drawing the net through the
water. A series of field experiments (to be described in a
later paper) upon the progressive clogging of the net and the
coefficient of various plankton nets, in a wide range of season
and situation, have abundantly justified our abandonment of
the system of collection in which the net is drawn through the
water for one in which a known quantity of water is put
through the net.

II. THE PUMPING METHOD.

For many years the biological examination of potable water
has been conducted by straining or filtering water delivered
through service pipes at the faucet by pressure due to the use
of a pump.

Giesbrecht ('96) describes the collection of Copepoda in the
Eed Sea by Kramer, who strained the water delivered by the
ship's pump to the bath-tub of an ocean steamer.

Cleve ('96), at the suggestion of Dr. John Murray, collected
plankton on board a steamer in the North Sea by attaching a
silk net to the pump when the deck was washed.

Methods in Plankton Investigations. 13

<b '

Previous to this, Hensen ('87) used the steam pump for
putting known amounts of surface water through the filtering
net. Hensen's quantitative work was, however, based upon
collections made by vertical hauls of the plankton net. Peck
('96), in his work upon the marine plankton of Buzzard's
Bay, obtained water for examination by the Sedgwick -Rafter
method (see Rafter, '9*2, and Twenty-third Annual Report of
the State Board of Health of Massachusetts for 1891, pp.
395-421) by means of a steam-pump connected with a two-
inch hose which was lowered to the desired depth. Beyond
these instances no other applications of the pump to the col-
lection of plankton have come to my notice, and there appears
to be no record of its use in quantitative work by the Hensen
method.

The impossibility of using the vertical haul in shallow
waters, the difficulties in the operation of the oblique haul,
and especially the error involved in the variable coefficient of
the net, have led to the adoption of the pumping method in
the plankton work at Havana.

1. The Pnmp (Plates Y. and VI. ). — The pump we use is
a double acting force-pump, known in the trade as a "Thresher
Tank Pump." It is worked by an upright handle, and has
two cylinders, each 6x9 inches, and throws an almost contin-
uous stream. Its capacity is one cubic meter of water per six
hundred strokes, provided that the water is delivered to the net
without elevation. The stroke is of definite length and its
action is regular, the rate employed being one stroke per sec-
ond. The pump is provided with 20 feet of 2 -inch spiral-
wound suction hose, terminating in a funnel 20 cm. in diam-
eter. The mouth of the funnel is covered with a linen net
of ^-inch mesh to prevent the entrance of stray bits of vegeta-
tion, and the end of the hose is weighted to insure its sink-
ing readily. It was found necessary to paint all exposed iron
in the water chambers of the pump with a thin coat of asphal-
tum to prevent the formation of rust scales.

Before the pump was put in use for regular plankton col-
lections, tests were made of the straining capacity of the silk
under the impact of the current from the discbarge hose. It

14 Illinois State Laboratory of Natural History.

was found that when the water was delivered from a 1-inch
hose into the plankton net and the filtrate refiltered in a second
net of the same silk (No. 20), a considerable quantity of the
more minute forms, Rot if era and Protozoa, were forced through
the meshes of the first net. This led to the adoption of the
l^-inch discharge hose, and of a net devised hy the writer
to reduce the force of the discharge, to protect the silk from
direct contact with the current, and to equalize the pressure
upon the filtering surface.

2. The Net (Plate IV., Fig. 8-10).— The net consists of
the cover with its accessories and the net proper, the two
being so constructed as to he readily separable. From the
under side of the conical copper top to which the hose
is attached hangs the silk net. When in use the net
is supported in a wooden frame, which also serves as a
float. The rim fits into the circular central opening and rests
upon a projecting ledge of the frame (Fig. 8, fl.) in such a
manner that the silk does not come in contact with the wood.
The frame is so proportioned that the net projects about 8 cm.
above the level of the water. Experience has demonstrated
that even when the water is full of silt or the plankton is very
abundant this elevation is sufficient to provide for filtration
without forcing the water into the net by the pump. In ordi-
nary circumstances the water does not rise more than 2-4
cm. above the level of the water in which the net is sub-
merged. Thus practically the whole straining surface is under
water. Two turn buttons (t. b.) hold the net firmly in place
so that it cannot be dislodged by the action of the waves when
the water is rough.

The cover (Plate IV., Fig. 8, cov.) is an obtuse
cone of sheet copper, 33 cm. in diameter and 20 cm. on the
side. The apex bears a curved connector {con.) upon which
the H-inch hose can be slipped. The cover is beaded for
rigidity, and carries two handles (//.) for lifting the net from
the frame. • After the water enters the net two devices are
employed to check the force of the discharge. The first is an
inner copper cone (i. c), with diameter of 13 cm. and side of 10,
placed in the axis of the net immediately below the orifice of

Methods in Plankton Investigations. 15

<b '

the connector. The cone is suspended from the top by means
of three stays (st.), and sheds the water centrifugally against
an inner net (/. n.) of No. 12 silk. This net is hung from a
ring (/-. /.) lixed to the under surface of the cover by three
supports, one of which (t. s.) swings upon the pivot (/>.) and
permits the removal of the net. The inner net conforms to the
proportions of the outer net but is only 27 cm. in diameter at
the top. At its apex is an opening 8 cm. in diameter, through
which plankton caught on the sides can be washed into the
lower part of the outer net.

To secure rigidity the margin of the cover is provided with a
projecting horizontal wing (ti'.), to which is attached the foot
(Plate IV., Fig. 8-10,"/.). This in cross-section is L-shaped,
extending obliquely downward and outward, the oblique and
horizontal arms being respectively 2.5 and .75 cm. in length.
The foot fits into a circular trough (/;-.) 1-1.25 cm. in width
and 2.75 in height. The inner wall (Fig. 9, 10, i. w.) of the
trough is parallel to the oblique face of the foot, against which
it rests when the cover is in place. The cover is held in the
trough by means of four turn clamps (Fig. 9, c), which are
fastened by straps (str.) upon the outer wall (o. w.) of the
trough. When the clamps are released and swing to the posi-
tion c-', the cover can be removed, and the upper margin of the
outer net (Fig. 9, o. n.) can be folded over the inner wall of
the trough. When, now, the cover is replaced, the net is
firmly clamped between the oblique face of the foot and the
inner wall of the trough. (Cf. Fig. 9 and 10.) This method
of attachment permits the ready removal of the net for the
purpose of drying the silk, and at the same time insures a
tight joint.

The net is made of the customary No. 20 silk and meas-
ures 92 cm. on the side. The upper border is faced upon
the outer surface for 0 cm. and upon the inner for 2 cm.
with butchers' linen, so that the wear in the fastening of
the net falls upon the linen, while the silk only is exposed to
the water to be filtered (Fig. 10). To insure the uniform
placing of the margin of the net in the fastening, a heavy cord
(at.) is sewed in the border, against which the angle of the foot

16 Illinois State Laboratory of Natural History.

rests when placed in position. The plankton bucket, with its'-
method of attachment to the net, is similar to that described
for the vertical net.

3. The Method of Operating the Pump. — The pump is
carried in a suitable row-boat, and the suction hose is operated
from the stern by one person while a second attends to the
pump and the net (Plate VI.). In the choice of a location
and in the position of the boat, due regard must be had to the
direction of the wind and the current, if any, so that no fil-
tered water may reenter the pump. In our work in the lakes it
has been our custom to tie the boat to poles set for this
purpose ; but in the river the boat has been allowed to drift
with the current in order to make the collection, so far as may
be, from the same body of water. After the depth is ascer-
tained the suction hose is lowered to within a foot of the
bottom, the pump is thoroughly rinsed, and while still filled
with bottom water the discharge hose is connected with the
net. As the pumping progresses the funnel is raised at regu-
lar intervals ; for example, every tenth stroke, the interval and
the distance raised varying, however, with the total depth of
the water to be traversed. Since the pump is filled with
bottom water when pumping begins, it is necessary to shorten
the first interval by the number of strokes required to fill the
pump and to correspondingly lengthen the last one. In this
manner a vertical column of water of the desired volume may
be pumped through the net. In addition to the vertical catch we
have followed the custom of making one from bottom water and
another from surface water. After the requisite number of
strokes of the pump have been made the hose is disconnected
and the net removed from the frame and thoroughly rinsed
down. The catch is concentrated in the bucket and trans-
ferred to the bottle of alcohol or formalin.

The pumping method has been successfully employed in
freezing weather by attaching a foot- warmer to the side of the
pump and encasing the whole in a wrapping of felt paper.
The foot-warmer burns a cake of specially prepared coal, and
will keep the pump warm during a day's work of ten hours.
A special drain-cock (not shown in Plate Y.) provides for the'

Mel hods in PI a nk ton Investigations. 17

<b '

removal of all water from the cylinders when the pump is not
in use.

4. Advantages of the Pumping Method. — As compared with
methods dependent upon hauling the plankton net through
the water, several points of advantage are to be found in
the pumping method. It is more accurate, since the actual
volume of water strained can he determined, and the changes
in the coefficient of the net due to seasonal and local varia-
tions in the quantity and composition of the plankton and to
alterations in the silk of the net with use are to a very large
degree eliminated. The method is also widely applicable : as
water may be drawn from any desired level, it may be applied
to the problem of vertical distribution ; and it may be used in
very shallow water, in the midst of vegetation, in creeks, in
strong currents, under the ice — in fact, in a wide variety of
situations from which the vertical or oblique hauls are wholly
excluded or to which they are with difficulty applied. Again,
no matter how poor the water may be in plankton, it is always
possible to strain an amount sufficient to furnish enough plank-
ton for measurement. The method is also a comparatively rapid
one, requiring for a plankton collection only about one third of
the time consumed in making the oblique haul.

The pumping method is thus admirably adapted to the
situation with which we deal at Havana, i. e., shallow water
and an abundance of vegetation. It is not, however, limited
in its applicability to such situations, but with the help of a
steam-vessel and a steam-pump it is capable of application to
larger and deeper bodies of water.

III. PRESERVATION AND EXAMINATION OF THE PLANKTON.

1. Preservation. — The living plankton is transferred di-
rectly from the bucket of the net to a wide-mouth two-ounce
bottle, and the sides of the bucket are rinsed down thoroughly
with a spray of 1% formalin to insure the complete removal
of all of the catch. Enough strong alcohol is then added to
the bottle to make a grade of about 75%". Surface and bot-
tom collections are usually preserved in 1% formalin, or in
75% alcohol after killing inpicro-sulphuric acid. The bottles
are all labeled with a gummed slip bearing the accessions'

18 Illinois State Laboratory of Natural History.

catalogue number, designation of the catch (whether surface,
bottom, vertical, or qualitative), station, killing agent, and
date. For convenience in handling they are then arranged
chronologically in racks, each holding six bottles. Data blanks
bearing the catalogue number are rilled out for each station
examination. The locality, date, time of day, the condition of
the sky, the direction and force of the wind, the stage of the river
and the amount and direction of its change in the twenty-four
hours preceding, the depth of the water, its turbidity (measured
by means of a porcelain disk), the disturbance of the surface,
the temperature of the air and that of the water at surface
and bottom, the current, the kind of vegetation and distance
from it, the manner of collection and means of preservation
of the catches made, — all are matters of regular record,
together with any other data peculiar to the collection which
could possibly interest the student of the plankton.

2. Quantitative Examination. — The quantitative exam-
ination of all of the plankton collections made at Havana has
been undertaken by the writer. Determination of the quan-
tity of the plankton by both the volumetric and enumeratiye
methods is necessary, owing to the presence, especially in
flood waters, of a large amount of silt. The gravimetric or
weighing method suggested by Zacharias ('95) is, as Ward
('96) has suggested, objectionable on account of the unknown
and presumably variable amount of water or alcohol present
in the still moist plankton. Many of the planktons at
Havana taken in silt-laden waters contain a considerable
amount of mineral and earthy matter. This constitutes a
further objection to the application of the gravimetric method
to our collections. A combination of the gravimetric and
volumetric method has been suggested by Ward ('96) ), in which
plankton of known volume is dried to a constant weight, burned,
the ash weighed and afterwards digested in concentrated
HC1, and the residue then washed, dried, and weighed. The
amounts of organic matter, of soluble salts (calcareous), and
of silicious matter can then be determined, and thus correc-
tions for sand-laden planktons can lie approximately com-
puted. It is evident that this method cannot be applied to

Methods in Plankton Investigations. 1!»

planktons rich in diatoms nor to the silt-laden planktons from
Havana, for a large part of the silt is debris of organic origin,
and the method above described does not differentiate the
organic material of the plankton from that of the silt. For
the quantitative investigation of these silt-laden planktons we
are thus practically limited to the enumerative method with
such incidental help as may be derived from volumetric
determination.

The volumetric determination has taken two forms, the
settling and the centrifugal methods. The former as used by
us is the same as that employed by Eeighard ('94) and Ward
('96a). The plankton is transferred to graduated tubes and is
allowed to stand twenty-four hours, when the amount of the
plankton settled at the bottom of the fluid, is read by the
graduations upon the tube. The tubes used are the carbon
tubes employed by chemists in the Eggert color test for the
estimation of carbon in steel. Our tubes in most frequent use
contain 25 and 50 cubic centimeters respectively, are about
twelve millimeters in inside diameter, and are graduated to
tenths of a cubic centimeter. For very small planktons
another tube, containing only ten cubic centimeters and
measuring six millimeters in inside diameter, was used. After
a series of measurements in the tubes above described it
became evident that a considerable error was involved in the
method. Kepeated measurements of the same plankton in
the same tube, after standing twenty-four hours, revealed a
considerable variation in the volume, as high as 30% in some
instances. Furthermore, planktons do not settle to an equal
density. Those composed of Rotifera or small Cladoeera (as
Chydorns) pack closely, while others containing filamentous
forms, as Oscillaria or Fragillaria, and those in which the larger
Entomostraea are predominant, settle very loosely. Thus the
determination of the volume of the plankton by the settling-
method does not give a uniform test of the amount of plankton
present. Furthermore, the process is a tedious one, especially
when large numbers of catches are to be handled.

The centrifugal machine (Plate VII.) was finally hit upon
as affording the best solution of the difficulties presented in

20 Illinois State Laboratory of Natural Hist

or

the settling method. In our machine we have utilized the
double arms, aluminum shields, and percentage tubes of the
Purdy Electric Centrifuge. The tubes contain 15 cubic cm.,
are graduated to tenths of a cubic cm., and the conical tips
permit the measurement of small planktons with accuracy.
The arms are borne upon an upright shaft which is driven by
a system of gears turned by means of a crank handle, one
turn of the crank giving 24 revolutions of the vertical shaft.
The direction and the speed are thus easily controlled by the
operator. The machine is clamped firmly to a table when in
operation. All parts of the machine, except those from the
Purdy Centrifuge, were devised by Professor W. H. VanDer-
voort, of the College of Engineering, and were constructed in
the University shops. Planktons are subjected to 2,000 revo-
lutions in two minutes, the motion at first being slow and
frequently reversed. The practical limit of compression by
this machine is thus reached, and successive measurements of
the same planktons show that its action is quite uniform.
The average amount of compression in a wide range of
planktons is about 50%, the volume by the centrifuge
method ranging from 30°o to 70% of that obtained by the
settling method. No discussion is needed to prove that the
more perfect the compression the more accurate are the volu-
metric determinations of the plankton. In this lies the main
argument for the use of the centrifuge in quantitative plank-
ton work. It also permits rapid work and is easily manipu-
lated. Our machine was completed in January, 1896, and
this is, I believe, the first application of the centrifugal
machine to quantitative plankton work. Cori ('96) has de-
vised a simple centrifugal machine for precipitation purposes
in zoological work, but it does not seem to be fitted for quan-
titative determination of plankton.

The machine employed by us was also in use for the precipi-
tation of living plankton from the water when Dolley's paper
('96) was received describing a large and powerful centrifuge,
"the planktonokrit," devised for the same work. It is only by
means of some such machine as this that a complete exami-
nation of the contents of the water is possible.

Methods in Plankton Investigations. 21

The enumerative or counting method involves a recogni-
tion of all of the different organisms composing the plank-
ton and the enumeration of the individuals of each spe-
cies present in a part or the whole of the catch. The number
present under a square meter of surface or in a cubic meter
of water can then be computed. This work is the basis of the
discussion of the seasonal range, local distribution, and
interrelations of the components of the plankton. The
method of counting at present employed by us is that described
by Rafter ('92) as a part of the Sedgwick-Eafter method of
microscopical examination of potable waters. This method
was employed by Professor J. I. Peck ('96), and I am indebted
to him for many kind suggestions on its use. The apparatus
consists of a brass cell, 20x50 mm. and 1 mm. in depth,
cemented upon a glass slide, a 1-cubic-cm. pipette, a mechan-
ical stage, and an area-stop for the eyepiece. After the
plankton to be examined is diluted to the desired degree and
thoroughly stirred, one cubic centimeter is transferred with the
pipette to the cell, in which one cubic millimeter underlies each
square millimeter of the cover-glass. By means of the
mechanical stage any desired cubic millimeter of the cell can
l)e placed in the center of the field. The area-stop is a circle
of black paper to be placed in the eyepiece, which cuts off
all the field except that visible through a square opening at its
center. This opening should be of such a size that with the
objective employed for the counting work exactly one square
millimeter of the cell is subject to inspection.

Ordinarily the counting of from ten to twenty squares
suffices for a fair test of the occurrence of organisms in plank-
ton ; but in the work upon the richly diversified plankton at
Havana we have found it necessary to increase the number to
fifty or even one hundred for the commoner and smaller species,
while for the larger and the rarer forms a great part or even the
whole of the catch must be examined.

Ukbana, Illinois, November 23, 1896.

22 Illinois State Labor a lory of Natural History.

BIBLIOGEAPHY.

Apstein, C.

'91. Ueber die quantitative Bestimmung des Plankton im Siiss-
wasser. In Zacharias's ''Die Tier- unci Pllanzenwelt des Siisswas-
sers." Bd. 1 1.. pp. 255-294. Leipzig1.

'92. Das Plankton des Siisswassers und seine quantitative Bestim-
mung. Schrift d. Naturw. Ver. f. Schlesw.-Holstein, Bd. IX., Heft
2, pp. 267-273.

'96. Das Siisswasserplankton, Methode und Resultate der quantita-
tiven Untersuchung. Mit 113 Abbildungen. 200 pp., 5 Tab. Kiel
und Leipzig.

Borgert, A.
'96. Ein einfacbes Netz zum Fischen von Plankton bei schneller
Fahrt. Zeitschr. f. wiss. Mikr., Bd. XIL, pp. 307-312.

Cleve, P. T.
'96. Microscopic Marine Organisms in the service of Hydrography.
Nature, Vol. 55, pp. 89, 90.
Cori, C. J.

'96. Ueber die Verwendung der Centrifuge in der zoologischen
Technik und Beschreibung einer einfachen Ilandcentrifuge. Zeit-
schr. f. wiss. Mikr., Bd. XIL, pp. 303-306.
Dolley, C. S.
'96. The Planktonokrit, a Centrifugal Apparatus for the Volumetric
Estimation of the Food-Supply of Oysters and other Aquatic
Animals. Proc. Acad. Nat. Sei. Phila., 1896. pp. 276-239.
Forbes, S. A.
'94. Illinois State Laboratory of Natural History, Champaign. 111.,
Biennial Report of the Director, 1S93-1894. 36 pp., 17 Pis. Chicago.
Giesbrecht, W.
'96. Leber pelagische Copepoden des Rothen Meeres, gesammelt
von Marinestabarzt Dr. Augustin Kramer. Zool. Jahrb.. Abth. f.
Syst., Bd. IX., pp. 315-328, Taf. 5, 6.
Hensen, V.
'87. Leber die Bestimmung des Planktons, oder des im Meere
treibenden Materials an PHanzen und Thieren. V. Bericht d.
Kommission zu wiss. Untersuchung d. deutschen Meere zu Kiel,
1887. XIL-XIV. Jahrg., pp. 1-107. 6 Taf.Nebst Anhang, pp.I.-NIX.
'95. Methodik der Lntersuchungen bei der Plankton-Expedition.
Mit 111 Kigg. im Text. 260 pp.. 11 Taf. und 1 Karte. Kiel und
Leipzig. (Ergebnisse der Plankton-Expedition der Hum bold t-
Stiftung. Bd. I. B.)
Peck, J.I.
'96. The Sources of Marine Food. Bull. U. S. Fish Coram., Vol.
XV., pp. 351-368, Pis. 64-71.

Methods in Plankton Investigations.

23

Rafter, G. W.
'92. The Microscopical Examination of Potable Water. No. 103,
Van Nostrand's Science Series. 160 pp., 5 Pis., New York.
Reighard, J. E.
'94. A Biological Examination of Lake St. Clair. Bull. Mich.
Fish Comm. No. 4. 60 pp., 2 Pis., and map.
Ward, H. B.

'96. A New Method for the Quantitative Determination of Plank-
ton Hauls. Proc. Am. Micr. Soc, Vol. XVII., pp. 255-260.
'96a. A Biological Examination of Lake Michigan in the Traverse
Bay Region. Bull. Mich. Fish Comm., No. 6. 100 pp., 5 Pis.
Zacharias, O.

'93-'96. Forschungsberichte aus der Biologischen Station zu Plon,

Theil I.-IV. Berlin.
'95. Ueber die Wechselnde Quantitat des Planktons im Crossen
Planer See. Forschungsberichte a. d. Biol. Station zu. Plon, Theil
III., pp. 97-117.

♦EXPLANATION OF PLATES.

Plate I.

Fig. 1. Longitudinal section of plankton net. X Lj.
c.b.l. Cone of butchers* linen, s.l. Stay-line.

Fig. 2.

Fig. 8.

cd. Cord. sm.

Seam.

cs. Cover-strip. s. n.

Silk net.

e. Eye. st.

Strip fastening cone to stay

h. p. Head-piece of bucket. th.

Thread.

1. e. Lower eye of wire stay. u. e.

Upper eye of wire stay.

1. r. Lower wire ring. u. r.

Upper ring.

n. c. Net clamp. w. s.

Wire stay.

Seam in silk net. X 2.

a. Backstitch. b.

Fell.

Plate IT.

-Longitudinal section of head-piece of plankton bucket. X 1.

e. Eye. s.

Silk.

h.p. Head-piece. s. 1.

Stay-line.

n. c. Net clamp. t. s.

Thumb-screw.

m. Thread, screwing w.n.c.

Wing of net clamp.

into n of Fig. 4.

*Plates I., II., III., and IV. were drawn by C. A. Kofoid and inked by Miss L. M. Hart.

24 Illinois Slate Laboratory of Natural History.

Fig. 4. — Longitudinal section of plankton bucket. X 1.

■ 6.

Bottom.

pi.

Plata of clamp.

ba.

Base.

pi.

Pillar.

b.c.

Band clamp.

s.

Silk.

'/. p.

1 trip-point.

sc.

Screw.

e.

Eye.

sh,

Shoulder.

n.

Thread, serewin

g

on m,

w.

Window.

Fig. :?.

x-y.

Line of section shown

V-

Plug.

in Fig. 5.

Fn;. 5.— Cross-section of plankton bucket at x-y, Fig. 4. X 1. Letter-

Plate III.

ing as in Fig. 4.

Fig G. — Carriage, with suspended plankton
a b c. Line of separation of s.

carriage. s.l.l,s.l 2,8.1.3.
/in. Bucket.

c. r. Carriage rope. s. I. 4.

d. I. Draw-line. sn.
h. Hook. th.
k. End knot. w. s.
I. Lead. w xy z.

p. Front pulley.
p.' Hear pulley.

Fk;. 7. — Operation of the oblique haul. X ;
h. r. Brace rope. e. s.

b. s. Brace stake. in.
/it. Boat. m. s.

c. r. Carriage rope befoi'e n.

release. n.'

c. r.' Carriage rope after r. I.

release. sur.

d. I. I ) raw-line.

net. X i
Staple.

Stay-lines from the draw
line to net and bucket.
Stay-line to carriage.
Snap.
Thread.
Wire stay.

Screw-eyes for attach-
ment of net.

sos-
End stake.
30-meter knot.
Main stake.
Xet before release.
Xet after release.
Release line.
Surface of water.

Plate IV.

FlG. 8. Plankton net used with the pump, shown in longitudinal
section.

X >,.

b. I. Butchers' linen.

con. Connector.

cov. Cover.

f. Foot.

.//. Float.

h. Handle.

i. c. Inner cone or spreader.

i. n. Inner net.

o. n. Outer net.

p. Pivot for support of ring.

ri. Ring for inner net.

st. Stay for inner cone.

(. I). Turn button.

t. .*>•. Turn support.

tr. Trough.

w. Wins:.

Methods iii Plankton Investigations. 2o

Fi<;. 9. — Rim of cover of net, showing clamp for holding cover in
place. X 1.

c Clamp, in position. i. w. Inner wall of trough.

c'. Clamp, released. o. to Outer wall of trough.

coo. Cover. str. Strap of clamp.

/. Foo.t of cover. w. Wing of cover.

Fie. 10. — Same, showing method of fastening outer silk net; cover
partially removed. X 1.

//. I. Butchers' linen. o. n. Outer net.

cd. Cord.
Other lettering as in Figure 9.

Plate V.
The plankton pump. X iV

Plate VI.
The plankton pump in operation.

Plate VII.
The centrifugal machine. X J^.

Plate I.

cs.
lr.~

Plate II.

•5*.

Plate III.

r-~

±1

£

Plate IV.

'> v' V' "s' *%/ " **'

Plate V.

*

Plate VI.

Plate VII.

BULLETIN

OF THF.

Jllinois 2tate Laboratory

OF

NATURAL HISTORY,

Urbana, Illinois.

VOLUME V.

ARTICLE II. — A CONTRIBUTION TO A KNOWLEDGE OF
NOR Til AMERICAN FRESH- \VA TER CYCLOPID.E.

By ERNEST R. FORBES, B. S.

Illinois State Laboratory of Natural History,
URBANA, ILLINOIS.

1897.

State Laboratory of Natural History

LABORATORY STAFF

Professor Stephen Alfred Forbes, Ph.D.,
Director of State Laboratory and State Entomologist.

Charles Arthur Hart,

Systematic Entomologist and Curator of Collections.

Frank Smith. A. M.,
Assistant Zoologist.

Charles Atwood Koeoid, Ph. D.,

Zoologist, and Superintendent of Biological Station.

Charles Christopher Adams. B. S.
Entomological Ass istant.

Ralph Waldo Bralcher, B. S.',

Entomological Assistant.

Mary Jam; Snyder,

Secretary.

Henry Clinton Forbes,
Business Agent and Librarian.

Lvdia Moork Hart,
Artist.

Article II. — A Contribution to a Knowledge of North Ameri-
can Fresh-water Cyclopia" ce.* By Ernest B. Forbes.

INTRODUCTION.

During the past twenty years the fresh-water Copepoda of
North America have received considerable attention from a
small number of pioneer investigators, but as yet no one
has made a careful comparative study of authentic repre-
sentatives of the species described by them. It is my pur-
pose in this paper to make a first contribution to a revision
of the nomenclature of this genus, such as is usually found
necessary when, for the first time, the work of unaffiliated
investigators is brought into careful comparison. I have
embodied in this paper, not a complete revision of the Ameri-
can species of Cyclops, but only such results of my study on
that group as have now been brought to a satisfactory eon-
elusion.

The excellent work of Claus and Schmeil in Germany has
greatly modified our ideas of the comparative value of certain
specific characters; and the revision of the European species
of this genus in Schmeil's monograph! has made it possible
for me to begin a revision of the American species along the
same general lines.

The receptaculum seminis, which has recently come to be
considered as the most important structure for purposes of
specific distinction, has received almost no attention from
American investigators; but after studying this organ in
series of specimens of closely related forms from a great
variety of widely separated situations, I have been forced to
include under the same species name forms which have here-
tofore been considered valid species, and to discard as local
or at the most varietal differences, distinctions which have

*This paper was prepared in the course of undergraduate study at the University
of Illinois, and was accepted by the Faculty of the University June 7. 189", as a
thesis for the degree of Bachelor of Science in Zoology.

HDeutschlands freilebende Siisswasser-Copepoden, I. Teil: Cyclopidae.

28 Illinois State Laboratory of Natural History.

been used for the separation of species by our most emineni
workers.

I have made a vigorous effort to obtain authentic examples
of all the species considered; and while I have been in
general successful, f have been forced in the case of Herriek's
species to depend wholly upon the collections to which I have
had access myself, and the identifications of other men who
have collected in Herriek's localities.

The collections which I have had an opportunity to study
in the preparation of this paper are those of the Illinois
State Laboratory of Natural History, extending over a period
of more than twenty years ; several made under the auspices
of the l". S. Fish Commission in Wisconsin and in the far
West ; collections made in Florida by Mr. Adolph Hempel and
in Manitoba by Prof. L. S. Ross, of Drake University, Iowa,
and kindly loaned me by these gentlemen ; and all of the col-
lections made at the Lllinois Biological Station at Havana,
Illinois. This material is from the following states : Massa-
chusetts, Florida, Ohio, Indiana, Michigan, Wisconsin, Illi-
nois, Kentucky, Iowa, Missouri, Minnesota, Idaho, Wyoming,
Washington, and Oregon, and from Manitoba, in the Domin-
ion of Canada.

The localities represented by these collections are widely
distributed and of great variety. They extend from the
New England states in the northeast to Florida in the south-
east, to Manitoba on the north and to Washington and Oregon
in the northwest, and from the sea-level in Massachusetts
and Florida to some of the highest lakes in the Rocky and
Sierra Nevada Mountains. In these collections are Cyclops
from small temporary points of a few weeks' duration, from
the greatest lakes and rivers in the world, and from a great
number and variety of situations intermediate in character.
They have been made in every season -of the year; and
although the southwestern part of the United States is not
represented, they probably contain nearly all of the American
species of the genus.

The results published in this paper do not, however, repre-
sent an exhaustive study of the distribution of the species

North American FresJi-tvatcr Cyclopidce. 29

treated, and a more careful inspection of the collections
examined would doubtless make evident many interesting
facts with regard to the details of distribution.

I have had, for comparison with our American forms,
named European specimens from S. A. Poppe, Prof. G. 0.
Sars, and Dr. Otto Schmeil. Those from Poppe were received
in 1883 by Dr. S. A. Forbes and represent the following
species : Cyclops agilis, helgolandicus, pulchellus, signatus,
and strenuus. During the present year Dr. Schmeil has
sent specimens of Cyclops fuscus, varicans, leuckarti, albidus,
strenuus, serrulatus, viridis, and phaleratus, while Prof. Sars
has sent to Dr. Forbes examples of the species of the follow-
ing list : Cyclops viridis, nanus, robustus, hyalinus, oithonoides,
albidus, fuscus, v emails, macrurus, gigas, leuckarti, insignis,
bisetosus, fimbriatus, bicuspidatus, a/ffinis, crassicaudis, phal-
eratus, bicolor, scutifer, serrulatus, varicans, dybowskii, l<i-
custris, and strenuus. These authoritatively named European
specimens have given me the opportunity for comparative
studies of American and European Cyclopidse — the first, so
far as I am aware, which have been made in America.

The mere study of American specimens of species first
described from European material has not given me, in many
cases, the data necessary for a critical judgment of the
synonymy of such forms, and I have consequently accepted,
as a rule, the determinations of Claus and Schmeil, whose long
experience and critical and exhaustive work give to their con-
clusions the highest authority.

The genera and subgenera of Clans ('93a, '93c, '93d) seem
to me very convenient subdivisions of this varied genus, and
the species of this paper have, so far as possible, been ar-
ranged under Claus's groups. I find it necessary, however,
to create two new subgenera, Orthocyclpps and Homocyclops,
for the two American species C. modestus and ('.titer. The
descriptions are incomplete, however, because of the lack of
knowledge concerning the males of these two species.

Certain characters used by some of our American investi-
gators for specific distinction have proven unreliable, and a

30 Illinois State Laboratory of Natural History.

brief discussion of their comparative values may be of service
to beginners in the study of this genus.

The number of antennal segments may be depended upon
as fairly constant. It never varies in adult specimens by
more than a single segment, and then only in the case of a
very few species. The length of the antennae, while constant
in some species, is remarkably variable in others, notably in
C. serrulatus. The proportionate length of antennal seg-
ments does not always remain the same in species in which
the antenna is variable as to length. Sensory structures
and the hyaline plates of the distal antennal segments are
reliable characters.

In certain species, C. phaleratus for instance, the propor-
tions of the stylets are quite constant, but in ('. viridis, serru-
latus, and bicuspidatus , the range of variation is very great;
consequently such measurements are not of the highest spe-
cific value. The apical bristles of the stylets are not very
variable as to comparative lengths, but the minute details of
their structure are not constant. This fact is illustrated by
the variation in the shape of the outer apical spine of ( '.
viridis var. brevispinosus (PI. XL, Fig. 1).

The armature of the swimming feet is of considerable value ii i
certain cases, and is constant as a rule. Sometimes, however,
the presence or absence of a spine or seta is not accompanied
by other perceptible differences. The general character of
the armature with regard to strength, etc., may usually be
relied upon ; but I have often seen in a single specimen all
of the gradations between spines and seta^, and it would be
impossible from this character to say which of the two nanus
should be applied.

Of the easily observable structures, the fifth foot is the
most valuable for specific distinction. Slight variations
sometimes occur in the shape of the segments and in the
comparative lengths of spines and setre, but, as a rule,
characters drawn from this appendage are quite constant.

Of all the specific characters, the most valuable are those
derivable from the receptaculum seminis. Unfortunately, it
is often very difficult to see this organ distinctly, especially if

North American Fresh-water Cyclopidce. 31

the specimens have been killed in alcohol ; but this difficulty
is readily avoided by the use of formalin as a preservative.
A 1% solution is amply strong, and the osmosis of fluids is
not rapid enough to rupture the receptaculum, as is the case
when strong alcohol is used. Some slight differences in the
appearance of the receptaculum are due to stage of sexual
activity of the animal. In the case of C. viridis var. insectus
such a difference is noticeable. In Fig. 3, PL XL, the solid
line represents the outline of the empty receptaculum ; the
dotted line, the shape when fully distended.

Through the generosity of Prof. G. 0. Sars and Dr. Otto
Schmeil, I have received much valuable material from Europe,
by means of which I have been able to compare American and
European forms. I wish also to acknowledge the assistance
received from my co-laborers, Messrs. Pi. W. Sharpe and F.
W. Schacht, and also to thank Prof. L. S. Eoss, of Drake
University, and Mr. Adolph Hempel, now of the Museu
Paulista, Brazil, for the courtesies shown me in the loan
and collection of material. A very great part of the credit
for such portions of this paper as may be of value is due to
my instructor, Dr. S. A. Forbes, whose kind supervision and
encouragement have constantly guided and aided me in this
work.

Genus Cyclops 0. F. Muller.
Subgenus Cyclops s. str. Glaus.
Cyclops leuckarti Claus. (PL VIII., Fig. 1-3.)

Cyclops leuckarti, Claus, '57, p. 35, PI. I., Fig. 4; PJ. II., Fig. 13, 14.
Cyclops leuckarti, Schmeil. "92, pp. 57-64, PI. III., Fig. 1-8.
Cyclops leuckarti, Herrick and Turner, '95, pp. 90-98, PI. XVI.;
XVIII., Fig. 1, A-J: XXIV., Fig. 2-0.

This species is of medium size, but is rather more slender
than usual (PL VIII., Fig. 1). The cephalothorax is broadest
at the first segment and tapers conspicuously toward the
posterior end. The length as compared to the breadth is
about as eleven to six.

The abdomen is long and slender, but the stylets are short,
being one third or one fourth as broad as long. They are

32 Illinois State Laboratory of Natural History.

not markedly divergent, and there is no conspicuously broad
space between their points of attachment. The outer apical
seta is delicate and as long as the stylet. Of the remaining
three, all of which are well developed, the middle one is the
longest and the innermost the shortest.

The first antennae are long and slender, terminating at the
middle or end of the third cephalothoracic segment. The last
two segments are both long, but the sixteenth (penultimate)
is the longer of the two. These two segments bear broad
hyaline plates (PI. VIII., Fig. 2). The margin of the one
borne by the sixteenth segment is entire, but the one on the
following segment besides being finely serrate its whole length
is deeply notched near its distal end. This notch is very
characteristic of the species. On the twelfth segment is the
usual sense-club.

The posterior border of the second segment of the outer
maxillipeds usually bears a series of rounded transverse
ridges, which extend in a series from the proximal end of
the segment nearly to the other end. The presence of this
structure seems characteristic of the European form, but may
rarely be entirely absent in American specimens.

The setae and spines of the swimming feet are conspicuously
long and strong. The margin of the connecting lamella of
the fourth pair of feet bears a pair of sharp teeth. The
feet are armed as follows: — First pair: outer ramus, two
spines, four seta? ; inner ramus, one seta, one spine, four setae.
Second and third pairs : outer ramus, three spines, three
seta'; inner ramus, one seta, one spine, four setae. Fourth
pair: outer ramus, three spines, four seta-; inner ramus,
one seta, two spines, two seta-.

The rudimentary foot (PL VIII., Fig. 3) is two-segmented.
The basal segment is short and roughly quadrate, with a long
plumose seta borne on its outer angle. The distal segment is
long and slender. On the middle of the inner side is borne a
long pectinate spine, and at the tip a seta of about equal length.

The receptaculum seminis is large and elliptical, and the
anterior part, from which proceed the canals, is laterally
expanded.

North American Fresh-water Cyclopidce. 33

The egg-sacs are carried at a broad angle from the
abdomen.

In length the female varies, in American specimens, from
.95 to 1.5 mm.

The color is always inconspicuous and may be light blue
or gray.

This is in general a very rare species in America. I have
never, until recently, found it in collections in any great
numbers, but in twos or threes at long intervals. I lately
found it, however, in immense numbers in a collection made
in August, 1896, from Fox River, Illinois. It is found in
just such situations as is C. edax, but usually in very much
smaller numbers. I have seen this species in collections
from Lake Harriet, Minnesota; Delavan Lake, Wisconsin ;
and from Quiver, Flag, and Dogfish lakes, and the Sangamon
and Fox rivers — all in Illinois. It is widely distributed in
the lakes and rivers of America, but has not been reported
from temporary pools.

Cyclops edax Forbes. (PI. IX., Fig. 1-3.)

Cyclops edax. Forbes, '90a, p. 709. PI. III.. Fig. 15; IV.. Fig. 16-19.
Cyclops annulatus, Wierzejski, "92, pp. 237. 238. PI. VI., Fig. 14-1S.
Cyclops leuckarti, Marsh, '93. pp. 209-211, PI. IV.. Fig. 17: V..
Fig. 2-6.

SYNONYMY AND COMPARISON.

This form has been confounded with ('. leuckarti Claus,
from which, however, it is very easily separated by a careful
comparison of specimens.

The original description of this species was incomplete in
that no mention was made of the sense-club on the twelfth
antenna! segment, or of the hyaline plates of the sixteenth
and seventeenth segments. As in ('. leuckarti (Pi. VIII.,
Fig. 2), the plate of the sixteenth segment has an entire edge,
though the plate itself is much narrower. The plate of the
seventeenth segment (PI. IX., Fig. 2) differs markedly from
the corresponding structure in ('. leuckarti. in ('. edax the
edge of the plate is cut by a series of deep oblique notches,
forming teeth which point strongly backward. These notches

34 Illinois State Laboratory of Natural History.

are deepest near the distal end and thence diminish in hoth
directions. The segment itself is deeply excavated within and
the plate merely completes its usual outline, while in ( '.
leuckarti the segment is but slightly excavated and the broad
plate projects far beyond the outline of the segment.

In C. edax the last two segments are equal, while in
C. leuckarti the sixteenth segment is a fourth longer than
the last.

The two pointed teeth of the connecting lamella of the
fourth feet, which are characteristic of C. leuckarti, may
sometimes be present in ('. edax, though they are in this
species not so sharp as in the other and are placed farther
apart.

The transverse ridges of the outer maxillipeds, which
Schmeil describes as characteristic of C. leuckarti, are usually
absent in ('. edax and when present are quite inconspicuous.
They begin, as in C. leuckarti, at the proximal end of the seg-
ment, but soon fade away.

The abdominal stylets in ( '. edax are more divergent than
in C. leuckarti, and are inserted farther apart.

The fifth feet (PL IX., Fig. 3) are markedly different. In
C. edax the two seta- of the distal segment are parallel and
the surfaces to which they are attached are at right angles to
the long axis of the segment. In ('. leuckarti the surface of
attachment of the lower seta is at an angle of about forty-five
degrees to the long axis of the segment. Furthermore, the
whole distal segment is broader in ( '. edax.

There are differences in general proportions and appear-
ances which make it very easy for one well acquainted with
these species to distinguish them at a glance, but these
differences can only be demonstrated by a long series of
measurements. The structure of the receptaculum scminis
is identical in the two species, so far as 1 can tell; but
though the species are undeniably closely related, I think
that on account of the above-mentioned differences they
should be kept distinct.

Cyclops edax may possibly be the same as ( '. leeuwenhoekii
Hoek, which Schmeil has made synonymous with ( '. leuckarti.

North American Fresh-water Cyclopidce. 35

If the figures as published by Hoek are correct, C. edax differs
from ('. leeuwenhoekii in the following particulars : In edax
the labrum has eleven teeth; in leeuwenhoekii it has but ten.
In edax the seventeenth antennal segment is longer than the
sixteenth; in leeuwenhoekii the sixteenth is longer than the
seventeenth. In edax the first foot, outer ramus, bears on the
distal segment two spines and four sets; in leeuwenhoekii the
corresponding segment bears three spines and two sets. In
edax the inner margin of the distal segment of the fifth foot
is not incurved as in leeutvenhoekii. In edax there are never
less than five prominent teeth in the lamella of the seven-
teenth antennal segment; in leeuwenhoekii but three are fig-
ured. The transverse ridges on the maxilliped of leeuwenhoekii
are more prominent, smaller, and more numerous than in
edax.

DISTRIBUTION'.

This form is very abundant and widely distributed in
America. I have found it, among many other places, in col-
lections from the Mississippi and Illinois rivers ; from various
lakes and ponds of Illinois ; from Sister Lake and Lake
Butler in Florida ; from Spirit Lake and Lake Okoboji in
Iowa ; and also from lakes Michigan, Superior, Winnebago,
and Michigamme, and Yellowstone, Delavan, and Cedar
lakes. It was described in 1892 by Wierzejski from the
Argentine Republic under the name of C. annulatus.

SPECIFIC DESCRIPTION".

The cephalothorax is oval, compact, and broadest before
the middle. The first segment is as long as the remainder.
The last thoracic segment is scarcely broader than the first
abdominal.

The first abdominal segment is very long, equaling the fol-
lowing three. The last segment is the shortest and is bordered
by the usual row of spinules. The preceding segments are
bordered posteriorly by coarse serrations, more pronounced
and regular on the ventral than on the dorsal side. The
stylets are one third as wide as long, and in a long series of
measurements of individuals from the most widely separated

36 Illinois State Laboratory of Natural History.

localities this proportion only varied by one thirtieth. The
inner margins of the stylets are filiate. The lateral spine is
a trifle behind the middle ; the outer seta about as long as
the ramus; the inner live sixths the length of the third from
within ; the latter two thirds as long as the second.

The antennae terminate between the end of the second and
the end of the third segments. There is a sense-club and
seta on the twelfth segment. The sixteenth segment is never
longer than the seventeenth. The sixteenth and seventeenth
segments bear hyaline plates (PL IX., Fig. 2), that of the six-
teenth segment being very narrow, with its edge entire, and
that of the seventeenth broader, with its edge deeply notched.
The notches are most pronounced near the distal end and fade
away in each direction. The intervening teeth point strongly
toward the base of the antenna. The segment is excavate on
the inner side, and the hyaline lamella completes the normal
outline of the segment by filling up the depression.

The swimming feet are armed as follows : —First pair : outer
ramus, two spines, four setae; inner ramus, one seta, one
spine, four seta1. Second and third pairs : outer ramus, three
spines, three seta-; inner ramus, one seta, one spine, four
seta-. Fourth pair: outer ramus, three spines, four setae;
inner ramus, one seta, two spines, two seta1.

The feet of the fifth pair (PL IX., Fig. 3) are two-segmented.
The distal segment bears two parallel setae, the outer one of
which is set at about the middle of the segment. This seta is
most strongly spinulose on the outer side, while the distal one
is plumose on both sides.

The receptaculwm seminis is large and elliptical, the long
axis corresponding to the long axis of the segment. The
lateral canals are connected with the expanded upper portion.
The receptacnlum is almost exactly as in C. leuckarti.

The egg-sacs are elliptical and stand out from the abdomen.

The usual length of the female is 1.2-1.4 mm.

North American Fresh-water Cyclopidce. 37

Cyclops viridis Jurine. (PI. X., Fig. 1-3.)

Monoculus quadricornis var. viridis, Jurine. '20. p. 46, PI. III., Fig. 1.
Cylops viridis, Schmeil, "92, pp. 97-101, PI. VIII., Fig. 12-14.

SYNONYMICAL DISCUSSION.

Though the subdivision of the viridis group here proposed
is not entirely satisfactory and may not be final, still after
long study of more extensive collections than have heretofore
been brought into comparison in America, I have arrived at
some conclusions with regard to the subdivision of the group
which may be of service to any one following me in the study
of the American Cyclopidce.

C. rifi dis occurs in America, so far as I now know, only in
the larger forms of that species. C. ingens (Herrick, '82a)
seems to me the only described form corresponding very
nearly to the European viridis, and 1 therefore regard it as
the American representative of that species. It is considered
by Marsh as equivalent to C. americanus (= ('. insectus), and
Herrick himself says that it is distinguished from this form
only by its greater size. From Fig. 3, PI. XXV., in Herrick
and Turner '95, I judge that C. ingens is synonymous with
( '. viridis, thus representing in America the maximum devel-
opment of the species, as does ('. gigas in Europe.

Dr. Forbes has for years recognized such a form as ('.
ingens, and it is to be found in the temporary ponds of central
Illinois. The species was in 1870 given the manuscript and
label name of ('. levis, but the description was never pub-
lished. This ('. ingens or levis differs from specimens of
viridis received from Sars and Schmeil only in its greater
size, and from specimens of ( '. gigas received from Sars only
in some of the more minute details in the outline of the two
segments of the fifth foot. The two forms gigas and ingens
are undoubtedly typical C. viridis. It is of interest to note
that in both of these large forms the small spine of the fifth
foot is not separate from the segment, but is a process of the
segment itself. Schmeil states that in C. viridis it may or
may not be separated from the segment by a suture. ( '.
ingens is the only form in America having the stylets ciliate

38 Illinois State Laboratory of Natural History.

internally. In the smaller forms most closely related to
viridis, in which the small spine of the fifth foot is always
separate from the segment, the inner border of the stylet is
never filiate, though in rare cases the whole inner aspect of
the stylet seems to be set with the shortest of hairs, only
visible on account of their points of attachment.

The first species closely related to viridis described in
America was C. insectus, described in 1882 by Dr. Forbes.
Later in the same year C. L. Herrick described a very closely
related form under the name of C. parens. This species has
been most profusely figured by Herrick, but his drawings of
the fifth foot are so very different as to make it impossible to
say where it belongs in this most perplexing group. I have
failed in my attempts to obtain authentic examples of ( '.
parens, but have found a few specimens answering to Herrick's
description in a temporary pond in Urbana, Illinois. I can-
not, however, vouch for their identity. In the same collec-
tion I found other specimens differing from those above men-
tioned only in the presence of the additional spine of the first
and fourth feet — the feature separating this form from C.
insectus.

So variable is C. insectus, found, as it is, in an endless vari-
ety of situations and localities, that the lack of a single spine
on the distal segment of the outer ramus of the first and
fourth feet is. not sufficient ground for the distinction of even
a variety, for I find, as does Dr. Schmeil, that the armature
of the swimming feet is not in all species absolutely con-
stant.

In Herrick and Turner '95 (PI. XXXIY., Fig. 5), is a draw-
ing of the fifth foot of ('. parens. This drawing was evidently
made with somewhat greater care than were those on Plates
XX. and XXL, and represents approximately the same ap-
pendage in ('. insectus.

Cyclops amerieanus, described by C. I). Marsh in 1892,
proves on examination of authentic examples to be synony-
mous with C. insectus. Undoubtedly C. amerieanus of Herrick
and Turner is identical with Marsh's form and is consequently
also a synonym of insectus.

North American Fresh-water Cyclopidee. 39

Cragin in 1883 figured a form as C. viridis and stated that
it was found at Cambridge, Mass. This form is C. ins,, -tux.
Cyclops miiangulatus, described as new in the same article, is
also C. insectus, the only apparent difference being a very
slight one in the armature of the swimming feet.

Cyclops brevispinosus, described in 1884 by Herrick, differs
from C. insectus principally in the shape of the outermost
terminal spine of the stylet. In the type of brevispinosus this
spine is very broad, heavy, and knife-like in character. I have
seen considerable variations in the shape of this spine and
have observed all of the gradations between it and the usual
slender spine of C. insectus. I think, however, that C. brevi-
spinosus should be considered as a good variety. The follow-
ing description of ('. viridis is a translation of the description
by Schmeil ('92).

SPECIFIC DESCRIPTION.

"The two axes of the cephalothorax compare about as two
to one ; the ratio of the length of the cephalothorax and the
abdomen is almost the same. The cephalothorax tapers about
equally in both directions; each segment projects laterally
far beyond the following. Seen from the side, the posterior
angles of all the plates of the cephalothoracic segments are
rounded, those of the first and fifth segments being at first
straight, then convexly produced at their ends ; and the
second, third, and fourth segments, in which such promi-
nences are lacking, are slightly lengthened posteriorly.

" The first abdominal segment is but little broadened in its
anterior part. The posterior borders of all the segments are
coarsely serrate, with the exception of the last, which bears
a fringe of spinules.

"The stylets are often two, three, or even four times as long as
the last abdominal segment. The innerborder is always ciliate.
The lateral spine is set beyond the middle of the outer edge.
The outermost of the apical bristles (all of which are nar-
rowly plumose) is not, as is the case with most species,
changed into a spine, and is exceeded in length by the inner-
most. Both middle bristles are well developed, but their

40 Illinois State Laboratory of Natural History.

proportional lengths arc not entirely constant. Usually the
smaller of the two is as long as the abdomen, and the larger

exceeds it in length. They are often of exactly the same size,
and often the difference is considerable.

" The first antennae are seventeen-segmented, usually reach-
ing hack only to the posterior border of the first cephalo-
thoracic segment. The last three segments are but little
longer than those immediately preceding. The twelfth seg-
ment bears a projecting sense-club.

"The remaining pairs of appendages, with the exception of
the rudimentary feet, present no notable characters and hence
arc systematically valueless. Spinous armature of swim-
ming feet, 2. 3. 3. 3.

"The rudimentary foot (PL X., Fig. 2) is two-segmented.
The extraordinarily broad basal segment bears on the Lower
outer angle a long plumose hair. On the lower border,
immediately at the inner angle of this segment, is attached
the relatively small distal segment, which bears at its distal
end a plumose hair and at the inner margin a very minute
spine.*

"The receptaculum seminis (PI. X., Fig. 3), the two small
lower divisions of which terminate in the lateral canals, are
usually covered by the larger, more or less heart-shaped upper
division. Exact knowledge of the structure of this organ is
usually first possible after the application of delicate pressure.

" The large elliptical egg-masses stand off from the abdomen
at a very sharp angle.

"The color is usually a dirty green, seldom a light brown.
In a pool in Diemitz I met with quite fire-red examples.

" The size is very variable. With individuals 1.5-2 mm. one
finds others 2.5, 3, 4, or even 5 mm. in length.

"The clearest and simplest recognition characters are the
rudimentary feet and the structure of the receptaculum
seminis."

*In a foot-note Schmeil states that Claus, Hoek, Richard, and Lande, consider

this spine as a process of (he segment, that Ulianin figures it as separated from the
segment by a suture, and that lie. Schmeil, had observed it both ways.

North American Fresh-water Cyclopidce. 41

Var. brevispinosus Herrick.
(PL XL, Fig. 1 and 2.)

Cyclops brevispinosus, Herrick. '84, p. 148, PL S. Fig. 7-11.
Cyclops brevispinosus, Marsh, '93, pp. 205-206, PI. IV., Fig. 11. 12.
Cyclops brevispinos us, Herrick and Turner. '95, p. 95, PI. XXIII.,
Fig. 1-4: XXIV., Fig. 7-12.

This species of Herrick's, which I reduce to a variety, is dis-
tinguished from typical C. viridis, as follows: 1. By the
form of the outer terminal spine of the stylet, which is short,
broad, and knife-like. This form of spine is connected in
series (PL XL, Fig. 1) with the slender spine of the variety
insectus. 2. By the fifth foot (PL XL, Fig. 2). In this
appendage the small spine is never a part of the segment as it
may he in the European viridis and always is in the American
form. This spine is also longer than in riridis and is lanceolate
in shape. 3. By the armature of the swimming feet. The
spines of these appendages are extravagantly long and heavy.
While at first sight these differences might seem sufficient for
the complete separation of the two forms, the distinguishing
characters are in most species of Cyclops so variable that it
seems to me best to consider brevispinosus as merely a variety.

The receptaculum sen/in is is as in insect us.

I find this variety in collections from Lakes Michigan,
Manitoba, Okoboji, (Iowa) ; and from Lake Winnebago, Green
Lake, and Lake Geneva in Wisconsin; from Swan Lake in
Montana, and Lake Pend d'Oreille in Idaho ; from the Detroit,
Calumet, and Illinois Livers; and from Sand, Fox, Quiver,
Dogfish, Phelps, and Thompson's lakes — all in Illinois. It
is never especially abundant but seems to lie quite generally
distributed.

Var. insectus Forbes.
(LI. XL, Fig. 3-6.)

Cyclops insectus, Forbes, '82a, p. U49. PI. IX.. Fig. i>.
Cyclops parous, Herrick, *S2a, p. 229, PI. VI.. Fig. 12-15.
Cyclops insectus, Herrick. '84, pp. 151, 152, PJ. U, Fig. 9.
( 'yclops viridis, Cragin, '83, p. 68, PI. IV., Fig. 8-16.
< 'yclops unlangulatus, Cragin, '83, p. 71, PI. IV., Fig. 17.
Cyclops insectus, Sehmeil, '92, p. 95.

4'2 Illinois State Laboratory of Natural History.

Cychps parcus, Marsh, "93, pp. 208, 209. PJ. IV.. Fig. Ki: V.. Fig. 1.
Cyclops americanvs, Eerrick and Turner, '95, pp. 91, 92, PI. XIV..

Fi<;. 1-9.
Cyclops parcus, Herriek and Turner. '95, pp. 03, 94, PJ. XX.. Fig.

12-15: XXI.. Fig. 22: X X 1 1 1.. Fig. 8 : X X X .. Fig. 1-8.

This variety represents in America the smaller members of
the viridis relationship. It is distinguished from viridis in
Europe by the lack of cilia on the inner side of the stylets,
by some slight differences in the shape of the receptaculum
seminis (PI. XL, Fig. 3), and by the different shape of the fifth
foot. The receptaculum seminis differs in that the upper part
is larger in proportion to the segment in insectus and is some-
what different in outline. In the fifth foot (PI. XL, Fig. 4
and 5), the outer distal angle of the basal segment is much
less produced and the spine of the distal segment, which is
always separated from the segment by a suture, varies in
length from a minute barbule to a long heavy spine, longer
than the segment itself. The armature of the swimming feet
(PI. XL, Fig. 6) is not constant and is not in C. viridis useful
even as a varietal distinction.

This brief diagnosis includes under the varietal name
insectus, forms which differ superficially to a marked degree,
but after continuous work for more than a year with very
large collections from all parts of the United States I have
been forced to throw ^hem all together for the simple reason
that there is no one set or combination of characters suffi-
ciently invariable to subdivide the group.

The antenna^ of this variety usually terminate at or before
the end of the first cephalothoracic segment, but in examples
from Alturus Lake, they reach the middle of the second seg-
ment.

The stylets of this variety vary considerably in proportions.
The following series of measurements of nine specimens
shows the extent to which this character varies. On the left
is a list of the localities from which the specimens were
obtained and on the right are figures representing the propor-
tion between the length and breadth of the stylet.

North American Fresh-water Cyclopidcc. 43

Pond, Normal, 111.. . . . . 63:9

Creek, AVyoming, . . . . 52:11

Lake Winnebago, . . . . 52:8

Lake Superior, . . . . 44:9

Illinois River, . . . . . 40:9

Mississippi River, . . . . 37:8

Pond, Urbana, 111 34:7

Pond, Yellowstone Park, . . 33:9

Slough, Manitoba, . . . . 33:9

There is a very peculiar semicircular indentation of the
outer side of the basal segment of the inner ramus of the
fourth foot often present in this variety, hut it may he
entirely absent or only present in a slight degree of develop-
ment. Whatever the function of this peculiar indentation, it
does, not seem to he essential to the animal.

The fifth foot varies but little in the basal segment but the
distal segment is peculiarly variable. In one extreme, which
reaches its highest development in the Illinois River, this seg-
ment is very short, its length compared to its breadth being
as 3.5 to 3, and its sides strongly outcurved. The small
spine is situated some distance from the end of the segment
and is very small indeed. Examples of the other extreme
are common in the ponds of central Illinois. In these the
last segment is much longer, its length being to its breadth
as 9 to 5. In this form the spine is parallel to and often
longer than the segment.

The shape of this distal segment seems to vary independ-
ently of the other specific characters, and all gradations
between the two forms may be found in a single pond. These
variations are not demonstrably connected with the environ-
ment.

The receptaculum seminis (PL XL, Fig. 3) is, when fully
distended, of the shape represented by the dotted line, but
otherwise may have the shape outlined by the solid line. As
will be seen by comparing this figure with that of the recep-
taculum seminis of C. viridis (PL X., Fig. 2), the anterior
portion of the receptaculum is comparatively larger in insectus
and its outline as a whole is somewhat different.

I find that the coloring of this species is so variable that no

44 Illinois State Laboratory of Natural History.

dependence can be placed upon it for purposes of distinction.
This variety may be wholly red or blue or greenish or it
may even be colorless.

It is found everywhere in the United States and Canada
where Cyclops have been collected, and no situation seems to
be free from them. In Illinois by far the greater portion of
the Cyclops of the small ponds and temporary pools and
puddles belong to this species.

Cyclops bicuspidatus Claus. (PL XII. , Fig. 1-4.)

Cyclops bicuspidatus, Claus, '57, p. 209.

Cyclops pulchellus, Sars, '63, pp. 246,247, PI. XI., Fig. 6 and 7.

Cyclops navus, Herrick, "82a. p. 229, PI. V.. Fig. 6-13, 15-17.

Cyclops tfwmasi. Forbes. "82a. p. 649.

( 'yclops bicuspidatus, Suhmeil, '92, pp. 75-87, PJ. II., Fig. 1-3.

Cyclops minnilus, Forbes, '93, p. 247.

Cyclops serratus, Forbes, '93, pp. 247, 24S.

Cyclops Jbrbesi, Herrick and Turner, '95, p. 104.

SYNONYMICAL DISCUSSION.

This immensely variable and widely distributed species is
represented in the United States by a number of forms which
have been described by our most reliable zoologists as species
new to science. As more complete series of collections from
the United States have been studied, it has become evident
that these forms are so closely connected in series, that dis-
tinctions which a few years ago were considered as specific
must be cast aside and the whole group united under the
name of the European form.

With regard to Cyclops thomasi Forbes, I must agree with
Dr. Schmeil that there is no need of considering this form as
even a variety. A close study of the type specimens of
( 'yclops tli mil <i si reveals a number of small differences between
it and Cyclops bicuspidatus as described by Dr. Schmeil, but
they agree almost exactly with other descriptions, by European
investigators, of forms included in Dr. Schmeil's synonymy of
C. bicuspidatus Clans. Only a single specimen of the form
as described by Dr. Schmeil has been found by me in collec-
tions from this country. This single individual came from a

North American Fresh-water Cyclopidce. 45

pond at Wood's HolJ, Mass. The most conspicuous difference
between this form and C. thomasi is a slight one in the shape
of the fifth foot.

In the Illinois River are specimens which bridge over com-
pletely the gap between C. bicuspidatus and Herrick's C.
navus, and I see no reason for considering navus as a good
variety.

Cyclops minnilus Forbes is distinguished from C. thomasi
by different proportions alone. It is one of the western rep-
resentatives of this species and has been collected in the
lakes and rivers of Wyoming.

Cyclops serratus Forbes is found in the same situations as
C. minnilus, from which it is distinguished by a slight differ-
ence in the armature of the feet and by the fact that the
vertical comb of spines of the furcal stylets is but poorly
developed. The name xerrtrfiiH being already in use, Herrick
renamed the species forbesi. This is the most elongate of
the American representatives of the species.

SPECIFIC DESCRIPTION.

This is a long and slender species (PI. XII., Fig. 1) with
seventeen-segmented antennae, oval cephalothorax, slender
abdomen, very long and slender caudal stylets, and but two
developed seta; to each stylet. The longer of these setaa is
about twice as long as the shorter. The cephalothorax is
widest at about the middle. In specimens from the eastern
United States the posterior angles of the cephalothorax are
not usually prominent except in the case of the last segment,
where they are laterally produced. In the far western speci-
mens the posterior angles of all the segments are prominent.
The peculiar appearance of the cuticle caused by circular pits
or depressions which Dr. Schmeil mentions, is rarely present
in the iVmerican form. I have found it in greatly varying
degrees of definiteness in specimens from Lake Superior
and from Wyoming.

The first segment of the abdomen of the female (PI. XII.,
Fig. 1) is emarginate behind the prominent lateral angle.
This segment is about as long as all the others together. The

46 Illinois State Laboratory of Natural History.

posterior margins of all but the last segment are irregularly
and often very obscurely serrate. The last segment is
bordered posteriorly by the usual row of spinules. The sty-
lets are often slightly outcurved. In relative length to breadth
they vary from four to one to nine to one, but the usual
proportion is as seven to one. The inner of the two longer
seta; is as long as the entire abdomen, and the outer of the
two but half that length. The extreme outermost of the
terminal setae is two thirds as long as the inner. On the
outer side of each stylet, a little behind the middle, is
placed a spine surrounded at its base by a ring of spinules,
and at one fourth of the distance from the proximal end is a
vertical comb of small spines (PI. XII., Fig. 2). This
character seems to be invariably present.

The antennae of the female are moderately robust and
terminate in the American forms between the posterior end
of the first segment and the middle of the third segment.
A sense-club is borne on the distal end of the twelfth segment.
No hyaline plate is present on the terminal segments. The
last three segments gradually increase in length toward the
distal end of the antenna, the antepenult being two fifths
the length of the last. The two segments preceding the
former, taken together, are shorter than the last segment,
and about equal to the penultimate.

The armature of the thoracic legs is as follows : — First pair :
outer ramus, two spines, four seta ; inner ramus, one seta,
one spine, four seta. Second pair : outer ramus, three spines,
four seta ; inner ramus, one seta, one spine, four seta.
Third pair, exactly like second. Fourth pair : outer ramus,
three spines, four seta; inner ramus, one seta, two spines,
two seta.

The fifth pair (PI. XII., Fig. 3) are two-segmented, the
basal segment about as long as broad, with a plumose seta at
the outer angle, the terminal segment roughly cylindrical, at
least twice as long as broad, with two terminal seta-, the outer
of which is as long as the seta of the preceding segment and
the inner a little more than half that length. This inner seta
is sometimes spine-like.

North American Fresh-water Cyclopidce. 47

The receptacidum seminis (PI. XII., Fig. 4) is regular in
outline, the anterior border being a low arch extending com-
pletely across the segment. The posterior portion is much
deeper and about half as wide. The broad spermal canals
arise from the anterior angles. The porus is exactly between
the two anterior angles.

The egg-sacs are usually small and round in the specimens
from large lakes ; otherwise they are elliptical and very large.

The usual length of the female is 1-1.4 mm.

This species is very widely distributed in America. It has
been found in Massachusetts and Wyoming and in all the
intervening territory. It is the common pelagic species of the
Great Lakes, but also occurs in large numbers in our ponds
and rivers. Inhabiting, as it does, such a great amount of
territory and such a variety of situations, it is not strange
that it proves to be a very variable form. The Massachusetts
form is exactly as described by Dr. Schmeil. In Wyoming
this species is very much more slender in all its details,
though not differing markedly in any other way from the type.
Between these two extremes in location are a great number
of intermediates in form. The fifth foot is rather variable,
but I note no variation in the shape of the receptacidum semi-
nis. The vertical combs of spines on the stylets are always
present, but are not always conspicuous in the Western speci-
mens. Although the most attenuate specimens examined
were usually from large lakes and the most robust from ponds,
I find that no other generalizations are possible with regard
to the character of the specimens in connection with the
nature of the situation — probably on account of the frequent
transfers of individuals from one of these situations to another.

Subgenus Macrocyclops Claus.
Cyclops albidus Jurine. (PI. XIII.)

Monoculusquadricornis var. albidus, Jurine.'20, p. 44. PI. II.; Fig. 10,11.
Cyclops gyrinus, Forbes, '90a, pp. 707-709, PI. II., Fig. 9; III.. Fig. 14.
Cyclops signatus var.tr mi icoi-tiis^Herrick and Turner, "95. pp. 106.107,

PI. XV.. Fig. 5-7: XX.. Fig. 1-7; XXXIII., Fig. 1,2.
Cyclops albidus, Schmeil, '92, pp. 128-132, PI. I., Fig. 8-14b; PI. IV.,

Fig. 15.

48 Illinois State Laboratory of Natural History.

SYNONYMY.

Since the description of C. gyrinus by Dr. Forbes in 1890,
more careful descriptions of C. albidus in Europe and fur-
ther studies in America have established the identity of the
two forms. The original description of C. gyrinus was in-
complete in that the presence of the sense-club and hyaline
plates was not observed.

SPECIFIC DESCRIPTION.

This is a stout, heavy species, with a strongly arched
cephalothorax, which, as a whole, is usually quite elliptical,
with the lateral angles of the segments almost invisible ;
but in specimens from Manitoba I find the cephalothorax
shaped much as in C. viridis. The first segment in these is
subspherical, narrowing posteriorly, and the posterior end
of the second segment is much broader than the anterior
end. All of the lateral angles are prominent. The breadth
of the first segment compared with its length is as ten or
eleven to twelve.

The dorsum of the fifth segment in this species is or-
namented by three or four transverse rows of spinules, the
posterior one of which borders the segment.

The abdomen is thick and heavy. The first segment in the
female is but slightly enlarged and tapers very little. The re-
maining segments are cylindrical. The stylets are short and
slightly divergent. The proportion of the length to the
breadth of the stylet varies but slightly. The usual ratio is
two and one half to one. The apical bristles are all well
developed, the third from without being the longest, and the
innermost three times as long as the outermost.

The first antenna? of the female are seventeen-segmented,
and reach to the first abdominal segment. The distal three
segments bear hyaline plates, entire, except for minute ser-
rations on the distal half of the plate of the seventeenth seg-
ment. The twelfth segment bears an unusually large sense-
club.

The swimming feet are armed as follows : — First pair :
outer ramus, four spines, four setae; inner ramus, one seta,

North American Fresh-water Cyctopidce. 49

one spine, four seta?. Second and third pairs : outer ramus,
four spines, five seta ; inner ramus, one seta, one spine, four
setas. Fourth pair: outer ramus, three spines, five setge;
inner ramus, one seta, two spines (inner naked and movable),
two setae (distal one minute).

The fifth foot is two-segmented. The basal segment is two
thirds as wide as long, its outer margin straight, its inner,
convex and minutely hairy. The distal end is truncate, with
a very long seta at the outer distal angle. The second seg-
ment is about as long as the preceding is wide, lobed in the
middle and trisetose, the outer seta shorter than the inner,
and the latter about half as long as the median.

The anterior portion of the receptacuhim seminis is kidney-
shaped and the posterior is two-lobed. The lateral canals
are attached to the lower portion.

The usual length of the female in America is from
1.26-1.4 mm., but it seems to be much greater (2.5 mm.) in
the European representatives of the species.

The color, which is blue or green, is distributed in dark
bands with nearly colorless intervals on the thorax, the last
abdominal segment and stylets, and on the second, third,
ninth, and tenth antennal segments.

This species is very generally distributed, having been
found in all the localities in America from which collections
have been examined. It is not common in temporary ponds,
but I have several times noted its occurrence in wells.

Subgenus Homocyclops n. subgen.

Cephalothorax very robust. Antennas seventeen-segmented.
Eami of swimming feet three- segmented. Fifth feet one-
segmented, bearing one spine and two seta'.

Cyclops ater Herrick. (PI. XIV., and PI. XV., Fig. 1-3.)

Cyclops ater, Herrick, "82a, p. 228, PJ. III.. Fig. 9-12.
Cyclops ater, Marsh, '95. pp. 13, 14, PJ. VI., Fig. 1-4, 6, 12.
Cyclops ater, Herrick and Tinner, '95, pp. 89, 90, PL VII., Fig.
11. 12; XII., Fig. 9-12; XXL, Fig. 13-15, 17, IS.

The cephalothorax is peculiarly short and broad. Its first

5 0 Illinois State Laboratory of Natural History.

■

segment is very large and is twice as long as the remaining
segments together. The posterior edges of all the segments
are smooth.

The abdomen is relatively small, but is broad in proportion
to its length. It tapers but little and the first segment is
scarcely at all enlarged. The segments, except the last, are
finely and irregularly notched posteriorly. The caudal stylets
are short, the length to the breadth being about as three to
one. They are not ciliate within. In the small number of
specimens which I have had an opportunity to examine there
is no outer lateral spine, but at the usual place for this spine,
a little behind the middle, is a shallow scar where a spine
might at some time have been attached. I do not think,
however, that this is probable. The terminal setae are all
well developed, but the median pair is much longer than the
lateral ones. The innermost seta is slightly longer than the
outermost. Of the four, the second from the inside is the
longest.

The first antenna' of the female are seventeen-segmented
and reach to the middle or end of the second cephalothoracic
segment. The twelfth segment bears the usual seta and
sense-club, though the latter organ is unusually small. The
fourteenth segment bears an especially long, strong seta.
The last two segments (PI. XV., Fig. 1) bear a narrow hyaline
lamella which projects some distance beyond the end of the
seventeenth segment. The edge of this plate is entire. Of the
last three segments, the middle one (sixteenth) is the longest.

The seta? of the swimming feet are short and stout. The
armature is as follows : — First pair : outer ramus, three
spines, five seta? ; inner ramus, one seta, one spine, four
seta?. Second and third pairs : outer ramus, four spines, five
seta? ; inner ramus, one seta, one spine, four seta?. Fourth
pair : outer ramus, three spines, five setae ; inner ramus,
one seta, two spines, two setae.

The fifth feet (PI. XV., Fig. 2) are one-segmented and bear
one strong spine and two seta' each. The spine is about one
third the length of the seta?. The inner seta, that is the one
next the spine, is borne on a conical projection from the

North American Fresh-water Cyclopidcc. 51

body of the segment. Neither the seta? nor the spine seem
to be provided with hairs or spinules.

The receptaculum seminis (PL XV., Fig. 3) is of an unusual
and very characteristic shape. The anterior part is small,
and its outline is marked by two anterior and two lateral
rounded prominences. The posterior part consists of a
median lobe, partially divided posteriorly, and two curved
lateral lobes from which lead the lateral canals. The porus
is in the median part connecting the upper and lower divisions.

The egg-sacs are of the usual size and shape.

In length the female varies from 1.77 to 2.88 mm.

The color is unusually variable. It is commonly dark blue
or green but may be gray or red. The deep color and large
size make this a conspicuous species.

Herrick says that it is widely but sparingly distributed over
the Mississippi Valley. Marsh reports it from Rush, Round,
St. Clair, Intermediate, Twenty-sixth, and Susan lakes in
Wisconsin. I have noted its occurence in collections from
Thompson's, Quiver, Flag, Phelps, and Dogfish lakes near
Havana, Illinois.

Subgenus Orthocyclops n. subgen.
Antenna? sixteen-segmented. Rami of swimming feet, three-
segmented. Fifth feet three-segmented, distal segment bear-
ing two apical seta?.

Cyclops modestus Herrick. (PI. XV., Fig. 4, and PI.
XVI., Fig. 1-3.)

Cyclops modestus, Herrick, '83a, p. 500.

Cyclops modestus, Herrick and Turner, '95, pp. 108, 109, PI. XXI.,

Fig. 1-5.
Cyclops modestus, Marsh, '93, pp. 213, 214, PI. V., Fig. 10-13.
Cyclops capilliferus, Forbes, '93. pp. 248. 249. PI. XL., Fig. 14-17:

XLL. Fig. 18.

SYNONYMY AND DISTRIBUTION.

By a study of the type specimens of Cyclops capilliferus I
find that they agree almost completely with Herrick's descrip-
tion of C. modestus. The descriptions differ with respect to

52 Illinois State Laboratory of Natural History.

the position of certain spines of the feet, but this is really a
difference in description rather than in characters. I find
also that specimens collected in "Wyoming agree exactly with
the Illinois representatives of the specie.-.

I have noted its occurrence in collections from Quiver, Dog-
fish, and Thompson's lakes, and from the Illinois River,
near Havana, 111. ; from the Sangamon River, in Champaign
county, Illinois; and from Grebe Lake in Yellowstone Park.
Marsh reports it from Rush Lake, Wisconsin, and Herrick finds
it in Cullman county, Alabama, and in Minnesota lakes. I
have never found it in temporary ponds nor in any of the
Great Lakes. From the situations in which it occurs I judge
that this species seeks shallow, weedy water rather than
pelagic situations. It is not an especially rare species, hut I
have never found more than a very few individuals in a single
collection.

SPECIFIC DESCRIPTION.

The cephalothoracic segments are closely articulated and
the sides regularly convex. The first segment is longer than
usual and the fourth is semicircularly excavate behind. The
posterior edges of the first three segments are irregularly
notched and the fourth is smooth. The length of the cepha-
lothorax is to its breadth as two to one.

The abdomen is long, slender, and cylindrical, and is pecu-
liar in lacking the usual fringe of spines on the posterior edge
of the last segment. The posterior edges of the other seg-
ments are likewise smooth. The anterior end of the first
segment is but little enlarged. The segments diminish regu-
larly in length from first to last. The caudal stylets are about
twice the length of the last segment and four times as long as
broad. The lateral seta is placed a trifle beyond the middle
of the ramus. Behind the lateral spine the stylet is pecu-
liarly excavate. The outer terminal bristle, which is set
farther forward than in most species, is a short, sparsely
plumose seta, but the other three seta- are well developed. Of
these three the middle one is considerably the longesi and
the inner one slightly shorter than the outer.

North American FresJi-zvater Cyc'opidce. 53

The antennae are regularly sixteen-segmented, though
Herrick mentions having notes on a similar form in which
the antennae are seventeen-lsegmented. They reach to the
middle of the second cephalothoracic segment. On the third,
tenth, and thirteenth segments are remarkably long, heavy
seta?. The antenna (PL XVI., Fig. 1) is given a characteristic
appearance by the conspicuous seta on the third segment
and a sharp change in direction between the third and fourth
segments. The last segment is much shorter than the one
preceding.

The seta? of* the three-segmented legs are long and slender.
The distal segments of the third and fourth pairs of legs turn
inward in a way peculiar to this species. The legs are armed
as follows : — First pair : outer ramus, four spines, four seta' ;
inner ramus, six seta?. Second pair : outer ramus, four spines,
five seta? ; inner ramus, six seta?. Third pair : outer ramus,
three spines, five seta?; inner ramus, six seta?. Fourth pair:
outer ramus, three spines, five seta?; inner ramus, one seta,
two spines, two seta?.

The fifth foot (PI. XVI., Fig. 2) has three freely movable
segments, though the basal one is small. The second seg-
ment bears one seta without, and the third segment bears two
seta? — both at the tip. The outer seta is apt to be bent inward
across the inner one. These feet are usually large and placed
very close together.

The receptaculum seminis (PL XVI., Fig. 3) is very much
as in Cyclops bicuspidatus Claus. It is nearly elliptical in
outline, and only a small part of the anterior end extends
farther forward than the suture in which the porus is situated.
The lateral canals lead from the anterior part.

The egg-sacs are long and narrow and lie close to the
abdomen.

In length this species does not vary to any marked degree
from an average of 1.2 mm.

The coloring is most beautiful, varying from violet to
purple. It is evenly distributed, and is quite persistent in
specimens preserved in formalin.

54 Illinois State Laboratory of Natural History.

Subgenus Eucyclops Claus.
Cyclops serrulatus Fischer. (PI. XVII., and PI. XVIII.,
Fig. 1-3.)
Cyclops serrulatus and (J. serrulatus var. montanus, Brady. '78, Vol.

I., pp. 109-111, PI. XXII., Fig. 1-14.
Cyclops serrulatus and C. serrulatus var. elegans, Merrick, '81, PI. <,».

Fig. 17-19; PI. Q;. Fig. 10.
Cyclops serrulatus, Schmeil. '92, pp. 141-14U, PJ. V.. Fig. 0-14.

SYNONYMY, VARIATION, AND DISTRIBUTION.

This is one of the most common and widely distributed of
American ( 'yclops. It occurs almost everywhere between
Maine and California and from Florida to Manitoba.

Herrick's variety elegans is based on such variable charac-
ters that no one acquainted with the species throughout its
range could for an instant consider this form as worthy of a
varietal name, especially since the measurements and descrip-
tions of the type and the variety are contradictory as pub-
lished in his "Synopsis of the Entomostraca of Minnesota."
Herrick says that the variety is distinguished from the type
by its greater size and by the elongation of the antennae and
caudal stylets; but gives 1.5 mm. as the length of the type,
and 1.34 as that of the larger variety. In Europe the largest
specimen on record measured 2.2 mm. in length, much more
than Herrick's large variety. As to the length of the antennae,
I find that this varies immensely and quite independently
of other variations in proportion. Below is a series of meas-
urements of seven egg-bearing females of this species, from
widely separated situations and exhibiting its variability.
Further study of a much larger number of specimens has
convinced me that there are no varietal distinctions possible
among the American representatives of this species, unless
for convenience we arbitrarily separate off the extreme forms.
With the exception of the specimen from Thompson's Lake,
each individual is fairly representative of the species as found
in its own locality.

North American Fresh-water CyclopiUce.

55

Locality

Length to breadth
of caudal stylet

Antenna terminates

Length

Breadth.

Portage La Prairie.
Manitoba

.078:. 018=4. 3:1

Before end of
tirst segment.

.7

.252

Urbana 111

.027:. 015=1. 8:1

End of first
segment.

.54

.198 '

072:. 0225 =3. 2:1

End of first
segment.

.792

.324

Thompson's Lake,
I]]

.075:.01S=4.2:1

End of third
segment.

.72

.216

Pelican Creek, Wyo.

.087:. 03=2. 9:1

Middle of second
segment.

.8S2

.324

Wood's Holl, Mass..

.111:. 027=4.1:1

Middle of third
segment.

.882

.36

Lake Geneva, Wis. .

.24:. 027=8. 9:1

End of third
segment.

1.426

.45

It is also my opinion that Brady's variety montanus should
be considered as merely a variation of the typical form.

SPECIES DESCRIPTION.

The cephalothorax (PL XVII.) is quite regular in shape,
being almost exactly elliptical in outline. Its segments
are closely joined and its lateral outlines smooth. The fourth
segment is deeply excavated behind and is usually bordered
by fine sharp teeth or by long hairs.

The abdomen (PL XVII., and PL XVIII., Fig. 1) is broad
in front, but narrows so rapidly posteriorly that the greater
part of the first segment is as narrow as the slender segments
following. Behind the enlargement of the first segment the
abdomen tapers very little. The last segment is bordered
posteriorly by the usual row of spinules, and the preceding
segments by fine sharp serrations. The stylets are commonly
about straight, but are occasionally strongly outcurved and
divergent. Their length to breadth varies from 1 : 1.8 to 1:9
but 1 : 4 is the commonest proportion. A row of spinules,
spines, or curved hooks marks the outer border of each stylet
and extends from its base to the point of insertion of the outer
apical spine, near the posterior end. These projections in-

56 Illinois State Laboratory of Natural History.

crease rapidly in length at the posterior end and lade away
in front. The male does not have this character, and adult
females are very rarely found without it. Of the four apical
bristles the middle two arc well developed. The inner one
of this pair is much longer than the outer. The innermost
of the four is a very slender seta. The outermost varies in
character from a long seta bordered externally by harbules
and internally by long slender cilia, to a long strong spine
serrate on both sides. It may be anywhere from one half
to four fifths as long as the stylet.

The first antennae are twelve-segmented. Dr. Schmeil
notes the presence of a minute sensory bristle on the ninth
segment in the place occupied by the sense-club on the
twelfth segment of seventeen-segmented antenna?. It is
very inconspicuous indeed. The last three segments are
usually very long and are armed on the inner side by hyaline
plates.

The usual armature of the swimming feet is as follows : —
First pair : outer ramus, three spines, live seta* ; inner
ramus, one seta, one spine, four seta?. Second and third
pairs : outer ramus, four spines, five setaj ; inner ramus,
two spines, four seta?. Fourth pair : outer ramus, three
spines, five seta?; inner ramus, one seta, two spines, two
seta.

The fifth foot (PI. XVIII., Fig. 2) is one-segmented and
plate-like. On the inner side is a very strong serrate spine.
At the tip, borne on a cone-shaped projection, is a very long
slender seta, parallel to the spine. On the outer side i> a
delicate little seta projecting outward at a considerable angle.

The receptaeulum semi7iis (PL XVIII., Fig. 3) is almost com-
pletely divided into an anterior and a posterior part, by a
median constriction. The porus is situated in the middle of
this narrow connecting part. The lower half extends down
into the narrow part of the first abdominal segment. The
spermal canals are attached to the receptaeulum at the outer
angles of the lower part.

The egg-sacs are usually long, with many eggs, but some-
times contain only a few, arranged in a spherical mass.

North American Fresh-ivater Cyclopidce. 57

Ordinarily the egg-sac tapers to a sharp point at the lower
end, and stands out from the abdomen at a wide angle.

The size is remarkably variable. In Europe, the length
varies from .883 to 2.2 mm. In America I have measured
specimens varying in length from .54 to 1.47 mm. A com-
mon length is .9 mm.

Cyclops prasinus Fischer. (PI. XIX., Fig. 1 and 2, and

PI. XX., Fig. 1 and 2.)

Cyclops pr a stmts, Fischer, '(iO. pp. C52-654. PI. XX., Fig. 19-26a.
Cyclops fliiviatllis, Ilerrick, '82 a. p. 231, PI. VI I.. Fig. 1-9.
Cyclops magnoctavus, Cragin, "83, pp. 70.71, PI. III.. Fig. 14-23.
Cyc/ups prasinus, Schmeil, '92. pp. 150-15G. Pi. V., Fig, ]-5.
t )/c lops fluviatilis, Ilerrick and Turner. '95, pp. 114. 115, PJ. XXVI.,
Fig. 1-8; XXX., Fig. 1.

SYNONYMY AND DISTRIBUTION.

On account of the great difficulty in determining the struc-
ture of the receptaculum seminis of C. prasinus, this organ
has escaped study in the American representatives of this
species, and although Marsh had noted a general resemblance
of Herrick's C. fluviatilis to Yosseler's ('. pentagonus (C.
prasinus Fischer), he did not consider these as identical. By
a careful study of a large number of specimens of C. fluviat-
ilis from Illinois, Florida, and Wisconsin, I find a complete
agreement in the characters of the receptaculum seminis of C.
prasinus and C. fluviatilis and in all other specific characters
as well.

I have noted the occurrence of ('. prasinus in collections
from Sister Lake, Florida ; Long Lake, Adams county, 111. ;
ponds and temporary pools at Urbana, 111. ; Illinois Piiver at
Havana, 111. ; Phelps, Flag, and Thompson's lakes in Ful-
ton county, 111. ; Dogfish and Quiver lakes in Mason county,
111. ; and from Lake Geneva, Wisconsin. Ilerrick reports it
from Lake Minnetonka, Minn., and from an estuary of the
Mississippi. Marsh finds the species in Lakes Erie, Michi-
gan, and St. Clair, and in fifteen smaller lakes of Michigan
and Wisconsin. Cragin found it in ditches at Cambridge,
Mass.

58 Illinois State Laboratory of Natural History.

It is thus, in all probability, quite generally distributed
over the eastern and central United States, but I have not
found it in collections from the far AVest. It occurs in all
situations from great lakes and rivers to temporary roadside
puddles of but a few weeks' duration.

SPECIFIC DESCRIPTION.

This minute species has a slender cephalothorax which is
very nearly elliptical in outline. The first segment is regu-
larly convex anteriorly and is unusually long. The posterior
borders of the segments are entire. The lateral edges of the
last segment are fringed by a row of the finest hairs.

The abdomen is long and slender and tapers but little.
The enlargement of the anterior segment is slight. The pos-
terior borders of all the abdominal segments are very finely
serrate. The stylets are short and divergent but are not
themselves outcurved. The lateral spine is inserted just
beyond the middle of the stylet. The inner and outer apical
bristles are very short and delicate, the inner one, the longer
of the two. Only the middle pair of setae are well developed,
and the outer of these is three fourths the length of the inner.

The first pair of antennae (PI. XIX., Fig. 2) of the female are
twelve-segmented and often reach quite to the first abdominal
segment. The seventh, eighth, and ninth segments are very
long. The last three segments are curved and the last four are
freely movable. Schmeil states that the ninth segment bears
a sense-club. I do not find it present in the American repre-
sentatives of the species, although there is a minute sensory
bristle on the end of the tenth segment. The last three seg-
ments bear a hyaline plate whose edge is entire.

The spines and setae of the three- segmented swimming feet
are very long and slender. The armature is as follows : —
First pair : outer ramus, three spines, five seta' ; inner ramus,
six setae. Second pair : outer ramus, four spines, five setae ;
inner ramus, six setae. Third pair armed like second. Fourth
pair: outer ramus, three spines, five seta-; inner ramus,
one seta, one spine, three setae.

The fifth foot (PL XX., Fig. 1) is one-segmented and bears

North American Fresh-water Cyclopida?. 59

three bristles. The inner one is a ciliate spine while the other
two are plumose sette. The middle one of the three is borne
at the tip of a cone-shaped process. The inner edge of the
foot is bordered by a row of minute hairs.

The receptaculum seminis (PI. XX., Fig. 2) is most peculiar
and characteristic. It consists of two parts, anterior and
posterior, separated by the suture marking the original division
of the first abdominal segment. The upper part consists of
two S-shaped canals, one on each side of the median line,
extending across the abdomen. The inner ends which point
downward, fuse in a thicker portion connecting the anterior
division with the posterior. The part of the receptaculum
behind the suture consists of two lateral sacs, which connect
with each other and with the upper part of the receptaculum
at the same point. In the middle of this common part is the
porus. The outer ends of the tubular portion are slightly
enlarged ; otherwise the diameter is uniform. The structure
of this organ has never before been observed in the American
representatives of Cyclops prasinus.

The egg-sacs contain few ova and are closely adherent to
the abdomen.

The length of the female varies from .48 to .7 mm.

The color is unusually variable. The prevailing color of
European specimens seems to be green. I have seen both
blue and pink individuals. Herrick says that the color varies
from deep indigo to greenish brown.

Subgenus Paracyclops Claus.
Cyclops phaleratus Koch. (PI. XX., Fig. 3.)

Cyclops phaleratus, Koch, '35-41, Heft 21, pp. 8, 9. PI. IX.
Cyclops perannatus, Cragin, '83, pp. 72, 73, PI. I., Fig. 0-18.
Cyclops phaleratus, Schmeil, '92, pp. 170-178, PJ. VIII., Fig. 1-11.
Cyclops phaleratus, Herrick and Turner, '95, pp. 120, 121, PL XVII. ,

Fig. 1-7 ; XVIII., Fig. 2-2d ; XIX.. Fig. 1; XXI., Fig. 6-10.
Cyclops phaleratus, Marsh, '95, pp. 19, 20.

DISTRIBUTION.

In America this species is rare, though evidently widely
distributed. I have noted its occurrence in collections from
the Illinois River at Havana, 111. ; a pond at Urbana, 111. ;

60 Illinois State Laboratory of Natural History.

Delavan Lake, Wisconsin ; Quiver Lake, 111. ; Green Lake,
Wisconsin ; Cedar Lake, 111. ; and a slough at Portage La
Prairie, Manitoba. Marsh reports it from Lake St. Clair ;
and from Twenty-sixth Lake, Pigeon Paver, and Intermediate
Lake, Michigan. Cragin describes this species as Cyclops
perarmatus from Glacialis Pond, Cambridge, Mass. It is a
littoral rather than a pelagic form and where occurring in
large bodies of water it is found only in the marginal vegeta-
tion.

SPECIFIC DESCRIPTION.

The cephalothorax is broad and elliptical. The first seg-
ment is longer than the remainder. The chitinous covering
of the fifth segment, which in all other species of this genus is
composed like the four preceding cephalothoracic segments
of a dorsal and ventral plate, is in C. pkaleratus like the
chitinous covering of the abdominal segments in that it con-
sists of but one piece. The ventral portion of the posterior
border of this segment is set with a row of fine teeth, evanes-
cent in the middle. About the rudimentary feet are several
rows of fine spinules.

The abdomen is large and cylindrical, and very little smaller
than the last cephalothoracic segment. The first segment
tapers very little. The posterior borders of the first, second,
and third abdominal segments of the female are finely serrate.
The last segment is very short and the spines on its posterior
border are especially long and strong.- The profusely spinose
stylets are short and broad and taper very rapidly. On the
ventral side of each ramus is a row of long spinules, extend-
ing from the middle line of the anterior border to the point
of insertion of the lateral spine. From this point on, the
rami taper much more rapidly. The inner border of the
stylets is ciliate* and the whole inner aspect may be spinose.
The outermost apical bristle, which is placed high up on the
side of the stylet, is short, and plumose on both sides. The
inner bristle is very slender and is about as long as the outer.
It is plumose on the outside only.* The two median bristles

* Incorrect in figure.

North American Fresh-water Cyclopid(2. 61

alone are well developed. The inner one of this pair is from
two to three times as long as the outer. Except for the outer
side of the outer one of the pair, the anterior third of each is
naked. The remainder is usually sparsely plumose.

The antennae of the female may be either ten- or eleven-
segmented and reach only a little beyond the middle of the
first cephalothoracic segment. In the ten-segmented antenna
the seventh segment bears a delicate sensory hair at its
distal end. This hair is borne on the eighth segment of the
eleven-segmented antenna.

The second antennae are short and proportionately broad.
On the outer side of the second segment is a double row of
spinules. On the upper border of this segment is a spine
and a fringe of spinules. This spine and the shortest one at
the end of the third segment are very peculiar. Both are
strongly curved near the tip, and the inner side of this curve
is fringed by a comb-like row of teeth.

The three-segmented swimming-feet are strongly armed
and their outer borders bear rows of long spinules. The
armature of the distal segments is as follows : — First pair :
outer ramus, three spines, five setae ; inner ramus, one spine,
four setae. Second pair : outer ramus, four spines, four setae ;
inner ramus, one spine, four setae. Third pair : outer ramus,
four spines, five setae; inner ramus, one spine, four setae.
Fourth pair: outer ramus, three spines, five setae; inner
ramus, one seta, two spines, two setae.

The rudimentary feet are lateral rather than ventral and
consist of mere flange-like processes. They are connected
by a row of strong serrations extending across the ventral
side of the segment. Each foot is armed by three subequal
spines, one naked and the other two plumose.

The receptaculum son in is consists of two sections, which
extend as two narrow bands across the segment. The porus
is situated on the median line where the two divisions unite.

The egg-sacs contain many eggs and are closely appressed
to the abdomen. Schmeil calls attention to the fact that the
oviducts, which in all other species are contained wholly
within the cephalothorax, in ('. phaleratas extend as blind

62 Illinois State Laboratory of Natural History.

sacs as far back in the abdomen as the anterior border of
the third segment.

The female varies in length from .9 mm. to 1.26 mm., and
the male is usually about .2 mm. shorter. The largest
specimens measured came from Portage La Prairie, Manitoba.

This is a beautifully colored species. The ground color is
reddish brown. The second cephalothoracic segment, the
last abdominal segment with the stylets, the swimming feet,
and the last segment of the first antennae are sky-blue. A
yellow spot surrounds the eye.

The egg-sacs are dark blue or black.

The best character for the ready recognition of this species
is its strong superficial resemblance to the genus Cantho-
camptus.

GENERAL DISTRIBUTION OF CYCLOPS IN NORTH AMERICA.

Of the eighteen species and three varieties of Cyclops which
have been reported as occurring in North America, but three
species and two varieties, namely, ater, modestus, and edax,
and varieties insectus and brevispinosus of viridis are char-
acteristic of America, while the remaining fifteen species and
one variety are common to both Europe and America.

Probably bicuspidatus, serrulatus, viridis, albidus, and edax
might be found in any state in the Union, so general is their
distribution.

In the Great Lakes by far the most abundant species are
bicuspidatus and edax. Often either one or the other of these
two species will constitute nearly the whole of the crustacean
plankton.

Collections from the high lakes and ponds of the Northwest
usually contain Cyclops, often in considerable numbers, but
they are never present in such great quantities as is the genus
Diaptomus and the Cladocera. The commonest of these
mountain forms are as follows: bicuspidatus, viridis var.
insectus, serrulatus, and albidus, though viridis var. brevis-
pinosus, bicolor, dybowskii, modestus, and edax have been
found in such situations. In collections from Crater Lake,
Oregon, I found a very few specimens of albidus and ser-

North American Fresh-water Cyclopidce. 63

rulatas. This lake is in the Cascade Mountains and is the
highest lake of its size in the world.

As very few observations have been made on the Cyelopidse
of rivers, I examined a continuous series of collections made
in the Illinois Eiver at the Illinois Biological Station, ex-
tending from May to September, 1896. In the first of these
collections bicuspidatus was the predominating form, but it
soon disappeared entirely, its place being taken by viridis
var. insectus. From this time throughout the summer insectus
was by far the most abundant form. Edax, viridis var.
brevispinosus, leuckarti, prasinus, semdatus, and vari cans were
common in the collections, while Jimbriatus var. poppei, viridis,
modestus, bicolor, albidus, and phaleratus were of rare occur-
rence.

LIST OF NORTH AMERICAN SPECIES.

Below is a list of the fresh-water Cyclopidre reported from
America. I have myself seen all of the species of this list
except those herein credited to Herrick.

Genus CYCLOPS.

I. Subgenus Cyclops s. str. Claus.

1. Cyclops leuckarti Claus.

This is a rare species throughout the north central States.

2. Cyclops insignis Claus, fide Herrick.

Herrick has found at Long Island a form which he identi-
fies as this species.

3. Cyclops edax Forbes.

This is a very common species in the Great Lakes and in
the waters of the north central States, Florida, and Wyoming.
It occurs in Argentina, South America.

4. Cyclops oithonoides Sars^/zWt' Herrick.

I regard the occurrence of this species in America as very
doubtful.

5. Cyclops dybowskii Lande.

A rare species found only in the small mountain lakes of
Wyoming and in a temporary pond at Urbana, Illinois.

64 Illinois State Laboratory of Natural History.

G. Cyclops viridis Jurine.

Either the typical form or its varieties occur everywhere
in the fresh waters of the United States. It is the commonest
form of the temporary ponds.

a. var. brevispinosus Herrick.

b. var. insectus Forbes.

7. Cyclops bicuspidatus Glaus.

This species is of the widest range and greatest abundance.
It is the commonest Cyclops in the Great Lakes.

8. Cyclops vernalis Fischer.

Occurs in small numbers in Lake Geneva, Wisconsin.

II. Subgenus Macrocy clops Clans.

9. Cyclops fuscus Jurine.

Occurs sparingly in the ponds and lakes of Wisconsin,
Michigan, Illinois, and Massachusetts.

10. Cyclops albidus Jurine.

Rather a common species throughout the whole range of
the genus.

III. Subgenus Homocyclops n. subgen.

11. Cyclops ater Herrick.

Very rare throughout the Mississippi Valley. Also in Lake
St. Clair (Kofoid).

IV. Subgenus Orthocyclops n. subgen.

12. Cyclops mod est us Herrick.

An uncommon species in the lakes and streams of Wyo-
ming, Alabama, and the north central States.

V. Subgenus Microcyclops Claus.

13. Cyclops bicolor Sars.

Rare in Wyoming, Illinois, Wisconsin, Michigan, and Min-
nesota.

14. Cyclops varicans Sars.

A fairly common species throughout the range of Cyclops
in North America.

North American Fresh-water Cyclopidce. 65

VI. Subgenus Eucyclops Claus.

15. Cyclops serrulatus Fischer.
Very common everywhere.

16. Cyclops prasinus Fischer.

Abundant in all sorts of waters in the Mississippi Valley,
Massachusetts, and Florida.

VII. Subgenus Paracyclops Claus.

17. Cyclops phaleratus Koch.

A rare species in Manitoba, Massachusetts, Alabama, and
the north central States.

18. Cyclops Jimbriat us var. poppei Rehberg.

A rare species in Manitoba, Alabama, and the north central
States.

19. Cyclops ajjinis Sa,vs,Jide Herrick.

If this form occurs in America it is very rare, and limited
in its distribution.

66 Illinois State Laboratory of Natural History.

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'48. Conspectus Crustaceorum qua1 in Orbis terrarum circumnaviga-
tion e, Caroli Wilkes e Classe Reipublica? Fo?derata2 duce. col-
lectorum. Proc. Am. Acad. Arts and ScL. Vol. I., pp. 149-155.

Eusebio, J. B.
'88. Recherches sur la faune des eaux du Plateau Central. Le
Faune Pelagique des Lacs d'Auvergne. Trav. Labor. Zool. Girod,
T. I., pp. 1-29, PL I.

Fischer, S.
'60. Beitriige zur Kenntniss der Entomostraceen. Abhandl. d. kgl.
bayerisch. Acad. d. Wissensch., Bd. VIIL, Abth. III., pp. 645-682,
Taf. XX.-XXII.

Forbes, S. A.
'76. List of Illinois Crustacea, with Descriptions of Xew Species.

Bull. 111. State Lab. Nat. Hist,, Vol. I., Xo. 1, pp. 3-25.
'82. On the Food of Young Whitefish (Coregonus). Bull. U. S.

Fish Comra., Vol. L. pp. 269, 270.
'82a. On some Entomostraca of Lake .Michigan and Adjacent

Waters. Am. Nat,, Vol. XVI.. pp. 537-543, 640-650. Pis. VIIL. IX.

Nor tli American Fresh-water Cytlopidee. 69

'87. The Lake as a Microcosm. Bull. Peoria Sci. Ass'n, 1887. 15 pp.

'90. Preliminary Report upon the Invertebrate Animals inhabiting
Lakes Geneva and Mendota. Wisconsin, with an Account of the
Fish Epidemic in Lake Mendota in 1884. Bull. U. S. Fish Coram.,
Vol. VTIL, pp. 473-4S7.

'90a. On some Lake Superior Entomostraea. Ann. Rep. U. S. Comm.
Fish and Fisheries, 1887, pp. 701-717, Pis. I.-IV.

'93. A Preliminary Report on the Aquatic Invertebrate Fauna of
the Yellowstone National Park. Wyoming, and of the Flathead
Region of Montana. Bull. U. S. Fish Comm., 1891, pp. 207-258,
Pis. XXXVII.-XLII.

Fric (Fritsch), A.
'72. Die Krustenthiere Bohmens. Archiv der naturw. Landes-
durchf. Bohmen, Band 11., Abth. IV., pp. 203-269.

'95. Uber Schmuckfarben einiger Siisswasser-Crustaceen. Bull.
Internat" 1 Acad, des Sci. de l'Empereur Francois Joseph I., Classe
des Sci. Math, et Xat. II. 7 pp., 2 colored plates.

Fritsch (Fric), A., u. Vavra, V.

'92. Vorlaufiger Bericht liber die Fauna des Unter-Pocernitzer- und
Gatterschlager Teiches. Zool. Anz., XV. Jahrg., No. 382, pp. 26-30.

'94. Untersuchungen fiber die Fauna der Gewiisser Bohmens. IV.
Die Tierwelt des Unterpocernitzer und Gatterschlager Teiches als
Resultat der Arbeiten an der iibertragbaren zoologischen Station.
Arch. d. naturw. Landesdurchf. v. Bohmen. Bd. IX., Nr. II. 123 pp.

Fric, J. A.
'82. Note preliminaire sur rontogenie de nos Copepodes d'eau
douce. Zool. Anz., V. Jahrg., No. 121, pp. 498-503.

Garbini, A.
'94. Primi materiali per una Monografia limnologica del Lago di

Garda. Bull, della Soc. Entom. It., Anno XXVI., pp. 1-50.
'95. Appunti di Carcinologia Veronese. Estratto dal Vol. LXXL,
Serie III., Fasc. I., dell' Accademia di Verona. 91 pp.
Giesbrecht, W.
'81. Die freilebenden Copepoden der Kieler Fohrde. Ber. d. Kom.
z. w. Unters. d. deutsch. Meere in Kiel, pp. S7-168, Taf. I.-XII.
Gruber, A.

'78. Die Bildung der Eiersiickchen bei den Copepoden. Zool. Anz.
I. Jahrg.. p. 247.

Guerne, J. de
'87. Notes sur la faune des Acores. Diagnoses d'un Mollusque, d'un
Rotifere, et de trois Crustaces nouveaux. Le Naturaliste, 1887.
7 pp.

70 Illinois State Laboratory of Natural History.

'87a. La faune des eaux donees des Acores et le transport des ani-
nianx a grande distance par l'intermrdiaire des oiseanx. Compt.
rend, de la Soe. Biol., Seance du 22 oet., 1887. 4 pp.

'88. Excursions zoologiques dans les lies de Fayal et de San Miguel
(A9ores). Campagnes seientifiques du Yacht monegasque l'Hiron-
delle. Troisieme Ann. (1887). pp. 7-110.

Guerne, J. de, et Richard, J.
'89. Sur la faune des eaux douces du Groenland. Compt. rend, de

l'Acad. des Sci., 25 mars, 1889.
'89a. Xote sur les Entomostraces d'eau douce recueillis par M. Charles

Rabot dans la Province de Nordland, Norvege septentrionale.

Bull de la Soe. zool. de France. T. XIV.. pp. 27-31.
'91. Entomostraces, Rotiferes,etProtozoaires proven ant des reeoltes

de M. E. Belloc dans les etangs de Cazau et de Hourtins (Gironde).

Bull, de la Soe. zool. de France, T. XVI., pp. 112-115.
'91a. Sur quelques Entomostraces d'eau douce de Madagascar.

Bull, de la Soe. zool. de France, T. XVI., pp. 223. 224.
'91b. Entomostraces recueillis par M. Charles Rabot en Russie et

en Siberie. Bull, de la Soe. zool. de France, T. XVI.. pp. 232-236.
'92. Cladoeeres et Copepodes d'eau douce des environs de Rufisque.

Mem. de la Soe. zool. de France. T. V.. pp. 526-538.

'92a. Voyage de M. Charles Rabot en Islande. Sur la faune des
eaux donees. Bull, de la Soe. zool. de France, T. XVII., pp., 75-80.

'92b. Sur la faune pelagique de quelques lacs des Hautes-Pyrenees.

Assoc, franc,, pour l'avanc. des Sci., Congres de Pau, seance du 19

sept. 3 pp.
'93. Sur la faune pelagique des lacs du Jura francais. Compt. rend.

de l'Acad. des Sci. 3 pp.

Hacker, V.
'95. Uber die Selbstiindigkeit der vaterlicheu und miitterlichen
Kernbestandtheile wahrend der Embryonalentwicklung von Cy-
clops. Arch. f. ruikr. Anat., Bd. 46, pp. 579-618,Taf. XXVII1.-XX X.

Hartog, M. M.
'88. The Morphology of Cyclops and the Relations of the Copepoda.
Trans. Linn. Soe. London, Vol. V., Part L, pp. 1-46, Pis.. l.-IV.

Hartwig, W.
'93. Verzeichniss der lebenden Krebsthiere der Provinz Branden-
burg. Statt haudschriftl. Mitteilungen herausgeg. v. Markisehen
Prov.-Mus. der Stadtgemeinde Berlin. Pp. 1-44.

NortJi American Fresh-water Cyclopid<z. 71

'94. Die lebenden Krebstiere der Provinz Brandenburg. Nachtrag
zu meinem "Verzeiehniss" von 1893. " Brandenburgia." Monats-
blatt der Gesellsch. f. Heimatkunde der Prov. Brandenburg zu
Berlin, Nr. 7, Okt., 1894, pp. 165-169.

Hay, W. P.
'92. The Crustacea of Indiana. Proc. Ind. Acad. Sci., 1891, pp.
147-151.

Heller, C.
'71. Intersuchungen iiber die Crustaceen Tirols. Ber. des med.-
naturw. Yereins in Innsbruck, 1 Jahrg., pp. 67-96, Taf. I., II.

Herrick, C. L.
'79. Microscopic Entomostraca. Seventh Ann. Rep. Geol. and
Nat. Hist. Surv. Minn., pp. 81-123, Pis. I -XXI.

'82. Habits of Fresh-water Crustacea. Am. Nat., Vol. XVI., pp.

813-816.

'82a. Papers on the Crustacea of the Fresh Waters of Minnesota.
Tenth Ann. Rep. Geol. and Nat. Hist. Surv. Minn., pp. 221-255,
P1S.I.-XI.'

'83. Ileterogenesis in the Copepod Crustacea. Am. Nat., Vol. XVII.,
pp. 208-212.

'83a. Heterogenetic Development in Diaptomus. Am. Nat., Vol.
XVII., pp. 381-389, 499-505, Pis. V.-VII.

'83b. Types of Animal Life selected for Laboratory Use in Inland
Districts. 33 pp.. 1 PI. Minneapolis.

'84. A Final Report on the Crustacea of Minnesota included in the
Orders Cladocera and Copepoda. Twelfth Ann. Rep. Geol. and
Nat. Hist. Surv. Minn., pp. 1-191.. Pis. A-V.

'87. Contribution to the Fauna of the Gulf of Mexico and the
South. List of Fresh-water and Marine Crustacea of Alabama,
with Descriptions of the New Species and Synoptical Keys for
Identification. Mem. Deuison Sci. Ass'n, Vol. I., No. I., pp. 1-56,
Pis. I.-VII.

Herrick, C. L., and Turner, C. H.
'95. Synopsis of the Entomostraca of Minnesota. Geol. and Nat.
Hist. Surv. Minn., Zool. Series, II. 525 pp., 81 Pis.

Hoek, P. P. C.
'76. Zur Kenntniss der freilebenden Siisswasser-Copepoden der
Niederliindischen Fauna. Nied. Arch. f. Zool., Bd. 111., Heft II..
pp. 127-140, Taf. VII.-IX.

'78. De vrijlevende Zoetwater-Copepoden der Nederlaudsehe
Fauna. Tijdschr. der Nederlandsche Dierkundige Vereeniging,
Deel III., pp. 1-36, Taf. I.-V.

72 Illinois State Laboratory of Natural History.

Imhof, O. E.

'83. Die pelagische Fauna und die Tiefseefauna der zwei Savoyer-
seen : Lac du Bourget und Lac d'Annecy. Zool. An/... VI. Jahrg.,
No. 155, pp. 655-657.

'84. Weitere Mittheilungen iiber die pelagische Fauna der Siiss-
wasserbecken. Zool. Anz., VII. Jahrg., No. 169, pp. 321-327.

'85. Pelagische Thiere aus Siisswasserbecken in Elsass-Lothringen.
Zooi. Anz., VIII. Jahrg., No. 211, pp. 720-723.

'85a. Weitere Mittheiluug iiber die pelagische and Tiefseefauna der
Siisswasserbecken. Zool. Anz., VIII. Jahrg., No. 190, pp. 160-163.

'86. Xeue Besultate iiber die pelagische und Tiefseefauna einiger im
Flussgebiet des Po gelegener Siisswasserbecken. Zool. Anz., IX.
Jahrg. No. 214, pp. 41-47.

'86a. A"oii;iufige Notizen iiber die horizontale und verticale geo-
graphische Verbreitung der pelagischen Fauna der Siisswasser-
becken. Zool. Anz., IX. Jahrg., No. 224, pp. 335-342.

'86b. Uber mikroskopische pelagische Thiere aus der Ostsee. Zool.
Anz., IX. Jahrg., No. 235. pp. 612-015.

'87. Uber die raicroscopische Thierwelt hochalpiner Seen. Zool.
Anz., X. Jahrg., Nos. 241 u. 242, pp. 13-17. 33-42.

'87a. Notizen iiber die pelagische Fauna der Siisswasserbecken.
Zool. Anz., X. Jahrg., Nos. 2G4 u. 265, pp. 577-582, 604-606.

'87b. Studien iiber die Fauna hochalpiner Seen insbesondere des
Kantons Graubiinden. Jahresber. d. naturf. Gesellsch. Graubiin-
dens. N. F., XXX. Jahrg., pp. 45-104.

'88. Die Vertheilung der pelagischen Fauna in den Siisswasser-
becken. Zool. Anz., XI. Jahrg., Xo. 280, pp. 284-291.

'88a. Beitrag zur Kenntniss der Siisswasserfauna der Vogesen.
Zool. Anz., XI. Jahrg.. No. 290, pp. 565, 500.

'90. Notizen iiber die pelagische Thierwelt der Seen in Karnthen
und in der Krain. Zool. Anz., XIII. Jahrg., Nos. 335, 33S, 339. pp.
201-263, 347-349, 372-377.

'90a. Notiz iiber pelagische Thiere aus einem Teiche in Galizien.
Zool. Anz., XIII. Jahrg., No. 336, pp. 2S4-2S5.

'95. Tierwelt der hochalpinen Seen. Biol. Centralbl., Bd. XV., Nr.
13, pp. 507-517.

Joseph, G.
'82. Systematisches Verzeichnis der in den Tropfstein-Grotten von
Krain einheimischen Arthropoden nebst Diagnosen der vom
Verfasser entdeckten und bisher noch nicht beschriebenen Arten.
II. Theil. Erfahrungen im wissenschaftlichen Sammeln und
Beobachten der den Krainer Tropfstein-Grotten eigenen Arthro-
poden. Berl. Entomol. Zeitschr., Bd. XXVI.. Heft 1, pp. 1-50.

North American Fresh-water Cyclopidce. 73

Jurine, L.
'20. Histoire ties Monocles qui se trouveut aux environs de Geneve,
pp. I-XVI. + 1-258, Pis. I -XXII. Geneve et Paris.

Kafka, Josef.
'92. Untersuchuugen liber die Fauna der Gewiisser Bohmens. II.
Die Fauna der Bohmischen Teiche. Archiv d. Naturwissensch.
Landesdurchf. von Bohmen, VIII. Bd., No. II.

Kerville, H. G. de.
'88. Les Crustaces de la Normandie: Especes fluviales, stagnates et
terrestres. Bull, de la Soe. des Amis des Sci. nat. de Kouen, 1888,
lre Sem., pp. 133-158.

Kingsley, J. S.
'84. Entomostraca. Stand. Nat. Hist., Vol. II., pp. 22-41.

Koch, C. L.
'35-'41. Deutschlands Crustaceen, Myriapoden, und Arachniden,
Heft. XXI., XXV. Regensburg.

Kochs, W.
'92. Versuche iiber die kiinstliche Vermehrung kleiner Crustaceen.
Biol. Centralbl., Bd. 12. Xr. 18 u. 19, pp. 599-606; Translation in
Bull. U. S. Fish Cornm., Vol XIV., pp. 306-308.

Ladenburger, R.
'84. Zur Fauna des Mansfelder Sees. Zool. Anz., VII. Jahrg., No.
168, pp. 299-302.

Lande, A
'92. Quelques Remarques sur les Cyclopides. Mem. de la Soc. zool.
de France, T. V., pp. 156-173.

Lauterborn, R.
'94. Uber die Winterfauna einiger Gewiisser der Oberrheinebene.
Mit Beschreibungen neuer Protozoen. Biol. Centralbl., Bd. XIV.,
Xr. 11., pp. 390-398.

Lilljeborg, W.
'53. De Crustaceis ex ordinibus tribus : Cladocera, Ostracoda, et Cope-
poda, in Scania occurrentibus. Pp. I.-XV. -4- 1-122, Pis. I.-XXVI.

Loven, S.
'61. Om nagra i Vettern och Venern funna Crustaceer. Ofv. Kongl.
Vet.-Akad. Forhandl., Arg. XVIII., No. 7, pp. 285-314.

Lubbock, J.
'63. Notes on some New or Little-known Species of Fresh-water
Entomostraca. Trans. Linn. Soc. London, Vol. XXIV., pp. 197-210
PI. XXXI.

74 Illinois State Laboratory of Natural History.

Marsh, C. D.
'91. Preliminary List of Deep-water Crustacea in Green Lake, Wis.,

U. S. A. Zool. Anz., XIV. Jahrg., No. 370, pp. 275, 276.
'92. On the Deep-Water Crustacea of Green Lake. Trans. Wis.

Acad. Sci., Arts, and Letters, Vol. VIII., pp. 211-213.
'93. On the Cyclopidaj and Calanidae of Central Wisconsin. Trans.

Wis. Acad. Sci., Arts, and Letters, Vol. IX.. pp. 189-221, Pis.

III.-VI.
'93a. Notes on the Copepoda of Wisconsin. Science, Vol. XXIL,

No. 544. pp. 3, 4.
'95. On the Cyclopida? and Calanidre of Lake St. Clair, Lake Mich-
igan, and certain of the Inland Lakes of Michigan. Bull. Mich.

Fish Comm., No. 5. 24 pp., 9 Pis.

Milne-Edwards, H.
'34-'40. Histoire naturelle des Crustaces, comprenant l'anatomie,
la physiologic et la classification de ces anirnaux. Tome I., II.,
III. 42 Pis. Paris.

Moniez, R.
'87. Liste des Copepodes, Ostracodes, Cladoctres, et de quelques

autres Crustaces recueillis a Lille en 188G. Bull, de la Soc. zool. de

France. T. XII.. pp. 568-578.
'89. Note sur la faune des eaux douces de la Sicilie. Feuille des

jeunes Naturalistes, Annee 20, No. 230, pp. 17-19.
'89a. Faune des eaux souterraines du Departement du Nord, et en

particulier de la ville de Lille. Kev. Biol, du nord de la France.

lre Ann., pp. 175-179.
'89b. Sur quelques Cladoceres et sur un Ostracode nouveaux du

Lac Titicaca. Rev. Biol, du nord de la France, lre Ann., p. 421.

Mrazek, A. v

'91. O hermafroditismu u Copepodu. Vestnik Krai. Ceske Spol.

Nauk., pp. 389-393, PI. XII.
'93 Pffspevky k poznnai Sladkovodnich Copepodi°i. Vestnik Krai.

Ceske Spol. Nauk. Tfida math.-pf ir., 1893. 74 pp., Pis. VI.-VIII.
'93a. Uber abnorme Vermehrung der Sinneskolben an dera Vorder-

fiihler des Weibchens bei Cyclopiden und die niorphologische

Bedeutungderselben. Zool. Anz., XVI. Jahrg., No. 417, pp. 133-138.
'93b. Uber die Systeraatik der Cyclopiden und die Segmentation

der Antennen. Zool. Anz., XVI. Jahrg., No. 424. pp. 285-289; No.

425, pp. 293-299.
'93c. Zur Morphologie der Antenna der Cyclopiden. Zool. Anz..

X VI. Jahrg.. No. 430. pp. 376-385.

North American Fresh-water CyclopidcB. 75

'95. Copepoden. Deutsch-Ost-Africa Wiss. Forschungsresultate,
etc., Band IV., Die Thierwelt Ost-Afrikas. 11 pp., 3 Pis.

Miiller, O. F.

1792. Entomostraca sen Insecta testacea quae in aquis Daniae et
Norvegiae reperit, descripsit et iconibus illnstravit. 134 pp., 21
Pis. Havniae.

Nordqvist, O.
'86. Bidrag till Kannedomen om Crustacefaunan i nagra af mellersta
Finlands sjoar. Acta Soc. pro Fauna et Flora Fenn., T. III., No. 2.
pp. 1-26.

'87. Die pelagische und Tiefsee-Fauna der grosseren finnischen
Seen. Zool. Anz., X. Jahrg., Nos. 254, 255, pp. 339-345, 358-362.

'90. Bidrag till Kannedomen om Bottniska vikens och norra
Ostersjons evertebratfauna. Meddel. af Soc. pro Fauna et Flora
Fenn., 17 Haft., pp. 83-12S.

Nusbaum, J.
'92. Zur Kenntnis der Wiirmerfauna und Crustaceenfauna Polens.
Biol. Centralbl., Bd. XII., Nr. 2, pp. 54-58.

Pavesi, P.
'79. Nuova serie di ricerche della fauna pelagica nei lagbi italiani.
Rend, del R. Inst. Lombardo, Ser. II., Vol. XII., fasc. XI., XII.
10 pp.
'79a. Ulteriori studj sulla fauna pelagica dei lagbi italiani. Rend,
del R. Inst. Lombardo, Ser. II., Vol. XII., fasc. XVI. 21 pp.

'82. Excursione Zoologica al Lago di Toblino. Atti della Soc. Ital.
di Sci. Nat., Vol. XXV. 5 pp.

'83. Altra serie di ricerche e studi sulla fauna pelagica dei laghi
italiani. Atti della Soc. Ven.-Tren. di Sci. Nat., Vol. VIII., pp.
340-403, Pis. VIII.-XIV.

Poggenpohl, M. J.
'74. Verzeichniss der Copepoden, Cladoceren, und Ostracoden der
Umgebung von Moskau. Schriften der Gesellsch. v. Freunden d.
Naturwissensch., etc., zu Moskau, Bd. X., Abt. II., pp. 69-77, Taf.
XV.-XVII. (German title of Russian article.)

Poppe, S. A.
'84. Bemerkungen zu R. Ladenburger's: Zur "Fauna des Mans-
felder Sees" in No. 168 des Zoologischen Anzeigers. Zool. Anz..
VII. Jahrg., No. 175, pp. 499, 500.

'89. Xotizen zur Fauna der Stisswasser-Becken des nordwestlichen
Deutschland mit besonderer Beriicksichtiguug der Crustaceen.
Abh. d. Naturw. Ver. zu Bremen, Bd. X., pp. 517-550, Taf. VIII.

76 Illinois State Laboratory of Natural History.

'89a. Berichtigung zu Dr. O. E. linhol's Aufsatz: " Fauna tier Siiss-
wasserbecken " in Xo. 275 des Zool. Anz. 1888, p. 106. Zool. Anz.,
XII. Jahrg., Xo. 300. pp. 99, 100.

'91. Beitrage zur Fauna der Insel Spiekerooge. Abh. d. Xaturw.
Ver. zu Bremen, Bd. XII. 6 pp.

Poppe, S. A., u. Mrazek, A.
'95. Entomostraken des Xaturhistorischen Museums in Hamburg.
Jahrb. der Hamburgischen Wiss. Anstalten, XII.. Beiheft. 20 pp.,
4 Pis.

Poppe, S. A., et Richard, J.
'90. Xote sur divers Entomostraces du Japon et de la Chine.
Bull, de la Soc. zool. de France, T. XV., pp. 73-78.

Rath, O. v.
'91. Zur Kenntniss der Hautsinnesorgane der Crustaceen. Zool.
Anz., XIV. Jahrg., Nos. 365, 366, pp. 195-200, 205-214.

Rehberg, H.
'80. Zwei neue Crustaceen aus einem Brunnen auf Helgoland. Zool.
Anz., III. Jahrg., Xo. 58, pp. 301-303.

'80a. Beitrag zur Kenntniss der freilebenden Siisswasser-Copepoden.
Abh. d. Xaturw. Ver. zu Bremen, Bd. VI., pp. 533-554, Taf. VI.

'80b. Weitere Bemerkung uber die freilebenden Siisswasser-Copep-
oden. Abh. d. Xaturw. Ver. zu Bremen, Bd. VII., pp. 61-67, Taf. IV.

Richard, J.
'87. Liste des Cladoceres et des Copepodes d'eau douce observes en

France. Bull, de la Soc. zool. de France. T. XII., pp. 156-163.
'88. Cladoeeres et Copepodes non marins de la Faune francaise.

Rev. Sci. du Bourbonnais. mars-avril, 18S8, pp. 1-28
'90. Sur les Entomostraces et quelques autres animaux inferieurs

des lacs de TAuvergne. Bev. des Sci. Nat. Appliquees. Xo. 10. 20

mai, 1890.
'90a. Sur la glande du test des Copepodes d'eau douce. Xote pie-

liminaire. Bull, de la Soc. zool. de France, T. XV., pp. 113-118.
'90b. Description du Bradya Edwardsi. < opepode.aveugle nouveau,

vivant an Bois de Boulogne avec divers Entomostraces dans les

eaux alimentees par le puits artesien de Passy. Mem. de la Soc.

zool. de France, T. III., pp. 214-222.
'90c. Entomostraces d'eau douce recueillis a Belle He (Morbihan).

Bull, de la Soc. zool. de France, T. XV., pp. 33, 34.
'91. Sur les Entomostraces du Lac Balaton. Bull, de la Soc. zool.de

France, T. XVI., pp. 135-137.
'91a. Entomostraces d'eau douce de Sumatra et de Celebes. Zool.

Ergeb.einerReiseinXiederland.Cv-t-Ind., Bd. II., pp. 118-134, PI. X.

North American Fresh-water Cyclopidce. 77

'91b. Recherehes sur le Systeme glandulaire et sur le Systeme
nerveux des Copepodes libres d'eau douce. Ann. Sei. Xat., Zool.,
T. XVI., pp. 113-270, PJs. V.-VIII.

'92. Sur quelques Entomostraees de Pile d'Elbe et de 1'ile de Monte-
Cristo. Bull, de la Soc, zool. de France, T. XVII., pp. 226-229.

'93. Copepodes recueillis par M. le Dr. Theod. Barrois en Egypte,
en Syrie, et en Palestine. Rev. Biol, du nord de la France, 5e aim.,
Xo. 10, juillet, 1893. 36 pp., 51 Fig.

'94. Sur quelques aniraaux inferieurs des eaux douees du Tonkin
(Protozoaires, Roti feres, Entomostraees). Mem. de la Soc. zool. de
France, T. VII., pp. 237-243.

'94a. Entomostraces recueillis par M. E. Modigliani dans le Lac
Toba (Sumatra). Ann. del Mus. Civ. di Storia Natural e di Genova,
Serie 2. a, XIV. (XXXIV.). pp. 565-578.

'95. Sur quelques Entomostraces d'eau douce d'Hai'ti. Mem. de la
Soc. zool. de France, T. VIII. 11 pp. 11 figs.

'95a. Cladoeeres et Copepodes recueillis par M. Kavraisky pres de
Tillis et dans le Eac Goktsha. Bull, de la Soc. zool. de France. T.
XX.. pp. 91,92.

'95b. Contribution a la Faune des Eutornostraces de la France.
Feuille des jeunes Naturalistes, III. Serie, 25e Ann., Nos. 295 et
296. 9 pp.

Riickert, J.
'95. Zur Befruehtung von Cyclops strenuus (Fisch.). An at. Anz., X.
Bd., Xo. 22, pp. 708-725; Abstract, Zool. Centralbl., II. Jahrg., pp.
555. 556.

'95a. Uber das Selbstandigbleiben der vaterliehen und miitter-
licben Kernsubstanz wahrend der ersten Entwicklung des befrueh-
teten Cyclops-Eies. Arcb. f. Mikr. Anat.. Vol. 45, pp. 339-369. Taf.
XXI., XXII.; Abstract, Zool. Centralbl., II. Jahrg., pp. 554, 555.

Sars, G. 0.
'62. Oversigt af de indenlandske Ferskvandscopepoder. Forhandl.
Vidensk.-Selsk. i Christiania, 1862, pp. 212-262.

'63. Beretning om en i Sommeren 1S62 foretagen zoologisk Reise i
Christianias og Trondbjems Stifter. Xyt Mag. f. Xaturvidensk.,
Bd. XII., pp. 193-252.

'64. Beretning om en i Sommeren 1S63 foretagen zoologisk Reise i
Christianias Stifter. Nyt Mag. f. Naturvidensk., Bd. XIII. 36 pp.

'89. On a small Collection of Fresh-water Entomostraca from Syd-
ney. Christiania Vidensk.-Selsk. Forhandl., 1889, No. 9, pp. 1-9.

'96. On Fresh-Water Entomostraca from the Neighborhood of
Sydney partly raised from dried Mud. 81 pp., 8 PJs. Kristiania.

78 Illinois State Laboratory of Natnial History.

Say, T.
'18. An Account of the Crustacea of the United States. Journ.
Acad. Nat. Sci. Phil., Vol. I., pp. 421-458.

Schmankewitsch, W.
'77. Zur Kenntniss des Einflusses der ausseren Lebensbedingungen
auf die Organisation der Thiere. Zeitschr. f. wiss. Zool.. Bd.
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Schmeil, O.
'91. Beitriige zur Kenntniss der Siisswasser-Copepoden Deutsch-
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'94. Zur Hohlenfauna des Karstes. Zeitschr. f. Xaturwiss. Halle.
Bd. 06, pp. 339-353.

Scott, T.
'94. On the food of Utricularia vulgaris, an Insectivorous Plant.
Ann. Scot. Xat. Hist,, Xo. 10. pp. 105-112.
Scourfield, D. J.
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'94. Entomostraca and the Surface-film of Water. Journ. Linn. Soc.
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'91. Materiaux pour servir a l'etude des Crustaces d'eaux douces

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North American Fresh-water Cyclopidce. 79

Turner, C. H.
'92. Notes upon the Cladocera, Copepoda, Ostracoda, and Eotifera
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Vernet, H.
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Voeltzkow, A.
'91. Vorlauriger Bericht iiber die Ergebuisse einer Untersuchung
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Vosseler, J.
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1886, pp. 167-202, Taf. IV.-VI.

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'82, Materyaly do fanny jezior tatrzanskich. Copepoda. Sprawozd.
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80 Illinois State Laboratory of Natural History.

'92. Skorupiaki i Wrotki (Rotatoria) slodkowodne zebrane w
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'85. Ergebnisse einer zoologiscbeu Exkursion in das Glatzer-.Iser-,

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deutscher Seen. Zeitscbr. f. wiss. Zool., Bd. XLV.. pp. 255-2S1.

Taf. I.
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VIII.. Xo. 17. pp. 540.541.
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'93. Fauna des grossen Ploner Sees. Biol. Centralbl., Bd. XIII.. Xr.

11 u. 12 pp. 377-4S4.

'94. Uber die Verteilung der Flanktonorganismen innerhalb eines
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'95. Uber die vertikale Verteilung limnetiscber Crustaceeu, insbe-
sondere iiber diejenige von Cyclops oithonoides. Biol. Centralbl.,
Bd. XV.. Xr. 18, pp. 6S6-688.

Zaddach, E. G.
'44. Synopseos Crustaeeorum Prussicorum Prodromus. pp. I -VIII.
-\- 1-33. Regiomonti (Konigsberg).

Zenker, W.
'54. Uber die Cyclopiden des siissen Wassers. Archiv fiir Xatur-
gesch.. XX. .Tabrg., Bd. 1, pp. S8-103, Taf. VI.. Fig. 8-14.

Zschokke, F.
'90. Faunistiscbe Studien an Gebirgsseen. Verbal. Naturf. Gesellseh.
in Basel. Bd. IX. 62 pp.

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Anz .XIII. Jabrg., Xo. 326, pp. 37-40.

Nortli American Fresh-water Cyclop idee. 81

'91. Weiterer Beitrag znr Kenntnis tier Fauna von Gebirgsseen.
Zool. Anz., XIY. Jahrg., Nos. 360 n. 361, pp. 119-123 u. 126-129.

'94. Die Tierwelt tier Juraseen. Rev. Suisse tie Zool., T. II., pp.
349-376, PI. XIV.

'95. Die Fauna hochgelegener Gebirgsseen. Yerhandlung der
Naturf. Gesellsch. in Basel. Btl. XI., Heft I., pp. 36-133, Taf. I.

EXPLANATION OF PLATES.

Plate VIII.

Fig. 1. Cyclops leuckarti Clans.

Fig. 2. Last two segments of antenna of same.

Fi<;. 3. Fifth foot of same.

Plate IX.

Fig. 1. Cyclops edax Forbes.

Fit;. 2. Last two segments of antenna of same.

Fig. 3. Fifth foot of same.

Plate X.

Fig. 1. Cyclops viridis Jnrine.

Fit;. 2. Fifth foot of same.

Fig. 3. Reeeptacnlum seminis of same.

Plate XL

Fig. 1. Variations in outer terminal spine of stylet of Cyclops viridis

var. hrevispinosus Herrick.
Fig. 2. Fifth foot of same.

Fig. 3. Keceptaculum seminis of Cyclops viridis var. insectus Forbes.
Fn;. 4 and 5. Fifth foot of same.
Fig. 6. Swimming foot of same.

Plate XII.

Fig. 1. Cyclops bicuspidatus Clans.

Fig. 2. Stylet of same.

Fig. 3. Fifth foot of same.

Fig. 4. Receptaculum seminis of same.

Plate XIII.
Cyclops albidus Jurine.

Plate XIV.
Cyclops ater Herrick.

82 Illinois State Laboratory of Natural History.

Plate XV.

Y\(.. 1. Last two segments of antenna of Cyclops ater Herriek.

Fit;. 2. Fifth foot of same.

Ftg. 3. Receptaculum seminis of same.

Fur. 4. Cyclops modestus Herriek.

Plate XVI.

Fig. 1. Antenna of Cyclops modestus Herriek.

Fig. 2. Fifth foot of same.

Fig. 3. Receptaculum seminis of same.

Plate XVII.

Cyclops

serrulatus Fischer.

Plate XVIII.

Fig. 1.

Cyclops serrulatus Fischer.

Fig. 2.

Fifth foot of same.

Fig. 3.

Receptaculum seminis of same.

Plate XIX.

Fig. 1.

Cyclops prasinus Fischer.

Fig. 2.

Antenna of same.

Plate XX.

Fig. 1. Fifth foot of Cyclops prasinus Fischer.
Fig. 2. Receptaculum seminis of same.
Fig. 3. Cyclops phaleratus Koch.

INDEX.

(Synonyms in Italics.)

Canthoeamptus. 62.
Claeocera, 62.
Copepoda, 27.
Cyclopidje. European, 29.

list of North American species,
63.
Cyclops, 31,63.

afflnis, 29, 65.

agilis, 29.

albidus, 29, 47, 62, 63, 64.

americanus, 37, 38, 42.

annulatus, 33, 35.

ater, 29, 49, 62, 64.

bicolor, 29, 62. 63, 64.

bicuspiclatus, 29, 30, 44, 53, 62,
63, 64.

bisetosus, 29.

brevispinosus, 39, 41.

capilliferus, 51.

crassicaudis, 29.

dybowskii, 29, 62, 63.

edax, 33. 62, 63.

fitnbriatus, 29.

var. poppei, 63, 65.

fluviatilis, 57.

forbesi, 44, 45.

fuseus, 29, 64.

general distribution of. in
North America, 62.

gigas, 29, 37.

gyrinus, 47, 48.

helgolandicus, 29.

hyalinus, 29.

ingens, 37.

insectus, 37,38, 39, 41.

insignis. 29, 63.

lacustris, 29.

leeuwenhoekii, 34, 35.

leuckarti, 29, 31, 34, 36, 63.

leuckarti, 33.

lev is. 37.

macrurus, 29.

Cyclops — continued,
magnoctavus, 57.
minnilus, 44, 45.
modestus, 29, 62, 63, 64.
nanus, 29.
navus, 44, 45.
oithonoides. 29. 63.
parens, 38, 41, 42.
pentagonus, 57.
peramatus, 59, 60.
phaleratus, 29, 30, 59, 63, 65.
prasinus, 57, 63, 65.
pulchellus, 29, 44.
robustus, 29.
scutifer, 29.
serratus, 44, 45.

serrulatus, 29, 30, 54, 62, 63, 65.
var. ele/jans. 54.
var. montanus, 54, 55.
sigriatus, 29.

var. tenuicornis, 47.
strenuus, 29.
thomasi. 44, 45.
unianguiatns, 39, 41.
varicans, 29, 63, 64.
vernalis, 29, 64.
viridis, 29, 30,37, 41,42, 43,
48, 62, 63, 64.
var. brevispinosus, 30, 39,

41, 62, 63, 64.
var. insectus, 31, 41, 62,
63, 64.
Diaptomus, 62.
Eucyclops, 54, 65.
Ilomocyclops, 29. 49, 64.
Macrocyclops, 47, 64.
Microcy clops, 64.
Monoculus quadricornis var. albidus,
47.
var. viridis, 37.
Orthocy clops, 29, 51,64.
Paracyclops, 59, 65.

Plate VIII.

Q

ffl

Pv

Plate IX.

Plate X.

Plate XL

Plate XII.

Plate XIII.

Plate XIV.

Plate XV.

Plate XVI.

Plate XVII.

Plate XVIII.

Plate XIX.

Plate XX.

ERRATA.

Page 31, line 8, for solid read dotted; line 10, for dotted read solid.

Page 34, line 6, for eqwd read subequal.

Page 44, line 8, for species read variety.

Pase 63, line 10, before America insert North.

Page 6(5, under Birge, E. A., for '94 read '95.

Page 73, under Koch, C. L., for XXV. read XXXV.

Page 77, line 2, before Zoology insert 7e Ser.; line 3, for XVI. read XII.

Page 78, line 13, for Heft II. read Heft 11.

Page 79, for Villipoix, R. M. de, read Villepoir, R. M. de.

Page SO, under Zacharias, O., for '85 read '80; and in entry for 'a7, for
Taf. I. readTaf. XV.

Page SI. line 5. for '95 read '94.

BULLETIN

OF THE

[llinois 3tate Laboratory

OK

NATURAL HISTORY,

Urbana, Illinois

VOLUME V.

ARTICLE III.— THE NORTH AMERICAN SPECIES OF

DIAPTOMUS.

By FREDERICK WILLIAM SCHACHT, B. S.

Illinois State Laboratory of Natural History,
URBANA, ILLINOIS,

1897.

State Laboratory of Natural History.

LABORATORY STAFF.

Professor Stephen Alfred Forbes, Ph. I).,
Director of State Laboratory and State Entomologist.

Charles Arthur Hart,
Systematir Entomologist and Curator of Collections.

Frank Smith, A. M.,

Assistant Zoologist.

Charles Atvvood Kofoid, Ph. D.,

Zoologist, awl Superintendent of Biological Station.

Charles Christopher Adams, B. S.

Entomological Assistant.

Ralph Waldo Brauciier, B. S..

Entomological Assistant.

Mary Jane Snyder.

Secretary.

Henry Clinton Forbes,
I!)isi7iess Agent and Librarian.

Lydia Moore Hart,
Artist.

Article III. — The North American Sj>ccies of Diaptomus.

By Frederick William Schacht.

INTRODUCTION.

The first published reference to that group of genera of
Entomostraca now known under the family name of Centro-
pagidce is contained in 0. F. Muller's "Entomostraca seu
Insecta testacea quae in aquis Daniae et Norvegiae reperit,"
etc., published at Frankfort-on-the-Main in 1785, in which

The following paper was prepared in the course of
undergraduate study in the Zoological Department of the
University of Illinois, and was accepted by the Faculty
of the University June 7, 1897, as a thesis for the degree
of Bachelor of Science in Zoology.

187 7 ana tnose oi marsii in iodi. » »niyjc a^x^i^a v^.
kentuckyensis) named by Chambers in 1881 is so imperfectly
described that its recognition is apparently impossible. Since
the publication of Underwood's " List of the described Species
of Fresh- water Crustacea from America North of Mexico"
('86) the number of recognized North American species of
Diaptomus has increased from five to twenty-three.

The literature of the genus previous to 1889 was widely
scattered and the synonymy greatly complicated, but the
comprehensive and careful "Revision" published in that
year by de Guerne and Richard ('89b) has had the effect
greatly to facilitate its study. The most important recent
European contributions to a knowledge of the Centropagidce

9?

State Laboratory of Natural History.

LABORATORY STAFF.

Professor Stephen Alfred Forbes, Ph. D.,

Director of State Laboratory and State Entomologist.

Charles Arthur Hart,

£j>iwmo logical jissisiam.

Mary Jane Snyder,

Secretary.

Henry Clinton Forbes,
Business Agent and Librarian.

Lydia Moork Hart,
Artist.

Article III. — The North American Sp)ccies of Diaptomus.
By Frederick William Schacht.

INTRODUCTION.

The first published reference to that group of genera of
Entomostraca now known under the family name of Centro-
pagidee is contained in 0. F. Midler's "Entomostraca seu
Insecta testacea quae in aquis Daniae et Norvegiae reperit,"
etc., published at Frankfort-on-the-Main in 1785, in which
paper certain copepod species now included under the genus
Diaptomus were treated under the general name of Cyclops.
Species of Diaptomus were later described by Jurine ('20)
under Monoculus, but the genus Diaptomus was first estab-
lished by Westwood ('36). Various names have since been
applied more or less closely to the generic group : Cyclopsina,
Milne-Edwards ('38); Qlaucea, Koch ('38); and Cyclops,
Nicolet ('48).

The first American species of Diaptomus recognizably
described was D. sanguineus Forbes ('76). Later Dr. Forbes
( '82a) described three additional species of this genus (sicilis,
leptopus, and stagnalis), and two new genera of Centropagidce
(Epischura and Osphranticum), with a single species of each.
Prof. C. L. Herrick's publications on the group began in
1877 and those of Marsh in 1891. A single species (D.
kentuckyensis) named by Chambers in 1881 is so imperfectly
described that its recognition is apparently impossible. Since
the publication of Underwood's " List of the described Species
of Fresh-water Crustacea from America North of Mexico"
('86) the number of recognized North American species of
Diaptomus has increased from five to twenty-three.

The literature of the genus previous to 1889 was widely
scattered and the synonymy greatly complicated, but the
comprehensive and careful "Kevision" published in that
year by de Guerne and Richard ('89b) has had the effect
greatly to facilitate its study. The most important recent
European contributions to a knowledge of the Centropagidce

97

98 Illinois state Laboratory of Natural History. .

have been made by Claus, Schmeil, Poppe, Imhof, Zacliarias,
and others, in Germany ; by Brady, in England ; by Nord-
qvist, in Finland; by Bars, in Norway; and by Lilljeborg in
Sweden, the latter especially having described a number of
American species. Perhaps the finest work yet published
on Copepoda in general is Giesbrecht's monograph on the
" Pelagischen Copepoden des Golfs von Neapel" ('92), the
general classification of which is followed in the present
article.

It has been my purpose in preparing this paper to do for
the students of American Centropagidce a service similar to
that which de Guerne and Richard have rendered to students
of this group as distributed throughout the world. I am
under especial obligation to my instructor, Prof. S. A. Forbes,
to whose encouragement and aid any value this paper may
have is to be largely attributed. I am indebted also for
specimens or other favors to Dr. Wilhelm Lilljeborg, of
Upsala, Sweden ; to Dr. Otto Schmeil, of Magdeburg, Ger-
many; to Herr S. A. Poppe, of Vegesack, Germany; to Prof.
C. Dwight Marsh, of Ripon College, "Wisconsin ; to Prof. L.
S. Ross, of Drake University, Des Moines, Iowa; to Mr.
Adolph Hempel, now of the Museu Paulista, Sao Paulo, Bra-
zil ; to Prof. Frank Smith, of the University of Illinois ; to Mr.

C. E. Phillips, of Millington, 111. ; and to my friend and fellow
student, Mr. E. B. Forbes. I have also to call attention to
the fact that most of the figures accompanying this paper
were drawn by the Artist of the State Laboratory, Miss
Lydia M. Hart.

From Dr. Lilljeborg I received specimens of Diaptomus
signicauda, D. minutus, 1>. trybomi, D. eiseni, I). francisca-
nus, Epischura nevadensis, and K. nordenskibldi. Prof. Ross
and Mr. Hempel kindly loaned me their personal collections,
the former thus furnishing me D. siciloides, I >. piscina, and

D. clavipes sp. nov., and the latter, D. mississippiensis and
D. albuquerquensis. Prof. Marsh has sent me slides or entire
specimens of D. ashlandi, 1 >. mississippiensis, and D. reighardi.
To Dr. Schmeil I owe thanks for several kind letters, for the
European species 1>. gracilis, I>. graciloides, I>. castor, D.

North American Species of Diaptomus. 99

salinus, D. coeruleus, and D. zachariasi, and for specimens
of Heterocope and Temorella, — all of which, however, arrived
too late to be of service to me in connection with this paper.
From Herr Poppe I received the following species : D. tyrrelli,
D. gibber, D. incongruens, D. deitersi, D. drieschi, D. zacha-
riasi, and Limnocalanus sinensis.

The material at my command was nearly complete, includ-
ing all but two of the known North American forms (D.
novamexicanus and D. birgei), and the collection of the liter-
ature of the group to which I have had access is probably as
ample as that to be found in any library in this country.
In compiling the bibliographical list appended to this paper,
Schmeil's monograph on the Ccntropag'uhe ('96) was taken
as a basis and was especially helpful, while a great deal was
also gained from the works of de Guerne and Eichard.

By far the greater part of the collections examined are the
property of the Illinois State Laboratory of Natural History.
They represent localities distributed over the entire continent,
from Massachusetts in the East to Oregon in the West, as far
south as Florida and as far north as Canada, and including the
following states : Massachusetts, Florida, Mississippi, Ohio,
Indiana, Illinois, Iowa, Minnesota, Michigan, Wisconsin,
Oregon, Washington, Montana, Wyoming, California, Idaho,
and Nevada. In addition to the above I have examined
specimens from Manitoba, Newfoundland, and Greenland.

The localities represented by these collections vary widely
in character, ranging from temporary pools on the Illinois
prairies to Lakes Michigan and Superior; from the warm
lakes of the Florida swamps to the cold mountain lakes of
the Eockies ; and from the small head-water streams of the
Kaskaskia to the sluggish Illinois and the mighty Mississippi.
The collections were made at all seasons of the year and at
nearly all times of the day and night.

Although no very complete data for any single locality are at
hand, it is found that in ordinary years the spring and early
summer are the most favorable seasons for collecting in our
latitudes. Individuals are found, however, at all times ; and
in some cases the normal habitat is a lake whose waters are

100 Illinois State Laboratory of Natural History.

but little above the freezing point, or even, as in the case of
J>. minutus, water flowing from the foot of a glacier- Although
this would seem to indicate that these crustaceans are quite
hardy, I have repeatedly found that in jars containing living
specimens of Cyclops, Diaptomus, and Osphranticum, those
of Diaptomus were the first to succumb to unfavorable con-
ditions.

The genus Diaptomus is the most cosmopolitan of its
family, species having been reported from North and South
America, Europe, Asia, Africa, and Australia. No species,
however, is known to be common to the mainlands of Europe
and of America. This fact is the more remarkable since
almost the direct opposite is true of the companion genus,
( 'yclops, only one or two species of which are, so far as known,
peculiar to this continent. Even 1>. minutus, which is found
in Oregon, Illinois, Wisconsin, Minnesota, Michigan, New-
foundland, Greenland, and Iceland, has not as yet been found
in northern Europe or even in Great Britain, although the
expanse of salt water between Iceland and Scotland or be-
tween Iceland and Scandinavia is but little greater than that
between Greenland and the mainland of North America. But
few species of this genus have been described from tropica)
regions, most of them having thus far been found in the north
temperate zone ; a fact to be attributed doubtless in large
measure to the greater attention paid to zoological studies in
these northern latitudes.

In this paper the plan followed by de Guerne and Richard
in their "Revision" has been adopted, separate keys being
made for males and for females. When females are so nearly
alike as in 1>. sicilis, siciloides, pallidus, and ashlandi, it ig
somewhat difficult to find distinguishing characters, and
differences not usually taken into account must be seized
upon. The males are much more easily separated, since they
offer a larger number of peculiarities. Giesbrecht and
Schrneil have paid considerable attention to the armature of
the entire male prehensile antenna instead of regarding only
that of the last three segments, and in one or two cases I
have done the same. In this connection a fact became

North American Species of Diaptomus. 101

evident which if found to be generally true will necessitate a
slight modification of the description of the family Centro-
pagidce. I refer to the presence of a sense-club on the first
segment of the right male antenna. In his monograph
Giesbrecht in his description ('92, p. 85), says, "Vordere
antennen almlich wie bei den Calaniden gebaut." On another
page (42) we find this statement: "The normal number of
processes seems to be three for each segment, a proximal
seta, a distal seta, and a sensory structure [asthetask], but
this triad is never complete on all segments, the sense-club
on the first segment being always wanting and the sense-club
and proximal seta nearly always absent on the twentieth to
the twenty-fourth." In Diaj)tomus stagnalis and D. clavipes
a sense-club is present on the first segment. The statement
that the inner rami of the fifth pair of feet are "rudimentary,
one-segmented, or lacking" will not hold in many species.
Taking only those forms among non-American species which
were described in de Guerne and Richard ('89b), we find the
following with fat'o-segmented inner rami : D. minis, D.
lobatus, D. thceli, and D. glacialis, Lilljeborg; D. ccrruleus
Fischer, D. gibber Poppe, and D. wierzejskii Richard ; and
at least three American species have the inner ramus two-
segmented — D. stagnalis Forbes distinctly, and T). eiseni
Lillj. and D. albuquerquensis Herrick indistinctly so.

It is expected that the keys here printed will be used in con-
nection with the descriptions and figures, since the species
vary within certain limits, and no hard and fast description
can be given which will cover the peculiarities of every indi-
vidual of a species. Local varietal differences or slight vari-
ations in proportion may make a key useless, and in all
cases the totality of characters should be considered. A
glance at the figures will indeed often be found more helpful
than any verbal description.

Following the usual plan of specific descriptions, the first
paragraph, referring to the general appearance of the body,
thorax, abdomen, and furca and their relative proportions,
applies always to the female unless especially stated other-
wise.

102 Illinois State Laboratory of Natural History.

SYNOPSIS OF THE RELATIONSHIPS OF THE GENERA Os]>h f(l liticiim,

Limnocalanus, Diaptomus, and Epischwra,
of the family C entropagidce .

(Adapted and compiled from Giesbrecht ('92), and from manuscript
of Prof. S. A. Forbes.)

1 (19). Division of body into cephalothorax and abdomen

between the thoracic segment bearing the fifth pair
of feet and the segment bearing the genital apertures.
In the male the fifth pair of feet assists in copulation.
Abdomen with five segments ; without appendages.
Genital organs of the male unsymmetrical. Pulsating
dorsal vessel generally present. Female deposits eggs
singly or carries them with her in single sac until emer-
gence of the nauplii. Suborder I. GYMNOPLEA.

2 (3). Anterior antennae of male symmetrical or nearly so,

and more richly provided with sense-clubs [cesthctasks]
than those of the female. Fifth pair of feet of female
either normal, or degenerate to complete disappear-
ance. Secondary sexual distinctions of male not con-
fined to peculiarities in the structure of the body, the
antennae, the fifth pair of feet, and the segmentation of
the abdomen, but usually present in the cephalic
appendages and sometimes also in the swimming feet.
Marine. Tribe I. Amphaskandria.

3 (2). Anterior antennae of male unsymmetrical. Fifth pair

of feet in the female either normal or degenerated, but
never absent. Secondary sexual characters of male
generally confined to peculiarities in the structure of the
body, the antennae, and the fifth pair of feet. Marine
and fresh- water. Tribe II. Heterarthrandria.

4 (18). Eostrum present. Fourth and fifth thoracic seg-

ments confluent.
5(6). Abdomen of female 1-3-segmented. Antennae 16-24-
jointed ; last two segments always confluent. In the
male the fifth pair of feet rarely with a rudimentary
inner ramus. Antenna1 with segments 19-21 and
sometimes 22-25 confluent. Marine.

Family Pontellid^:.

North American Species of Diaptomus. 103

6(5). Abdomen of female 3- or 4-segmented ; sometimes
unsymmetrical. Antennae never with less than 24 seg-
ments. In the male, segments 19-21 and generally 22
and 23 are confluent. Abdomen 5-jointed ; either right
or left antenna prehensile. The fifth pair of feet are
grasping organs and both always present, but with
inner ramus normal, or degenerate to complete dis-
appearance. Family Centropagims.

7 (8). Thorax 6-jointed. All the feet of female with 3-seg-

mented rami. Abdomen 3-jointed. Antenme 25-
jointed, segments 24 and 25 confluent. Eight male
antenna prehensile. Outer ramus of left fifth foot
2-jointed ; of right, subchelate.

Subfamily Centeopagina.

8 (7). Thorax 5-jointed. Fourth and fifth thoracic seg-

ments confluent.

9 (16,17.) Abdomen of female 3-jointed, sometimes unsym-

metrical. Antennae 23- or 24-jointed. Four anterior
pairs of feet generally with 3 -segmented rami. Fifth
pair of feet degenerate, with inner ramus wanting or
small and 1-jointed, outer ramus 1-3 jointed. Pre-
hensile antenna generally the right; segments 19-21
and 22 and 23 confluent. Subfamily Temorina.

10 (11). Furca with but three large terminal setae to each

ramus. Abdomen of male unsymmetrical, provided
with lateral prehensile apparatus. Fifth pair of legs
of female uniramose, 3-jointed, not terminating with
a long spine. Genus Epischura.

11 (10). Furca with four large terminal setae to each ramus.

12 (13). Inner ramus of first pair of legs 2-jointed; of the

following three pairs 3-jointed. Fifth pair of legs in
both male and female biramose, inner ramus rudi-
mentary. Genus Diaptomus.

13 (12). Both inner and outer rami of the first four pairs of

legs 3-jointed. Fifth pair of legs in both sexes biramose,
those of the female differing from the other legs only
by the presence of a strong inner hook on the second

104 Illinois State Laboratory of Natwral History.

joint of the outer ramus ; those of the male with the
inner ramus 3- jointed and provided with plumose
hairs, as in the other legs.

14 (15). Fifth pair of legs of female with the inner hairs of the

last joint of the outer ramus transformed into short
thick spines. In the male, outer ramus of left leg of
fifth pair with two joints ; outer ramus of right leg with
three. Genus Osphranticum.

15 (14). Fifth pair of legs of female with the inner hairs of

the last joint of the outer ramus long and plumose.
Fifth pair of legs of male with both outer rami 2- jointed.

Genus Limnocalanus.

16 (9, 17). Abdomen of female 4-jointed, symmetrical.

Antennas 25-jointed, articles 24 and 25 not confluent.
Four anterior pairs of feet generally with 3-segmented
rami, the fifth with 3-segmented outer and 2- or 3-seg-
mented inner ramus. Male antenme with segments
19-21 and 21-23 confluent. Fifth pair of feet sub-
chelate ; the right with 2-, the left with 3-segmented
rami. Subfamily Leuckartiixa.

17 (9,16). Abdomen 3- or 4-jointed, not always symmetrical.

Four anterior pairs of feet with 3-jointed rami. Gen-
erally the left antenna of the male geniculate. Articles
19-21, 22 and 23 (or 22-25), and 1 and 2 confluent.
Fifth pair of legs with 3-segmented outer and 1-3-
segmented inner rami. ChelaB undeveloped or want-
ing. Subfamily Heteroch.etixa.

18 (4). Rostrum wanting. Fourth and fifth thoracic segments

of female not confluent. Abdomen 3-segmented. Male
genital opening on the left ; right antenna prehensile,
segments 17 and 18, and 19 and 20 confluent. Inner
rami of fifth pair of feet wanting; outer ramus of left
foot 4-segmented, of right foot 3-segmented. Marine.

Family C'axdacid.e.

19 (1). Division of body into anterior and posterior parts in

front of the last (fifth) thoracic segment. This bears,
almost without exception, a more or less rudimentary

North American Species of Diaptomus. 105

pair of feet, which in the male never assist in
copulation ; on the contrary, the male attaches the
spermatophores directly to the vulva of the female
without the help of appendages. Genital organs of
the male generally paired, the openings always sym-
metrical. Pulsating dorsal vessel almost always
absent. The female carries the eggs wTith her, gener-
ally cemented into one or two egg sacs, until emer-
gence of the young.

Suborder II. PODOPLEA.

Diaptomus Westwood.

Cyclops, O. F. Miiller, 17S5.
Monoculus, Jurine, *20.
Diaptomus, Westwood, '36.
Cyclopsina, Milne-Edwards. ";58.
Glaucea, Koch, 'So- 41
Cyclops, Xicolet, '48-49.

" Cephalothorax always with seven segments, of which the
anterior two, indistinctly confluent, form the head. The last
thoracic segment in the female rather large, posteriorly deeply
emarginate in the middle, and often produced laterally on
both sides into a biangulate lamina. Abdomen short, nar-
rower than the thorax ; in female of four segments (caudal
rami included), of which the first is dilated anteriorly and
very often armed with a lateral spine on each side ; in male
composed of six obvious segments of about equal width.
Caudal rami with five uniarticulate plumose setae and with
another much smaller, more slender seta within. The front
provided with two minute tentaculiform appendages. The
first pair of antennas composed of 25 segments, increasing
slightly in length toward the tip. The geniculate articulation
between the 18th and 19th segments of the right male
antenna ; the six preceding segments swollen, the five following
sometimes confluent into two articles. The outer ramus of
the second pair of antennas 7 -jointed, longer than the inner
ramus, the last article longest of all and armed with very
long apical seta? ; setse of preceding articles short and

106 Illinois State Laboratory of Natwral History.

subequal. Second pair of maxillae short and thick ; third
pair elongate, directed forward, 7 -segmented, and provided
with short setae. The eight anterior swimming feet biramose,
the inner ramus of the first pair 2-, of the following pairs 3-seg-
mented. The last pair of feet different from the rest, 5-seg-
mented, the second segment armed within with a small
appendage or rudiment of an inner ramus ; in the female
short, equal, the last segment very short and rudimentary,
the penultimate always produced into a strong hook curved
inward ; in the male the right foot subchelate, the last article
formed into a very long movable hook. Eye single."*

The following remarks on the genus are from de Guerne
and Kichard's "Revision " :

"The genus Diaptomus, known at a very early date, was
for a long time confounded with Cyclops. Clearly distin-
guished much later, it contained for a very long time only a
few recognized species, and even these were insufficiently
denned. Since their study has been taken up with more
attention other forms have been distinguished, and the num-
ber of species now exceeds forty, and further explorations will
undoubtedly bring others to light.!

" If we attempt to arrange characters in the order of their
importance from a systematic point of view, we must say
in the beginning that they are furnished almost wholly by
the males. Except in certain cases the isolated females are
difficult to determine. They are, however, rarely met with
alone, and collections commonly contain, whatever the season,
both sexes together.

" Among the characters furnished by the male, the greatest
importance must be assigned to those of the fifth pair of feet.
The length of the inner rami, composed of one or two seg-
ments, varies considerably (minutus to castor). As for the
outer rami, the last article of the left foot should be examined
first. It sometimes has the form of a kind of forceps and
sometimes terminates in a sort of cushion bearing two short
obtuse spines, which perhaps represent the branches of the

*Translated from the Latin diagnosis of de Guerne ami Richard's "Revision des
Calanides <1 I'.uu Douce. ' pp. 9 and Id.

■jsixty-tivenow. many having been added since the publication of the '-Revision."

North American Species of Diaptomus. 107

forceps. All the transitions between these two forms may be
found in a series of species. Certain articles of the right
ramus may also bear divers characteristic appendages.
Finally, the terminal claw and the lateral spine of the last
article often present by their form and their position enough
peculiarities to greatly facilitate the determination.

" The right antenna of the male also furnishes some good
characters, among which figure in the first rank the append-
ages of the antepenultimate article, much varied as to form
and size (I>. bacillifer, wierzejskii, coeruleus).

" Generally speaking, the fifth pair of feet of the females
furnish the most important specific characters, although they
do not have the same technical value as in the male. At the
same time various peculiarities drawn from the conformation
of the last cephalothoracic and of the first abdominal seg-
ments and from the length of the antennae, aid greatly in the
determination."

.KEY TO THE NORTH AMERICAN SPECIES OP DiaptomUS, BASED ON
THE CHARACTERISTICS OF THE MALE.

1 (15). Antepenultimate article of right antenna without

hook-like process at tip.

2 (3). Antepenultimate article of right antenna with narrow

hyaline lamina. Second basal segment of right fifth
foot armed at the inner margin with two hook-like proc-
esses, and on the anterior surface at the apical
margin, with a hook-like process extending beyond the
middle of the first segment of the outer ramus. Inner
ramus extending barely beyond the middle of the first
segment of the outer ramus ; heavily spined at apex.
Marginal spine below the middle of the segment,
near the apical angle ; short, stout, much less than
half as long as the segment. Terminal hook very
stout, longer than preceding segment. Left leg ex-
tending about to end of first segment of outer ramus
of right leg ; second basal segment tuberculate on
inner margin. Inner ramus very long, extending about
to middle of last segment of outer ramus ; incurved,

108 Illinois State Laboratory of Natural History.

tuberculate, and armed at apex with short, blunt
spines. Last segment of outer ramus armed with a
short blunt spine and a very long spinulose one.

clavipes.

3 (2). Antepenultimate article of right antenna without

hyaline lamina.

4 (5,10). Inner ramus of right fifth foot not reaching end of

first segment of outer ramus ; sharply pointed. First
segment of outer ramus with hyaline lamina. Marginal
spine below middle of segment ; less than half as long
as segment. Terminal hook longer than the two pre-
ceding segments. Left leg extending slightly beyond
end of first segment of outer ramus of right leg ; inner
ramus reaching slightly beyond end of first segment of
outer ramus, indistinctly 2 -segmented, apex bluntly
rounded. tyrrelli.

5 (1,10). Inner ramus of right fifth foot reaching end of first

segment of outer ramus.

6 (7). Inner ramus of left fifth foot extending to base of

second segment of outer ramus, or slightly beyond.
Marginal spine below middle, near apical angle; less
than half as long as segment. Terminal hook at least
as long as the two preceding segments. Left leg reach-
ing about to middle of second segment of outer ramus of
right leg. Last segment of outer ramus armed with
forcipate structure ; inner digitiform process armed
with cushion on inner margin. pallidus.

7 (6). Inner ramus of left fifth foot reaching to middle of

second segment of outer ramus.

8 (9). Marginal spine of right leg above middle of segment,

very stout, as long as or longer than segment. Term-
inal hook almost as long as the two preceding segments
and second basal segment taken together. Inner ramus
as long as first segment of outer ramus. First seg-
ment of outer ramus with broad hyaline lamina on
inner margin. Left leg not quite reaching middle of
second segment of outer ramus of right leg. birgei.

North American Species of Diaptomus. 109

9 (8). Marginal spine of right leg below middle of segment ;

slender, less than half as long as segment. Terminal
hook longer than the two preceding segments, a sharp
angle dividing it approximately into halves. Inner
ramus reaching end of first segment of outer ramus ;
apex bluntly rounded. Left leg reaching beyond middle
of last segment of outer ramus of right leg. Last seg-
ment of outer ramus ending in a forcipate structure ;
outer digitiform process stout, armed on inner margin
near tip with cushion-like hairy process. reighardi.

10 (4, 5). Inner ramus of right fifth foot reaching well

beyond end of first segment of outer ramus.

11 (12). Inner ramus of left fifth foot long, extending beyond

middle of second segment of outer ramus ; leg itself
(disregarding terminal spines) not reaching end of first
segment of outer ramus. Marginal spine of right leg
inserted below middle of segment, near apical angle ;
much less than half as long as segment. Terminal
hook shorter than the preceding segment. piscine?.

12 (11). Inner ramus of left fifth foot short, not extending

beyond middle of second segment of outer ramus.

13 (14). Inner ramus of left fifth foot not reaching to middle of

second segment of outer ramus ; leg itself reaching end
of second segment of outer ramus of right leg. Mar-
ginal spine below middle of segment near apical angle ;
almost as long as segment. Terminal hook longer
than the preceding segment. Inner ramus of right
foot extending beyond end of first segment of outer
ramus. oregonensis.

14 (13). Inner ramus of left fifth foot reaching middle of sec-

ond segment of outer ramus ; leg itself reaching about
to middle of second segment of outer ramus of right leg.
Marginal spine below middle of segment, about half as
long as segment. Terminal hook longer than the two
preceding segments. Inner ramus of right foot ex-
tending to middle of second segment of outer ramus.

mississippiensi8.

110 Illinois State Laboratory of Natural History.

15 (1). Antepenultimate article of right antenna with hook-

like process at tip.

16 (27). Process on antepenultimate article as long as or

longer than penultimate article.

17 (20). Process curved.

18 (19). Inner ramus of right leg alone 2-segmented, extend-

ing almost to middle of second segment of outer ramus.
Marginal spine below middle, near distal angle,
smooth, about half as long as segment. Terminal hook
fully as long as the two preceding segments and the
second basal segment taken together. Second basal
segment not dilated. Left leg reaching about to middle
of first segment of outer ramus of right leg; inner
ramus barely reaching middle of last segment of outer
ramus. franciscanus.

19 (18). Inner ramus of both legs 2-segmented. Marginal

spine below middle, near apical angle ; hairy, almost as
long as segment. Terminal hook longer than the two
preceding segments, but not as long as those and the
second basal segment taken together. Second basal
segment dilated into rugose lamella. Inner ramus of
right leg extending about to middle of second segment
of outer ramus. Left leg extending about to middle of
second segment of outer ramus of right leg ; inner
ramus extending beyond middle of last segment of
outer ramus. eiseni.

20 (17). Process straight.

21 (22). Process sharply pointed. Marginal spine below mid-

dle, about half as long as segment. Terminal hook
longer than the two preceding segments. Inner ramus
of right leg extending a little beyond end of first seg-
ment of outer ramus. Left leg reaching slightly beyond
end of first segment of outer ramus of right leg ; last
segment of outer ramus with hairy cushion on inner
margin ; inner ramus extending almost to middle of
last segment of outer ramus. shoshone.

22 (21). Process blunl or swollen at tip.

North American Species of Diaptomus. Ill

23 (24). Inner ramus of right leg rudimentary, barely sur-

passing end of segment from which it arises. Mar-
ginal spine about at middle of segment, very small.
Terminal hook shorter than the very long preceding
segment. Left leg extending slightly beyond end of
first segment of outer ramus of right leg ; inner ramus
very narrow, extending about to middle of second seg-
ment of outer ramus. minutus.

24 (23). Inner ramus of right leg not rudimentary, longer

than first segment of outer ramus.

25 (26). Marginal spine well above middle of segment, about

half as long as segment. Terminal hook longer than the
two preceding segments. Inner ramus of right leg very
narrow. Left leg reaching slightly beyond end of first
segment of outer ramus of right leg ; inner ramus extend-
ing to middle of last segment of outer ramus, ashlandi.

26 (25). Marginal spine below middle of segment, less than

half as long as segment. Terminal hook very slender,
longer than the two preceding segments. First seg-
ment of outer ramus with hyaline lamina at inner distal
angle. Left leg extending about to middle of second
segment of outer ramus of right leg ; inner ramus ex-
tending barely to middle of second segment of outer
ramus. sicilis.

27 (16). Process shorter than penultimate article.

28 (33). Process the continuation of a hyaline lamina.

29 (30). Process extending at least to middle of penultimate

article. Hyaline lamina extending but little more than
the distal half of the segment. Marginal spine below
middle of segment ; shorter than segment. Terminal
hook longer than the two preceding segments but not
as long as those and the second basal segment together.
Inner ramus of right leg extending slightly beyond end
of first segment of outer ramus. Left leg extending
slightly beyond end of first segment of outer ramus of
right leg ; inner ramus extending about to middle of
last segment of outer ramus. novamexicanus.

112 Illinois State Laboratory of Natural History.

30 ("29). Process extending very slightly beyond end of article

of which it is a part. Hyaline lamina extending entire
length of segment.

31 (32). Inner ramus of right leg reaching well beyond mid-

dle of the very long first segment of the outer ramus.
Marginal spine below middle, near apical angle ; less
than half as long as segment. Terminal hook shorter
than the preceding segment. Left leg (excluding ter-
minal spines) reaching about to middle of first segment
of outer ramus of right leg. Last segment of outer
ramus terminated by two spines ; inner ramus reach-
ing well beyond end of first segment of outer ramus,
but not to middle of last segment. leptopus.

32 (31). Inner ramus of right leg rudimentary (the suture

being rarely visible), barely reaching the end of the
very short first segment of the outer ramus. Marginal
spine below middle of segment, less than half as long as
segment. Terminal hook stout, longer than the pre-
ceding segment. Second basal segment very broad,
armed at outer distal angle with a process about as
large as the inner "ramus." Left leg very short, barely
reaching end of second basal segment of right leg;
inner ramus very short, extending barely beyond end
of first segment of outer ramus. sanguineus.

33 (28). Process not the continuation of a hyaline lamina.

34 (41). Process straight.

35 (36). Process serrate on outer margin, extending beyond

middle of penultimate article. Inner ramus of right
leg very broad and short, extending but slightly be-
yond middle of first segment of outer ramus. Margi-
nal spine above middle of segment, less than half as
long as segment. Terminal hook longer than the very
long preceding segment. Left leg very short, extend-
ing barely beyond end of first segment of outer ramus
of right leg. First basal segment of both legs with
long slender spine on posterior surface. trybomi.

36 (35). Process not serrate.

North American Species of Diaptomus. 113

37 (38). Inner ramus of right leg rudimentary, extending but

slightly beyond the end of the segment to which it is
attached. Marginal spine below middle of segment,
slender, fully half as long as the very long segment.
Terminal hook shorter than the preceding segment.
Left leg (disregarding terminal spines) not reaching end
of first segment of outer ramus of right leg. Last seg-
ment with two spines : one long, slender, outcurved ; the
other short, stout. Inner ramus extending almost to
end of last segment of outer ramus. lintoni.

38 (37). Inner ramus of right leg not rudimentary, extend-

ing to middle of first segment of outer ramus or beyond.

39 (40), Inner ramus of right leg extending about to middle

of first segment of outer ramus. Marginal spine below
middle, about half as long as segment. Terminal
hook longer than the preceding segment. Second basal
segmen^ with hyaline lamina on inner margin. Left
leg (disregarding terminal spines) reaching about to
middle of first segment of outer ramus of right leg ;
inner ramus reaching end of first segment of outer
ramus, corrugate on inner margin. stagnalis.

40 (39). Inner ramus of right leg extending beyond the end of

the very short first segment of outer ramus. Marginal
spine below middle of segment, stout, longer than
segment. Terminal hook very long, stout, longer than
remainder of leg. Left leg extending beyond end
of first segment of outer ramus of right leg ; second
segment with ciliate lamina on inner margin ; inner
ramus reaching end of first segment of outer ramus.

albuquerquensis.

41 (34). Process curved.

42 (43). Process small, not reaching middle of penultimate

article. Marginal spine below middle ; rather stout,
less than a third the length of segment, Terminal hook
noticeably longer than the two preceding segments.
First segment of outer ramus with hyaline lamina on
inner margin, the inner apical angle of which is not

114 Illinois State Laboratory of Natural History.

produced. Inner ramus of right leg not reaching end
of first segment of outer ramus ; apex bluntly rounded.
Left leg reaching about to end of first segment of outer
ramus of right leg ; inner ramus reaching middle of last
segment of outer ramus, margins sinuously curved.

siciloides.
43 (42). Process stout, reaching to middle of penultimate
article or beyond. Marginal spine below middle of seg-
ment, less than half as long as segment. Terminal hook
not much if any longer than the two preceding seg-
ments. First segment of outer ramus with hyaline
lamina on inner margin, which is much produced at
the outer apical angle. Inner ramus of right leg conical,
not reaching end of first segment of outer ramus. Left
leg reaching to tip of first segment of outer ramus of
right leg. Inner ramus extending beyond middle of
last segment of outer ramus ; margins parallel ; armed
on outer margin near base with small hemispherical
process. signicauda.

KEY TO THE NORTH AMERICAN SPECIES OF DiaptomilS, BASED ON
THE CHARACTERISTICS OF THE FEMALE.

1 (18). Inner ramus of fifth pair of legs noticeably shorter

than first segment of outer ramus.

2 (10). Outer ramus distinctly or indistinctly 3-segmentrd.

3 (4,7). Inner ramus distinctly 2-segmented, the first seg-

ment very short and subquadrate ; barely reaching end
of first segment of outer ramus ; armed with two straight
hairy spines, almost as long as the ramus. Second
segment of outer ramus with small spine near base of
third segment ; spinose on both margins. Third seg-
ment armed with two stout spines, the inner hairy,
about twice as long as the outer, which is about as
long as the spine on the preceding segment. Last
thoracic segment strongly produced. First abdominal
segment longer than remainder of abdomen, greatly
dilated, armed on each side with large spine ; second
segment shorter than third. Furcal rami about as

North American Species of Diaptomus. 115

long as wide, hairy within. Antenna? extending barely
to base of abdomen. stagnalis.

4 (3,7). Inner ramus indistinctly 2-segmented.

5 (6). Terminal spines of inner ramus about half as long as

ramus. Second segment of outer ramus armed with a
single spine. Two spines on the third segment ; suture
between this and preceding segment indistinct. Inner
ramus extending beyond middle of first segment of
outer ramus ; armed at apex with two long spines.
Third segment of outer ramus armed with two very
large stout spines, the inner hairy, less than twice as
long as the outer. First abdominal segment longer
than remainder of abdomen ; armed anteriorly with
large lateral process. Antennae reaching process on
first abdominal segment. eiseni.

6 (5). Terminal spines of inner ramus not nearly half as long

as ramus. Second segment of outer ramus with a spine.
Inner ramus extending slightly beyond middle of first
segment of outer ramus. Third segment of outer
ramus hairy and about twice as long as the inner, which
is smooth. First abdominal segment longer than re-
mainder of abdomen, armed laterally with strong spines.
Antennae extending beyond tips of f ureal setae.

albuquerquensis.

7 (3,4). Inner ramus 1-segmented.

8 (9). Terminal spines of inner ramus smooth, more than

half as long as ramus, which is rounded at apex and
hairy. Second segment of outer ramus straight, as
long as or longer than preceding segment ; armed at
base of third segment with short spine, shorter than
either of the two on third segment. Inner spine of
third segment hairy, about twice as long as the outer,
which is smooth. Both spines considerably longer
than the segment itself. Last thoracic segment armed
on each side wTjth two small spines. First abdominal
segment shorter than remainder of abdomen, dilated,
armed with large spines ; second segment very short.

116 Illinois State Laboratory of Natu/ral History.

Third segment and furca] rami about equal. Antennae
reaching base of abdomen. shoshone.

9 (8). Terminal spines of inner ramus smooth, not nearly

half as long as ramus, which is hairy at apex and on
inner margin. Second segment of outer ramus curved,
barely as long as preceding segment; armed at base
of third segment with an inconspicuous spine. Third
segment armed with two short spines but slightly longer
than the segment. Last thoracic segment armed with
small spines. First abdominal segment with a sharp
spine ; longer than remainder of abdomen. Antenna?
reaching furcal rami. novamexicanus.

10 (2). Outer ramus 2-segmented.

11 (12). Inner ramus almost rudimentary, not nearly reach-

ing the middle of first segment of outer ramus. Second
segment of outer ramus considerably shorter than first ;
third segment represented by two spines, the inner
about twice as long as the outer. Last thoracic seg-
ment armed on each side with small spine. First
abdominal segment as long as remainder of abdomen ;
second segment very short ; third, longer than furcal
rami. Antennae reaching slightly beyond furca.

minutus.

12 (11). Inner ramus not rudimentary, reaching beyond the

middle of first segment of outer ramus.

13 (14). Second segment of outer ramus armed with a short

spine ; denticulate within and without. Third segment
represented by two subequal spines. Inner ramus not
nearly reaching end of first segment of outer ramus ;
hairy on inner margin ; terminal spines fully half as
long as segment. First abdominal segment dilated,
about equal in length to remainder of abdomen ; sec-
ond segment and furcal rami each longer than third
segment. piscina.

14 (IB). Second segment of outer ramus not armed with a

spine.

North American Species of Diaptomus. 117

14 (15). Inner ramus armed with very short subequal spines

and hairy at apex. Second segment of outer ramus
curved, denticulate on inner margin ; third segment
represented by two spines, the inner the longer and
about half as long as the second segment. Last tho-
racic segment produced, armed with two large spines on
each side ; penultimate thoracic segment produced into
dorsal hump. First abdominal segment as long as
remainder of abdomen, armed with large spine on
each side ; second segment shorter than the third,
which is about equal to the furcal rami. Antennae
extending about to base of abdomen. sanguineus.

15 (11). Inner ramus armed with long conspicuous spines.

16 (17). Second segment of outer ramus straight, about as

long as the first, armed with a spine at base of third
segment. Inner spine of third segment slightly the
longer. Inner ramus hairy at apex ; terminal spines
straight, hairy, about a third as long as the ramus.
Last thoracic segment armed on each side with a spine.
First abdominal segment short, unarmed. Antennas
extending to end of thorax. leptopus.

17 (16). Second segment of outer ramus straight, slightly

shorter than first ; third segment represented by two
subequal spines. Inner ramus barely as long as first
segment of outer ramus, hairy at apex, armed with
two rather long spines. Antennae extending to end of
furca. birgei.

18 (1). Inner ramus clearly reaching end of first segment

of outer ramus or beyond.

19 (22). Outer ramus 3 -segmented.

20 (21). Third segment of outer ramus small but distinct ; in-

ner of the two spines slightly the longer. Second seg-
ment curved, shorter than first ; denticulate on inner
margin ; armed with small spine at base of third seg-
ment. Terminal spines of inner ramus very long,
almost as long as the ramus. Last thoracic segment
armed with two minute spines. First abdominal

118 Illinois State Laboratory of Natural History.

segment as long as remainder of abdomen, dilated,
armed with small spines ; second segment very short ;
third segment longer than f ureal rami. Antennae
extending to furca. franciscanus.

21 (20). Third segment of outer ramus very indistinct or

aborted ; armed with two short subequal spines. Second
segment of outer ramus about as long as the first, hairy
within and without. Inner ramus reaching about to
end of first segment of outer ramus, hairy, armed with
two long hairy subequal spines. First abdominal seg-
ment shorter than remainder of abdomen, dilated but
unarmed; second segment shorter than the third,
which is longer than the furca. Antennae not reaching
end of furca. piscinae,

22 (19). Outer ramus 2-segmented.

23 (26). Second segment of outer ramus armed with a spine

in addition to the two spines representing the third
segment.

24 (25). Terminal spines of inner ramus hairy, nearly half as

long as ramus, which reaches to the end of the first
segment of the outer ramus. Second segment of outer
ramus shorter than the first, slightly curved, denticulate
within ; third segment represented by two spines, the
inner hairy, about half as long as the outer, which is
smooth. First abdominal segment longer than re-
mainder of abdomen ; second segment shorter than
third; the third longer than furca. Antennas reaching
tip of furcal rami. lintoni.

25 (24). Terminal spines of inner ramus hairy, not nearly

half as long as ramus, which is hairy at the apex. Third
segment of outer ramus represented by two spines, the
inner about twice as long as the outer. Second seg-
ment armed with a small spine. Last thoracic seg-
ment greatly produced laterodorsally ; armed on each
side with two small spines. First abdominal segment
about as long as remainder of abdomen and armed
with two large spinose processes ; second segment

North American Sjiecies of Diaptomus. 119

shorter than third and about equal to f ureal rami.
Antennae extending beyond base of furca but not be-
yond the tip. tyrrelli.

26 (23). Second segment of outer ramus not armed with

an additional spine.

27 (32). Second segment of outer ramus longer than preced-

ing segment.

28 (29). Outer of the two spines representing the third seg-

ment of outer ramus very small and inconspicuous ;
second segment shorter than the first, denticulate.
Inner ramus reaching slightly beyond end of first seg-
ment of outer ramus ; hairy on outer margin and at
apex ; armed with two rather long subequal spines.
Last thoracic segment produced laterodorsally, armed
with two spines on each side. First abdominal seg-
ment slightly shorter than remainder of abdomen,
dilated, armed on each side with a large spine ; second
segment shorter than third ; third segment and furca
about equal. Antennae reaching beyond tip of furca.

clavipes.

29 (28). Outer spine rather conspicuous.

30 (31). Terminal spines of inner ramus smooth. Inner

ramus reaching end of first segment of outer ramus ;
apex hairy ; spines small. Second segment of outer
ramus about as long as the first, denticulate, point
acute ; third segment represented by two spines. First
abdominal segment as long as remainder of abdomen,
dilated, armed with small spines ; second segment
shorter than third ; third about equal to the furca.
Antennae extending to tips of furcal setae.

oregonensis.

31 (30). Terminal spines of inner ramus hairy, subequal.

Second segment of outer ramus about equal to the
first; third segment represented by two subequal
spines. Last thoracic segment armed on each side with
two small spines ; the penultimate thoracic segment
with a small hump. First abdominal segment slightly

120 Illinois State Laboratory of Natwral History.

shorter than remainder of abdomen ; second segment
shorter than third ; third segment and furca about
equal. Antennas extending beyond end of furca but
not to tips of fureal setae. signicauda.

32 (27). Second segment of outer ramus shorter than preced-

ing segment.

33 (34). Last thoracic segment with a large dorsal process,

armed with two spines, one minute. First abdominal
segment longer than remainder of abdomen, with short
mucronate process anteriorly, and posteriorly with
large triangular process. Second segment of outer
ramus straight, hairy ; third segment represented by
two spines, the inner about twice as long as the outer.
Inner ramus noticeably shorter than first segment of
outer ramus, with two long subequal spines at the
apex. Antennae barely reaching furca. trybomi.

34 (33). Last thoracic segment without dorsal process.

35 (36). First abdominal segment longer than remainder of

abdomen, dilated, armed with small spine on each side ;
second segment very short; third segment shorter
than fureal rami. Second segment of outer ramus
shorter than the first ; third segment represented by
two spines of which the inner is the longer. Inner ramus
extending beyond end of first segment of outer ramus,
hairy, armed with two smooth subequal spines. An-
tennae extending just beyond furca. ashlandi.

36 (35). First abdominal segment about equal to remainder

of abdomen.

37 (38). Second abdominal segment very much shorter than

the third. Last two thoracic segments confluent ; the
last one armed on each side with two small spines.
First abdominal segment with large spine on each side ;
third segment longer than the second or the furca.
Second segment of outer ramus shorter than the first ;
third segment represented by two small spines, the
inner about twice as long as the outer. Inner ramus

North American Species of Diaptomus. 121

hairy, armed with two small spines. Antennae reach-
ing slightly beyond end of furcal rami. siciloides.

38 (37). Second abdominal segment slightly shorter or at

least not longer than the third.

39 (42). Furca longer than third abdominal segment.

40 (41). First abdominal segment nearly as long as remain-

der of abdomen ; dilated laterally, armed with one
small spine on each side. Second segment of outer
ramus shorter than the first ; third segment represented
by two spines, the inner the longer and pointed
obliquely outward. Inner ramus reaching end of first
segment of outer ramus ; apex hairy and armed with
two spines. Antennae reaching end of furcal setae.

reighardi.

41 (40). First abdominal segment as long as remainder of

abdomen ; dilated laterally but unarmed. Last tho-
racic segment produced, armed with one small spine on
each side. Head partially divided by a suture. Third
segment of outer ramus represented by two spines, the
inner smooth, about twice as long as the outer, which
is delicately hairy. Inner ramus hairy, armed with
two long subequal spines. Antennae reaching beyond
end of furca. pallidus.

42 (39). Furca about equal to third abdominal segment.

43 (44). First abdominal segment about as long as remainder

of abdomen and armed with small spines, equal on the
two sides. First thoracic segment armed with small
spine on each side. Second segment of outer ramus
shorter than the first ; third segment represented by
two spines, the inner about twice as long as the outer.
Inner ramus longer than first segment of outer ramus ;
hairy, armed with two spines, the inner twice as long
as the outer; margins sinuously curved. Antennae
reaching beyond tip of furca. sicilis.

44 (43). First segment of abdomen as long as remainder of

abdomen; armed with two large lateral spines, the

122 Illinois State Laboratory of Natural History.

right somewhat the longer. First two thoracic seg-
ments equal, together about half as long as entire
thorax ; last segment armed with two small spines.
Second segment of outer ramus very broad, especially
at the base. Inner ramus hairy on outer margin and
at tip, which is armed with two rather long slender
spines. Antennae reaching beyond furca.

iiiississippiensis.

Diaptomus sicilis Forbes. (PI. XXI., Fig. 1-3.)

Diaptomus sicilis, Forbes, 'S2a, p. 645, PI. VIII., Fig. 9, 20.
Diaptomus pallidus var. sicilis, Herrick, '84, p. 142, PI. Q, Fig. 18.
Diaptomus sicilis, tie Guerne et Kichard, '89b, p. 23, Fig. 13, 14; PI.

II., Fig. 13.
Diaptomus sicilis. Forbes, '90, p. 702, PI. I.. Fig. 6.
Diaptomus sicilis, Marsh, '93, p. 197. PI. III., Fig. 8, 10.

Body slender, widest in front of the middle ; suture between
head and thorax distinct. Last two thoracic segments con-
fluent ; the last one produced laterodorsally and armed on each
side with one or two small spines ; (in the male unarmed.)
Abdomen long and narrow, especially in the male, in which
the first segment is the longest and slightly the broadest. In
the female (PI. XXL, Fig. 3) this segment is fully as long as
the remainder of the abdomen, dilated, and armed on each
side with a spine ; last three segments subequal. Furcal
rami fully twice as long as broad and hairy within.

Antennae 2 5 -segmented, reaching well beyond the tips of
the furcal rami. Male geniculate antenna moderately swollen
beyond the twelfth segment ; first two segments without
special armature ; antepenultimate segment armed with nar-
row spine-like process with swollen apex, reaching to the
middle of the penultimate segment; segments 19, 20, and
21 confluent, as are also 22 and 23.

Fifth pair of legs in the male (PI. XXL, Fig. 1) rather
long and slender. First basal segment of the right foot with
a large tubercle on the posterior surface near the outer mar-
gin, bearing a minute blunt spine. Second basal segment
subquadrate, about one and a half times as long as broad.
At the beginning of the distal third of its outer margin, is a

North American Species of Diaptomus. 123

small cuticular projection bearing a delicate hair. First seg-
ment of the outer ramus subquadrate, slightly longer than
broad, the inner distal angle provided with a small semi-
elliptical hyaline lamina arising from the anterior surface of
the leg; second segment slightly arcuate, the two margins
parallel, fully twice as long as wide. Marginal spine long
and slender, slightly curved, about half as long as the seg-
ment, and inserted at the beginning of the distal third. Ter-
minal hook long, slender, and regularly curved ; very minutely
denticulate on the inner margin.

Inner ramus of the right leg either one- or two-segmented,
extending beyond the end of the first segment of the outer
ramus ; minutely hairy at the tip.

There is nothing distinctive about the basal segments of
the left leg. The first segment of the outer ramus is about
one and a half times as long as broad ; the inner distal angle
gradually rounded and minutely hairy- The second segment
is narrow, twice as long as broad ; armed at the tip with two
digitiform processes and sometimes with a much smaller
third process between the two. This segment appears very
broad and fleshy because of a cushion-like process with rugose
surface which extends beyond the inner margin of the seg-
ment for half its length. The other, upper, half is occupied
by a minutely hairy semicircular cushion.

Inner ramus of the left foot either one- or two-segmented, ex-
tending to the middle of the last segment of the outer ramus ;
hairy at the tip.

Basal segments of the fifth pair of feet in the female (PL
XXI., Fig. 2) not characteristic. The usual delicate hair is
found on the outer margin of the second basal segment.
First segment of outer ramus long and narrow, more than
twice as long as broad. Second segment almost as long as
the first, narrow, tapering to a fine point, delicately spinose
at the inner margin. Third segment wanting; represented
by two spines, both sharp and slender, the inner about twice
as long as the outer.

Inner ramus of fifth leg of female one-segmented, project-
ing slightly beyond the end of the first segment of the outer

124 Illinois State Laboratory of Natural History.

ramus, the proximal four fifths of uniform width. At the
beginning of the distal fifth of the inner margin is a rather
sharp angle, from which projects a long, slender, slightly
curved spine, about one fifth the length of the ramus.
Beyond this the ramus tapers to a blunt point, hairy at the
apex. Besides the spine already mentioned there is a smaller
one, only about half as long, having its point of insertion
very near and slightly above the first.

Length of female 1.23-1.28 mm; of male 1.00-1.18 mm.

D. sieilis closely resembles both D. ashlandi and D.
pallidus, differing from the latter, however, in the presence of
a hook on the right male antenna, and from both in the details
of structure of the fifth pair of feet of the male.

A very interesting variation was noticed in the inner rami of
the fifth pair of feet of the male. In specimens taken from
Lake Superior, at Marquette, Mich., the rami were sometimes
both one-segmented, sometimes both were two-segmented,
and at other times one ramus was two-segmented while the
other was one-segmented. Herrick (Herrick and Turner, '95)
states that all his specimens had one-segmented rami; also
that the process on the right male antenna was shorter than
described by Dr. Forbes.

Although I), sieilis is not at all uncommon, it has occurred
less frequently in the collections I have examined than have
D. siciloides Lillj., D. ashlandi Marsh, or D. oregonensis
Lillj. Marsh ('93) records D. sieilis from the Great Lakes
and from Green Lake, Wis., it being the common pelagic
species in 1890 and 1891, while in 1892 not a single specimen
was found there although the collections were made at the
same time of year. The type was described (Forbes '82a)
from Lake Michigan and had not then been found anywhere
else. In 1890 Dr. Forbes found it in Lake Michigamme, in
northern Michigan, as well as in Lake Michigan. His variety
imperfectus is D. ashlandi Marsh. In the Yellowstone Park
collections sieilis was found in considerable quantities, but
as both D. sieilis and D. ashlandi were present, it would
require a re-examination of the material to determine the
distribution of the two species in that locality.

North American Species of Diaptomus. 125

Diaptomus piscinae Forbes. (PL XXII. , Fig. 1-4.)

Diaptomus piscinas, Forbes, '93, p. 253, PI. XLL, Fig. 22.
Diaptomus piscinas, Herrick and Turner, '95, p. 74, PI. V., Fig. 13.

"A species of medium size and symmetrical proportions,
antennae reaching to the tip of the abdomen, cephalothorax
broadest about the middle, with four distinct sutures, the
posterior lateral angles not produced but armed with two
distal spines.

"The right antenna of the male is without appendage to
the antepenultimate joint, and the fifth pair of legs in the
same sex has the inner ramus well developed on both the
right and left sides. The usual length is 1.75 millimeters,
the transverse diameter 0.45 millimeters ; the abdomen with
furca is a little more than one third the length of the cephalo-
thorax.

" The fifth pair of legs of the female [PI. XXII., Fig. 2, 4] is
without especially marked characters, except that the inner
ramus, which reaches to the tip of the principal segment of
the outer, is provided with two long, stout, equal seta? more
than half as long as the ramus itself. The third joint of the
outer ramus is aborted and bears two short, stout spines,
and the joint preceding bears a slender spine outside the
base of the last. The terminal claw of this joint is simple
and nearly straight, viewed in the usual position.

"In the male the fifth pair of legs [PI. XXII., Fig. 1] has
a considerable resemblance to the corresponding append-
ages of D. leptopus, from which, however, this species differs
by its more slender form and by the absence of the antennal
hook. The peduncle of the left leg is quadrate and equal in
length to the basal segment of the outer ramus, but is nearly
twice as wide. The sides of this latter segment are parallel,
the inner terminal angle is broadly rounded and minutely
ciliate, and to the outer terminal angle is attached the second
segment of the ramus. This segment is a trifle shorter than
the preceding and less than half as wide, and bears at its tip
a stout, blunt, conical spine, whose length is equal to that of
the diameter of the ramus, and within this a long flexible

126 Illinois State Laboratory of Natwal History.

hair as long as the ramus itself. The inner ramus of this
leg is very long, reaching beyond the middle of the terminal
joint of the outer ramus. It is slightly concave towards this
ramus and terminates with a broadly rounded or subtruncate,
thickly ciliate end, forming an acute outer angle and an
obtuse inner one. Seen at right angles to this view, the tip
is simply obtusely pointed.

" The right leg of the male is without remarkable distin-
guishing characters. Basal joint of the outer ramus about
two thirds as long as the peduncle and nearly as wide; sec-
ond joint slightly longer than the peduncle, equal to the first in
width ; and the terminal claw sinuate or irregularly curved.
The stout seta on the outer margin of the second segment of
this ramus is borne at about a quarter the length of the seg-
ment from the distal end, and is approximately half as long
as the segment to which it is attached. The inner ramus is
a little longer than the basal joint of the outer. It is not
dilated or otherwise modified, but terminates bluntly, bearing
at the tip a covering of long cilia,

"The right antenna of the male is without notable dis-
tinctive characters. The antepenultimate segment is as long
as the two following taken together ; the fourth from the tip
bears two long sword-like spines at its margin, both attached
to its basal fourth ; the expanded segments are well armed
with conical spines, straight and curved, but without hooks.

" Small lakelet near Gardiner, Montana."*

This is the only one of the four species described by Dr.
Forbes ('93) which I have found in any other collections than
the original ones. In collections loaned me by Prof. L. S.
Eoss, of Drake University, Iowa, made by him at Portage
Slough, Manitoba, Canada, in June, 1895, I found quite a
number of specimens of this species, which, however, exhibit
a number of peculiarities. The fifth pair of legs in the
female are stouter and the inner ramus is relatively shorter
than in the Montana specimens, the latter not reaching to
the end of the first segment of the outer ramus as it does in the
type. The spines on the inner ramus also have a more

♦Description quoted from Forbes, '93

North American Species of Diaptomus. 127

'distinct and broader basal portion than the individuals from
Yellowstone Park. Both the inner and outer margins of the
second segment of the outer ramus are hairy in Dr. Forbes's
specimens, but much more pronouncedly so in the specimens
from Portage Slough.

The fifth pair of feet of the male are very similar to the
corresponding appendages of I), clavipes sp. nov. and D.
leptopus Forbes. Dr. Forbes notes the differences between his
species (piscina and leptopus), and from clavipes both may be
distinguished at a glance by the inner rami and the other
peculiarities mentioned in the description of that species. A
characteristic of D. piscina, and one which was neither figured
nor described, is a fin-shaped process on the middle of the
anterior surface of the second basal segment of the right fifth
foot of the male. This is armed on the inner margin with a
row of bead-like tubercles and is more distinct in the Portage
Slough specimens. This process corresponds to a similar
one in D. clavipes. The lower two thirds of the inner margin
of this segment are hairy, and at the end of the proximal
third is a small triangular projection.

The terminal hook and the marginal spine of the outer ramus
of the right male foot are both denticulate on the lower half of
the inner margin.

In the "Preliminary Pieport on the Aquatic Invertebrate
Fauna of the Yellowstone National Park, Wyoming, and of,
the Flathead Region of Montana" the inner ramus of the right
fifth leg of the male (Fig. 22) by mistake was not figured.
The description was correct but the figure did not correspond.

The first and second segments of the outer ramus of the left
fifth foot of the male are hairy on the inner margin.

The length of the Portage Slough specimens is as follows :
female, 2.11 mm; male, 2.06 mm.

Diaptomus lintoni Forbes. (PI. XXVII. , Fig. 1.)

Diaptomus lintoni, Forbes, '93, p. 252, PI. XLIL, Fig. 26-28.
Diaptomus lintoni, Herrick and Turner. *95, p. (58, PI. V., Fig. 12.

"A large red species occurring commonly with D. shoshone,
but distinguishable from it at a glance by its different shape,

128 Illinois State Laboratory of Natural History.

its longer antennas, its smaller size, and by characters derived
from the right antenna and the fifth foot of the male. The
thorax is symmetrically elliptical in shape, broadest at the
middle. The posterior angles are not produced or bifid, but
are each armed with a minute spine. The first segment of
the abdomen of the female is not especially produced, but
bears at its broadest part a minute spine on each side. The
abdomen itself is very short, its length contained about three
and one third times in that of the cephalothorax. The
antenna of the female is long and slender, 25-jointed, reach-
ing a little beyond the tip of the abdomen.

" The fifth pair of legs in this sex is similar to those of D.
shoskone, but much smaller. The inner ramus is not jointed.
It is longer than the basal joint of the outer ramus, bears
two stout plumose setae at its tip, somewhat shorter than the
ramus itself, and has likewise at its inner tip a patch of small
spines or fine hairs. The second segment of the outer ramus
with its terminal claw is two thirds as long again as the pre-
ceding segment, the breadth of the latter two thirds its length.
The third joint is indicated by a single long stout seta and
one or two smaller ones.

"In the male the geniculate antenna is relatively rather
slender, its last two joints without special appendages, its
penultimate with a slender transparent apical process, reach-
ing about to the middle of the succeeding segment, acute at
tip, but neither serrate nor emarginate. Fifth pair of
legs in the male [PL XXVII., Fig. 1] usually without inter-
nal ramus to the right leg, but this ramus sometimes repre-
sented by a small rudiment. The limb is usually slender
and its terminal claw short. The basal segment of the outer
ramus is nearly as long as the adjacent segment of the
pedicel, and the slender second segment of this ramus is
fully as long. Long lateral spine borne near the tip of this
segment. The terminal claw is about two thirds as long as
the segment, is somewhat abruptly angulated near its base
and slightly recurved at the tip. The inner ramus of the left
leg is very stout and long, reaching almost to the tip of the
outer ramus, is slightly curved outwards and has the apex

North American Species of Diaptomus. 129

minutely hairy. The basal segment of the outer ramus is
thick, two thirds as broad as long, somewhat inflated within,
where it extends downward and beyond the articulation with
the second segment as a rounded expansion covered with ex-
tremely fine hairs. Second segment of this ramus longer
than first, but only half as wide, bearing at its tip, within, a
rather small, obliquely projecting cushion covered with cilia,
and with two stout terminal spines, one short, blunt, straight,
and smooth, the other curved and plumose, its length about
half that of the segment to which it is attached.

"The total length of this species is about 2.5 millimeters,
excluding caudal seta3 ; depth, 0.42 millimeters.

"This species is closely related to D. stagnalis, Forbes,
from which it differs conspicuously by its smaller size, more
symmetrical cephalothorax, without prominent or bifid angles,
and longer and more slender antennae, with longer and more
slender appendage to the antepenultimate segment.

"In the fifth legs of the female this species differs from
stagnalis especially with respect to the inner ramus, which is
larger and longer than in the other, lacks the characteristic
segmentation of stagnalis, and bears at its tip shorter and
broader sets. In the male the terminal claw of the outer
ramus of the right fifth leg is much more slender than in
stagnalis, and the inner ramus is much less developed. The
left leg of this pair is different in a number of details, espe-
cially in the length and strength of the inner ramus and the
length and dissimilarity of the setae at the end of the outer.

" Common in lakes and pools of Yellowstone Park."*

This species is one of the three American forms in which
the inner ramus is rudimentary or wanting, the other two
being Z). sanguineus Forbes and 1). minutus Lilljeborg. It
has not been recorded from any' localities outside of those in
which it was originally found.

* Description quoted from Forbes, '93.

130 Illinois State Laboratory of Natv/ral History.
Diaptomus leptopus Fokbes.

Cyclops lonyicornis (?), Derrick, 77, p. 238, Fig. 1.

Diaptomus kentuckyensis (?), Chambers, '81, p. 48, PI. A, Fig. 12-1S;

PI. B, Fig. 19-23.
Diaptomus leptopus, Forbes, '82a, p. G46, PI. VIII.. Fig. 17-1 U.
Diaptomus castor (?), Herrick, '82, p. 221, Pi. I., Fig. 1-7; PI. II., Fig!

12, 1G.
Diaptomus longicornis var. leptopus. Herrick. '84, p. 140.
Diaptounis leptopus. tie Guerne et Richard, '89b, p. 21, PI. II.. Fig. 19;

PL III., Fig. 9.
Diaptomus leptopus, Marsh, '93. p. 195, PI. III., Fig. 4. 5.
Diaptomus leptopus, Herrick and Turner, '95, p. 64, PI. II.; PI. IX.,

Fig. 9.

Body long and slender, widest a little before the middle.
Head rather noticeably narrower than thorax, suture between
them distinct. Fifth and sixth thoracic segments confluent,
the last produced dorsally on each side into a triangular
process with a bluntly rounded apex armed with a single blunt
spine. The last thoracic segment of the male and the first
abdominal segment of both sexes unarmed. First abdominal
segment short, a little more than half as long as the succeed-
ing segment. Furcal rami about one and a half times as
long as wide, hairy within.

Antennre 25-jointed, extending to the tip of the furcal rami.
The male prehensile antenna rather thickly swollen, the first
segment without armature, the other segments armed as fol-
lows : 2, with a short seta and a sense-club ; 3, short seta and
sense-club ; 4 and G, long spine ; 5 and 7, long seta and sense-
club ; 8, long spine and very short spine; 9, long seta, long
spine, and sense-club ; 10 and 11, process and long spine;
12, long spine, very short spine, and sense-club ; 13, process,
long spine, and sense-club; 14, long seta, long spine, and
sense-club; 15, process, short seta, long spine, and sense-
club; 16, process, long spine, long seta, and sense-club ; 17,
process and short thick spine; 18, process; 19,. 20, and 21
(completely ankylosed), a process, a long seta, and a very
short spine; 22 and 23 (completely ankylosed), a narrow
hyaline lamina produced into a hook which extends but little
beyond the end of the segment, and two long setae ; 24, two

North American Species of Diaptomus. 131

long setae; and 25, four long set 33 and a sense-hair. Some
of the setae on the last segments are sparsely hairy.

Second basal segment of the right fifth leg of the male sub-
quadrate, about twice as long as wide ; a delicate hair at the
outer margin a short distance above the distal angle. First
segment of the outer ramus somewhat narrower than the
second basal segment, about twice as long as wide; sec-
ond segment very long and narrow, about three times as
long as wide. Marginal spine slender, about one third the
length of the segment, inserted about half its length above
the outer distal angle of the segment. Terminal hook slender,
regularly curved, about as long as the preceding segment;
distal half of inner margin denticulate.

Inner ramus of right fifth foot one-segmented, reaching
almost to the end of the first segment of the outer ramus ;
apex broadly triangular and minutely hairy.

Second basal segment of the left leg of the male subquad-
rate, slightly broader than long ; provided with a delicate hair
a short distance above the outer apical angle. First segment
of the outer ramus irregular in form, about one and a half
times as long as broad, with two rounded protuberances, the
one forming the inner apical angle delicately hairy. Second
segment long and narrow, almost as long as the preceding
segment and a fourth as wide as long; delicately hairy
at the inner margin ; armed at the apex with a short, thick,
blunt digitiform process, and a long curved spine as long as
the segment itself and hairy at the inner jnargin.

Inner ramus of left fifth leg long and narrow, extending
beyond the middle of the second segment of the outer ramus ;
margins sinuous ; apex triangular, hairy.

Second basal segment of the fifth pair of feet in the female
with the usual marginal hair. First segment of the outer
ramus subquadrate, about twice as long as wide ; second seg-
ment narrow, about as long as the first, tapering to a rather
blunt point, finely dentate on the inner margin and with a
single tooth on the outer, opposite the last tooth on the inner
margin; third segment small but distinct, armed with two
short sharp spines, the inner slightly longer than the outer.

IB 2 Illinois State Laboratory of Natural History.

Just without these, on the second segment, is a third spine,
shorter than either of the other two.

Inner ramus of fifth leg of female one-segmented, extend-
ing beyond the end of the first segment of the outer ramus ;
apex hairy ; armed with two long subequal spines hairy on
both margins and about a third the length of the ramus.

Length of female 1.89 mm. ; of male 1.83 mm.

Breadth of female 0.70 mm. ; of male 0.60 mm.

The numerous published figures and descriptions of this
species have probably made it well known to all students of
North American Centropagidce. The synonymy, however, is
interesting. In the Geological and Natural History Survey
of Minnesota, Herrick ('77, p. 238) describes and figures
"A New Cyclops." It is evident at a glance that this is a
Diaptomus, but of what species cannot be determined. In
"Microscopic Entomostraca " (Herrick, '79, p. 90) he refers
to this "Cyclops" and says, "In the Eeport of the Geological
and Natural History Survey of Minnesota for 1878 it
[Diaptomus longicornis] was mentioned and a figure given,
but erroneously called Cyclops." In a "Final Eeport on the
Crustacea of Minnesota" (Herrick, '84, p. 140) he makes D.
leptopus Forbes a variety of D. longicornis Herrick, estab-
lishing a second variety, similis (Plate Q, Fig. 5-7). In his
" Synopsis of the Entomostraca of Minnesota" (Herrick and
Turner, '95) he recognizes D. leptopus Forbes as a distinct
species, making 1>. longicornis var. leptopus a synonym ;
although in this same work I>. longicornis var. similis Her-
rick is not set up as a species, neither is the name regarded
as a synonym. The figures (Herrick '84, PI. Q, Fig. 5-7) are
not well drawn, but it is not likely that this form is leptojjus.
D. similis is referred to once (Herrick and Turner '95, p. 58)
in connection with D. franc iscanus Lilljeborg. Diaptomus ken-
tuckyensis Chambers ('81) is also quite possibly D. leptopus,
although the description is very vague and the figures are
inaccurate.

North American Species of Diaptomus. 133

Diaptomus sanguineus Forbes. (Pis. XXIII., XXIV.,
and XXV.)

Diaptomus sanguineus, Forbes, '76. pp. 15, 16, 23, Fig. 24, 28-30.

Diaptomus sanguineus, Forbes, '82a, p. 647. PI. VIII., Fig. 1-7, 13.

Diaptomus armatits(?), Herrick. '82, p. 223. Fig. 1, a, b.

Diaptomus armatus^?), Herrick, '84, p. 139.

Diaptomus sanguineus, Herrick, '84, p. 138, PI. Q, Fig. 12.

Diaptomus minnetonka, Herrick, '84, p. 138, PI. Q, Fig. 8-10.

Diaptomus sanguineus, de Guerne et Richard, '89b, p. 20, Fig. 9-11 ;

PI. IV., Fig. 24.
Diaptomus sanguineus, Marsh, '93, p. 195, PI. III.. Fig. 1-3.

A rather large species, one fourth to one third as wide as
long. The cephalothorax widens gradually to the third seg-
ment (being broadest at the suture between that segment and
the fourth), then narrows less gradually to the abdomen. In
the male the thorax is less uniform in breadth than in the
female. The last cephalothoracic segment is greatly pro-
duced on each side laterodorsally and bears a large spine,
slightly swollen at the base, varying in length from that of
the segment to one fourth its length. On the same segment
and midway between the outer spine and the abdomen is
another broader and shorter spine. Both of these spines are
slightly curved. In the female (PL XXIV., Fig. 3) they are
generally quite noticeably larger than in the male. On
the first abdominal segment is still another spine, slightly
outcurved and pointing outward, about as large as the sec-
ond of the spines mentioned above. In the female the
penultimate cephalothoracic segment bears a dorsal hump at
its anterior margin (PI. XXIV., Fig. 5, 6). This is wanting
in the male. The abdomen is produced dorsally and ven-
trally at the anterior part, making it look like a keel (PI.
XXIV., Fig. 1, 2), the keel being most pronounced on the
ventral side. The egg-mass is large and elliptical, with the
major axis transverse to the body.

Antennae 25-segmented, the seventeenth or eighteenth seg-
ment reaching about to the base of the abdomen. The right
male antenna is thickly swollen beyond the geniculate joint.
The last two segments have no special armature, but the
antepenultimate one (PI. XXIII., Fig. 6-8) is armed at the

134 Illinois State Laboratory of Natural History.

inner distal angle with a short thick recurved hook with
smooth edges, extending hut little heyond the joint. This is
merely the continuation of the hyaline lamina at the side of
the segment.

Second basal segment of the right fifth leg of the male
(PI. XXIII., Fig. 1-5), seen from behind, irregularly trape-
zoidal in form, very broad distally, and about twice as long
as its narrowest part is wide. On the outer distal angle of
this segment is another projection, equal to or greater in
length than the inner ramus. This also shows great varia-
tion, and is either rounded or acute or even acuminate at
the apex. First and second segments of outer ramus sub-
quadrate, the second about as wide as the first and about two
and a half times as long. About a third the length of the
second segment from its base is a considerable contraction,
the width here being about half the width of the broadest part.
Slightly below the middle, on the outer margin, is a spine,
minutely serrate at the inner edge. This is generally long
and straight, about half the length of the segment, but varies,
and is sometimes shorter, thicker, curved, and less than one
third the length of the segment (PL XXIV., Fig. 4 ; PI. XXY.,
Fig. 3-5). Terminal hook rather long and slender, slightly
and sometimes sinuously curved, about one and a fourth
times the length of the preceding segment. The inner margin
is serrate, beginning about the middle of the hook and con-
tinuing to the tip.

Inner ramus of the right fifth foot wanting, a peculiarity
rarely found among the American species of Diaptomus, but
approached most closely by I), lintoni Forbes and D. minutus
Lilljeborg, in which the ramus is very small, almost rudi-
mentary. The ramus is represented by an immovable spine,
minutely spinose at the tip. This is greatly diverse in shape
and sometimes gives indications of a joint (PI. XXIII., Fig.
2), as if a case of ankylosis.

Left fifth foot of the male biramose; second basal segment
quadrate, with a short thick spine just above the outer distal
angle. Second segment of outer ramus irregularly subquad-
rate, about two thirds as wide as long, provided at the inner

North American Species of Diaptomus. 135

margin with a cushion-like protuberance densely covered with
minute hairs. This segment is produced into two spines,
forming a forcipate structure. The inner spine is slightly
shorter than the main part of the segment, thick, incurved,
and movable, and armed on its outer margin and on the distal
third of the inner one with minute hairs. The outer spine is
immovable, ending in a blunt point, and its curve is rather
more pronounced than that of the inner one.

Inner ramus of left fifth foot one-segmented, straight, and
armed with minute hairs at the apex. It is about three times
as long as broad and reaches beyond the middle of the second
segment of the outer ramus.

First basal segment of the fifth foot of the female (PI. XXV.,
Fig. 1,-2") subquadrate, slightly longer than broad, bearing
a short thick spine near the outer distal angle. The distal
segment is also subquadrate and bears the usual delicate hair.
Outer ramus two- jointed, the first segment oblong, about
twice as long as wide ; second segment in the form of a thick
incurved hook, with a broad, quadrate basal portion. The
hook is about three times as long as its greatest breadth, the
distal fourth of the inner edge armed with a variable number
of teeth (8-15). Third segment wanting, represented by two
spines ; the outer short, thick, about one third the length of
the segment ; the inner rather longer and more slender, sin-
uously curved, and about half as long as the second segment.

Inner ramus of fifth foot of female straight, one-segmented,
about four times as long as broad ; armed at the tip with two
smooth spines of almost equal length and but slightly curved.
The tip of the ramus is delicately hairy.

Length of female 1.4-2.12 mm; of male l.-2."mm.

Breadth of female .4-.43 mm; of male .3-.33 mm.

The synonymy of this species is almost as complicated as
that of D. leptopus. First described by Dr. Forbes (76), it
was next described under two different names (D. sanguineus
and D. minnetonka) by Herrick ('84). I am also led to
believe very strongly that Herrick's D. armatus is nothing
but a variant of D. sanguineus. The descriptions and figures
(Herrick, '82, p. 223, Fig. 1, a and b) seem to me to be

136 Illinois State Laboratory of Natural History.

without specific value. The following, taken from Herrick and
Turner '95a, p. 72, is his most complete description. "It
appears to be allied to sanguineus . The antennae are said to be
shorter than the body, the caudal stylets narrow, the right
male antenna has a hook upon its antepenultimate joint
and is strongly geniculate. But the one feature which may
determine the species is the existence of a tooth or spur near
the base of the claw of the right fifth foot of the male."

In collections from Phelps Lake, Havana, 111., made May
18, 1894, occurred a single male specimen of a variant of D.
sanguineus which might easily be described as a new species
if the spine at the base of the terminal hook were taken as
the one specific characteristic to which all others must be
subordinated. This spine is straight and minutely dentate
on both margins. In all other respects, except a slight dif-
ference in the length of the terminal hook, the specimen is
a normal D. sanguineus. The fifth pair of legs is shown in
PI. XXV., Fig. 5. The occurrence of this specimen, taken in
connection with the loose descriptions of armatus, has led me
to believe in the identity of Herrick' s species and this variant.

In regard to D. minnetonka, Marsh ('93) points out that
it is probably but a variety of D. sanguineus. In his "Synopsis
of the Entomostraca of Minnesota" Herrick says : "We are
inclined to agree with Marsh that this form is but one of the
many variations of 1>. sanguineus" ; but he nevertheless retains
minnetonka as a species name instead of making it a synonym
of sanguineus.

Diaptomus sanguineus occurs in early spring in standing
water in connection with D. stagnalis Forbes, from which it
may be distinguished at a glance by the difference in size,
D. stagnalis being about twice as large as D. sanguineus. The
latter is generally a deep red, but D. stagnalis is often blue,
with abdomen and antennas a brilliant red.

The theory of Herrick (Herrick and Turner, '95) in regard
to the transition of forms, "beginning with J >. stagnalis and
passing through several varieties to I), sanguineus later in
the season," will not hold owing to the fact that sexually
mature specimens of both species have been found in the
same pools at the same time.

North American Species of Diaptomus. 137

The collection from which the variant mentioned above
was taken, made in May, 1894, consisted almost entirely of
D. sanguineus. Collections from the same waters made in
July, 1896, did not contain a single individual of this species,
but D. siciloides Lilljeborg and D. pallidas Herrick, were
present in immense numbers.

VARIATION IN D. SANGUINEUS FORBES.

Plates XXIII. , XXIV., and XXV. were prepared before the
thesis work proper was undertaken and exhibit the results of
a study in variation. From these figures it will at once be
evident that D. sanguineus is an unusually variable species,
and without the intermediate forms the extremes might
almost be regarded as distinct. The specimens examined
were all from the collections of the Biological Station at
Havana, so that the variations are probably not so great as
they would be if widely separated localities were represented.
Especial attention was given to variations of specific char-
acters, and most particularly to the relative proportions.

The second basal segment of the right leg of the male,
which is usually very broad, in fact one of the most charac-
teristic features of the male, is shown in PL XXIII., Fig. 2, to
be sometimes of very ordinary width, the other extreme being
shown in PI. XXIV., Fig. 4. The relative position and length
of the projection on the outer distal angle of this segment
also vary a great deal, the extremes noted being shown in PI.
XXIII., Fig. 1 and 2.

The marginal spine of the outer ramus of the right fifth leg,
the position, relative length, and characters of which are of
specific value in most species, lacks such value almost entirely
in D. sanguineus. The extreme variation is shown in PI.
XXIV., Fig. 4, and PI. XXV., Fig. 3.

The inner ramus of the right fifth leg, though always very
short, varies in length from that shown in PL XXIV., Fig. 4, to
that in PL XXIII., Fig. 2, on the latter of which is also shown
a rather clearly marked suture which is usually wanting.

The variation in the size of the males is indicated by the
drawings of the fifth pair of legs. (See PL XXV., Fig. 3-5,
and PL XXIV., Fig. 4.)

138 Illinois State Laboratory of Natural History.

The antepenultimate article of the prehensile antenna (PL
XXIII., Fig. 6-8) is not so variable, but still quite a differ-
ence may be noted in the width of the hyaline plate and in
the relative lengths of the segments.

In the female the variation in size is even greater than
in the male, the fifth legs being shown in PL XXV., Fig. 1, 2.
The variation in the "hump" of the female is slight (PL
XXIV., Fig. 5, 6), as is also that of the first abdominal seg-
ment (PL XXIV., Fig. 1, 2).

While I have found no variation whatever in the color of
D. sanguineus, all of the specimens I have seen alive being a
bright uniform red, as were also those examined by Dr.
Forbes (76), and by Gissler ('81), Gissler later ('81a) found
individuals colored as follows : body and legs bluish, an-
tenna? and furca red, and abdomen yellow. Herrick says
in the description of D.minnetonka (Herrick and Turner, '95),
which is a synonym of D. sanguineus, "color dark." In the
same work, in his description of D. sanguineus, he says
"brilliantly colored." According to my observation color is
of no certain specific value in Diaptomus, but it may be that
there are definite seasonal variations — a subject which I have
not investigated.

Diaptomus stagnalis Forbes. (PL XXVIII., Fig. 2.)

Diaptomus stagnalis, Forbes, '82a, p. 646, PL VIII., Fig. 8, 10-12, 14.
Diaptomus giganteus, Herriek,'82,p. 222, PI. II., Fig. 3, 11, 15.
Diaptomus stagnalis, Herrick. "84, p. 139, PI. Q, Fig. 11, 13.
Diaptomus stagnalis, de Guerne et Richard, '89b, p. 23, PI. IV.. Fig. 14.

Head distinct from thorax; fifth and sixth thoracic seg-
ments confluent. Lateral angles of last thoracic segment
strongly produced backward, each angle bilobed, the outer
lobe about twice as large as the inner; (in the male this seg-
ment is salient.) Abdomen peculiar in that there is a sudden
narrowing at the beginning of the third segment. First
abdominal segment armed with a large spine on each side
(in the male unarmed) ; second and third segments of the
abdomen subequal, about twice as wide as long. Furcal
rami subquadnite, hairy within. Furcal seta rather short,

North American Species of Diaptomus. 139

densely plumose. There is but little difference in the length
of the abdominal segments of the male.

Antennae 25-segmented, reaching to the middle of the
abdomen. Prehensile antenna of the male (PI. XXVIII.,
Fig. 2) thickly swollen anterior to the twelfth article, with
armature as follows: segments 1 and 5, long spine and
sense-club; 2, three long spines and sense-club; 3, short
seta; 4 and 6, long spine; 7, short seta and sense-club; 8
and 12, long spine and short spine; 9, long spine, short
seta, and sense-club; 10, 11, 13, and 17, process and
long spine; 14 and 16, long spine, short seta, and sense-
club ; 15, process, two long spines, and sense-club ; 18, proc-
ess ; 19, 20, and 21 (ankylosed, with the sutures indistinctly
indicated), two processes, a stunted spine, and a long seta;
22 and 23 (ankylosed), a broad hook-like process not reach-
ing the end of the penultimate segment, and four setae; 24,
two setae; and 25, four setae, a sense-hair, and a sense-club.

Second basal segment of the right fifth foot of the male
subquadrate, about twice as long as wide ; on the posterior
surface a large smooth hyaline lamina occupying about a
third of the inner margin near the middle, and near the outer
distal angle a minute cuticular process bearing a delicate
hair. First segment of the outer ramus almost three times
as long as broad ; second segment about as long as the first
and for about the proximal third nearly as wide, but beyond
this considerably broader. Marginal spine near the outer
distal angle ; straight, very strong and thick, little less than
half as long as the segment. Terminal hook rather short
and very stout, irregularly curved, heavily and closely den-
ticulate at the distal half of the inner margin.

Inner ramus of the right fifth leg spatulate, not nearly
reaching the middle of the first segment of the outer ramus ;
apex rounded, armed with a few strong spines.

Second basal segment of the left fifth foot armed at the
outer margin, a short distance above the distal angle, with a
short, thick, pointed spine. First segment of the outer ramus
about three times as long as wide, armed at the distal third
of the inner margin with a few strong hairs. Second segment

1 40 Illinois State Laboratory of Natural History.

about half as long as the first, having on the inner margin
two cushion-like processes (the upper, smaller one hairy, and
the lower densely tuberculate), and being armed at the tip
with two processes forming a forcipate structure, the outer
broad, plowshare-shaped, the inner a long and narrow spine,
hairy within.

Inner ramus of left fifth foot one- segmented, of the same
width throughout, with a broadly rounded tip ; inner margin
rugose.

Second basal segment of the fifth foot of the female with
the usual delicate hair at the outer margin. First segment
of outer ramus short and broad. Second segment large,
about one and a half times as long as the first, armed on the
middle third of the inner margin with seven or eight very
large, strong, pointed spines, and on the outer margin and
opposite the upper spines of the inner margin with three or
four spines. Third segment distinct, armed with two spines,
the outer one short, thick, sharp, smooth, the inner one about
twice as long and armed with a few rather strong spinules.
Just without these spines, on the second segment, is a shorter,
smooth spine.

Inner ramus of the fifth foot of the female distinctly two-
segmented, the first segment subquadrate, the second as wide
as the first and nearly twice as long, and armed at the tip
with two thick heavy spines reaching to the end of the second
segment of the outer ramus. These spines are armed with
heavy spinules. Disregarding the spines, the ramus reaches
just to the end of the first segment of the outer ramus.

Length of female 4.0-4.5 mm. ; of male 3.5-4 mm.

This Diaptomus is the largest of the American species and
a very beautiful one. Dr. Forbes states in his original des-
cription ('82a) that "all were red throughout." Specimens
taken in April, 1897, from ponds south of Urbana, 111., when
they were in the height of sexual activity, were colored as
follows: thorax and anterior appendages (all but the first
pair of antenna') blue ; first pair of antenna, fifth pair of
legs (in the male), and abdomen red. In the female all the
legs were blue.

North American Species of Diaptomus. 141

The pool from which they were taken was particularly rich
in decaying vegetable material and received the drainage of a
pasture in which cattle and horses were allowed to graze.
The water literally swarmed with Volvox; and Diaptomus,
Cyclops, and insect larvae were very abundant. The food sup-
ply was practically inexhaustible and the specimens taken
were unusually large.

Diaptomus shoshone Fokbes. r(Pl. XXVI., Fig. 1-3.)

Diaptomus shoshone, Forbes, '93, p. 251, PI. XLIL, Fig. 23-25.
Diaptomus shoshone, Herriek and Turner, '95, p. 61, PI. V., Fig. 11.

"A very large and robust species. Thorax broadest in
front, across the maxilla?, tapering gradually, with little con-
vexity, to the posterior third. In the female the angle of the
last segment is bifid, both projecting points being minutely
spinose at tip. The first segment of the abdomen (PL XXVI. ,
Fig. 1) is laterally expanded, the expansion of the left side
with a minute spine at the apex, behind, that on the right
produced at the same point into a small, prominent, rounded
tubercle, 0.03 millimeter in length, about as broad as long,
making this first segment somewhat unsymmetrical. This is
not merely a modified cuticular appendage, but is penetrated
by the hypodermis. Egg-mass very large, obovate (narrowest
forward).

"Eight antenna of male robust, the last two joints without
special appendages, antepenultimate with a very long inartic-
ulate process at its outer apex, extending beyond the tip of
the penultimate and to the middle of the last segment. The
margins of this process are smooth, but it is broad and
emarginate at the tip.

" The fifth pair of legs in the male resemble the correspond-
ing appendages of Diaptomus stagnalis, but differ notably in
detail. The left ramus of the right leg is borne at the inner
terminal angle of the second joint ; is longer than the joint
following ; is armed at the apex with a few small acute spines ;
and bears upon its outer margin, near the tip, a broad fas-
cicle of delicate hairs. The basal joint of the outer ramus is
two thirds the length of the second joint of the peduncle,

142 Illinois State Laboratory of Natural History.

and without hairs or spines of any description. The second
joint of this ramus is about equal in length to the second
joint of the peduncle, and bears on its outer margin, close to
the tip, the usual stout seta, which is two thirds as long as
the joint to which it is attached. The terminal claw is not
regularly curved, but is nearly straight for the basal three
fourths. The left leg is biramose, the inner ramus straight,
slender, extending about to the middle of the second joint of
the outer, and armed at its tip. The second joint of this
ramus is as long as the first, if measured from the tip of the
apical spine. This spine, seen from behind, is stout, conical,
rather blunt, and has opposed to it within, projecting from the
inner angle of the segment, a stout, curved seta, slightly
plumose on its distal half. Between these, but more closely
applied to the outer spine, is a hemispherical cushion-like
elevation, set with small, short spinules. On the basal half
of the inner margin of this terminal segment is also a much
larger hemispherical cushion, but with longer and more slen-
der hairs, while the terminal half of the inner margin of the
segment preceding is also moderately inflated and covered
with delicate hairs.

"The antenna? of the female are 25-jointed, as usual,
and reach to the base of the abdomen. The legs of the fifth
pair (PL XXVI., Fig. 2) closely resemble those of stagnalis,
but have the terminal sette of the inner rami much less devel-
oped. This ramus is a little shorter than the basal joint of
the outer ramus, and of about half its diameter. It bears at
its tip two stout setae equaling the ramus itself in length, plu-
mose under a high power, and has, in addition, at its inner
tip and on the inner margin adjacent, a patch of delicate
hairs and spines. The second joint of the outer ramus is as
long as the first, if measured to the tip of its terminal claw!
The latter is nearly straight, very slightly recurved. This
joint bears a single spine at its outer distal angle, just within
which is the rudiment of the third segment of the ramus, which
bears two spines similar to the above, the inner of which is the
longer, the outer itself being longer than the adjacent spine
of the second joint. Adults of both sexes are blood-red
throughout except the egg-sac of the female, which is purple.

North American Species of Diaptomus. 143

"Dimensions of female: Length to. tip of caudal setae,
3.1 millimeters; abdomen, with setae, 1.16 millimeters, with-
out, 0.67 millimeters; thorax, 1.95 millimeters in length;
depth, 0.725 millimeter; width, 1 millimeter.

" Male averaging scarcely smaller, but somewhat differ-
ently proportioned: Thorax, 1.85 millimeters in length;
depth, 0.58 millimeter; width, 0.08 [1.08]* millimeter;
abdomen, without setae, 0.745 millimeter; with setae, 1.35
millimeters in length.

"Especially abundant in Shoshone Lake, but occurring in
other lakes and even in pools of some size in Yellowstone
Park."t

The drawings here given are in some cases the same as
those in the original description with unimportant correc-
tions or additions, but two new figures (PI. XXVI. , Fig. 1,
3) have been added. I have not found this species in any
collections except those from Yellowstone Park and the Flat-
head region, in which it is rather abundant.

A few points may be added to the original description. In
the female the first basal segment of the fifth pair of legs
bears a short sharp spine on the outer margin a short dis-
tance above the distal angle. Both spines of the rudiment-
ary third segment of the outer ramus are distinctly spinose
on the inner margin. The first abdominal segment is almost
as long as the remainder of the abdomen ; the second segment
very short, about half as long as the succeeding segment or
the furca. Furcal rami about one and a half times as long
as wide and hairy within. My observations differ from those
of Prof. Forbes in that, as a rule, the abdomen of the female
is not asymmetrical, the first segment bearing on each side a
small tubercle armed with a minute spine. In the male the
first abdominal segment is very slightly dilated laterally but
unarmed, and about half as long as any one of the five suc-
ceeding segments, which differ very little in length. The
furcal rami are fully twice as long as wide and hairy within.

*The 0.08 in the original description is probably a typographical error, since the
sperinflns measured by myself were about 1.08 millimeters in length.

tDescription quoted from Forbes, '93.

144 Illinois State Laboratory of Natural History.
Diaptomus pallidus Herrick. (PL XXVII., Fig. 3.)

Diaptomus pallidus, Herrick, *79, p. 91, PI. II.
Diaptomus pallidus, Herrick, '83a, p. 3S3, PL VII., Fig. 1-6.
Diaptomus pallidus, Herrick, '84, p. 142, PI. Q, Fig. 17.
Diaptomus pallidus, de Guerne et Richard, '89b, p. 62, Fig. 34.
Diaptomus pallidus, Marsh, '93, p. 196, PI. III., Fig. 6, 7, 9.
Diaptomus pallidus. Herrick and Turner, '95, p. 73, PI. IV, Fig. 1-6;
PI. V., Fig. 10; PL XIII., Fig. 17.

Of medium size, slender; cephalothorax widest near the
middle ; bead partially divided by a suture ; suture between
bead and thorax distinct. Fifth and sixth thoracic segments
confluent ; last thoracic segment produced laterodorsally,
bearing a small spine on each side. First abdominal seg-
ment unarmed but dilated laterally (not dilated in the male),
about as long as the remainder of the abdomen ; second
segment the shortest. Furcal rami hairy within.

Antennae 25-segmented, reaching about to the tips of the
furca or slightly beyond. Male prehensile antenna moder-
ately swollen ; no special armature on the last three seg-
ments ; segments 19 and 20 ankylosed, armed with a process
and a long seta; 21, 22, and 23 ankylosed, armed with two
long setae; 24, with two long setae; and 25 with four long
setae and a sense-club. Some of the antenna! setae are
very minutely and sparsely hairy.

First basal segment of right fifth foot of male (PI. XXVII.,
Fig. 3) with large tubercle bearing a small spine on the pos-
terior aspect ; second basal segment as usual, about equal in
length to the first. First segment of the outer ramus sub-
quadrate, about as long as wide ; second segment about as
wide as the preceding and about one and a half times as
long, bearing on the inner margin, at the end of the proxi-
mal third, a small sharp-pointed cuticular projection. The
outer margin of this segment is almost straight to the begin-
ning of the distal third, where a sharp angle is made from
which springs the marginal spine. This spine is sharp,
slender, slightly curved, a little more than one third the
length of the segment. Terminal hook slender, about^ one
and a half times as long as the second segment ; not regularly

North American Species of Diaptomus. 145

curved, but with a sharp angle at the beginning of the distal
third ; minutely denticulate within.

Inner ramus of right fifth foot one-segmented, slender,
narrowing gradually from base to tip, extending but slightly
beyond the proximal third of the second segment of the outer
ramus; hairy at the apex and very delicately denticulate on
the outer margin.

Basal segments of left fifth foot subquadrate, the second
slightly longer than the first and both slightly longer than
broad; second segment delicately tuberculate dli the inner
margin. First segment of outer ramus about half as wide
and three fourths as long as the basal segment. Second seg-
ment about as long as the first, and very similar to the cor-
responding segment of D. sicilis Forbes, from which it differs,
however, in its armature. This consists of a movable claw,
blunt or slightly thickened at the tip, forming a forcipate
structure with an inner cushion-like process. The claw
usually lies close against this and is difficult to make out.
It is hairy on both margins.

Inner ramus of the left fifth foot one-segmented, hairy at
the apex and delicately denticulate on the outer margin,
extending to the end of the first segment of the outer ramus
or slightly beyond it.

Second basal segment of the fifth foot of the female with
the usual hair at the outer distal angle. First segment of the
outer ramus subquadrate, about twice as long as broad.
Second segment about as long as the first, tapering to a blunt
point ; inner margin denticulate. Third segment wanting,
represented by two spines, the inner about twice as long as
the outer and smooth, while the outer is delicately hairy.

Inner ramus of fifth foot of female one-segmented, reach-
ing the end of the first segment of the outer ramus ; hairy at
the apex and within, and armed at the tip with two long sub-
equal delicately hairy spines.

I have found specimens from the Illinois Eiver at Havana
with the inner ramus of the right fifth foot reaching barely
beyond the end of the first segment of the outer ramus. The
first basal segment of the left foot of the male is provided with

146 Illinois State Laboratory of Natural History.

a hyaline lamina ending in a pointed spine-like projection;
and the second basal segment is tuberculate at the inner
margin, as is also the outer margin of its inner ramus. All
of these differences are quite constant but not of sufficient
importance to constitute even a variety.

D. pallidus was found in immense numbers in connection
with D. siciloides Lilljeborg during the entire time of my stay
at the Biological Station at Havana — that is July and part of
August, 1896. So far as I was able to ascertain, siciloides
was slightly the more abundant, but the difference was not
Very evident.

Herrick's original description of D. pallidus ('79) was very
indefinite, and the establishment of the species really dates
from 1893, when Marsh figured and described it in a manner
to make it recognizable by later students. De Guerne and
Eichard ('89b) place it among their "species insufficiently
described."

Diaptomus albuquerquensis Herrick. (PI. XXYIL, Fig.
2, 4.)

Diaptomus albvquerquensis, Herrick. '95, p. 45. Fig. 16-26.
Diaptomus albuqurrquensis, Herrick and Turner, "95, p. 67, PI. VI.,
Fig. 1-3; Pi. VII., Fig. 1-11.

A medium-sized species. Cephalothorax widest about the
middle. Suture between head and thorax distinct. Last
two thoracic segments, seen from above, indistinctly conflu-
ent, the last one produced laterodorsally and armed on each
side with two rather long spines ; in the male produced but
but very slightly and armed with only one spine on each side.
First abdominal segment in the female longer than the
remainder of the abdomen, dilated laterally, and armed on
each side with a single spine ; second and third segments
subequal; each shorter than the furcal rami, which are
barely twice as long as wide and hairy within. First abdomi-
nal segment in the male short, a little more than half as long
as any one of the succeeding three segments ; dilated very
slightly, and armed on each side with a spine; fifth segment
about as long as the first. Furcal rami barely twice as long
as wide and hairy within.

North American Species of Diaptomus. 147

Antennae of the female 2 5 -segmented, extending well be-
yond the tips of the furcal setae ; somewhat shorter in the
male, reaching about to the tips of the furcal setae. Eight
male antenna moderately swollen beyond the thirteenth seg-
ment. Beyond the twelfth segment the antenna is armed as
follows: 13, with large process; 14, process, short seta, and
very long seta; 15, very short stunted spine, short seta, and
long seta; 16, a short and a long seta; 17, process, short
seta, and long seta ; 18, large process ; 19 and 20 (completely
ankylosed), short stunted spine and long seta; 20, 21, and
22 (also completely ankylosed), two setae, and a hooked
process extending beyond the middle of the penultimate
article; 24, two seta?; and 25, four setae.

Left fifth leg of the male (PL XXVII. , Fig. 4) short, not
reaching to the end of the second segment of the outer ramus
of the right leg. First and second basal segments subequal,
the first armed at the middle of the outer margin with a
rather long sharp spine ; the second slightly broader than
the first, and provided a short distance above the outer distal
angle with the usual delicate hair, and at the middle of the
inner margin with a small hyaline plate. First segment of
the outer ramus about twice as long as wide ; outer margin
arcuate, inner margin convex and delicately hairy. Second
segment racket-shaped, the broad basal half being almost
circular ; hairy on the inner margin. The digitiform termi-
nal half is blunt and delicately denticulate on the margin.
From the anterior aspect projects a delicately hairy spine
about as long as the digitiform process, but more acute and
pointing inward.

Inner ramus of left fifth leg short, one-segmented, barely
reaching to the end of the first segment of the outer ramus ;
margins slightly sinuous ; apex bluntly rounded, very deli-
cately hairy, the hairs at the apical angles being somewhat
stouter and spine-like.

First basal segment of right fifth leg of male subquadrate,
slightly longer than broad ; armed at the outer distal angle
with a stout, sharp spine pointing straight outward. Second
basal segment subquadrate, about equal to the first, and

148 Illinois State Laboratory of Natural History.

armed on the outer margin, a short distance above the apical
angle, with a spine-like hair. First segment of outer ramus
subquadrate, slightly narrower than the second basal seg-
ment, and about as wide as long ; second segment about as
wide as the first and twice as long, provided at the end of
the proximal third with a small bead-like tubercle. Mar-
ginal spine very large and strong, longer than the segment
itself, somewhat sinuously curved, and inserted near the
distal angle. Terminal hook very long, as long as the remain-
der of the right leg including the basal segments, but not
twice as long as the marginal spine ; very slightly recurved
at the tip and denticulate at the inner margin.

Inner ramus of the right fifth leg one-segmented, very
short, barely reaching the end of the first segment of the
outer ramus ; apex bluntly rounded and delicately hairy.

First segment of outer ramus of fifth foot of female (PI.
XXVII., Fig. 2) subquadrate, about twice as long as wide.
Second segment, or unguiform process, about as long as the
first, subcorneal or but slightly curved, delicately denticulate
on the inner margin. Third segment small but distinct, armed
with two spines, the inner of which is more than twice as
long as the outer, reaching about to the middle of the second
segment.

Inner ramus of fifth foot of female indistinctly two-seg-
mented, short, reaching just beyond the end of the first seg-
ment of the outer ramus ; apex bluntly triangular, armed
with a few short hairs, the innermost of which is longer than
the rest and spine-like.

Length of female 1.2 mm. ; of male 1.05 mm.

The material in Avhich the specimens described were found
was loaned me by Mr. Adolph Hempel, of Gotha, Florida,
and was collected by him in a series of Florida lakes from
January to March, 1896.

D. albuquerquensis is one of the few American species of
Diaptomus in which the inner ramus of the fifth leg of the
female is two-segmented. In some cases this ramus, instead
of being bluntly triangular, is acute, and reaches only to the
end of the first segment of the outer ramus. The first basal

North American Species of Diaptomus. 149

segment is sometimes armed at the outer distal angle with
a short, sharp spine.

Herrick (Herrick and Turner, '95) states that he found the
second segment of the left fifth leg of the male to be granular
on the inner margin, and the marginal spine of the right leg
denticulate on the inner margin and at the base. In both
these respects my specimens differ from his, the second seg-
ment of the left foot being hairy instead of granular, and
the marginal spine of the right foot perfectly smooth. Her-
rick's statement that "the first pair of antennae reach to the
extremity of the furca or surpass them" leads me to think
that they are longer in the Florida specimens than in his,
since they clearly reach beyond the tips of the f ureal setse in
every individual which I have examined.

In New Mexico Herrick found this species, in connection
with D. novamexicanus, in the water supply of the city of
Albuquerque; but in the Florida lakes it was found with
I). mississippiensis Marsh, the two forms being about equally
abundant. They are very much alike in general appearance,
but the males may be distinguished without dissection by the
antepenultimate article of the right antenna, which is armed
in D. albaquerquensis while it is unarmed in D. mississippien-
sis. Herrick gives the length of the female as 1.4-1.6 mm.,
but the largest female from Florida was 1.2 mm., while the
male was only 1.05 mm. in length, the average being con-
siderably smaller.

Diaptomus novamexicanus Herrick.

Diaptomus novomexicanus , Herrick, '95, p. 46, Fig. 27-29.
Diaptomus novamexicanus, Herrick and Turner, '95, p. 70, PI. VI.,
Fig. 7-10.

Among the smaller species of the genus, moderately robust.
Cephalothorax widest somewhat in front of the middle. Last
two thoracic segments distinct, the last armed on each side
with a small, short spine. First abdominal segment very
long, much exceeding the remainder of the abdomen, pro-
vided on each side with a short, sharp spine; second seg-
ment the shortest. Furcal rami equal in length to the

150 Illinois State Laboratory of Natural History.

preceding segment and about twice as long as wide; provided
with short apical setse.

Antennae of the female 2 5 -segmented, reaching to the base
or the end of the furca. Antepenultimate article of the right
male antenna armed with a lamina produced anteriorly into
an unguiform process which is shorter than the penultimate
article.

Outer ramus of the fifth pair of feet in the female obviously
three-segmented. Unguiform process of the second segment
arcuate, finely denticulate within and at the end, armed on
the outer margin near the base of the last segment with a
small spine. Last segment small but distinct and armed
with two short subequal spines.

Inner ramus of fifth foot of female one-segmented, as long
as the basal segment of the outer ramus ; apex ciliate and
armed with two subequal spines,

Left fifth leg of male reaching slightly beyond the end of
the first segment of the outer ramus of the right foot. First
basal segment armed on the outer margin with a short, sharp
spine. Second segment of the outer ramus oblong-ovate,
armed with two large spines ; inner margin delicately aculeate
toward the apex, and bearing a ciliate lamina.

Inner ramus of left fifth leg one-segmented, quite long,
reaching beyond the middle of the second segment of the
outer ramus ; hairy at the apex.

First basal segment of right fifth leg of male armed on the
outer margin with a rather long, sharp spine. First segment
of the outer ramus subquadrate, slightly longer than broad ;
second segment very long and narrow, more than twice as
long as the preceding segment. Marginal spine slender,
more than half as long as the segment itself, and inserted at
about the beginning of the distal third. Terminal hook long
and slightly curved.

Inner ramus of right fifth leg one-segmented, rather long,
reaching beyond the end of the first segment of the outer
ramus ; apex acute, minutely ciliate.

Length of female 1.1-1.2 mm.

North American Species of Diaptomus. 151

The above description is compiled from Herrick's first
paper on this species ('95) and from the figures and the
English and Latin descriptions in his later paper (Herrick
ai d Turner, '95). Both of these articles are published as
original descriptions, although there was nine months' differ-
ence in the time of their appearance.

Diaptomus oreg-onensis Lilljeborg. (PL XXIX., Fig.
1, 2.)

Diaptomus oregonensis, de Guerne et Richard. '89b, p. 53, PI. II., Fig.

5; PI. III.. Fig. 8.
Diaptomus oregonensis, Marsh, '93, p. 200, PI. IV., Fig. 4, 5.
Diax>tomus oregonensis, Marsh, '95, p. 8, PI. VII., Fig. 5.
Diaptomus oregonens is, Herrick and Turner, '95. p. 72, PI. IV., Fig.

7-12 ; PI. IX., Fig. 3.

A species of medium size. Cephalothorax widest about
the middle. The last two thoracic segments confluent above,
the last one, seen from above, slightly produced laterally,
bluntly rounded but unarmed ; in the male armed with two
very minute spines on each side. First abdominal segment
as long as the rest of the abdomen.* Third segment and
furcal rami subequal, the latter about one and a half times
as long as broad and delicately hairy within. In the male
the first abdominal segment is short and unarmed ; second
and third segments and furcal rami about equal ; fourth
segment the longest, about equal in length to the first two
segments taken together. Furcal rami about as in the female.

Antennae of the female 25 -segmented, extending beyond the
tips of the furcal seta?. Prehensile antenna of the male but
slightly swollen, the antepenultimate article entirely unarmed.

First basal segment of fifth leg of female (PI. XXIX., Fig.
2) with the usual delicate hair on the outer margin. First
segment of outer ramus about twice as long as wide, slightly
arcuate, margins parallel ; second segment about as long as
the first, moderately curved, terminating in an acute point,

*This segment hart a very peculiar appearance. Owing to the thicker anterior
part, the segment seemert to have a suture at about the middle, and this was so mis-
leading that I doubted if the specimens on the slides were really females until I could
see the antennae, and not until 1 could get a side view was I at all certain that there
was only one segment.

152 Illinois State Laboratory of Natural History.

very minutely hairy on the inner margin ; third segment
wanting, represented by two short spines, the inner twice as
long as the outer.

Inner ramus of fifth leg of female one-segmented, extend-
ing very slightly beyond the first segment of the outer ramus ;
apex obtuse, hairy, armed on the inner margin and at the
tip with two rather long subequal spines.

First basal segment of right fifth leg of male (PI. XXIX.,
Fig. 1) with a small tubercle on the outer margin; second
segment subquadrate, about one and a half times as long as
the first. First segment of the outer ramus subquadrate,
about as long as the first basal segment with overhanging
outer apical angle ; second segment slightly narrower than
the first, about twice as long as wide, with a small projection
at the middle of the inner margin. Marginal spine near the
apical angle, slender, with a slight angle about one fourth
its length from the base ; length about equal to the distance
between its base and the base of the segment. Terminal
hook long and slender, longer than the two preceding seg-
ments but not as long as those and the second basal segment ;
very minutely denticulate on the inner margin.

Inner ramus of right fifth leg one-segmented, extending to
a point about midway between the base of the second seg-
ment of the outer ramus and the projection on the inner
margin of this segment ; outer margin hairy ; apex bluntly
triangular and hairy.

Second basal segment of left fifth leg of male subquadrate,
about one and a half times as long as broad, slightly pro-
duced on the inner margin a short distance above the apical
angle. First segment of outer ramus slightly narrower than
the second basal segment and about twice as long as wide ;
outer margin moderately arcuate, the inner margin hairy.
Second segment produced into three digitiform processes :
the outermost blunt and .by far the longest ; the middle one
blunt, barely one fourth the length of the outer; and the last
very short, hardly more than a tubercle, with an acute apex
pointing straight inward. The segment is armed on the inner
margin with a hairy, cushion-like process.

North American Species of Diaptomus. 153

Inner ramus of left fifth leg somewhat spatulate, extend-
ing slightly beyond the end of the first segment of the outer
ramus ; inner margin hairy ; apex bluntly rounded and hairy.

Length of female 1.25 mm. ; of male 1.15 mm.

The above description is based on specimens found in col-
lections made in Lake Calhoun, Minn., in July, 1891, and
differs considerably from Lilljeborg's original description in
de Guerne and Richard's "Revision."

He gives the length of the female as about 1.5 mm. ; that
of the male, 1.4 mm.

I did not find in a single instance that the female had the
last thoracic segment armed with two minute spines on each
side, although they were present in the male. Lilljeborg does
not specify to which sex this part of his description applied,
but I assume that he followed the usual custom of referring to
the female unless especially stated otherwise.

The spines on the inner ramus of the female I found to be
on the inner instead of the outer margin, and they are so
figured by Marsh ('93).

In most cases I found but one spine representing the third
segment of the outer ramus of the fifth foot of the female,
while one specimen was found having one outer ramus as in
the type, the other with only one spine. I have thought it
best to make the description correspond to the type in this
particular, regarding the variation as local since Marsh ('93)
figures the two spines.

The inner ramus of the right fifth foot of the male in the
Minnesota specimens was longer than represented in the
original figures, and hairy on the inner margin and at the
apex. This hairiness is not mentioned in the original des-
cription and this ramus is figured smooth, while the inner
ramus of the left fifth foot, which is no more hairy than the
right, is hairy in the drawings.

In the left fifth foot of the male the first segment of the
outer ramus, although hairy, has not the definite cushion-like
process figured by Lilljeborg, and the outer two digitiform
processes of the second segment instead of being serrate
within are perfectly smooth. From Herrick's statement

154 Illinois State Laboratory of Natural History.

(Herrick and Turner, '95, p. 73) that "according to Richard's
drawing the spines are dentate," I judge that he also found
them smooth, since his own figures show them to be so.

This species was first found in 1888 at Portland, Oregon,
by Trybom, and described in 1889 byLilljeborg in de Guerne
and Richard's "Revision." Marsh says ('93) that it is the most
common form in central Wisconsin, being found quite gener-
ally in the shallower lakes, and that it occurs in the Great
Lakes, but not abundantly ('95). Herrick (Herrick and
Turner, '95) says that within the limits of Minnesota it had
been found only in Lake Minnetonka. I can now add Lake
Calhoun, Minn., and Sand Lake in northern Illinois.

Diaptomus siciloides Lilljeborg.

Diaptomus siciloides. tie Guerne et Richard, 'S9b, p. 54, PI. I., Fig.

7,8,28,32.
Maptomus siciloides, Herrick and Turner, '95, p. 69, PI. VIII.. Fig. 10.

"Among the smaller of this genus. The general form of the
body agrees almost exactly with that of D. gracilis Sars.
Cephalothorax slender, widest at the middle. The last two
thoracic segments confluent above. Lateral lobes of the
last one, seen from above, short and rounded, with rather
large mucros. First abdominal segment long, fully as long
as the remaining part of the abdomen (without the setae) ;
with distinct lateral processes at the anterior part, acuminate
and bending forward slightly. Furcal rami short, but fully
one and a half times as long as broad.

" First pair of antennae of the female, reflexed, surpass the
furca but do not reach the tips of the furcal setae ; composed
of 25 articles. Antepenultimate article of the prehensile
antenna of the male provided with a rather long hook-like
process reaching about to the middle of the penultimate
article.

"Fifth pair of feet in the female small but rather thick;
outer ramus biarticulate, hook-like process of second seg-
ment slightly curved, and almost equal to the first segment ;
the inner margin partly ciliate. Inner ramus simple, slightly
longer than the first segment of the outer ramus ; with a
small seta, slightly hairy at the apex.

North American Species of Didptomus. 155

" The inner margin of the first segment of the outer ramus
of the right fifth foot of the male dilated into a rather large
hyaline lamella. The second segment of this ramus moder-
ately curved, the outer margin ohtusely biangulate, the spine
placed below the middle. Claw simply curved. Inner ramus
small and slightly surpassing the middle of the first segment
of the outer ramus.

" The second segment of the outer ramus of the left fifth
foot almost triangular, with a beak-like spine and delicately
hairy within (intus tenai ore et subtiliter hispido); the apical
process obtuse, with a spine at the inner margin. Inner
ramus simple, sinuous, and reaching to or beyond the middle
of the second segment of the outer ramus.

"Length of female about 1.3 mm.; that of male slightly
less.

" Found in the month of May in Lake Tulare near the city
of Fresno, Cal., by G. Eisen.

"In the general form of the body this Diaptomus closely
resembles D, gracilis Sars as well as D. sicilis Forbes. It is
on account of this last resemblance that it was called siciloides.
It differs, however, from both : from D. gracilis in the shape of
the last thoracic segment and of the abdominal segments, of
the first pair of antennae, and of the fifth pair of feet ; from D.
sicilis in the shape of the fifth pair of feet, although this dif-
ference is not very great. It resembles D. sicilis more closely
than D. gracilis.

"It seems to live in great numbers in Lake Tulare near
Fresno, Cal. The female bears only four eggs."*

The statement concerning the number of eggs borne by the
female is erroneous, the number being variable, and appar-
ently dependent to a great degree on the temperature of the
water and on the food supply. In the high mountain lakes
from which the species was first described the statement
above quoted may hold true, but in the warm sluggish waters
of the Illinois Eiver, where food is abundant, the egg-sac is
very large, as many as eighteen eggs having been counted
on a single female. This is true also of specimens taken

*Lilljeborg*s description from de Guerne et Richard, 89b.

156 Illinois State Laboratory of Natural History.

from other localities, and no tendency toward constancy in
number of eggs for the same locality was made out.

The furcal rami in both sexes are hairy within, a point not
mentioned in the original description, although the rami are
so figured. All the specimens which I examined from the
various localities had this characteristic, although individuals
varied slightly in this particular.

As mentioned under the description of D. pallidus, D. sicl-
loidcs was the most abundant form found at Havana. It also
formed the greater part of the material from Spirit Lake,
Iowa, which was kindly loaned me by Prof. L. S. Ross, of
Drake University, Iowa.

The individuals taken from the Illinois River at Havana,
Illinois, in July and August, 1896, were all of an indefinite
color about like opalescent glass. The egg-sac in these was
blue, and there was a small pink spot near the eyes and just
behind them. These were the only specimens of slcllolcles
which I had opportunity to examine alive.

Diaptomus minutus Lilljeborg. (PI. XXX., Fig. 5-8.)

Diaptomus minutus, de Guerne et Richard, '89b, p. 50, PL I., Fig. 5,

6,14; PI. III., Fig. 25.
Diaptomus minutus, Marsh, '93, p. 199, PI. IV., Fig. 1-3.
Diaptomus minutus, Marsh, '95, p. S, Pi. VII., Fig. 3.

"Among the smallest of the genus. Body slender, widest
in front of the middle of the cephalothorax and at the pos-
terior part of the head. Fourth and fifth segments commonly
confluent above, sometimes in the adult specimen separated
by a suture; the lateral lobes, seen from above, short and
rounded, and provided with minute mucros. First abdomi-
nal segment of the female (PI. XXX., Fig. 8) about as long
as the remainder of the abdomen; rather dilated at its an-
terior part and rounded laterally ; furnished with very minute
spines. Second segment very short, third segment much
longer, and these segments indistinctly joined. Furcal rami
about twice as long as broad. Furcal setae unusually long.

"First pair of antennae of female somewhat surpass the
furca; composed of 25 segments. Antepenultimate article of

North American Species of Diaptomus. 157

the prehensile antenna of the male (PL XXX., Fig. 7) with a
slender process, long and straight, having a slight appearance
of an apical curve, and extending beyond the penultimate
article and sometimes almost reaching the end of the last
article.

"Setse of swimming feet unusually long. Outer ramus of
the fifth pair of feet in the female (PI. XXX., Fig. 5) In-
articulate; unguiform process of second article slightly
curved and minutely ciliate without. Inner ramus small
and almost rudimentary, with acuminate apex.

"Eight foot of the fifth pair of the male (PI. XXX., Fig. 6)
large but slender ; the second article of the outer ramus with
marginal spine minute and placed above the middle. Ter-
minal claw thick toward the base, rather short, and partly
minutely ciliate within. Inner ramus very small and quite
rudimentary.

"The left foot of the same pair very similar to that of J>.
siciloides and D. signicauda; the second article of the outer
ramus almost elliptical, the inner margin slightly emarginate
and partly ciliate at the lower part ; with a large and obtuse
apical spine and a smaller inner spine. Inner ramus simple,
attenuate toward the apex, and extending about to the middle
of the second article of the outer ramus.

"Length of female 1-1.1 mm ; of male hardly 1 mm.

"Found in Greenland, 61° 30'- G9° N. Lat., by Dr. C.
Nystrom and N. 0. Hoist, and at St. John's, Newfoundland,
by the former.

"This species is distinguished from others by its minute
size and by the fifth pair of feet. The female bears only two
eggs. D. minutus has been found in the Isle of Disko, north-
ern Greenland, but it seems to be more common in the
southern part. It is without doubt spread over the northern
part of North America, since it has also been found at St.
John's, Newfoundland."*

"We are able to confirm in every respect the description
given above by Professor Lilljeborg. We have, in fact, recog-
nized some rare specimens of D. minutus in a collection

*Lil]jeborg's description from deGuerne et Richard, 89b.

158 Illinois State Laboratory of Natwral History.

which M. Eiballier des Isles, French consul at Newfound-
land, was kind enough to make according to our directions
at Kinney's Pond near St. John's. This Calanid [centropa-
gid] was found in great numbers by M. Ch. Eabot in 1888
in the following localities in Greenland : Lake Egedesminde
(Bay of Disko) ; Godhavn ; near the glacier of Jakobshavn,
and in the Tasersuak of Julianehaab."*

"Marsh finds this form in Green Lake [Wisconsin], and
in the Great Lakes ; it may, therefore, be expected in Lake
Superior in Minnesota. "t

Marsh ('95) places sicilis var. imperfectus as a synonym
under minutus, but does it, as he says, "with considerable
hesitation." In looking over the drawings in the possession
of the State Laboratory I found some which had been repro-
duced but not published, and from these it was evident at a
glance that the var. imperfectus was not minutus but ashlandi,
although this was not evident from the description. A single
specimen of minutus was found among the collections from
Yellowstone Park, but it was so badly mutilated that no
drawings could be made from it.

Specimens from Greenland, kindly sent me by Professor
Lilljeborg, conform to his description but are somewhat
smaller than those figured by Marsh.

Diaptomus tryborni Lilljeborg. (PL XXXI., Fig. 1-5.)

lHaptomus trybomi, de Guerne et Richard, 'S9b, p. 58, PL I., Fig. 35;

PL II., Fig. 6; PL III., Fig. 14; PL IV., Fig. 28.
Diaptomus trybomi, Herrick and Turner, '95, p. 57, PL VIII., Fig. 17;

PI. IX., Fig. 4: PL X., Fig. 13.

" Of medium size. Cephalothorax widest about the middle.
Last two segments distinctly separated, and the last, seen
from above (PL XXXI., Fig. 3), slightly produced laterally,
provided with two spines (one of them minute) on each
side. Besides this the right part of this segment (PL XXXI.,
Fig. 2) bears a large dorsal appendage, triangular in form,
with mucronate apex, and extending toward the right. The

*de Guerne et Richard, 89b.

t Herrick. From Uerriek and Turner, '95.

North American Species of Diaptomus. 159

first caudal segment of the female is very characteristic of the
species (in the male it is of the ordinary form) and, unlike
that of D. signicauda, surpasses in length the rest of the
abdomen. This segment is provided at the anterior part on
both sides with a short and mucronate lateral process, and at
the posterior part with a large triangular process extending
almost directly toward the right, with apex slightly acumi-
nate. F ureal rami rather short, not twice as long as broad.

" First pair of female antennae 25 -segmented, almost reach-
ing the base of the furca. The antepenultimate article of the
prehensile male antenna (PI. XXXI., Fig. 1) armed with an
almost straight and rather slender process reaching almost
to the middle of the penultimate article, and provided with-
out with small teeth.

" Outer ramus of the fifth pair of feet in the female (PL
XXXI., Fig. 5) two-segmented; the unguiform process of the
second segment slightly curved, robust, moderately ciliate
within and at the middle part, last cilium broad, spine-like.
Third segment wanting, produced into two short spines, the
outer half as long as the inner.

"Inner ramus one-segmented, almost equal to the first seg-
ment of the outer ramus ; apex obliquely acuminate, pro-
vided with two rather long subequal spines.

" Second segment of the outer ramus of the right fifth foot
of the male (PI. XXXI. , Fig. 4) very long, longer than the
first segment and the basal segment taken together. Margi-
nal spine of this segment inserted above the middle. Termi-
nal hook slightly curved, inner margin ciliate.

" Inner ramus curved, ovate, broad, pointing inward, with
mucronate apex, barely reaching to the end of the first seg-
ment of the outer ramus.

" First and second segments of the outer ramus of the
left foot ciliate within, the second one obovate, hirsute toward
the apex, and bearing two short spines one of which points
inward.

" Inner ramus one-segmented, slender, equal to the first
segment of the outer ramus."

"Length of female about 1.5 mm. ; of male 1.4 mm.

160 Illinois State Laboratory of Natural History.

"This species, so remarkable from the peculiarities pre-
sented by the last thoracic and the first abdominal segments,
was found by the Swedish naturalist, Trybom, at Multrooma
Falls, Oregon."

The above is the description as given by Dr. Lilljeborg
(de Guerne et Richard, '89b). It agrees with the specimens
sent me by himself, but I note a few additional details.

The abdomen of the female, seen from above, is asymmet-
rical, as is also the last thoracic segment. The first abdom-
inal segment is dilated anteriorly, and posteriorly is produced
on the right to form a blunt, almost semicircular, process.
Seen from the side this is fin-shaped, and both this process
and the one on the last thoracic segment are penetrated by
muscles. The furcal rami are hairy within.

In the male the peculiar form of the right inner ramus,
the extreme shortness of the left leg, and the very irregular
shape of its last segment are especially characteristic. The
spines on the first basal segment of each leg and the teeth
on the terminal segment of the right leg are also conspicuous
because of their great size.

The peculiarity of a dorsal process is found, to my knowl-
edge, in but two other species: D. sanguineus Forbes, and D.
signieauda Lilljeborg. In the small size of the inner ramus
of the right fifth foot of the male, D. trybomi approaches the
male of D. sanguineus Forbes, D. minutus Lillj., and D. lin-
toni Forbes.

De Guerne and Richard give Multrooma Falls as the
locality, which was probably intended for Multnomah Falls,
Oregon, although Prof. Lilljeborg in a personal letter also
gives the former spelling.

Diaptomus franciscanus Lilljeborg. (PI. XXX.,Fig.l-4.)

Diaptomus franciscanus, de Guerne et Richard, *89b, p. 45, PI. I.,

Fig. 12, 13, 34; PI. III., Fig. 23.
DiapUxmus franciscanus, Ilerriek and Turner, *95, p. 5S, PI. VIII.,

Fig. 12. 1G.

"Larger and more robust than Diaptomus tyrreli. Cepha-
lothorax widest in the middle, and the last two segments
confluent above. Lateral lobes of the last thoracic segment

North American Species of Diaptomus. 161

seen from above, short and obtuse posteriorly ; armed with
small spines. First abdominal segment (PL XXX., Fig. 1)
about equal to the rest of the abdomen, moderately dilated
anteriorly, rounded at the sides, and armed here with small
spines or mucros ; always destitute of all lateral processes.
An imperfect suture remains long after maturity in the pos-
terior part of this segment. Second segment of the abdomen
much shorter than the third, and also more slender and
easily pushed within the preceding joint.* Furcal rami short,
fully one and a half times longer than broad ; sparsely ciliate
within.

"First pair of antennae of female, reflexed, extend about
to the furca ; composed of 25 articles. Antepenultimate
article of the male prehensile antenna (PI. XXX., Fig. 2)
provided with an unguiform process, slightly surpassing the
end of the penultimate article.

"Outer ramus of the fifth pair of feet in the female (PL
XXX., Fig. 4) three-segmented, the third segment very small
but distinct, and bearing two spines. The unguiform process
of the second segment of this ramus rather arcuate and finely
ciliate within at the lower part, the last spine thicker than
the rest. Inner ramus simple and equal to the first segment
of the outer ramus, bearing two long equal spines at the
apex, of which the outer is ciliate within at the base.

"The right fifth foot of the male (PL XXX., Fig. 3) rather
robust. The second segment of the outer ramus almost rect-
angular and comparatively short ; the outer marginal spine
placed near the apex, and the inner margin armed with a mi-
nute spine. Terminal hook long, distinctly sigmoid or S-
shaped and tapering toward the apex. Inner ramus small
and barely reaching the middle of the second article of the
outer ramus ; either imperfectly two-segmented or one-
segmented and armed with an apical spine.

"The second segment of the outer ramus .of the left fifth
foot of the male lamelliform, almost triangular, and thinner
within. This segment on the thicker, outer, side bears a short

* The meaning of the original at this point is rather obscure. It reads: "Seg-
mentum 2-dum caudcE 3-tio multo brevius ejusque testa tenuior et facile adstrtn-
genda."

162 Illinois State Laboratory of Natural History.

spine in the middle, and ends in a short obtuse process, the
inner apical angle of which exhibits three small oblique in-
cisions. The inner margin is minutely ciliate. The inner
ramus is simple and slender, attenuate toward the apex, and
reaching about to the middle of the second segment of the
outer ramus.

"Length of female, 2.3 mm. ; of male, 2.0 mm.

"Found near San Francisco by G. Eisen.

"This Diaptomus approaches IX. longicornis var. similis
Herrick in the shape of the body and of the lateral lobes of
the last thoracic segment, but it differs greatly in respect to
the fifth pair of feet, especially in the male. It seems to be
common in the vicinity of San Francisco, hence the name,
franeiscanus."*

The female is conspicuous chiefly for the extremely long
spines with which the inner rami of the fifth pair of feet are
armed. These are about as long as the ramus itself and
hairy at the base. The thorax and abdomen are of ordinary
form. The furca are hairy within, and also, but more
sparsely, on the outer margin. In the male the outer margin
is not hairy.

The outer ramus of the left fifth foot of the male is termi-
nated by a peculiarly flattened segment (PI. XXX., Fig. 3).
In a male of this species sent me by Professor Lilljeborg,
both inner rami of the fifth pair of legs are two-segmented.

Diaptomus eiseni Lilljebokg.

Diaptomus eiseni, de Guerne et Richard, '89b, p. 44, PI. I., Fig. 19,

29, 33.f
Diaptomus eiseni, Herrick and Turner, '95, p. 58, PI. X., Fig. 11.

"Among the largest of the genus. Cephalothorax widest at
the posterior part of the head. The last two thoracic seg-
ments usually confluent above or indistinctly segmented, and
the lateral lobes of the last segment, seen from above, short

*Lilljeborg's description and remarks from de Guerne et Richard, '89b.

t Confusion maybe caused by a slight mistake which crept into de Guerne and
Richard's "Revision." In the index and under the species names. Fig. id. PI. I. is
given as the fifth foot of D- zerricornis and also of D- eiseni. The "explanation of
plates' however, gives Fig. 29, PI. I., as that of I). eiseni, which by comparison with
the description is found to be correct.

North American Species of Diaptomus. 163

in the female; upper posterior angle rather acute, lateral
angle very obtuse, the spines of both angles thick and short.
First abdominal segment slightly longer than the remainder of
the abdomen (setae excepted), produced anteriorly into a rather
large lateral process with spines pointing obliquely backward.
Second abdominal segment very short. -Furcal rami short ;
sparsely hairy ; about one and a half times as long as broad.

"First pair of antennae reach to the lateral processes of the
first abdominal segment; composed of 25 segments. Ante-
penultimate article of the prehensile antenna of the male
with a long curved and acuminate process almost surpassing
the end of the antenna.

"Outer ramus of the first pair of feet, especially in the
female, pectinately setose.

"Outer ramus of the fifth pair of feet in the female two-
segmented, the second segment with large unguiform process
within and heavily spined without. The inner ramus of this
foot rather long, clearly not reaching the end of the first seg-
ment of the outer ramus ; suture sharply indicated ; pro-
vided at the apex with two spine-like setae and within with
minute spines.

"Eight fifth foot of the male rather robust. Second basal
segment dilated within into a rugose lamella ; second segment
of the outer ramus with marginal spine placed near the apex.
Inner margin of terminal claw slightly sigmoid; from the
middle toward the apex first delicately pectinately spined,
and thence tuberculate. Inner ramus small and indistinctly
two-segmented, extending slightly beyond the middle of the
second segment of the outer ramus; armed at the apex with
a spine, and at the same place and within with thick cilia.

"Left foot of the fifth pair of the male much smaller than
the right. Second or last segment of the outer ramus of this
foot with the apex narrowed but obtuse, and within this an
acuminate spine ; an emarginate narrow and hairy lamina
on the inner margin. Inner ramus slender, rather long, and
notably surpassing the middle of the second segment of the
outer ramus ; indistinctly two-segmented, the apex similar
to that of the right inner ramus.

164 Illinois State Laboratory of Natural History.

"Length of female, 4 mm. ; of male, 3.5 mm.

"Found, near Fresno, Cal., by G. Eisen, the Swedish zoolo-
gist, member of the San Francisco Scientific Academy."

"This Diaptomus is dedicated to Mr. G. Eisen, who found
it in California with a great number of other Entomostraca.
It was given by him to the Zoological Museum of the Uni-
versity of Upsala. D. eiseni is very distinct from all the
American species described by Profs. Forbes and Herrick."*

The last thoracic segment of the female is strongly pro-
duced posteriorly and the first abdominal segment is moder-
ately dilated and armed on each side with a large spine.
This form may also be recognized on account of its great
size, being but little smaller than D. stagnalis or D. shoshone
Forbes. The fifth pair of legs are remarkable for the ex-
treme size of the inner of the two spines representing
the third segment of the outer ramus, which is made still
more striking by a row of strong teeth on each margin. The
second segment of the outer ramus is also armed with strong
teeth on the inner margin.

The fifth pair of legs of the male may be easily recognized
from the fact that at least an indication of a suture is found
on each inner ramus, making it indistinctly two-segmented.
The rugose lamella on the second basal segment of the right
fifth leg is also very characteristic.

Diaptomus signicauda Lilljeborg. (PI. XXIX., Fig. 3-6.)

Diaptomus signicauda, de Guerne et Richard, 'S9b, p. 55, PI. I., Fig.

15,10,31; PI. III., Fig. 22.
Diaptomus signicaudatus, Herrick and Turner, '95, p. 63, PI. VIII.,

Fig. 13; PI. IX., Fig. 10.

"This species is among the smaller species of this genus.
Form of the body very slender. Cephalothorax widest in front
of the middle, at the second segment. Last two segments of
the thorax (PI. XXIX., Fig. 6) confluent above, the last, seen
from above, with rather large and projecting lateral lobes,
posterior angles acute, with small spines. Fourth thoracic
segment, seen from the side, provided above with a small

*Lilljeborg's description and remarks from de Guerne et Richard. 'S9b.

North American Species of Diaptomus. 165

hump. First abdominal segment of the female very char-
acteristic of the species, giving to it its name. This seg-
ment is provided at the anterior part with short, mucronate
lateral processes, and at the posterior part on the right side
with a large process bent obliquely backward and moderately
acuminate. Besides this an indication of a suture is also
often present. The length of this segment, posterior process
excepted, is slightly less than the remainder of the abdomen.
Furcal rami hardly more than half as long as broad.

"First pair of antennae of the female always 25-segmented;
reflexed, slightly surpass the furcal rami, but do not reach
the end of the furcal setae. The antepenultimate article of
the prehensile antenna of the male (PI. XXIX., Fig. 4) armed
with a medium-sized hook-like process.

"Fifth pair of feet of female (PL XXIX., Fig. 5) very simi-
lar to the corresponding pair of I), siciloides. Outer ramus
two-segmented; unguiform process of the second segment
slightly curved, almost parallel with the first article ; very deli-
cately ciliate within, the last cilia thicker and spine-like.

"Inner ramus one-segmented, longer than the first seg-
ment of the outer ramus ; apex obliquely acuminate and
ciliate, and bearing two equal ciliate spines.

"The right fifth foot of the male (PI. XXIX., Fig. 3) rather
slender. First segment of the outer ramus dilated within
into a small hyaline lamina. The second segment as long as
the first article and the second basal segment together. The
marginal spine of the second segment is situated a little
below the middle. Terminal hook simply curved.

"Inner ramus rather broad, acuminate, and short, not
reaching to the end of the first segment of the outer ramus.

' The second segment of the outer ramus of the left foot
elliptical or oblong-ovate ; within and toward the apex very
delicately aculeate, and bearing two large spines, one of
which inclines inward.

" Inner ramus simple and slender, but long, and extending
beyond the middle of the second segment of the outer ramus.

"Length of female about 1.5 mm. ; of male, 1.3 mm.

166 Illinois State Laboratory of Natural History.

"Found in the Sierra Nevada Mountains, California, at a
height of from 8,000-10,000 feet above sea-level by G.
Eisen. Appears to be very common in small pools in this
locality.

" This Diaptomus is very distinct from all known species
on account of the peculiar form of the first abdominal seg-
ment. In this respect it approaches I), roubaui Richard, and
the genus Epischura Forbes. In the case of these Copepoda,
however, it is the male which is distinguished by the irregu-
larity of the abdomen. The name which I have given it
refers particularly to the shape of the female abdomen."*

There is nothing to add to the above description of this
species except that the furca are delicately hairy within, a fact
neither shown in the drawings nor mentioned in the original
description. The last thoracic segment of the female is
strongly produced, and the first abdominal segment greatly
dilated at its anterior part. The process on the first abdomi-
nal segment is even larger in some cases than represented in
the original drawings.

In the male also the last thoracic segment is produced, but
not so much as in the other sex. The fifth pair of legs are
very similar to those of D. sieiloides, from which they may be
distinguished by the shape of the right inner ramus and of
the hyaline lamina on the first segment of the outer ramus of
the right fifth leg. Both inner rami are delicately hairy, but
I fail to find the smooth, cushion-like process on the outer
margin and at the base of the left inner ramus which is fig-
ured in the original drawings but of which no mention is
made in the text.

The females of D. signicauda and D. trybomi both have a
"dorsal process," and in this respect approach D. sanguineus
Forbes.

Individuals of this species were kindly sent me by Dr.
Lilljeborg, but were unavoidably delayed until after this
description was completed. There was no time to rewrite it,
hence these remarks are in the form of addenda. The same
is true of trybomi, eiseni, and franciscanus.

*Lilljeborg's description and remarks from de Guerne et Richard, '89b.

North American Species of Diaptomus. 167

Diaptomus ashlandi Marsh. (PI. XXXII., Fig. 1-4.)

Diaptomus sicilis var. imperfectus, Forbes '90, p. 703.
Diaptonms ashlandi, Marsh, '93, p. 198, PI. III., Fig. 11-13.
Diaptomus ashlandi, Herrick and Turner, '95, p. 60, PI. VI., Fig. 4-6.
Diaptomus ashlandi, Marsh, '95, p. 7, PI. VII., Fig. 2.

A small, slender species, about the same width throughout.
Suture between head and thorax distinct. Last two thoracic
segments distinct, the last one strongly bifid and armed on
each side with a small blunt spine. Abdomen long and
narrow ; inclusive of the f urea, about half as long as the ceph-
alothorax. First abdominal segment as long as the remainder
of the abdomen exclusive of the furcalrami ; dilated laterally ;
with a small spine on each side (unarmed in the male). Second
and third segments subequal. Furcal rami barely twice as
long as wide ; hairy within.

Antennae 2 5 -segmented, reaching to the base of the furcal
rami or slightly beyond. Prehensile antenna (PI. XXXII.,
Fig. 4) moderately swollen; segments 19, 20, and 21, and
22 and 23, ankylosed ; process on the antepenultimate seg-
ment extending almost to the middle of the last segment, the
end knobbed and roughened or tuberculate at the inner
margin.

Fifth pair of legs of the male (PL XXXIL, Fig. 3) rather
slender ; left leg reaching about to the end of the first seg-
ment of the outer ramus of the right leg. On the anterior
surface of the first basal segment of the right leg is a large
tubercle bearing at the tip a small acute spine. Second
basal segment without special characteristics. First seg-
ment of the outer ramus subquadrate, slightly broader than
long ; inner apical angle somewhat produced, the process
ending in an acute point. Second segment about three times
as long as the first, with a sharp angle at end of proximal
third, from the point of which springs the lateral spine. This
is about half as long as the segment, with an angle near its
base. Terminal hook long and slender, rather more robust
than that of D. sicilis Forbes, but shaped very much like it;
minutely denticulate on the inner margin.

168 Illinois State Laboratory of Natural Histor/i.

Inner ramus of right fifth leg one-segmented, very narrow,
extending about half its length beyond the end of the first
segment of the outer ramus ; apex with an acute triangle,
hairy at the tip ; sides parallel.

First basal segment of the left fifth leg produced on the
anterior aspect, near the outer margin, into a long tubercle
ending in a minute, sharp spine ; second basal segment with
delicate hair near the outer distal angle. First segment of
the outer ramus subquadrate, shorter than the preceding,
slightly longer than broad ; second segment about as long as
the first and about twice as long as wide ; very similar to the
corresponding segment of D. sicilis Forbes.

Inner ramus of left fifth leg long and narrow, margins sin-
uously curved; extending about to the middle of the last
segment of the outer ramus ; delicately hairy at the tip.

Second basal segment of fifth leg of female (PI. XXXII.,
Fig. 1, 2) with the usual delicate hair at the outer margin.
First segment of the outer ramus about twice as long as
wide ; second segment somewhat longer than the first, taper-
ing to a rather sharp point and curving outward slightly,
delicately denticulate on the inner margin; third segment
wanting, represented by two spines, the outer about twice as
long as the inner.

Inner ramus one-segmented, extending slightly beyond
first segment of the outer ramus, hairy, ending in acute tri-
angular tip ; armed at the apex with two rather long sub-
equal spines which are sometimes hairy.

Length of female .97 mm. ; of male .9 mm.

A reference to the "Distribution of American Species" (see
page 183), will show the wide range of this form. In the
collections of the U. S. Fish Commission from Lake Samma-
mish, Lake Union, and Lake Washington, "Wash. ; Tsiltcoos
Lake, Tahkenitch Lake, and Klamath Lake, Oregon ; and
Lake Pend d' Oreille and Gamble's Lake, Idaho, T>. ashlandi
was found in immense numbers, being either the only centro-
pagid or occurring in connection with Epischura nevadensis
Lilljeborg.

North American Species of Diaptomus. 169

Diaptomus ashlandi is very similar to D. sicilis Forbes and
hardly to be distinguished from it but for a slight difference
in the last segment of the left fifth foot of the male and the
position of the marginal spine of the right fifth foot. In the
Laboratory collections from Yellowstone Park and the Flat-
head region of Montana forms occur which seem to be inter-
mediate between the two, and it was exceedingly difficult to
decide to which, if either, of the two species they belonged.
D. ashlandi seems to me, however, to be a good species, since
the form, as described by Marsh ('93 and '95) and as found
by myself in other collections, exhibits constant, though some-
what minute, differences from sicilis hard to describe, but at
once evident from the figures.

A very peculiar modification of the inner ramus of the fifth
foot of the female was noted in a specimen taken from an
alkaline pond in Yellowstone Park. In this individual one of
the feet (PI. XXXII., Fig. 1) was normal in every respect,
while the inner ramus of the other was armed on its outer
margin, at the end of the proximal third, with a sharp, smooth
spine about half as long as the ramus itself.

D. sicilis var. imperfect us Forbes ('90) is here made a syn-
onym of D. ashlandi, because unpublished Laboratory draw-
ings of that variety clearly show it to be such. Marsh's de-
scription must stand, since the description of imperfectus was
not complete enough to identify the form. This species was
also noticed by Dr. Forbes in the collections reported on in
'93, but was erroneously regarded by him as an immature
form of D. sicilis.

Diaptomus reighardi Marsh. (PI. XXVIII. , Fig. 1.)

Diaptomus reighardi, Marsh, '95, p. 9, PI. I., Fig. 1-4.

A medium-sized species ; body about the same width
throughout. Sutures between the first and second, and between
the last two, thoracic segments distinct ; last thoracic seg-
ment not produced, armed on each side with a very minute
spine. First abdominal segment almost as long as the rest
of the abdomen, dilated laterally, armed on each side with a

170 Illinois State Laboratory of Natural History.

minute spine ; second and third segments subequal ; furcal
rami slightly longer than the third segment, about twice as
long as wide ; and delicately hairy within. In the male the
second abdominal segment and the furcal rami are subequal,
and each is longer than any of the other segments. The
furcal rami are considerably longer than the preceding seg-
ment, fully twice as long as wide, and hairy within.

Antennae 2 5 -segmented, reaching well beyond the tips of
the furcal setae. Right male antenna not much swollen
anterior to the geniculate joint • antepenultimate segment
unarmed.

Left fifth leg of male (PL XXVIII., Fig. 1) short, extending
beyond the middle, but not reaching the end of the second
segment, of the outer ramus of the right leg. First basal
segment armed at the outer distal angle with a short, sharp
spine. Second basal segment about equal to the first, almost
as wide as long. First segment of the outer ramus irregularly
trapezoidal in form, about half as wide as the second basal
segment, and delicately hairy on the inner margin. Second
segment somewhat as in D. oregonensis Lilljeborg. It is pro-
duced into two digitiform processes, the outer of which is
more than twice as long as the inner and armed on the inner
margin at the tip, with a small cushion-like, delicately hairy
process. There is a distinct suture between the main part of
the second segment and the inner of the two processes, and the
process itself is minutely denticulate on the outer margin.

Inner ramus of left fifth leg one-segmented, reaching to the
base of the inner digitiform process ; outer margin hairy,
almost straight ; inner margin somewhat sinuously curved.

First basal segment of the right fifth foot of the male sub-
quadrate, slightly longer than wide, armed at the outer distal
angle with a short, sharp spine. Second segment about as
wide as the first and one and a half times as long ; provided
with the usual hair on the outer margin. First segment of the
outer ramus a little more than half as long as the second
basal segment and slightly longer than wide ; second segment
less than half as wide as long and more than twice as long as
the preceding segment. Marginal spine rather short, about

North American Species of Diaptomus. 171

as long as the segment is wide ; inserted near the beginning
of the distal third ; slightly curved and distinctly denticulate
on the inner margin. Terminal hook rather slender, a little
more than twice as long as the preceding segment ; not regu-
larly curved, but divided approximately into thirds by abrupt
angles, the upper one very sharp, below which on the inner
margin, the hook is delicately but distinctly denticulate.

Inner ramus of right fifth foot short, one-segmented, reach-
ing just to, or extending very slightly beyond, the end of the
first segment of the outer ramus ; apex bluntly triangular and
delicately hairy.

First segment of the outer ramus of the fifth leg of the
female subquadrate, about twice as long as wide ; second seg-
ment slightly shorter than the first, moderately curved, the
inner margin distinctly denticulate ; third segment wanting,
being represented by two spines ; the outer short and thick
and only about half as long as the inner.

Inner ramus of fifth leg of female, one-segmented, extending
slightly beyond the end of the first segment of the outer ramus ;
delicately hairy at the apex and on the distal fourth, and
armed in addition to this with two slender spines about as long
as the shorter of the two representing the third segment of
the outer ramus.

Length of female, 1.1395 mm.; of male, 1.0248 mm.

The above measurements are those of Professor Marsh.
The largest female I examined was 1.13 mm. in length, the
smallest, 1 mm. ; while the largest male I measured was 1
mm. in length, the smallest, .96 mm.

Prof. Marsh originally described this species, and I am
greatly indebted to him for the specimens from which the
above description was made. He found D. reighardi in only
three localities, all in Michigan ; North Lake, on Beaver
Island, Intermediate Lake, and Crooked Lake. I do not
know of its having been recorded from any other place.

At first sight D. reighardi, in respect to the fifth pair of
legs of the male, is very like D. oregonensis Lilljeborg, but
the details of structure are very different in the two, and there
can be no doubt as to the validity of the species.

172 Illinois State Laboratory of Natural History.

Diaptomus birgei Marsh.

Diaptomus birgei, Marsh,'94, p. 16, PI. I., Fig. 4-6.
Diaptomus birgei, Herrick and Turner, *95, p. 79, PI. XLVIL, Fig.
4-6.

" Of moderate size. The first segment of the cephalothorax
is nearly equal in length to the three following. The first
segment of the abdomen of the female is as long as the
remainder of the abdomen and the furca. It is much dilated
in front. The second segment is nearly twice as long as the
third, and about equal in length to the furca. The second
and third joints are very closely united.

"The antennse extend to the end of the furca. The right
antenna of the male is much swollen anterior to the geniculat-
ing joint; the antepenultimate joint is produced on its distal
end into a short, blunt process, which makes very nearly a
right angle with the longitudinal axis of the joint.

"The outer ramus of the fifth foot of the female is two-
jointed, the third joint being represented by two spines. The
inner ramus is one- jointed, hardly as long as the first joint
of the outer ramus, and armed at the tip with minute setae
and two rather long spines.

" The basal joint of the right fifth foot of the male is elon-
gated, trapezoidal in form, its greatest breadth being at its
distal extremity. The first joint of the outer ramus is broader
than long, armed on its inner margin with a broad, thin ex-
pansion of the integument. The second joint is elongate,
broader at base; the lateral spine is situated at about the
middle of its length, is long and stout, and armed on its inner
margin with fine serrulations. The terminal hook is slightly
angular, and armed with fine serrulations on its inner mar-
gin. The inner ramus is one-jointed, equaling in length the
first joint of the outer ramus.

" The left fifth foot of the male reaches slightly beyond the
first joint of the outer ramus of the right. The basal joint is
quadrangular, considerably shorter than the right basal joint.
The first joint of the outer ramus is about twice as long as
broad. The second joint is slightly longer than the first joint ;
it is expanded at base, where it is armed with fine hairs, and

North American Species of Diaptomus. 173

terminates in a finger-like process bearing a falciform spine.
The inner ramus extends to about one half the length of the
second joint.

"Length of female, 1.5 mm.; of male, 1.3 mm."*

Marsh states, in connection with the original description,
that the material in which this species was found — collected
by Professor Birge at New Lisbon, Wisconsin — contained only
a few individuals, and that his own search for it in other
Wisconsin localities had been unsuccessful. He says also
that the species resembles the European species D. gracilis
more closely than any other American form.

The description quoted above is the only literature on the
subject, and while a request for slides or specimens of the
species by Professor Marsh was kindly complied with in the
case of most of his species, to his own as well as my regret
he was unable to let me have either slides or specimens of D.
birgei.

Unfortunately, as Marsh says, but few specimens were found,
and further study of the species must consequently be deferred
until later collections shall afford an opportunity.

Diaptomus mississippiensis Marsh. (PI. XXXIII., Fig.
1-4.)

Diaptomus mississippiensis, Marsh, "94. p. 15, PJ. I., Fig. 1-3.
Diaptomus mississippiensis, Herrick and Turner, '95, p. 78, PI.
XLVIL, Fig. 1-3.

A medium-sized species. Body slender, widest about the
middle of the posterior third, the male a little more slender
than the female, and the widest part slightly farther forward.
Last two cephalothoraic segments indistinctly confluent ;
suture between the first two distinct. Last cephalothoracic
segment, seen from above, not produced, but bearing a
minute obtuse spine pointing backward ; seen from the side
it is broadly rounded, with the spine in the middle, giving it
the form of a brace ( — ■— ^). First abdominal segment about
as long as the remainder of the abdomen (PI. XXXIII. , Fig.
4), with a short obtuse spine opposite the anterior margin of

♦Description quoted from Marsh, "94.

174 Illinois State Laboratory of Xatural History.

the receptaculum seminis ; the second segment the shortest ;
third segment slightly longer than the second. In the male
(PI. XXXIII., Fig. 1) there is little difference in the length
of the abdominal segments. Furcal rami broad, but little
longer than the third abdominal segment; distinctly hairy
within. Furcal setae thick at the base, tapering gradually
toward the tip ; distinctly setose. The inner furcal seta is
smooth in both sexes.

Antennae 2 5 -segmented, reaching to or slightly beyond the
tips of the furcal setae. The right male antenna with the six
segments preceding the geniculation greatly swollen ; ante-
penultimate article unarmed; segments 19, 20, and 21, also
22 and 23 ankylosed.

Fifth pair of feet of the female (PL XXXIIL, Fig. 2) of
moderate size. First basal segment trapezoidal, the longer
base forming the inner margin. Second segment of the outer
ramus long, narrow, acuminate, shorter than the preceding
segment, perfectly smooth within. Third segment wanting ;
represented by two straight and pointed spines, an inner short
one and an outer one more than twice as long.

Inner ramus of fifth foot of female one- segmented, reach-
ing almost to the middle of the second segment of the outer
ramus; distinctly hairy on inner margin near the apex, where
it is armed with two spines, the inner one being fully one
third as long as the ramus itself.

First segment of outer ramus of right fifth foot of male
(PL XXXIIL, Fig. 3) subquadrate, slightly longer than broad,
the second segment nearly twice as long as the first, its upper
half about as wide as the first. A little below the middle of
this segment the inner margin is produced into a short spine-
like process, concave toward the apex of the segment. Be-
tween this and the apex the segment is produced into a
narrow, triangular hyaline lamina, tapering from the broad
upper part to the inner apical angle. Marginal spine long
and curved, concave toward the apex of the segment and
inserted very near the outer apical angle. Terminal hook
long and very slender, with two sharp angles dividing it
approximately into thirds ; upper third rather thick as

North American Species of Diaptomus. 175

compared with the remainder; lower two thirds very minutely
spinose ; tip sometimes slightly recurved.

Inner ramus of right fifth foot one-segmented, narrowing
but slightly toward the tip. It reaches almost to the middle
of the last segment of the outer ramus, but not to the hook-
like process. Apex rounded ; unarmed or very delicately
hairy.

Outer ramus of the left fifth foot two-segmented. First
segment irregularly trapezoidal ; small and inconspicuous,
with a delicately hairy cushion-like process on the inner mar-
gin. Last segment consisting of two digitiform processes,
forming a forcipate structure. Seen from behind, the upper
process is smooth, the base slightly swollen. It is a little longer
than the other and about one and a half times as long as the
preceding segment, tapering gradually from the thickened
part to an obtuse point. The lower process (seen from behind)
is about equally broad at the base and at the beginning of the
last third, whence it narrows quite suddenly to form an obtuse
point. It is provided within and at the apex with four or
five small teeth.

Inner ramus of left fifth foot paddle- shaped, considerably
broadest at the apex ; reaching almost to the tip of the outer
ramus ; either smooth or very delicately hairy.

Length of female, 1.2 mm. ; of male, 1.1 mm.

Most of the specimens examined were taken from Lake
Maitland, Florida, from material kindly loaned me by Mr.
Adolph Hempel.

The above was prepared as a description of a new species,
but when I saw Professor Marsh's slides there was no longer
any doubt as to the identity of mississippiensis and this Florida
form. Prof. Marsh ('94) figures the furca of the female as
perfectly smooth within, while in all of the specimens from
Florida, as well as in those which he kindly loaned me, they
are distinctly, though not heavily, setose within. The inner
rami of the fifth pair of feet in the male, however, differ con-
siderably— probably a varietal difference, since in a few of my
specimens they approached the form shown in his figures.
In the Florida specimens I fail to find the asymmetry in the

176 Illinois State Laboratory of Natural History.

abdominal spine mentioned by Marsh, but since the speci-
mens from the two localities differ in other respects it is not
unlikely that this difference also may exist.

Found by Professor Marsh in collections from small lakes
and ponds in Mississippi, and by the writer in material col-
lected from a number of Florida lakes in March, 1896, by
Mr. Adolph Hempel. Professor Marsh states that in collec-
tions made in Mississippi in January and February, 1893,
D. mississippiensis was the only Diaptomus found ; but in the
Florida collections this species occurred in connection with
D. albuquerquensis Herrick, the two being about equal in
numbers. In general appearance these two species are very
similar, but they are widely different in the details of their
structure.

Diaptomus tyrrelli Poppe.

Diaptomus tyrrelli, Poppe, '88, p. 159.

Diaptomus tyrrelli, de Guerne et Richard, '89b, p. 39, PI. I., Fig.

17,18; PI. IV., Fig. 26.
Diaptomus fresnanus, Lilljeborg, in litt*
Diaptomus tyrrelli, Herrick and Turner, '95, p. 76, PI. X., Fig. 9.

"Of medium size. Cephalothorax widest at the middle
and at the lateral lobes of the last segment. Last two tho-
racic segments confluent above, and the last, seen from above,
produced obliquely into large lateral processes, almost ovate,
acuminate posteriorly, with a rather large mucro. First
abdominal segment almost as long as the rest of the abdomen,
somewhat dilated anteriorly, and provided with long mucro-
nate lateral processes. Second and third abdominal segments
rather short, with a vestige of a transverse suture anteriorly.
Furcal rami short, sparsely hairy, and almost one and a half
times as long as broad.

"First pair of antennae in the female, reflexed, reach
almost to, sometimes to the end of, the furca ; composed of
twenty-five segments. Antepenultimate article of the pre-
hensile antenna of the male wholly unarmed, or minutely
and scarcely perceptibly armed.

* The description given herewith is Unit <>f D.fresnanus Lilljeborg, sent by hiin
to de Guerne and Richard, and published by them under the name of I), tyrrelli.

North American Species of Diaptomus. 177

" Outer ramus of the fifth pair of feet in the female Inarticu-
late ; unguiform process of the second segment almost parallel
to the first segment, slightly curved within and minutely ciliate
on the inner margin, the last cilia spine-like. Inner ramus
simple and slender, about equal to the first segment of the
outer ramus ; armed at the outer margin and near the apex
with two medium- sized spines ; apex obtuse and finely hairy.

"Eight fifth foot in the male slender and of medium size.
First segment of the outer ramus with a small hyaline lamella
near the inner apical angle. Second segment comparatively
small and strongly curved ; the outer marginal spine at about
the middle. Terminal hook slightly sigmoid; inner margin
smooth. Inner ramus minute and simple, not reaching the
end of the first segment of the outer ramus.

" Second segment of the outer ramus of the left foot of the
same pair almost triangular ; inner margin slightly sinuate
and ciliate and armed with two obtuse processes (one apical,
the other lateral). Inner ramus indistinctly two-segmented
extending about to the middle of the second segment of the
outer ramus ; minutely hairy within and at the apex.

"Length of female 1.9 mm.; of male 1.8 mm."*

" This Diaptomus is distinguished from all its related forms
by the large lateral lobes of the last thoracic segment. These
lobes, seen from above, are acuminate, but seen from the side,
the posterior extremity is obtuse and armed with two spines.

" The first abdominal segment is remarkable on account of
its long, strong, pointed processes.

" The female of this species slightly resembles 1). ambiguus
Lillj., from Behring Isle, but the lateral projections of the
first abdominal segment are wanting in the latter. ]>. tyrrelli
differs from most other American species in the absence of a
prolongation on the antepenultimate article of the male pre-
hensile antenna.

"The first specimens of this copepod were collected in
Summit Lake, in the Eocky Mountains, at a height of 5,300
feet, and sent to Herr S. A. Poppe by Mr. J. B. Tyrrell, of
Ottawa, Canada.

*Lilljeborg's description from de Ouerne et Richard, "89b.

178 Illinois State Laboratory of Natural History.

"The description given was sent to" us by Prof. Lilljeborg
as that of a new species described by him under the name of
D.fresnanus. It was established from specimens found by
G. Eisen at Centreville, near Fresno, Cal. J>. tyrrelli here
reaches a size somewhat greater than that which it has at
Summit Lake, where it is only 1.5 mm. long."*

Owing to the kindness of Herr Poppe I was enabled to ex-
amine specimens of l>. tyrrelli, but found nothing to add to
the above description. I failed to obtain specimens from Dr.
Lilljeborg, and so am unable to say whether or not there are
minor differences to be found in individuals from the two
localities in which they have hitherto been found.

Diaptomus clavipes n. sp. (PI. XXXIV., Fig. 1-3 ; PL
XXXV., Fig. 1, 2.)

Body of about the same width throughout, except at the
head and at the last thoracic segment, where it narrows
slightly. Last two thoracic segments confluent, the last one
with slightly rounded posterior angles, armed on each side
with a short blunt spine. In the male the body is less
strongly bifid than in the female, and the spines are smaller.
There is but slight difference in the length of the abdominal
segments (PI. XXXV., Fig. 2), the second segment being
longest and about equal to the furcal rami. The first seg-
ment is asymmetrical and armed on each side with a thick
blunt spine, the one on the right side being the more conspic-
uous ; in the male the segment is unarmed. Furcal rami hairy
within ; furcal seta- long, slender, and covered with delicate
hairs.

Antenna? 25-segmented, extending beyond the furcal setae.
Geniculate antenna of the male (PI. XXXIV., Fig. 2) greatly
swollen from the twelfth to the eighteenth segments inclusive.
The armature of the segments is as follows : 1 and 7 have a
sense-club and a long spine ; 2, two long spines, a sense-club,
and a sense-hair; 8, a sense-club and a long seta; 4 and
8, a long spine; 5, a sense-club and a short .-eta: 8, a
short and a long spine; 9, a short spine, a long seta, and a

*De Guerne et Richard, '89b.

North American Species of Diaptomus. 179

sense-club; 10 and 11, two long spines, one much thicker
than the other, and a process; 12, a long spine, a short
spine, and a sense-club; 13, a long spine and a process ; 14,
a long spine, a long seta, and a sense-club; 15, a process,
a long spine, a short seta, and a sense-club; 16, a process, a
long spine, a long seta, and a sense-club ; 17, a plate-like proc-
ess, a long and a short spine ; 18, a plate and a short spine ;
19, 20, and 21 (usually completely ankylosed but some-
times with sutures indistinctly visible), a very long spine, a
long seta, and a short cuticular process ; 22 and 23 (com-
pletely ankylosed), a narrow hyaline lamina (bisected by a
sense hair) and two seta?; 24, two setae; and 25, two long-
seta and two short ones, a sense hair, and a sense-club.

Fifth pair of feet in the male (PL XXXV., Fig. 1) charac-
teristic. First basal segment of the right leg produced at the
inner apical angle into a process (generally blunt but some-
times spine-like) having on the posterior surface a tubercle
bearing a short blunt spine. Second basal segment (PI.
XXXIV., Fig. 1) armed at the inner margin with two proc-
esses, the proximal one broad, prominent, concave toward
the apex of the segment ; the other, slightly above the middle
of the segment, a mere sharp triangular point. At the outer
apical angle is a slight indentation from which springs a del-
icate hair, and from the inner apical angle arises the inner
ramus. First segment of the outer ramus irregular, about
one and a half times as long as broad, with a small sharp tri-
angular-point on the inner margin at about the beginning of
the distal fifth. On this segment is a structure which is not, to
my knowledge, found in any other Diaptomus. This is a hook
arising from the middle of the posterior aspect, and reaching
to the end of the segment. It is sickle-shaped, perfectly
smooth, and although supplied with muscles does not seem to
be movable. Second segment subquadrate, about twice as long
as wide. The marginal spine is short, almost straight, about
a third the length of the segment, delicately serrate within. Ter-
minal hook very stout, as long as the two preceding segments,
tapering gradually, and slightly recurved at the tip ; armed for
the distal two thirds of the inner margin with strong teeth.

180 Illinois State Laboratory of Natural History.

Inner ramus of the right iifth foot short, about the same
breadth throughout, almost reaching the middle of the first
segment of the outer ramus ; armed at the tip with a number
of strong blunt spines.

Second basal segment of the left fifth leg subquadrate, the
inner margin distinctly tuberculate, the outer apical jingle
with a delicate hair. First segment of the outer ramus sub-
quadrate, about a fourth longer than broad ; provided at the
inner margin with a narrow hyaline lamina, produced at the
inner apical angle into a delicately hairy cushion-like process.
The second segment is narrow, about half as broad as the
preceding ; delicately hairy within, and produced at the inner
distal angle into a cushion-like process densely covered with
minute hairs. On the posterior side of this segment are two
processes : one a long straight spine, more than half as long
as the segment itself and armed at the inner margin with
very strong hairs or spinules, largest at the base and decreas-
ing in size toward the tip ; the other a short, thick, blunt
process, perfectly smooth, about a third the length of the
spine.

Inner ramus of left fifth leg very long and narrow, arcuate
(the concavity toward the outer ramus), about one eighth as
broad as long, reaching beyond the end of the first and almost
to the middle of the second segment of the outer ramus. It
is broadest at the base and at the apex, armed at the tip with
a number of strong blunt spinules, and tuberculate its entire
length.

Second basal segment of the fifth pair of feet in the female
(PI. XXXIV., Fig. 3) trapezoidal, with the longest base form-
ing the inner margin. From the outer margin springs the
usual delicate hair. The first segment of the outer ramus is
subquadrate, not quite twice as long as broad. Second seg-
ment subcorneal, almost* straight, a little shorter than the
preceding segment ; the third segment wanting, represented
by two sharp slender spines, the outer more than twice as
long as the inner.

Inner ramus of fifth foot of female, one-segmented, longer
than the first segment of the outer ramus and of uniform

North American Species of Diaptomus. 181

width ; delicately hairy hoth within and without ; apex
bluntly rounded and armed with two spines, the inner long,
sharp, sinuously curved, the outer also sharply pointed hut
oiily ahout half as long as the inner.

Length of female, 1.37 mm. ; of male, 1.28-1.68 mm.

Found (not very abundantly) in material from West Oko-
boji Lake, Iowa, very kindly loaned me by Prof. L. S. Boss,
of Drake University, Des Moines, Iowa.

This species is very similar to Dr. Forbes's D. piscina and
D. leptepus, but the details of structure will serve at once to
distinguish it from them. The hook on the first segment of
the right fifth foot of the male is very characteristic, as are
also the processes on the inner margin of the second basal
segment of the same leg. 1>. clavipes offers such a mass of
peculiar details that it is distinguished with ease from all
other species heretofore described.

The name clavipes was chosen because of the club-like
inner rami of the fifth pair of legs of the male, the inner ramus
of the left leg especially resembling an Indian war- club.

A very curious fact in regard to the distribution of this
species was noted. East and West Okoboji lakes are united
by a very deep, somewhat narrowed channel, but are so nearly
one lake that no account of the division is taken by Rand &
McNally in their atlas. Although there is nothing whatever
to hinder free migration from one part of the lake to the
other, not an individual was found in material from E.
Okoboji, taken the same day and under the same circum-
stances as that from W. Okoboji in which the specimens
were found.

SPECIES INSUFFICIENTLY DESCRIBED.

Diaptomus caroli Heerick.

Diaptomus caroli, Ilerriek and Turner, '95, p. 69.

This species name occurs once in the description of I), sici-
loides (Herrick and Turner '95), but although I have searched
diligently in Herrick's writings for an original description or
even a previous reference to this species, I have been unable

182 Illinois State Laboratory of Natural History.

to find a word in addition to the following. Speaking of D.
siciloides, he says: "This species approaches J>. sicilis
Forbes and I). caroli Herrick very closely, and is said also to
resemble D. gracilis Sars. From caroli it may be at once dis-
tinguished by reason of the fact that the third joint of the
outer ramus of the fifth foot of the female is obsolescent."
The " D. caroli Herrick" would lead one to suppose that it
had been described before ; but, although this work contains
the names and short descriptions of all the other species, 1).
caroli is not among them. I doubt, therefore, whether I am
justified in putting it even under the head of "insufficiently
described" species.

Diaptomus longicornis var. similis Herrick.

Diaptomus longicornis var. similis, Herrick, 1884. p. 141, PL Q, Fig.

5-7.
Diaptomus similis. Herrick and Turner, '95, p. 58.

Something has already been said in regard to this doubtful
species under the head of D. lejptopus. First mentioned in
Herrick's "Final Keport," as one of two varieties, — the other
being the true leptopus as acknowledged by him ('95a), — it
is not mentioned again except in the description of D.francis-
canus, where he says "The form of the fifth feet chiefly sepa-
rates this species from Diaptomus similis Herrick." This
species cannot stand until a more complete description is
written.

DISTRIBUTION OF THE AMERICAN SPECIES OF DIAPTOMUS.

I), sicilis Forbes is one of the most common species in the
Great Lakes, and has been found in Wisconsin, Michigan,
Minnesota, and Yellowstone Park. In Illinois it is recorded
from Cedar Lake and Fox Lake.

D. piscinae Forbes has been recorded only from Yellowstone
Park, and I now add Portage Slough, Manitoba, Can.

D. lintoni Forbes has been found only in Yellowstone
Park.

I), leptopus Forbes is found in Massachusetts, Wisconsin,
Minnesota, and Illinois.

North American Species of Diaptomus. 183

D. sanguineus Forbes is very common throughout central
and southern Illinois, and has been recorded from New York,
Wisconsin, -Minnesota, and Alabama.

1>. stagnalis Forbes is also a common species, and is re-
corded from Minnesota, Illinois, Ohio, Kentucky, and Ala-
bama.

I), shoshone Forbes has never been found outside of Yellow-
stone Park.

D. pallidus Herrick is an exceedingly common species in
central Illinois and has been recorded from Ohio, Wisconsin,
and Minnesota.

1>. albuquerquensis Herrick was first described from Albu-
querque, N. M., and is also found in Florida.

I), novamexicanus Herrick has only been recorded from
Albuquerque, N. M.

I), oregonensis Lilljeborg is a very common species in Illi-
nois, occurring generally with 1>. siciloides Lillj. and 1). palli-
dus Herrick. It is also common in Wisconsin and is found
in Michigan, Minnesota, and Oregon.

I). siciloides Lilljeborg is found in immense numbers at
Havana, 111. I have found it also in Iowa and Indiana col-
lections, and it was originally described from L. Tulare,
Fresno, Cal.

1>. mi tint its Lilljeborg is probably the common species in
the northern tier of states. It has been found in Yellowstone
Park, in the Great Lakes, and in Wisconsin, Michigan,
Newfoundland, Greenland, and Iceland.

D. franciscanus Lilljeborg has been found only by G.
Eisen, near San Francisco, Cal.

/>. elseni Lilljeborg is also a California species.

1). signicauda Lillj., one of the most peculiar of American
species, is recorded only from the Sierra Nevadas.

J>. trybomi Lilljeborg is recorded only from Multnomah
Falls, Oregon.

7). ashlandi Marsh seems to be the most widely distributed
of American forms, having been found in the Great Lakes,
in Indiana, Michigan, Wisconsin, Oregon, Idaho, Washing-
ton, and in Yellowstone Park.

184 Illinois State Laboratory of Natural History.

D. reighardi Marsh has been recorded only from New
Lisbon, Wisconsin.

D. mississippiensis Marsh is common in Mississippi, and
has been found in Florida in connection withD. albuquerquen-
sis Herrick.

D. tyrrelli Poppewas described by the author of the species
from Summit Lake, and by Lilljeborg, under the name D.
fresnanus, from Fresno, near Centreville, Cal.

I), clavipes n. sp. is described in this paper from West
Okoboji Lake, Iowa.

North American Species of Diaptomus. 185

GENEKAL BIBLIOGRAPHY* OF THE GENERA DIAP-
TOMUS, EPISCHURA, LIMNOCALANUS,
AND OSPHRANTICUM.

This bibliographical list has been prepared principally in further-
ance of Dr. SehmeiTs purpose to compile a complete bibliography of
the Copepoda of the world. To this end the list published by him in
his Monograph (Schmeil, '96) has been critically reviewed and in some
instances corrected, and a number of additions have been made. New
species described since the publication of de Guerne and Richard's
Revision ('89b) are noted in connection with the articles containing the
original descriptions.

All articles except those marked with an asterisk are in the library
of the Illinois State Laboratory of Natural History or in that of the
University of Illinois.

Apstein, C.
'92. (See Article II.)

'96. Das Siisswasserplankton. Methode und Resultate der quantita-
tiven Untersuchung. 201 pp.. 113 Abbild., 5 Tab. Kiel u. Leipzig.
Review, Zool. Centralbl., III. Jahrg., No. 22, pp. 764-769.

Aurivillius, C. W. S., u. Cleve, P T.
'96. DaS Plankton des Baltischen Meeres. Bihang till K. Svenska
Vet.-Akad. Handl.. Bd. XXL, Afd. IV., No. 8, pp. 1-83, Taf. L, II.;
Abstract, Zool. Centralbl., IV. Jahrg., 1897, No. 16, pp. 546-550.

Baird, W.
'50. (See Article II.)

Barrois, Th.
'91. Sur trois Diaptomus nouveaux des environs du Caire. Rev.

Biol, du Nord de la France, T. III., Nos. 6, 7, 8.
*'95. Contribution a l'etude de quelques lacs de Syrie. Rev. Biol.

du Nord de la France, T. VI., No. 6, pp. 224-240; Abstract, Biol.

Centralbl., XV. Bd., Nr. 24, pp. 869-S73.
*'96. Recherches sur la faune des eaux douces des Agores. Mem.

Soc. sci., agr., arts, Lille, Ser. V., Fasc. VI. 172 pp., 3 cartes; Abstract,

Zool. Centralbl., III. Jahrg., No. 18, pp. 609-611.

Birge, E. A.
'95. On the Vertical Distribution of the Pelagic Crustacea of Lake
Mendota, Wis., during July, 1894. Biol. Centralbl., XV. Bd., Nr. 9,
pp. 353-355.

*As the bibliographical list published in connection with the preceding paper,
Article II. of this series, contains a large number of titles identical with those of this
bibliography, these duplicate titles are not reprinted here, but reference is made,
under the author's name and the year of publication, to the bibliographical list of the
preceding article.— S. A. Forbes.

186 Illinois State Laboratory of Natural History.

'95a. Plankton Studies on Lake Mendota. I. The Vertical Distri-
bution of the Pelagic Crustacea during July, 1894. Trans. Wis.
Acad. Sci.. Arts, and Letters, Vol. X., pp. 421-184, Pis. VII.-X.

'95b. Turkey Lake as a Unit of Environment, and the Variation of
its Inhabitants: Cladocera.f Proc. Ind. Acad. Sci., 1895, No. 5.
p. 245.

'97. The Vertical Distribution of the Limnetic Crustacea of Lake
Mendota. Biol. Centralbl., XVII. Bd., Xr. 10, pp. 371-375.

Blanchard, R.
'90. Sur une matiere colorante des Diaptomus. analogue a la carotine
des vegetaux. Compt. Rend, de l'Acad. des Sci., Paris, T. CX., pp.
292-294.

'90a. Sur une carotine d'origine animale, constituant le pigment
rouge des Diaptomus. Mem. de la Soc. zool. de France, T. III.,
p. 113.

Blanchard, R., et Richard, J.
'90. (See Article II.)
'91. (See Article II.)

'97. Sur la faune des lacs feleves des Hautes-Alpes. Mem. de la Soc.
zool. de France, T. X., pp. 43-61.

Brady, G. S.
'68. (See Article II.)
'78'80. (See Article II.)

'86. Xotes on Fresh-water Entomostraca from South Australia.
Proc. Zool. Soc. London, 1886, pp. S2-84. 3 Pis.

'86a. Xotes on Entomostraca collected by Mr. A. Haley in Ceylon
Journ. Linn Soc. London, Zool., Vol. XIX., pp. 293-317, PI.
XXXVIL, Fig. 21-26.

'91. (See Article II.)

Buchholz, R.
*'74. Crustaceen. Die zweite deutsche Xordpolfahrt in den Jahren
1869 u. 1870, Bd. II., pp. 262-398. 15 Pis.

Bundy, F. W.
'82. A List of the Crustacea of Wisconsin. With Xotes on some
*Sew or Little-known Species. Trans. Wis. Acad. Sci., Arts, and
Letters, 1877-S1, Vol. V., pp. 176-184.

Cajander, A. H.
'69. Bidrag till kannedom om sydvestra Finlands Krustaceer. Xot.
Sallsk. pro Fauna et Flora Fennica Forh., Heft X., pp. 373-376.

tKeference to Diaptomus and to Epischura lacustris.

North American Species of DiaptOmus. 187

Chambers, V. T.
'81. Two New Species of Entomostraea. Journ. Cincinnati Soc. Nat.
Hist., Vol. IV., pp. 47, 48. 2 Pis.

Chyzer, C.
'58. Uber die Crustaeeenfauna Ungarns. Verb., d. K.-K. zool.-bot.
Gesellsh. Wieu, Bel. VIII., p. 505.

Claus, C.
'58. (See Article II.)
'63. (See Article II.)
'76. (See Article II.)

*'77. Die Schalendriise der Copepoden. Sitzungsber. Akad. Wien,
Math. Nat. CI., LXXIV. Bd.. I. Abtb., pp. 717-721. 1 PI.

'88. Uber den Organistnus der Nebaliden und die systeinatische
Stellung der Leptostraken.f Arb. zool. Inst. Univ. Wien, VIII. Bd.,
pp. 1-148. Taf. I.-NV.

'93. (See Article II.)

'93a. (See Article II., '93b.)

'93b. (See Article II., '93c.)

'95. Uber die Wiederbelebung im Schlammeeingetrockneter Copep-
oden und Copepoden-Eier. Zugleich ein Beitrag zur Kenntniss von
Microcyclnps diaphanus (Fiscb.) = minutus (Cls.). Arb. Zool. Inst.
Univ. Wien, T. XI., 1 Heft, pp. 1-11, Taf. I., II.

'95a. Uber die Maxillarfiisse der Copepoden und die morphologi-
sche Deutung der Cirripedien-Gliedmassen. Arb. Zool. Inst. Univ.
Wien, T. XI., 1 Heft, pp. 49-63, Taf. VIII.

Cragin, F. W.
'83. (See Article II.)

Daday, E. v.

'84. Catalogus Crnstaceorum faunae Transylvania?, (e collectione
Musei transylvanici, collegitet determinavit). [Latin title of Hun-
garian article.] Orv. Termeszettud. Ertesito, Vol. IX., pp. 1G1-187

'85. (See Article II., 85a.)

'85a. Ujallatfajok Budapest edesvizi faunajabol. Term, fiiz., Vol.
IX., p. 127, PI. XI.

'85b. (See Article II., '85.)

*'90. Conspectus Diaptomorum fauna1 hungariere. Math, naturw.

Berichte a. Ungarn, Bd. XIII., pp. 114-143, Pis. IV.-V1.
*'90a. Ubersicht der Diaptoraus-Arten Ungarns. Math, naturw.

Berichte a. Ungarn, Bd. XIV., pp. 177-1SO.

tFutterung mit Farbstoffen an Diaptomus, pp. 99, 101.

188 Illinois State Laboratory of Natwral History.

'91. Adatok Magyarorszag edesvizi mikroskopos faunajanak isme-
retehez. Term fiiz., Vol. XIV., pp. 16-31, PI. I. Also in German:
Beitriige zur Mikr.opisehen Siisswasserfauna Ungarns, Ibid., pp. 107-
123.

'91a. Az eddig pontosan ismert Diaptomus-fajok meghatarozo tab-
lazata. Tabella synoptica specierum generis Diaptomus hucusque
recte cognitarum. [Article in Hungarian and Latin.] Term, fiiz.,
Vol. XIV, pp. 32-51.

'97. Beitriige zur Kenntniss der Miorofauna der Tatra-Seen. Term,
fiiz., Vol. XX., pp. 149-196.

Dahl, Fr.
*'94. Die Copepodenfauna des unteren Amazonas. Ber. d. naturf.
Gesellseh. zu Freiburg, i. B., Bd. VIII., pp. 10-23, Taf. I., Fig. 1-4.
Diaptomus kensenii n. sp.
'95. Neueres iiber Morphologie unci Ethologie der Copepoden. Zool.
Centralbl., II. Jahrg., No. 22 u. 23, pp. 673-678.

De Kay, J. E.

'44. Crustacea. Xat. Hist. New York, Zoology, Part VI., pp. 1-65.
Pis. I.-XIII.

Eusebio, J. B.
'88. Becbercbes sur la faune des eaux du Plateau Central. La Faune
pelagique des lacs d'Auvergne. Kev. d'Auvergne (Clermont-Fer-
rand) [Fide Scbmeil]. Separate, pp. 1-29, PI. I., Fig. 10.

Fellows, C. S.
'87. A description of Ergasilus cJiautauquaensis, a New Species of
Copepoda, and a List of other Entomostraca found at Lake Chau-
tauqua in August, 1886. Proc. Am. Soc. Microscopists, 1887. 4 pp.,
1 PI.

Ferussac, D. de
*'06. Memoire sur deux nouvelles especes d'Entomostraces et d'Hy-
drachnes (Cyclops miilleri[_= Diaptomus ccsruleus] and Cypris renifor-
mis). Ann. Mus. hist, nat., T. VII., p. 213.

Fischer, S.
*'51. Beitriige zur Kenntniss der in der Umgegeud von St. Peters-
burg sich fiudenden Cyclopiden. Bull. Soc. Imp. des Naturalistes
de Moscou, T. XXIV., Pt. II., pp. 409-438, Pis. IX., X.

*'53. Beitriige zur Kenntniss der in der Umgegend von St. Petersburg
sich findenden Cyclopiden. Fortzetzung. Bull. Soc. Imp. des Xat-
uralistes de Moscou, T. XXVI., Pt. II., No. 1, pp. 74-100, Pis.
II., III.

Forbes, S. A.
'76. (See Article II.)

Noiilt American Species of Diaptomus. 189

'78. The Food of Illinois Fishes. Bull. 111. State Lab. Xat. Hist,
Vol. I., No. 1, pp. 71-89.

'78a. On the Crustacea eaten by Fishes. Bull. 111. State Lab. Nat.

Hist, Vol. I., Xo. 2, p. 87.
'80. The Food of Fishes. Bull. 111. State Lab. Nat. Hist., Vol, I.,

No. 3. pp. 18-65; Rep. 111. State Fish Comm., 18S4. pp. 90-127.

'80a. On the Food of Young Fishes. Bull. 111. State Lab. Nat. Hist.,
Vol. I., No. 3, pp. 60-79.

'82. On the First Food of the Young White Fish. American Field,
Mar. 11,1882.

'82a. (See Article II.)

'82b. (See Article II., '82.)

'83. The Food of the Smaller Fresh-water Fishes. Bull. 111. State Lab.
Nat. Hist., Vol. I., No. 6, pp. G5-95; Rep. Bd. 111. State Fish. Comm.,
1886, pp. 114-138.

'83a. The First Food of the Common AVhite-Fish {Coregonus clupei-
formis Mitch.). Bull. 111. State Lab. Nat. Hist,, Vol. I., No. 6, pp.
95-109; Rep. Bd. 111. State Fish Comm., 1886, pp. 139-149.

'87. (See Article II.)

'90. (See Article II. '90a.)

'90a. (See Article II. '90.)

'93. (See Article II.)

Forel, A. F.
'78. Faunistische Studien in den Siisswasserseen der Schweiz. Zeit-
schr. f. wiss. Zool., Bd. XXX., Suppl., pp. 383-391.

'82. Die pelagische Fauna der Siisswasserseen. Biol. Centralbl., II.
Bd., Nr. 10, pp. 299-305: Translation, Ann. Mag. Nat. Hist., Vol. X.,
p. 320.

France, R. H.
'94. Zur Biologie des Planktons. Vorliiufige Mitteilung. Biol. Cen-
tralbl., XIV. Bd., Nr. 2, pp. 33-38.

Fric (Fritsch), A.
'72. (See Article II.)

'95. Uber Parasiten bei Crustaceen und Riiderthieren der siissen Ge-
wiisser. Bull. Internat'n'l d"Acad. des Sci.de TEmpereur Frangois
Joseph I , Classe des Sci. Math, et Nat., pp. 1-7.

'95a. (See Article II. "95.)

Fritsch. (Fric ), A., u. Vavra, V.
'92. (See Article II.)
'94. (See Article II.)

190 Illinois State Laboratory of Natural History.

Fric, J. A.
'82. (See Article II.)

Gadeau de Kerville, H.
'88. Les Crustaces de la Normandie: espeees fluviales, stagnates efc
terrestres; premiere liste. Bull, de la Soc. des Amis des Sci. nat. de
Rouen, 1888, lre Sem., pp. 133-158.

Garbini, A.
'93. Prirai Materiali per una Monografia Limnologica del Lago di

Garda. III. Limnofauna. Estr. dal Vol. LXIX., Ser. III., dell'

Aeead. Agric, Arti, e Comm. di Verona, pp. 28, 37, 49.
'94. (See Article II.)
'95. Fauna Limnetica e Profonda del Benaeo. Boll. Mus. di Zool.

ed Anat. eomp. della Univ. di Torino, Vol. X., Xo. 198, pp. 2, 4, 5.
'95a. Appunti di Careinologia Veronese. I. Elenco dei Crostacei

veronesi. Estr. dal Vol. LXXI., Ser. III., Fasc. I., dell'Accad. di

Verona, p. 3.
'95b. Appunti di Careinologia Veronese. II. Considerazione ecolog-

iche e corologiehe. Estr. dal Vol. LXXI., Ser. III., Fasc. 1, dell'

Accad. di Verona, pp. 9, 14.
'95c. Distribuzione e Intensita della Fauna atesina. Estr. dal Vol.

LXXI., Ser. III., Fasc. II., dell' Acead. di Verona, p. 10.

Gerst acker, A.

'54. Bericht iiber die Leistungen in der Xaturgeschichte der Crusta-
ceen, Araehniden, und Myriapoden wiihrend des Jahres 1852 und
1853. Arch. f. Xaturgesch., XX. Jahrg., Bd. 2, pp. 72-108.

'63. Copepoda. Handbuch der Zoologie, pp. 402, 403. Leipzig.

'66-'79. Copepoda. Bronn's Klassen und Ordnungen des Thier-
reichs, V. Bd., I. Abtheil., pp. 590-806.

Giesbrecht, W.

'81. Vorlauflge Mitteilung aus einer Arbeit iiber die freilebenden
Copepoden des Kieler Hafens. Zool. Anz., XIV. Jahrg., No. 83, pp.
254-258.

'82. Die freilebenden Copepoden der Kieler Fohrde. IV. Ber. d.
Xotnm. z. w. Unters. d. deutsch. Meerein Kiel, pp. S7-168, Taf. I-X 1 1 .

'92. Sj'stematik und Faunistik der pelagisehen Copepoden des Golfs
von Xeapel und der angrenzenden Meeres-abschnitte. XIX. Mono-
graph, der Fauna und Flora des Golfs von Xeapel. S31 pp., 54 Pis.
Berlin.

'93. Mitteihingen iiber Copepoden. G. Zur Morphologie der Maxil-
lipeden. Mitteilungen a. d. zool. Stat, zu Xeapel, Bd. XL, Heft
I., pp. 83-102.

North American Species of Diaptomus. 191

'95. Mitteilungen iiber Copepoden. 7. Zur Morphologie des weib-
lichen Abdomens. Mitteilungen a. d. zool. Stat, zu Xeapel, Bd.
XL, Heft IV., pp. 031-648.

Gissler, C. F.

'81. Variations in a Copepod Crustacean. Am. Nat., Vol. XV., pp.

6S9-698.

'81a. Note regarding Change of Color in Diaptomus sanguinexis.
Am. Nat., Vol. XV., p. 7-12.

Grobben, C.
'80. Die Antennendriise der Crustaceen. Arb. Zool. Inst. Univ.
Wien, Bd. III., pp. 93-110, Taf. IX.

'92. Zur Kenntniss des Stammbaumes und des Systems der Crusta-
ceen. Sitzungsber. der K. Akad. der Wissensch. in Wien, Math-
naturw. Classe, Bd. CI., Abt. I., Jan., 1892, pp. 1-38.

Gruber, Aug.
'78. fiber Bildung und Wirkung der Spermatopboren bei Diaptomus
gracilis und Heterocope robusta. Dissertation. Promotionsschrift
zur Erlangung der Doktorwiirde. der philosoph. Facult. der Univ.
Leipzig vorgelegt. 34 pp., 2 Pis. Leipzig.

'78a. Die Bildung der Eiersackchen bei den Copepoden. Zool. Anz.,
I. Jahrg., No. 11, p. 247.

Guerne, J. de
'86. Description du Centropages grimaldii, Copepode nouveau du
golfe de Finlande. Bull, de la Soc. zool. de France, T. XL, pp.

276-2S5.

'87. Sur les genres Ectinosoma Boeck et Podon Lilljeborg. a propos
de deux Entomostraces (Ectinosoma atlanticum G. S. Brady et Kob-
ertson, et Podon minutus G. O. Sars) trouves a la Corogne dans
Testomac des sardines.f Bull.de la Soc. zool. de France, T. XII.,
p. 29.

Guerne, Jul. de, et Richard, J.
'88. Sur la distribution geographique du genre Diaptomus. Compt.

rend, de l'Acad. des Sci., 2 juillet, 1888. 3 pp.
'88a. Diagnoses de deux Diaptomus nouveaux d'Algerie (D. blan-

cJiardi et D. lilljehorgi). Bull, de la Soc.zool.de France, T. XIII. ,

pp. 160-162.

'89. (See Article II., '89a.)
'89a. (See Article II., '89.)

'89b. Eevision des Calanides d'eau douce. Mem. de la Soc. zool. de
France. T. II., pp. 53-181, Pis. I.-IV. and 60 fig. in text.

tReference to Limnocalanus grimaldii.

192 Illinois State Laboratory of Natural History.

'90. La distribution geographique des Calanides d'eau douce. Asso-
ciation franeaise pour 1' a van cement des sciences fusionee avec
1' Assoc, scient. de France, Congres de Paris. Seance du 14 aoiit.1889.
5 pp., 1 PL

'90a. Diagnose d'un Diaptomus nouveau du Congo (2>. loveni). Bull,
de la Soc. zool. de France, T. XV., pp. 177. 178.

'90b. Description du Diaptomus alluaudi n. sp., recueilli par M.
Alluaud dans un reservoir d'eau douce a Lanzarotte (Canaries).
Bull, de la Soc. zool. de France, T. XV., pp. 198-200.

'90c. On the Fresh-Water Fauna of Iceland. Ann. and Mag. Xat.
Hist., Series VI.. Vol. X., pp. 340-342.

'91. (See Article II.)

'91a. Synonymie et distribution geographique de Diaptomus alluaudi.
Bull, de la Soc. zool. de France, T. XVI., pp. 213-217.

'91b. (See Article II., '91a.)

'91c. Entoinostraefes recueillis par M. Charles Raboten Russie et en
Siberie (Gouvernements de Kasau, de Perm, de Vologda, et de
Tobolsk). Bull, de la Soc. zool. de France, T. XVI., pp. 232-236.

'92. Sur.la faune des eaux donees de l'Islande. Compt. rend, de
PAcad. des Sci., T. CXIV., pp. 310-313.

'92a. (See Article II.)

'92b. Documents nouveaux sur la distribution geographique des
Calanides d"eau douce. Assoc, franc, pour l'avanc. des Sci.. Con-
gres de Marseille, 1S91, T. XX.. Plate V. 5 pp. Paris.

'92c. (See Article II., '92b.)

'93. (See Article II.)

*'94. Diaptomus chevreuxi, Copepode nouveau d'Algerie. Bull, de la

Soc. zool de France, T. XIX., p. 176.
'96. Premiere liste des Copepodes et Cladoeeres d'eau douce du

Portugal. Bull, de la Soc. zool. de France, T. XXI., pp. 157-159.
'96a. D. bland, Copepode nouveau recueilli par M. Edouard Blanc a

Boukhara (Turkestan). Bull, de la Soc. zool. de France. T. XXL.

pp. 53-56. 5 Fig.

Hacker, F.
*'95. Die Vorstadien der Eireifung. Zusammenfassende Unter-
suchungen tiber die Bildung der Vierergruppen und das Verhalten
der kernbliischennucleolen. Arch. f. mikr. Anat., Bd. 45, pp. 200-
273; Abstract, Zool. CentralbL, 11. Jahrg.. Xr. 18, pp. 551-553.

Hansen, H. J.
'93. Zur Morphologic der Cliedmassen und Mundteile bei ( 'rustaeeen
und Insekten. Zool. Anz., XVI. Jahrg., Nos. 420 u. 421, pp. 193-19S,
201-212.

North American Species of Diaptomus. 193

Hartog, M. M.
'80. On the Anal Respiration of the Copepoda. Quart. Journ. Micros.

Sci. London, Vol. XX., pp. 24-1-245: Proc. Manchester Lit. and

Philos. Soc, Vol. XIX., pp. 61, G2.
182. Del' oeil impair des Crustaces. Compt. rend. Acad. Paris, T.

XC1V., pp. 1430-1432; Ann. Mag. Nat. Hist,, Vol. X., pp. 71,72;

Archiv Zool. Experim., Vol. X., pp. 7, 8.
'88. (See Article II.)

Hartwig, W.
'93. (See Article II.)
'94. (See Article II.)

'97. Znr Verbreitung der uiederen Crustaceen der Provinz Bran-
denburg. Forschungsber. a. d. Biol. Stat, zu Plon, Theil V., pp.
115-149. Stuttgart.

Heller, C.

'71. (See Article II.)

Herrick, C. L.
'77. A Xew Cyclops.f Geol. and Xat. Hist, Surv. of Minn. 5th Ann.
Rep., pp. 238-239. 2 Figs.

'79. (See Article II.)

'79a. Fresh-water Entomostraca. Am. Xat.. Vol. XIII., pp. 620-629.
4 Pis.

'82. (See Article IL,'82a.)
'83. (See Article II.)
'83a. (See Article II.)
'84. (See Article II.)
'87. (See Article II.)

'95. Micro-Crustacea from Xew Mexico. Zool. Anz., XVIII. Jahrg.,
Nr. 467, pp. 40-47. 2 Taf.

D. albuquerquensis and D. novamezicanus.

Herrick, C. L., and Turner, C. H.
'95. (See Article II.)

Hoek, P. P. C.

'76. (See Article II.)

*'77-'78. Zur Entwickelungsoeschichte der Entomostraken. II. Zur
Embryologie der freilebenden Copepoden. Xiederl. Arch. f. Zool.
Bd. IV.. pp. 55-74. Taf. V.-VI.

'78. (See Article 11.)

Imhof, O. E.
'83. (See Article II.)

fDiaptouius sp. V

194 Illinois State Laboratory of Natural History.

'84. Resultate meiner Studien iiber die pelagische Fauna kleiner
und grosserer Siisswasserbecken in der Schweiz. Zeitschr.f. wiss.
Zool., Band XL., pp. 154-178.

'84a. (See Article II., '84.)
'85. (See Article II., '85a.)
'85a. Uber die blassen Kolben an den vorderen Antennen der Siiss-

wasser-Calaniden. Zool. Anz., VIII. Jabrg., Nr. 107, p. 353.
'85b. (See Article II., '85.)
'86. (See Article II.)
'86a. (See Article II., '86b.)
'87. Uber die microseopiscbe Tbierwelt bocbalpiner Seen (000-

2780 in. u. M.). Zool. Anz., X. Jahrg., Nos. 241 u. 242. pp. 13-17,

33-42 ; Abstract, Am. Nat., Vol. XXI.. p. 071.

'87a. (See Article 11.)
'87b. (See Article II.)

'88. Fauna der Siisswasserbecken. Zool. Anz., XI. Jahrg., Nos. 275
u. 270, pp. 106-172, 185-190.

'88a. (See Article II., '88.)

'90. (See Article II., '90a.)

'90a. (See Article II.. '90.)

'90b. Notizen iiber die Siisswasser-Calaniden. Zool. Anz., XIII.
Jahrg., Nos. 349 u. 350. pp. 029-033, 054-658.

'91. Uber die pelagische Fauna einiger Seen des Schwarzwaldes.
Zool. Anz , XIV. Jahrg., No. 355, pp. 33-38.

'92. Zusammensetzung der pelagischen Fauna der Siisswasserbecken.
Biol. Centralbl., XII. Band., Nr. 6, 7 u. 8, pp. 171-182, 200-205.

*'93. Les organismes inf erieurs des lacs a la region du RhOne. Arch.
des Sci. phys. et nat., octobre — decembre, 1893.

'94. Fauna hochgelegener Seen. Seen der Rocky-Mountains, Nord-
Amerika. Von S. A. Forbes. Biol. Centralbl., XIV. Bd., Nr. 8,
pp. 287-293.

'95. (See Article II.)

'96. Die Binnengewiisser Fauna der Azoren ; Referat nach de Guerne
und Barrois. Biol. < VntralbL. XVI. Bd., Nr. 18, pp. 683-688.

Jurine, L.
'20. (See Article II.)

Kafka, Josef.
'92. (See Article II.)

Kerville, H. (See Gadeau de Kerville, H.)

North American Species of Diaptomus. 195

King, It. L.

*'55. On Australian Entomostracans. Papers and Proc. Roy. Soc.
Van Dieinen's Land, Vol. III., Pt. I.

Koch, C. L.
'35-'41. Deutschlands Crustaeeen, Myriapoden, und Arachniden,
Heft. XXL, XXXV. Kegensburg.

Koelbel, C.
'85. ("arcinologisches. Sitzungsber. d. K. Akad. d. Wiss. Wien,
Math, naturw. Klasse., Bd. XC. 1 Abteil., pp. 312-323, PI. I , Fig.
1-5.

Kortchaguine, A. N.
*'87. Fauna der Umgebung Moskaus. I. Crustaeeen [German title
of Russian article]. (Arb. aus. d. Laborat. d. Zool. Mus. der Univ.
Moskau.) Sehriften der Gesellsch. v. Freundeu d. Xaturwis-
sensch. zu Moskau, Bd. LIT.

Ladenburger, It.
'84. Zur Fauna des Mansfelder Sees. Zool. Anz., VII. Jahrg., Nr.
1GS, pp. 299-302.

Lauterborn, It.
'94. Uber die Winterfauna einiger Gewiisser der Oberrheinebene.
Mit Beschreibungen neuer Protozoen. Biol. Centralbl., XIV. Bd.,
Xr. 11, pp. 391-398.

'94a. Beitriige zur Stisswasserfauna der Insel Helgoland. TYissen-
sehaftliehe Meeresuntersuchungen, "Xeue Folge,'' Bd. I., Heft 1. pp.
216-221.

Leydig, Fr.

'59. Bemerkungen iiber tlen Bau der Cyclopiden. Arch. f. Xaturg.
XXV. Jabrg., I. Bd., pp. 194-207, Taf. IV.

Lilljeborg, "W.
'53. (See Article II.)
'63. Beskrifning ofver twa arter Crustaceer af ordingarne Ostracoda

och Copepoda. Ofv. af K. Vet.-Akad. Forbandl., Arg. XIX.. p. 391.
'87. On the Entomostraca collected by Mr. Leonhard Stejneger, on

Bering Island. 1882-83. Contributions to the Natural History of

the Commander Islands. Proc. U. S. Xat'n'l Mus., 18S7, pp. 154-15(5.
'88. Descriptions de deux especes nouvelles de Diaptonius du nord de

l'Europe. Bull, de la Soc. zool. de France, T. XIII., pp. 156-158.

Lubbock, J.
*'53. On two New Species of Calanidre, with Observations on the
Spermatic Tubes of Pontella, Diaptomus, etc. Ann. Mag. Nat. Hist.,
Vol. XII., pp. 1 15-124, 159-165, Pis. V., VI.

196 Illinois State Laboratory of Natural History.

*'54. On the Fresh-water Entomostraca of South America. Trans.
Entoru. Soc. X.S., T. III.

*'56. On some Entomostraca collected by Dr. Sutherland in the At-
lantic Ocean. Trans. Entom. Soc. London, Vol. IV., Part II., pp.
8-39, Pis. II.-XI1.

*'57. Description of eight New Species of Entomostraca found at
Weymouth. Ann. Mag. Nat. Hist., Vol. X X., pp. 101-410. Pis. X.. XI.

*'60. On Some Oceanic Entomostraca collected by Capt. Toynbee.

Trans. Linn. Soc. London, Vol. XXIIL, pp. 295, 296; Ann. Mag.

Nat. Hist., Vol. XL, pp. 48S, 489.
'63. (See Article II.)

Maitland, It. T.
*'74. Naamlijst van Nederlandsche Schaldieren. Tijdschr. Nederl.
Dierk. Vereen., 1 Deel, pp. 228-269.

Marenzeller, E. v
'73. Uber Diaplomus amblyodon n. sp. Verb. d. K. K. zool.-bot. Ge-
sellsch. Wien, Bd. XXIIL, p. 593, Taf. VI.

Marsh, C. D.
'91. (See Article II.)

'92. (See Article II.)
'93. (See Article II.)
'93a. (See Article II.)

'94. On two New Species of Diaptomus. Trans. Wis. Acad. Sci.,
Arts, and Letters, Vol. X., pp. 15-17, PI. I.
D. mississipi>iensis and D. I>ir<j<ji, n. sp.

'95. (See Article II.)

'97. On the Limnetic Crustacea of Green Lake. Trans. Wis. Acad.
Sci.. Arts, and Letters, Vol. XL, pp. 179-224, Pis. V.-XIV.

Milne-Edwards, H.
'34-'40. (See Article II.)

'38. Extrait d' un Mcmoire sur la distribution geographique des
Crustaces. Compt. rend, des Seanees de l'Acad. des Sci. 9 pp.

Moniez, It.

'87. (See Article II.)
'89. (See Article II., '89a.)

Mrazek, A.

'91. (See Article II.)

'93. Pfi'spevky k poznani sladkovodnich Copepodu [Contributions
to the Knowledge of Fresh-water Copepoda ]. Vestnik Krai. Ceskfi
Spol. Nauk. Tfida math.-prir., 1893. 74 pp., 8 Pis.; Abstract, Zool.
Centralbh, 1. Jahrg., pp. 593, 594.

North American Species of Diaptomus. 197

'93. (See Article II., '93c.)

'95. (See Article II.)

*'96. Zwr Entwickelungsgesehiehte einiger Taenien.t Sitzungsber.

el. k. bohm. Gesellscb. Wiss. Math.-nat. Classe. 16 pp., 1 PI.;

Abstract. Zo'ol. Centralbl., IV. Jabrg., No. 15, pp. 522, 523.

M idler, 0. F.

1792. (See Article II.)

Nice-let.
*'48-'49. Crustaceos. In Gay, C, Historia fisica y politiea de Chile
etc., Zoologia, Vol. III., pp. 288-292.

Nordqvist, O.
'86. (See Article II.)
'87. (See Article II.)
'88. Die Calaniden Finlands. Bidrag till Kannedom af Finlands

Natur och Folk. Utgifva af Finsva Vetensk.-Soc, Heft 47, pp.

192-275. 10. Pis.
'89. liber einen Fall von androgyner Missbildung bei Diaptomus

gracilis G. O. Sars. Arch, f . Naturgesch. Jabrg. LV., pp. 241-243,

Taf. XI I.
'90. (See Article II.)

Norman, A. M.
'86. Museum Normanianum ; or a Catalog of the Invertebrata of
Europe and the Arctic and North Atlantic Oceans, pp. 22, 23.

OuchakofF, N.
*'55. Pontie de Wacarino. Bull, de la Soc. imp. des natural, de Mos-
cou, T. XXVIII.

Pavesi, P.
'79. (See Article II.)
'79a. (See Article II.)
'83. (See Article II.)

Pickering, C.
'44. Generic Description of Scopiphora vagans. Nat. Hist. N. Y.,
Zool., Part VI., Crustacea, p. 62.

Pitard, E.
*'97. Sur le Plankton du lac de Joux. Arch. Sci. phys. et nat., A'ms

per.. T. III. 3 pp.
*'97a. Sur le Plankton du lac Brenet. Arch. Sci. phys. et nat., 4':ae
per.,T. III. 2 pp.

Poggenpol, M. J.

'74. (See Article II.)

tContains reference to Diaptomus.

198 Illinois State Laboratory of Natural History.

Poppe, S. A.
'84. Bemerkungen zu R. Ladenburger's: Zur "Fauna ties Mans-

felder Sees" in No. 108 des Zoologischen Anzeigers. Zool. Anz.,

VII. Jahrg., No. 176, pp. 499, 500.
'86. Ein neuer Diaptomvs aus dem Hirschberger Thai. Zeitschr. f.

wiss. Zool., Bd. 43, pp. 285-289, Taf. X., Fig. 1-12.

'88. Diagnoses de deux especes du genre Diaptomus Westwood.
Bull, de la Soe. zool. de France, T. XIII., pp. 159, 1G0.

'89. (See Article II.)
'89a. (See Article II.)

'91. Ein neuer Diaptomus aus Brasilien. Zool. Anz., XIV. Jahrg.,
No. 308, pp. 248-250. 3 Fig.
[D. deitersi n. sp.]

Poppe, S. A., u. Mrazek, A.
'95. Entouiostraken des Naturhistorischen Museums in Hamburg.

1. Die von Herrn Dr. F. Stuhlmann auf Zanzibar und dem gegenliber-
liegenden Fesilande gesammelten Siisswasser-Copepoden. 2. Taf.

2. Entomostraken von Sud-Georgien. 1 Taf. 3. Die von Herrn
Dr. H. Driesch auf Ceylon gesammelten Susswasser-Entomostra-
ken. I Taf. Beiheft zum Jabrb. der Hamburgischen wissenscbaftl.
Anstalten. XII. 20 pp.

Poppe, S. A., et Richard, J.
'90. (See Article II.)

'92. Description du Diaptomus schmackeri n. sp., recueilli par M.
Schmacker dans le lac Tahoo (Chine). Bull de la Soc. zool. de
France, T. XVII., pp. 149-151. 6 Fig.

Rath, O. v.
'91. (See Article II.)

Rehberg, H.
'80. (See Article II., '80a.)
'80a. (See Article II., '80b.)

Richard, J.
'87. (See Article II.)

'87a. Sur la faune pelagique de quelques lacs d'Auvergne. Conipt.

rend. d'Acad. des Sci., 14 novembre et 12 decembre, T. CV. pp.

951-953.
'88. Entomostraces nouveaux on pen connus. Bull, de la Soc. zool.

de France, T. XIII., p. 15G.

'88a. (See Article II., '88.)

*'89. Anomalie de l'antenne droite chez Diaptomus c&rtdeus Fisch.,
male. Bull, de la Soc. zool. de France, T. XIV., pp. 38, 39.

North American Species of Diaptomus. 199

'89a. Xote sur les pecbes effectives par M. Ch. Rabot clans les lacs

Euara, Imandra, et dans le Kolozero. Bull, de la Soc. zool. de France,

T. XIV., pp. 100-109.
'89b. Description du Mesochra blanchardi, Copepode nonveau des

Sebkhas algeriennes. Bull, de la Soc. zool. de France, T. XIV.,

pp. 317-321.

'90. (See Article II., '00c.)

'90a. Sur les Entoinostraccs et quelques autres animaux inferieurs
des lacs de l'Auvergne. Rev. des Sci. Nat. Appl.iqu6es, 37e Ann.,
lre Sem., Xo. 10, pp. 472-181. 10 Fig.

'90b. (See Article 1 1., '90a.)

'90c. (See Article II., '90b.)

'90d. Xote preliminaire sur le systeme nerveux de quelques especes
de Diaplomus. Bull, de la Soc. zool. de France, T. XV., pp. 212-219.

'91. (See Article II.)

'91a. (See Article II.)

'91b. Recherches sur le systeme glandulaire et sur le systeme ner-
veux des Copcpodes libres d'eau douce, suivies d'uue revision des
especes de ce groupe qui vivcut en France. Ann. Sci. uat. zool., T.
XII., pp. 113-270, PI. V.-VIII.

'92. Free Fresh-water Copepoda. Ann. Sci. Xat., Vol. XII., pp. 113-
270; Abstract, Journ Roy. Micr. Soc., 1S92. p. 47s.

'93. Copcpodes recueillis par M. le Dr. Theod. Barrois.en Egypte, en
Syrie et en Palestine (Mars-Juin, 1890). Rev. Biol, du Xord de la
France, 5e aim., Xo. 10. juillet, 1893. 30 pp., 51 Fig.

'94. Entoinostraccs recueillis par M. E. Modigliani dans le Lac Toba
( Sumatra). Ann. del Mus. Civ. di Storia Nat. di Genova. Ser. II. a ,
Vol. XIV. (XXXIV.), Oct., 1894, pp. 5G5-57S, Fig. 9-14.
[Diaptomus doriai n. sp.]

'95. (See Article II., '95a.)

'95a. (See Article II., '95b.)

'97. Sur quelques Entoinostraccs d'Eau douce des environs de Buenos
Aires. Anales del Mus. Xac. de Buenos Aires, T. V., pp. 321-332,
Fig. 1-0.

[Diaptomus bergi n. sp.]

'97a. Entoinostraccs recueillis par M. leDirecteur Steindacbner dans
les lacs de Janina et de Scutari. Ann. d. K. K. Naturhist. Ilofmus.,
Bd. XII., Heft 1, pp. 03-06, Fig. 1-4.
[Diaptomus steindachneri n. sp.]

'97b. Entoinostraccs de rAmerique du Sud recueillis par MM. U.
Deiters, J. von Ihering, G. W. Miiller et G. O. Poppe. Mem. de
la Soc. zool. de France, T. X., pp. 263-301, Fig. 1-45.

200 Illinois State Laboratory of Natural History.

'97c. Sur deux Entomostraces d'Eau douce recueillis par M. Chaf-
fanjon en Mongolie. Bull. du. Mus. d'hist. nut.. 1897, No. -1. pp.
131-135, Fig. 1-5.

[Diaptomus chaffanjoni n. sp.]

Riickert, J.
*'94. Zur Eireifung bei Copepoden. Merkel-Bonnefs Anat. Hefte,
I. AM., XII. Heft, pp. 261-351, Taf. XX.-XXV.; Abstract, Zool.
Centralbl., II. Jahrg., Xo. 10, pp. 291-295.

Russki.
*'89. Le faune pelagique du lac de Kabane. (French title of Russian
work.) Trav. Soc. imp. des nat. de l'TJniv. de Kasan, T. XIX.
Sars, G. 0.
'62. (See Article II.)
'63. (See Article II.)
'64. (See Article II.)

'86. Crustacea. II. Den norske Nordhavns Expedition 1876-78, pp.
76-79. Christiana.

'89. On some Fresh-water Ostracoda and Copepoda raised from dry

Australian mud. Forh. i Vidensk.-Selskab. i Christiania. pp. 1-77,

PI. I.-VIII. (Pis. I. and II. colored.)
'95. On some South African Entomostraca raised from dried mud.

Vidensk.-Selskab. Skrifter. I. Math.-naturw. Klasse. 1895, Xr. 8,

pp. 1-55. 8 Pis.

[Paradiaptomus lamellatus, n. gen. and n. sp.]

'96. On a new Fresh-water Ostracod. Stenocypris chevreuXi, G. O.

Sars, with notes on some other Entomostraca raised from dried

mud from Algeria. Arch. f. Math, og Naturvid. Kristiania. 27 pp.,

3 Pis.
'97. Pelagic Entomostraca of the Caspian Sea. Extraitde I'Animaire

du Musee Zoologique de 1'Academie Imperiales des Sci. de St.-

Petersbourg, 1897. 7:5 pp., 8 Pis.

Schmeil, O.
'89. t'ber den Diaptomus des salzigen Sees (Diaptonius richardi n. sp.).
Zool. Anz.. XII. Jahrg.. No. 323. pp. UG-GV.).

'91. (See Article II.)

'92. Deutsehlands freilebende Siisswasser-Copepoden. I. TeilrCy-
clopidse. Bibliotheca Zoologica, Ileft 11. 191 pp., 8 Pis.

'94. (See Article II.)

'94a. Einige neue Harpacticidenformen des Siisswassers. Zeitschr.

f. Naturwissensch., Bd. LXVIL, pp. 341-350.
'95. Neue Spaltfusskrebse der Fauna der Provinz Sachsen. Zeitschr.

f. Naturwissensch., Bd. LXVIIL, i>i>- 126-130.

North American Species of Diaptomus. 201

'96. Deutschlands freilebende Susswasser-Copepoden. III. Teil:
Centropagidre. Abt. I. u. II. Bibl. Zool. Heft, 21, Lfg. I. u. II.,
Taf. I.-XIL, 3 Fig. in Text; Abstract, BioL Centralbl , XVI. Bd.,
Nr. 23, pp. 845-847.

'97. Deutschlands freilebende Susswasser-Copepoden. Nachtrag.
Bibl. Zool. Heft 21, Nachtrag, pp. 145-188, Taf. XIII., XIV.

Scott, T.
*'94. Diaptomus serricornis Lilljeborg, in Lochs in Barra and North,
Uist. Ann. Scot. Nat. Hist., Oct., pp. 258, 259.

Scourfield, D. J.
'93. (See Article II.)
'94. Entomostraca and the Surface-film of Water. Journ. Linn. Soc,

Vol. XXV., Zoology, No. 15S, pp. 1-19, Pis. I., II.
'95. A Preliminary Account of the Entomostraca of North Wales.

Journ. Quekett Micr. Club, Vol. VI., Ser. 11., Xo. 37, pp. 127-143,

PI. VIII.
'97. Verzeichniss der Entomostraken von Plon. Forschungsber. a.

d. Biol. Stat, zu Plon, Theil V., pp. 180-1S3. Stuttgart.

Seligo, A.
'90. (See Article II.)

Siebold, C. Th.

*'39. Beitriige zur Naturgeschichte der wirbellosen Thiere. II. Uber
das Begattungsgeschiift des Cyclops castor. Neueste Schrift, Nat.
Ges. Danzig, Bd. III., Heft 2, pp. 36-50, Taf. 2, Fig. 41-44.
(Ubersetzt in: Ann. Sci. Nat. Paris, T. XIV., pp. 26-38, Taf. V.
Nach Giesbrecht.) [Fide Schmeil.]

Sowinsky, W.

'91. (See Article II.)

*'91a. Sur la nouvelle espece du genre Diaptomus, trouvee dans le
lac Kibnoye-Ozero pres de la ville Stawropol. [French title of Kus-
sian article.] Mem. de la Soc. des natural, de Kiew, T. XI., Part I.
4 pp., 1 Fig. in text.

Steck. Th.
'93. Beitriise zur Biolog-ie des s-rossen Moosseedorfsees. Mitt. d.
naturf. Gesellsch. in Bern, Jahrg. 1893, pp. 20-73.

Stuhlinann, F.
'91. Beitriige zur Fauna central-afrikanischer Seen. Zool. Jahrb.,
Abteil. f. System., Bd. V., pp. 924-926.

Szekely, B.
*'82. I'anulmanyok a Diaptomus petefejlodescnek els("» phasisairol a
blastoderma fellepeseig. Kolozsvart.

202 Illinois State Laboratory of Natural History.

Thallwitz, J.
*'91. Die Siisswasser-Calaniden Deutschlands. fTat.Bundschaa.6d.
VI,, pp. 131, 132. Berlin.

Turner, C. H.
'92. (See Article II.)

TTlianin, W. N.

*'74. Cladoceren uud Copepoden eiuiger Seen des centralen Russ-
lands. Schriften d. Gesellsch. v. Freunden der Xaturwissensch.,
etc., zu Moskau, Bd. X., Abt. II., pp. 7S-81.

'75. Crustaceen von Turkestan. Reise A. P. Fedtschenkos in Turk-
estau. [German title of Russian article.] Schrift. de Gesellsch. v.
Freunden der Xaturwisseuseb., etc., zu Moskau, Bd. XL, Abt. VI.,
Copepoden, pp. 22-41, Taf. VI.-X1I.

Underwood, L. M.
'86. (See Article II.)

Vejdovsky, F.

'82. Thieriscbe Organismen der Brunnengevviisser von Prag. 66
pp., 8 Pis. Prag.

Villepoix, R. M. de
'88. (See Article II.)

Vosseler, J.
'86. (See Article II.)
'89. (See Article II.)

'91. Die Krebsfauna unserer Gewiisser. In Zacharias's "Die Thier-
und Prlanzenwelt des Siissvvassers,*' Bd. 1., pp. 323-3S0. 6 Fig. Leip-
zig.

Weber, Max.
'92. ()n the Fresh-water Crustacea of the Indian Archipelago with
Observations on the Fauna of Freshwater in General. Ann. Xat.
Hist., Ser. 6, Vol. XIV., pp. 237-253.

'92a. Die Siisswasser-Crustaceen des Indischen Archipels, nebst Be-
rnerkungen iiber die Siisswasser-Fauna ini Allgemeinen. Zool. Er-
geb. einer Reise in Niederliind, Ost-lnd., pp., 528-571, Taf. XXX.
Leiden.

Westwood, J. O.
*'36. Cyclops. Partington's Cyclopedia. Xat. Hist.

Wierzejski, A.
'82. Materyjaly do fanny jezior tatrzaiiskich. [Materials for the
Fauna of the Karpathian Lakes.] Copepoden. Sprawozd. Kora.
fiz. Akad. Umiej., T. XVI.. pp. 233, 234. Taf. 111.

North American Species of Diaptomus. 203

*'83. Zarys fauny stawow tatrzauskieh. Pamietn. Tow. tatrz., T.
VIII. Krakau.

'87. O. Krajowych skorupiakach z rodziny Calanidae. [On the na-
tive Copepoda of the Family Calanidae.] Kozpr. i Sprawozd.
Wydz. mat.-przyr. Akad. Umiej. Krakau, T. XVI. 13 pp., 1 PI.

'95. Prezeglad fanny skorupiakow galicyjskich. [Review of the
Crustacean Fauna of Galicia.] (See Article II. for citation.)

Wille, N.
'96. Mitteillungen aus der biologisehen Gesellsehaft in Christiania.
Biol. Centralbl., XVI. Bd., Nr. 3, pp. 124-126.

Zacharias, O.
*'85. Studien liber die Fauna des Grossen und Kleinen Teichs irn

Riesengebirge. Zeitschr. f. wiss. Zool., Bd. XLL, pp. 483-51G, Taf.

XXVI.
'87. (See Article II.)
'87a. Znr Entoraostrakenfauna der Umgebung von Berlin. Biol.

Centralbl., Bd. VII., Nr. 5, pp. 137-139.
'87b. (See Article II.)
'88. (See Article II., '88a.)
'88a. Die Tierwelt der Eifelmaare. Biol. Centralbl., VIII. Bd., Nr. 18,

p. 574.
'88b. Uber die geographische Verbreitung des genus Diaptomus.

Biol. Centralbl., VIII. Bd., Xr. 18, p. 575.
'89. Bericht iiber eine Zoologische Exkursion an die Kraterseen der

Eifel. Biol. Centralbl., IX. Bd., Xos. 2, 3, pp. 56-64, 76-80.
'90-91. Uber ein interessantes Kapitel der Seenkunde. Biol. Cen-
tralbl., X. Bd., Xr. 18, pp. 123-128.
'93. Fauna des grossen Ploner Sees. Forschungsber. aus der Biol

Station zu Plon, Teil I., pp. 3-13; Extract, Biol. Centrabl., XIII

Bd., Nr. 11 u. 12, pp. 377-382.
'94. Faunistische Mitteilungen. Fauna des grossen Ploner Sees.

Forschungsber. aus der Biol. Stat, zu Plon, Teil. II., pp. 57-66.
'95. Uber die horizontale und vertikale Verbreitung limnetischer

Organismen. Forschungsber. aus der Biol. Stat, zu Plon. T. III.,

pp. 118-128. Extract Biol. Centralbl., XIII. Bd., Nr. 11 u. 12, pp.

377-382.
'95a. Statistische Mitteilungen aus der Biologischen Station am

grossen Ploner See. Zool. Anz., XVIII. Jahrg., pp. 28, 70, 87, 125?

140, 190, 256, 305, 367, 414, 448.
'96. (Quantitative Untersuchungen iiber das Limnoplankton. 64 pp.

Berlin.

204 Illinois Slate Laboratory of Natural History.

'97. Biologisehe Beobachtungen an den Yersuchsteichen des Schles.
Fischerei-vereins zu Trachenberg. Forschungsber. a. d. Biol. Stat.
zu Plon, Theil V., pp. 10-28. Stuttgart.

Zaddach, E. G.
'44. Synopseos Crustaceorum Prussicorum Prodromus. Dissertatio
Zoologica. 47 pp. Regiomonti (Konigsberg).

Zenker. W.
'54. (See Article II.)

'54a. System der Crustaceen. Arch. f. Naturgeseh. XX. Jabrg.,
Bd. I., pp. 108-118.

'54b. Critik der Erichson'schen Gliedmassentheorie. Arch. f. Na-
turgesch., XX. Jahrg., Bd. I., pp. 118-138.

Zograf. N.
*'96. Essai duplication de rorigine de la faune des lacs de la Rus-
sie d'Europe. Compt. rend, des seance du troisieme congres internat-
de Zool.. Leyde, 16-21, sept., 1895, pp. 183-195. Leyde. Abstract,
Zool. Centralbl., III. Jahrg., No. 14, pp. 481-483.

Zopf. W.
'95. Conn's Hamatochrom ein Sammelbegriff. Biol. Centralbl., XV.
Bd., Nr. 11, pp. 417-427.

Zschokke, F.

'90. (See Article II.)
'90a. (See Article II.)
'91. (See Article II.)

*'91a. Die zweite zoologische Excursion an die Seen des Rhiitikon.
YerbandL Xaturf. Gesellsch. Basel, Bd. IX.. 2 Teil, pp. 425-508;
Abstract, Journ. Roy. Micr. Soc, 1892, p. 194.

'94. Die Tierwelt der Juraseen. Rev. Suisse de Zool. et Ann. du

Mus. d'hist. nat, de Geneve, T. II., Liv. II.. pp. 349-376, PL X1Y.
'94a. Die Fauna hoch gelegener Gebirgsseen. Ein Beitrag zur

Kenntniss der Yertikalen Yerbreitung niederer Tiere. Yerh. d.

Naturf. Gesellsch. in Basel, Bd. XL, Heft 1, pp. 36-133, Taf. I.
'95. Die biologische Station zu Plon nach den Forsehungsberichten.

Teil II. u. HI. Biol. Centralbl. XY. Bd., Nr. 10, pp. 408-415.

Nortlt American Species of Diaptomus. 205

EXPLANATION OF PLATES.

Plate XXI.

Fig. 1. Diaptomus sicilis, fifth feet of male. X '280.

Fig. 2. Fifth feet of female of same (minus one outer ramus). X 280.

Fig. 3. Last thoracic segment and abdomen of female of same. X 140.

Plate XXII.

Fig. 1. Diaptomus piscina', fifth feet of male.

Fig. 2. Fifth foot of female of same (Portage Slough specimen). X 280.

Fig. 3. Last thoracic segment and abdomen of female of same. X 140.

Fig. 4. Fifth foot of female (Yellowstone Park specimen). X 280.

Plate XXIII.

Fig. 1-5. Diaptomus sanguineus, second basal segment of right fifth foot

of male. X 210.
FiG. 6-8. Terminal segments of right male antenna of same. X 210.

Plate XXIV.

Fig. 1, 2. Diaptomus sanguineus, first abdominal segment of female, seen

from the side. X 110.
Fig. 3. Last thoracic and first abdominal segments of female of

same. X 110.
FiG. 4. Fifth feet of male of same. X 210.
Fig. 5, G. Dorsal outline of female of same, showing hump. X 110.

Plate XXV.

Fig. 1, 2. Diaptomus sanguineus, fifth foot of female. X 240.
Fig. 3, 4. Right fifth foot of male of same. X 210.
Fig. 5. Fifth feet of male of same (variant). X 210.

Plate XXVI.

Fig. 1. Diaptomus shoshone, last thoracic segment and abdomen of

female. X 80.
FiG. 2. Fifth foot of female of same. X 280.
FiG. 3. Abdomen of male of same. X 128.

Plate XXVII.

Fig. 1. Diaptomus lintoni, fifth feet of male. X 280.

Fig. 2. Diaptomus pallidas, fifth foot of female. X 280.

Fig. 3. Fifth feet of male of same. X 280.

Fig. 4. Diaptoimis albuquerquensis, fifth feet of male. X 400.

206 Illinois State Laboratory of Natural History

Plate XXYIII.

Fig. 1. Diaptomus reighardi, fifth feet of male. X 400.
Fig. 2. Diaptomus stagnalis, right antenna of male. X 80.

Plate XXIX.*

Fig. 1. Diaptomus oregonensis, fifth feet of male. X 240.

Fig. 2. Fifth foot of female of same. X 300.

Fig. 3. Diaptomus signicauda, fifth feet of male. X 200.

Fig. 4. Terminal segments of right antenna of male of same. X 200.

Fig. 5. Fifth foot of female of same. X 200.

Fig. 6. Last thoracic segment and abdomen of female of same. X 100.

Plate XXX.*

Fig. 1. Diaptomus franciscanus, last thoracic segment and abdomen

of female. X 40.

Fig. 2, Terminal segments of right antenna of male of same. X 200.

Fig. 3. Fifth pair of feet of male of same. X 200.

Fig. 4. Fifth foot of female of same. X 200.

Fig. 5. Diaptomus minut'us, fifth foot of female. X 300.

Fig. 6. Fifth foot of male of same. X 300.

Fig. 7. Terminal segments of right antenna of male of same. X 300.

Fig. 8. Last thoracic segment and abdomen of female of same. X 250.

Plate XXXI.

Fi<;. 1.* Diaptomus trybomi, terminal segments of right male antenna.

X160.
Fig. 2.* Last thoracic segment and abdomen of female of same, seen

from right side. X 96.
Fie. 3. The same, seen from above. X 140.
Fig. 4.* Fifth pair of feet of male of same. X 210.
Fig. 5.* Fifth foot of female of same. X 240.

Plate XXXII.

Fig. 1. Diaptomus ashlandi, fifth pair of feet of female (a variant).

X210.
Fig. 2. Fifth foot of female of same. X 240.
Fig. 3. Fifth pair of feet of male of same. X 240.
Fi<;.4. Anterior fifteen segments of right antenna of male of same.

X240.

*After de Uuerne and Richard, '89b.

North American Species of Diaptomus. 207

Plate XXXIII.

Fig. 1. Diaptomus mississii>pie7isis, last thoracic segment and abdomen

of male. X 256.
Fig. 2. Fifth foot of female of same. X 256.
Fig. 3. Fifth pair of feet of male of same. X 256.
Fi<;. 4. Abdomen of female of same seen from below (Prof. Marsh's

specimen). X 256.

Plate XXXIV.

Fig. 1. Diaptomus clavipes, right fifth foot of male (inner ramus want-
ing). X 280.
Fig. 2. Right antenna of male of same. X 140.
Fig. 3. Fifth foot of female of same. X 400.

Plate XXXV.

Fig. 1. Diaptomus clavipes, fifth feet of male. X 280.

Fig. 2. Last thoracic segment and abdomen of female of same. X 140.

INDEX.

(Synonyms
Amphaskandria, 102.
Candacidse, 104.

( lentropagulge, 97, 101, 102. 103.
Centropagiria, 103.
Cyclops, 100, 100, 141.
Cyclops, 97, 10G, 132.
tongicornis, I'M).
Cyclopsina, 97,105.
Diaptomus, 102, 103, 105.

albuquerquensis, 98, 113, 115,

146, 176, 183.
ambiguus, 177.
armatus, 133, 135, 136.
ashlaudi, 9S, 100. Ill, 120,124,

158, 167, 183.
bacillifei-,107.
birgei. 99. 108, 117, 172.
caroli. 181.
castor, 98, 106.
castor, 130.

.•lavipes,98,10S,119,127,178,184
cceruleus, 107.
deitersi, 99.
driesehi, 99.

eiseni, 98,110,115, 162,166,183.
franciscanus, 98, 110. 118, 132,

160.166,182,183.
fresnanus, 176, 178.
gibber, 99.
giganteus, 138.
gracilis, 98, 173, 182.
graciloides, 98.
incongriiens. 99.
kentuckyensis, 97, 130, 132.
leptopus, 97, 112, 117, 125, 127.

130, 135, 181, 182.
lintoni, 113418,1 27,134,160,182
longicornis, 132.

var. leptopus, 130, 132.
var. similis, 132. 162. 182.
minnetonka, 133, 135, 136, 138.
lninutus, 98, 106. Ill, 116, 129,

134, 156. 183.
mississippiensis, 98, 109, 122,

149,173,184.
novarnexicanus, 99, 111. 116,

149, 183.
oregonensis, 109, 119, 124.151,
169, 171, 183.

in Italics.)
Diaptomus — continut <L

pallidus, 100, 108, 121, 124, 137,
144, 156. 183.
var. sirilis. 122.
piscinae, 98, 109.116,118, 125,

127,181,182.
reighardi, 98,109, 121. 169,1S4.
roubaui, 166.
salinus. 99.
sanguineus. 97, 112, 117, 12&,

133, 160, 166, 183.
serricornis, 162.
shosbone.H0.116,141.164.1S3.
sicilis, 97, 100, 111. 121, 122.
145,155,169,182.
var. imperfectus, 124, 158, 167,
169.
siciloides, 98, 100, 114, 121, 124,

137, 146, 154. 157, 165,
166,181,182.183.

signicauda, 98, 114. 120, 157,

159, 160, 164,183.
signicaudatus, 164.
similis, 132, 182.
stagnalis, 97, 113, 115. 129, 136,

138. 141,142.164,183.
trybomi,98.112.120,158.166.183
tyrrelli, 99, 108, 119, 160, 176,

184.

wierzejskii, 107.

zachariasi, 99.
Epischura, 97, 102, 103, 166.

nevadensis. 98. 168.

nordehskiuldi, 9S.
Glaucea, 97, 105.
G ymnoplea. 102.
Heterarthrandria, 102.
Heteroebatina. 104.
Heterocope. 99.
Leuckartiiua, 104.
Limnoealanus, 102, 104.

sinensis. 99.
Monoculus, '.)7. 105.
Osphranticum, !)7, 102,104.
Podoplea, 105.
Pontellida', 102.
Temorella, 99.
Teniorina, 103.
Volvox, 141.

Plate XXI.

Plate XXII.

Plate XXIII.

Plate XXIV.

Plate XXV.

Plate XXVI.

If | 1

' \

Plate XXVII.

Plate XXVIII.

Plate XXIX.

Plate XXX.

1 \ \ j ;

Plate XXXI.

Plate XXXIL

Plate XXXIII.

Plate XXXIY.

Plate XXXV.

BULLETIN

OF THE

Illinois Qtate Laboratory

OF

NATURAL HISTORY,

Urbana, Illinois.

VOLUME V.

ARTICLE IV — THE NORTH AMERICAN CENTROPAGID.E
BELONGING TO THE GENERA QSPHRANTICUM, LIM-
NOCALANUS, AND EPISCHURA.

By FREDERICK WILLIAM SCHACHT, B. S.

Illinois State Laboratory of Natural History,
URBANA, ILLINOIS.

1898.

State Laboratory of Natural History.

LABORATORY STAFF.

Professor Stephen Alfred Forbes, Ph. D„

Director of State Laboratory and State Entomologist.

Charles Arthur Hart,

Systematic Entomologist and Curator of Collections.

Frank Smith, A. M.,

Assistant Zoologist.

Charles Atwood Kofoid, Ph. D.,

Zoologist, and Superintendent of Biological Station.

Ernest Browning Forbes, B. S.,

Entomo logica I Ass istant.

AVallace Crah;, B. S.,

Zoological Assistant.

Mary .Iane Snyder,

Secretary.

Henry Clinton Forbes.
Business Agent and Librarian.

Lydia Moore Hart,
Artist.

Article IV. — The North American Centropagidce belonging
to the Genera Osphranticum, Limnocalanus, and Epis-
chura* By Frederick William Schacht, B. S.

INTRODUCTION.

■

In Article III. of this Bulletin the writer discussed the
North American species of Diaptomus, and in the present
paper, in furtherance of the same purpose, the genera Os-
phranticum, Limnocalanus, and Epischura arc treated. In
the introduction to the former article was given a short
account of the work of writers on the Eutomostraca now
included in the family Centropagidce, especially those genera
found in North America. No reference is made there to the
genera Heterocope and Eurytemora, since at that time I re-
garded the presence of these two genera in North America as
rather doubtful.

The only statement that Heterocope was ever found on this
side of the Atlantic is made by Cragin ('83) t. After an
enumeration of the genera of fresh-water Oopepoda he says :
" Of these eleven genera, four — Diaptomus, Limnocalanus,
Cyclops, and Canthocamptus — have been recorded as common
to the Old World and the New. I add Heterocope on the
authority of my friend, Mr. William Patten, who informs me
that a species is common in Watertown, Massachusetts."
This evidence is not sufficient to justify the treatment of the
genus in this paper.

In regard to Eurytemora (=Temora Temorella) I was per-
haps overhasty in my conclusions, but it being now too late
to remedy the omission, the following statements must
suffice. In his "Final Tieport" Herrick ('84) notes the
occurrence of Temora affinis Poppe in the rivers flowing into
the Gulf of Mexico as well as in the brackish waters into
which these rivers flow. In the "Crustacea of Alabama"
('87) he notes, under the name of Temorella ajjinis, a species
which according to his statement is the same. The figures of

-This paper was accepted by the Faculty of the University of Illinois June 1.
1898, ;is ii thesis for the degree of Master of Science in /oology.

(The parenthetical figures in the text of this paper refer usually to the bibliog-
raphy of Article III., which is. however, supplemented bv an additional list appended
to this discussion.

226 Illinois State Laboratory of Natural History.

the species in question differ, however, so considerably in
these two articles that, as Schmeil ('98) says, nothing certain
can be said of this species until Herrick declares himself as to
which of the two sets of drawings are correct. Schmeil regards
Herrick's form as possibly a new species. The recent dis-
covery of a new species of this genus, Kurt/femora herdmani
I. C. Thompson and A. Scott, in the St. Lawrence River and
Gulf removes all doubt as to the presence of the genus in
American waters.*

Of the three genera treated in this paper, Osphranticuni,
containing a single species, &&& Epischura, containing threei ,
are, so far as now known, confined strictly to North America
and are strictly fresh- water in their habitat. Osphranticum
is ordinarily found in shallow or stagnant lakes and ponds
(Forbes] or in running water (Herrick), while Epischura
occurs, as a rule, in deep clear lakes. The genus Limnocalanus
is peculiar in its habitat. One of the two species, L. sinensis
Poppe, from China, is, so far as known, a strictly fresh-water
form, while the other, L. macrurus Sars, although found as
yet in America in freshwater only, occurs in Europe and Asia
in both fresh- and salt-water lakes and in the ocean. Since
there are only these two species known, it was thought best
to treat both in this paper. L. grimaldii de Guerne is re-
garded by the writer as a synonym of L. macrurus Sars^, for
reasons given in the discussion of the latter species.

A brief discussion of the structural similarities and differ-
ences indicative of the relationships of the genera Osphranti-
cum, Limnocalanus, Diaptomus, and Epischura may properly
precede this paper, special attention being given to characters
which are regarded as of generic or specific value.

Giesbrecht, in his "Monograph" (,(.>2), gives special rank
to the structure of the first pair of antenna- as a distinguish-

■M'e "On the Plankton collected continuously during two Traverses of the North
Atlantic in the Summer of 1897; with Descriptions of New Copepoda: and an Ap-
pendix on Dredging in Puget Sound." By W. A.. Herdman, I. C. Thompson, and An-
drew Scott. Trans. Liverpool Biol. Soc, Vol. XII. (1897), p. 79.

fE.fluviatilis Herrick is not considered one of these.

i'l'lie Zoologisch.es C'entraibfatt (Jahrg., 111., pp. 4si 183J contains a review of an
article by X. Zograf entitled " Essaid'Explication de L'origine de la Faune des lacsde
la Russie ii' lairope" in which a reference occurs to /.. mad-onyx G. <». S. This is
probably an error, since it is the only reference toaspecies of that name which I
have hem able t>> find.

North American Centropagidce. 227

ing character in the Copepoda. If this be taken as a basis
of classification here, Osphranticum, with its 2 3 -segmented
antennae, would form a group by itself, while Limnocalanus,
Diaptomus, and Epischura, with their 2 5 -segmented antennae
would constitute another group.

Osphranticum seems to be the most primitive of the Amer-
ican Centropagidce, the fifth legs especially being less differ-
entiated than in any of the other genera. This is particularly
true of the female, in which all of the legs are biramose, each
ramus consisting of three segments. In the male the left
fifth leg is similar to the preceding legs, but the right one has
a two-segmented outer ramus, the second segment being ap-
parently formed by the coalescence of the second and third
segments. In both sexes the inner rami of all the pairs of
legs are alike.

Limnocalanus apparently approaches most closely to Os-
phranticum, the fifth pair of legs of the female being very
similar in general structure to those of Osphranticum, as is
perhaps most strikingly illustrated in the case of L. macru-
rits Sars and 0 . labronectum Forbes. In Limnocalanus both
rami of the four anterior pairs of legs in both sexes are three-
segmented and but slightly modified, as are also those of the
fifth pair of legs of the female; but in the latter the second
segment of the outer ramus is produced on the inner margin
into a hook-like process, as in Osphranticum. The inner
rami of the fifth pair of legs of the male are still three-
segmented and similar to those of the preceding legs, but the
outer rami are modified and are two-, or indistinctly three-,
segmented.

Diaptomus is perhaps next in respect to modification.
In this genus all the legs are biramose, but the first pair con-
sists of a three-segmented outer, and a two-segmented inner,
ramus. The following three pairs have both rami three-seg-
mented. In the female the fifth pair of legs has a two- or,
more rarely, three-segmented outer ramus, and a one- or,
occasionally, two-segmented inner ramus. In the male the
inner ramus is one- or, rarely, two- segmented, while the outer
ramus of the right leg is three-segmented and that of the left
leg two- segmented.

228 Illinois State Laboratory of Natural History.

In Epischura, as in the other three genera, the cephalotho-
rax is six-segmented. All of the swimming legs have a
three-segmented outer, but a one-segmented inner, ramus.
In the female the inner ramus has entirely disappeared in
the fifth pair of legs, and the outer ramus is two-segmented. .
In the male also the fifth pair of legs are without inner rami,
and the outer ramus of the right leg is two- or three-segmented,
that of the left leg three-segmented. A peculiarity of this
genus is the modification of the abdomen of the male into a
clasping organ. The abdomen of the female is also modified
in at least one species (lacustris).

So much for the relationships indicated by the structures
considered. According to the above, Osphranticum must be
regarded as the most primitive form, Epischura as the most
modified, and Limnocalanus and Diaptomus as occupying an
intermediate position. I think that the mass of charac-
ters will support this statement, although there are other
characters which would lead one to doubt somewhat its
correctness. For example, in Osphranticum and Diaptomus
the females carry the eggs in an egg-sac, while in Limnocal-
anus and Epischura they do not. In Osphranticum, I>iaj>tn-
mus, and Epischura the spermatophore persists tor some time ;
but I have not seen a single female Limnocalanus with a
spermatophore, although according to Giesbrecht the fertili-
zation by means of a spermatophore is about the only charac-
teristic which all Copepoda have in common.*

The material at my command for the preparation of this
paper has been complete; that is to say, I have had speci-
mens of all the known species of the genera treated, ami
access to the most recent literature. The collections exam-
ined belong in great part to the Illinois State laboratory of
Natural History, in part to Prof. Frank Smith, of the Univer-
sity of Illinois, and in part to myself. The following localities
are represented : Norway, the Caspian Sea, Lake Sitai and
the Whangpoo River in China, Newfoundland, and the Stati -

* "The sexually mature individuals are to some extent mi transformed by para-
sit ism that unless the fertilization by menus of spermatophores be excepted they seem
tn have no characteristic common to all which would at the same time distinguish the
(inter Copepoda from the other orders of Entomostraca." (Giesbrecht, '5)2. p. i

North. American Centropagidce. 229

of Illinois, Indiana, Ohio, Michigan, Washington, Oregon,
Montana, Wyoming, Idaho, and Nevada.

Through the kindness of Professor Smith I was able to
examine collections from Lake George and Lake James in
Steuben County, Ind., in which I found specimens of Epis-
chura lacustris and Diaptomus oregonensis. Mr. Chancey
Juday, Curator of Collections, University of Indiana, kindly
sent me collections from Tippecanoe Lake, Eagle Lake, and
Turkey Lake, in Indiana, in which occurred Epischura lacus-
tris, Diaptomus sicilis, D. oregonensis, and 1 >. siciloides. I also
acknowledge my indebtedness to Prof. G. 0. Sars, who kindly
furnished me with specimens of Limnocalanus grimaldii, thus
enabling me to compare them with L. macrurus — also fur-
nished by him to the Illinois State Laboratory of Natural
History; to Herr S. A. Poppe, for specimens of Limnocalanus
sinensis', to Professor Lillejeborg for Epischura nevadensis;
and to Dr. C. A. Kofoid, Superintendent of the Illinois Biolog-
ical Station at Havana, to whom I owe thanks for his many
kindnesses during my stay at the Station in July, 1896, and
while at the University.

No illustrations accompany this paper, since the species
treated may be identified by figures already published.

OSPHRANTICUM Forbes.

Osphranticum, Forbes. '82a, p. 645.
Potomoichetor* , Herrick, '82, p. 23.

< Osphranticum, Herriek, "84, p. 134.
Osphranticum, Herrick, "87, p. 12.
Osphranticum, de Gnerne et Richard, '89b. p. 149.
Osphranticum, Herrick and Turner, '95, p. 85.

Cephalothorax compact, six-segmented, the first two seg-
ments continent above, the last segment produced into a
bluntly-rounded lobe on each side. Abdomen (furca in-
cluded) composed of five segments in the female, of six in
the male. Furcal rami hairy on the inner margins ; armed
with five plumose seta3, the second from within the longest,
and with a delicate smooth seta on the inner margin of the

*Spelled Potamoichetor in Ilerrick's subsequent references.

230 Illinois State Laboratory of Natural History.

dorsal surface. First pair of antennae 23-segmented : right
male antenna geniculate between the 18th and 19th seg-
ments, and the 19th and 20th segments ankylosed. Second
pair of antennae, mandibles, and first, second, and third
pairs of maxillae as in Diaptomus, but stouter. All the swim-
ming legs biramose, with three-segmented inner and outer
rami; armed with stout seta?. In the female the legs of the
fifth pair are alike, biramose, the rami three-segmented, the
inner ramus the shorter. Fifth pair of legs of male bira-
mose, dissimilar. Both rami of left leg three-segmented, the
inner ramus the shorter. Outer ramus of right leg two-
segmented, the inner three-segmented and like the inner
ramus of the left leg. Egg-sac obovate.

Osphranticum labronecturn Forbes.

Osphranticum labronecturn, Forbes, '82, p. 645, PI. VIII., Fig. 24. 28.
29; PL IX., Fig. 1, 2, 4. 5, 7, 9.

Potomoichetor* fucosus, Herriek, '82. p. 224, PI. II., Fig. 12-14: Pi.

III., Fig. 1-8. 13. 14.
Osphranticum labronecturn, Herriek, *84. p. 134, PJ. Q2, Fig. 1-8. 13. 14.
Osphranticum labronecturn, Herriek, "87. p. 12.

Osphranticum labronecturn, de Guerne et Richard. 89b, p. 149, Fig. 1 . 2.
osphranticum labronecturn, Herriek and Turner, *9">, p. 86. PL XII..

Fig. 1-8, 13, 14; PL LIX., Fig. 7, 8.

Of medium size, body compact, widest before the middle.
Ceplialothorax composed of six segments decreasing gradu-
ally in length from before backward ; first two segments con-
fluent above, the last segment slightly produced at the angles
into bluntly-rounded points, but unarmed. Abdomen (furca
included) composed of five segments, decreasing in length
from before backward. Furcal rami, however, slightly longer
than the preceding segment and about twice as long as wide ;
hairy on the inner margin and armed with five long plumose
seta? of which the second from within is the broadest and
longest, the middle one being next in length, and the other
three subequal ; dorsal surface of each ramus armed near
the inner apical angle with a delicate smooth seta. Abdo-
men of male composed of six segments : the first shorter

■Spelled Polamoichetor in Merrick's subsequent refereints.

North American Centropagidce. 231

than any of the others except the fifth, which is the shortest :
the second, third, and fourth segments decreasing in length
in regular order ; the second slightly shorter than the furcal
rami, which are armed as in the female.

Antenna? 23-segmented, extending about to the end of the
cephalothorax, or barely surpassing it. Eight male antenna
geniculate between the 18th and 19th segments; 19th and
20th segments ankylosed; six segments preceding the genieu-
lation rather thickly swollen; penultimate segment produced
at the inner apical angle into a broad bluntly-rounded process
extending slightly beyond the end of the segment.

Fifth pair of legs of male biramose. Second basal segment
of right leg armed above the middle of the outer margin with
a delicate hair slanting upward. First segment of outer
ramus slightly longer than the width at the base, irregularly
trapezoidal, the outer margin forming the longest side ; armed
at the outer apical angle with a stout spine about as long as
the segment itself and provided on ea-ch margin with a nar-
row hyaline lamella; just within this, another very minute
spine. Second segment irregular in form, the proximal third
subquadrate, about as wide as the preceding segment, pro-
duced at the inner apical angle in the form of a rather large
cushion-like pad sparsely covered with delicate hairs ; distal
two thirds subquadrate, about half as wide as the proximal
third, provided on the inner margin with delicate hairs, and
armed a short distance above the middle of the outer margin
with two spines, one large and one small, similar to those on
the preceding segment; apex of segment armed with three
spines fully as long as the segment itself, the outer two
straight, the inner curved inward slightly, and each of them
provided with a hyaline lamella, the edges of which seem to be
plumose. Just posterior to the inner apical seta is a short
slender spine.

First segment of inner ramus of right leg irregular in form,
about as long as wide, provided on the inner margin with a
few fine hairs. 'Second segment slightly wider than the pre-
ceding, barrel-shaped, and slightly longer than wide; pro-
vided on the inner margin with a few fine hairs, and at the

v28'2 Illinois Stale Laboratory of Natural History.

outer apical angle with a long delicate plumose seta. Third
segment slightly narrower than the second; margins sulcate,
armed with six subequal plumose seta? similar to the seta on
the preceding segment, of which three are apical, two are on
tin' outer margin, and one is on the inner. The seta' are so
placed as to form two groups of three each.

Basal segments of left fifth leu like those of right leg. First
segment of outer ramus similar to the corresponding segment
of the outer ramus of the right leg and similarly armed, hut
not quite so broad. Second segment subquadrate, about one
and a half times as long as wide; outer apical angle armed
as in the preceding segment; inner margin provided with a
few delicate hairs. Third segment considerably narrower
than the second and slightly shorter; armed at the apex with
two lamellate setaj and a short sharp spine. Inner ramus
like that of right leg.

Fifth pair of legs of female biramose. Second basal seg-
ment provided on the- outer margin, a short distance above
the middle, with a delicate hair slanting upward. First seg-
ment of outer ramus subquadrate, slightly broader than long ;
armed at the outer distal angle with a long lamellate spine;
and on each side of this with a very minute smooth spine.
Second segment somewhat shorter and narrower than the
preceding ; armed at the outer distal angle like the first seg-
ment, except that the inner of the small spines is wanting ;
inner apical angle produced into a long, moderately stout
lamellate hook, shaped about like the blade of a pruning
knife ; both margins provided with a few fine hairs. Third
segment slightly longer than the second, about twice as long
as wide; armed at the outer apical angle with a plumosely
lamellate spine almost as long as the segment itself, and at the
apex with two similar subequal spines (about twice the length
of the lamellate spine) and a short smooth spine; outer mar-
gin provided with a few long tine hairs ; inner margin sulcate
and armed with four slender subequal plumose seta- about as
long as the segment.

Inner ramus of fifth leg of female three-segmented, the
first segment irregular in' shape, with a somewhat projecting

North American Centropagidce. 233

inner apical angle. Second segment sub quad rate, about one
and a half times as long as wide ; armed at the outer apical
angle with a plumose spine almost twice as long as the seg-
ment, and on the inner margin with a few fine hairs. Third
segment slightly longer and narrower than the preceding;
irregularly triangular, with sulcate margins and truncate
apex ; armed on the outer margin with two long, slender, plu-
mose setae, at the apex with two similar setae and a short
smooth spine, and on the inner margin with one seta similar
to those already mentioned and one shorter lamellate seta,
and provided on the upper half with a few tine hairs.

Length of female, 1.703 mm.; that of male, 1.362 mm.

The above description was prepared from specimens col-
lected in the summer of 1896 at the Illinois Biological
Station, at Havana, 111. ; from type specimens; and from
other State Laboratory material collected at various times
and places, mostly in Illinois.

The single species of this exclusively North American
genus was first described by Herrick in a paper read before
the Minnesota Academy of Sciences in 1879, but which,
owing to a fire, was not published until 1882. The descrip-
tion then appeared, under the name Potomoichetor fucosus, in
the Tenth Annual Report of the Geological and Natural
History Survey of Minnesota (Herrick '82). This Report
was not distributed, however, until after the August number
of the "American Naturalist" appeared, which contained the
description of Osphranticum labronectum by Forbes ('82).

De Guerne and Richard, in their "Revision" ('89b), pub-
lish the best figures of this species. Although not strictly
correct in every particular, the omissions are of minor im-
portance, as may be seen by the following enumeration of
them. In the fifth legs of the female the hair on the second
basal segment, the small spines at the outer apical angles of
the segments of the outer ramus, the hairs on the outer
margins of these segments, and the lamella of the hook at
the inner apical angle of the second segment of this ramus
are not figured. The third segment of the inner ramus is
not quite correct. Here the hairs on the inner margin, the

234 Illinois State Laboratory of Natural History.

lamella on the upper spine of this margin, and the small
spine on the apex of the segment are all omitted, hi the
figures of the fifth pair of legs of the male, the small spines
at the outer apical angles of the segments of both outer rami,
the spine at the inner apical angle of the last segment of the
right outer ramus, and the hairs on the inner margin of the
first segment of both inner rami are wanting.

Although this species is widely distributed, — having been
found in Alabama, Illinois, Minnesota, Oregon, and Wyo-
ming,— no differences sufficient to establish even a new
variety have been found in specimens from these localities
so widely separated and so varied in character. Herrick, in
his papers, states that all the specimens examined by him,
from Alabama to Minnesota, had 24-segmented antennae.
Forbes found the antennae 23-segmented, de Guerne and
Richard, who examined specimens sent to Poppe by Forbes,
agreed with him, and the writer also found the antenna? of all
the specimens lie examined to be 23-segmented. The speci-
mens collected by Dr. Forbes in April, 1877, and described in
1882, were uniform pale brown; those collected by the
writer at Havana, 111., in July, 1896, were hyaline or opal-
escent white; while a single male found in June, 1897, at
Urbana, 111., in a temporary pool, was bright scarlet through-
out, and hardly to be distinguished from the specimens of
I), sanguineus among which it was found. Herrick has found
Osphranticum in "estuaries of running water," and says that
according to his observations it prefers such localities. The
writer's observations tend to confirm Forbes's statement
that it prefers swamps and pools, or at least quiet or stag-
nant water. At the Biological Station at Havana, during
the summer of 1896, a single specimen was captured in the
Illinois River, in midstream, while in Quiver Lake, in a mat
formed of Ceratophyllum and Lemna in a stagnant portion
near shore (substation C), they were comparatively numer-
ous, though not occurring in any such numbers as either
I >i<t]>h>nni* or Cyclops. In fact, in none of the collections
examined were they at all common.

Prof. Forbes, in connection with the original description,

North American Centropagidce. 235

makes a remark in regard to the "steady movement in the
water," and this is all, to my knowledge, that has been said
about the habits of Osphranticum. The following statements,
gathered from observation of a number of specimens kept
for some time in a large flat dish may therefore be of interest.
Their movements in the water are very different from the
short jerky springs of ( 'yclops, and they differ also from those
of Diaptomus in that they are more regular. The motions
of these three genera might perhaps be expressed by tele-
graphic symbols as follows : Cyclops, - -; Diapto-
mus, - -; and Osphranticum,- —
— . Osphranticum swims equally well on the

dorsal or ventral surface, seeming, however, to prefer the
former position. As in Diaptomus, the anterior end is ele-
vated in swimming, and the antennae are actively employed.
Sometimes it will turn backward somersaults, going over and
over in the water, but I have seen this done only when indi-
viduals were swimming on the back. When startled they
would dart to the bottom, hide for an instant under a bit of
debris, and then make another dash, repeating the perform-
ance until they deemed themselves out of danger.

Since 0. labronectum is the only species known, no key
will be required.

L.IMNOCALANUS G. 0. SaRS.

Limnocalamis, Sars, '62, p. 226.
Centropages, cle Guerne, '86, pp. 276-2S5.

Body long and narrow, the front armed with two book-like
processes. Cephalothorax widest at the middle, composed
of six well-defined segments ; last thoracic segment not pro-
duced laterally but slightly projecting posteriorly and armed
on each side with a minute blunt spine. Abdomen slender;
in the female composed (furca included) of four (macrurus)
or five (sinensis) segments. Furcal rami very long, hairy on
the inner margin ; armed with five stout plumose setae (the
second from within the longest), and one slender seta (plu-
mose in sinensis), shorter than the rest, on the dorsal surface,

236 Illinois State Laboratory of Natural History.

near the inner margin and opposite the outermost of the
other setae.

First pair of antenna1 shorter than the body, 25-segmented,
the hist segment very small. Eight male antenna geniculate
between the 18th and 19th segments, each of which is armed
with a hyaline lamina. Outer ramus of second pair of
antennae seven-segmented* and armed with very long setae.
Mandibles produced at the inferior extremity into nine
teeth, of which the outer two are longer than the rest, the
inner two slender and setiform ; palpus long and narrow,
three-segmented, the last two segments very short, outer
ramus small, armed with long seta?. First pair of maxillae
about as in Diaptomus. Second pair of maxilla; robust,
eight-segmented, the last segment produced into long stout
claws; margins otherwise sparsely hairy: the falcate apex
bare or' armed with very small dense spines. Maxillipeds
seven-segmented, much elongated and narrow, directed for-
ward, and armed with numerous long seta?.

All the swimming legs biramose. Both rami of the four
anterior pairs of legs three-segmented, the inner shorter than
the outer.

Outer ramus of fifth pair of legs of female three-segmented ;
;i rmed within, on the second segment, with a very strong,
curved, hook-like process. Inner ramus as in the other legs.

Outer ramus of right fifth leg of male two- (sinensis) or
indistinctly three- (macrurus) segmented, the second segment
produced into a stout hook-like process. Outer ramus of
left fifth leg two-segmented, the second segment armed with
a slender digitiform process. Inner rami three-segmented,
alike, and similar to £hose of the preceding pair (macrurus),
or differing from one another {sinensis). Eye single, near
the lower margin of the head.

This genus was established by Dr. Sars in 1802 to receive

*The parts of the generic description referring to the structure of the second
pair of antennae, the mandibles, maxillae, maxillipeds, and the swimming legs are
compiled from sars ("62 ami ''.i7i. Nordqvisl ('88), and de Guerneand Richard ('89b .
In regard to the second pair of antennae of macrurus the writers mentioned state
that the outer ramus is seven-segmented, anil Nordqvisl says further that the suture
between the second and third segments is indistinct, and figures the antenna with six
segments. Sars ("97) says of grimatdii that the outer ramus is six-segmented and so
figures it. After careful examination. I find no difference in the second pair of an-
tenna'of macrurus nn<\ grimaldii, the segmentation being equally distinct, each of
the four spines between the second and last segments markim; a segment.

North American Centropatjidce. 237

a fresh-water centropagid closely resembling the marine
genus Calanus, and until 1889 L. nun-rums was the only rep-
resentative known. In that year Poppe described (de Guerne
et Richard, '891)) a new species, L. sinensis, from China.
The latter, so far as now known, is a purely fresh- water form,
and L. macrurus was at first so regarded, but in Asiatic and
European countries it has been found to occur in both fresh
and salt water, — in America it has as yet been found only in
fresh water, — and further search may show that L, sinensis,
too, is common to both. L. macrurus is the only American
representative of the genus, but it was deemed best to in-
clude sinensis in this paper, thus making the revision of the
genera treated complete.

As already stated, the genus is represented by only two
species, macrurus and sinensis. The former is common to
America, Europe, and Asia, having been found in the river
J ana (in East Siberia), in the Caspian Sea, in the Arctic
Ocean, in the lakes of northern Norway, Sweden, and Fin-
land, and in the deeper northern lakes of North America;
the latter, sinensis, has been found only in eastern China.

Marsh, in his "Limnetic Crustacea of Green Lake" ('97),
records some observations on the habits of Limno calanus,
and states that it is repelled by bright light and high tempera-
tures, and hence performs diurnal migrations which are more
pronounced in cold weather. It seems to have two periods
of maximum occurrence, May and November, but is found at
all times, although never very abundantly. In March and
April most of the individuals are immature.

To my knowledge Limno calanus has never been found with
an egg-sac, differing in this respect from Ospliraniicum and
Diaptomus but agreeing with Epischura. The spermatophore,
a slender tubular structure, adheres to the female for a con-
siderable time after attachment.

From a practical and economic standpoint Limnocalanus
is of importance as contributing to the first food of ( '<>r<';i<>nns
clupeiformis (Forbes '83a), of Labidesthes sicculus*, and
probably of other lake fishes.

*See Forbes "On the Food Relations of Fresh-water Fishes: a Summary and Dis-
cussion." Bull. 111. State Lab. Nat. Hist., Vol. II., Art. VIII.. ]>. 532. 1885.

238 Illinois State Laboratory of Natural History.

Since there are only two species of Limnocalanus known,
the key is naturally very simple, and only the most striking
differences arc used.

KEY TO THE SPECIES OF LIMNOCALANUS.

Based on the Characters of the Female.

1 (2). Hook-like process at inner apical angle of second

segment of outer ramus of fifth leg armed for the entire
length of both margins with fine symmetrical teeth.
Outer apical angle of same segment armed with a
stout serrate spine. Second basal segment without
plumose seta at outer apical angle. macrurus.

2 (1). Hook-like process at inner apical angle of second

segment of outer ramus of fifth leg armed on the en-
tire inner margin with large teeth and on the outer
margin with a few line ones". Outer apical angle of
same segment without spine. Second basal segment
without plumose seta at outer apical angle.

sinensis.

Based on the Characters of the Male.

1 (2). Right outer ramus of fifth legs 3-segmented (third

segment indistinct). Hook-like process of second seg-
ment of this ramus simply and hut slightly curved ;
provided with hyaline plate. Inner rami alike.

macrurus.

2 (1). Right outer ramus of fifth legs clearly 2-segmented.

Hook-like process of second segment of this ramus
somewhat sinuously curved. Inner rami unlike.

sinensis.

Limnocalanus macrurus Sars.

Limnocalanus macrurus. Sars. '62, p. '22V>.
Limnocalanus macrurus, Forbes. !82a, p. 049.
Centropages grlmaldii, de Guerne, "SO. p. 276.

Limnocalanus macrurus, Nordqvist, *S8, p. 31. PI. I., Fig. 9-11; PJ.
II., Fig. 1-5; Pi. III.. Fig. 1-1.

-In de Guerue and Richard's "Revision," Fig. 5a in the description of Plate IV.
should be Fig. 15a.

North American Centropagida. 23!)

Limnocalanus macrurus, de Guerue et Richard, '89b. p. 77. PI. IV.,

Pig. 5, 11. 12.
Limnocalanus macrurus auctus, Forbes, '90, p. 6-18.
Limnocalanus macrurus, Marsh, *93. p. 201, PI. IV. Fig. 7.
Limnocalanus macrurus. Marsh, '95, p. 11, PI. IV., Fig. 1, 2; PI. V.,

Fig. 1-5.
Limnocalanus macrurus, Herrick and Turner, "95. p. 49, PI. I., Fig. 1-1.
Limnocalanus grimaldii, Sars, "97. p. 39, PI. IV., Fig. 1— IS.

Body slender. Thorax rather more than one fourth as
broad as long, and composed of six well-defined segments,
of which the first (constricted at about the middle and armed
at the front with two hook-like processes pointing forward
and downward) is the longest — about equal to the three suc-
ceeding segments taken together; third and fourth segments
subequal, together slightly longer than the second, which is
armed on the dorsal and lateral surfaces, near the distal end,
with a row of rather stout spines; fifth segment somewhat
longer than the last, which is not produced laterally, hut
armed on each side with a very small spine. Abdomen of
Innale composed of four segments, the first about a third
longer than either of the two succeeding segments, which are
subequal. Furcal rami about a fifth longer than the first
segment, and slightly shorter than the second and third seg-
ments taken together; sparsely provided on the dorsal sur-
face with short sharp spines, and on the inner margin with
spines and hairs; one plumose seta on the outer margin at
the beginning of the distal fifth; and four plumose apical
setae and a delicate smooth seta on the dorsal surface near
the inner apical angle. In the male the first and fourth
abdominal segments are subequal, each about a fourth longer
than the fifth, which is the shortest ; second and third seg-
ments subequal, each about twice as long as the fifth ; second,
third, and fourth segments armed like the second abdominal
segment of the female. Furcal rami proportioned about as
in the female and similarly armed.

Antenme 25-segmented ; right male antenna geniculate
between the lcSth and 19th segments. The armature of the
segments is as follows: 1 and 10 have a short seta and two
sense-hairs; 2, a short seta and three sense-hairs; 3, a short

240 Illinois State Laboratory of Natural History.

seta and a sense-hair; 4, a short seta and a short spine; 5
and 7, a long seta, a short one, and a sense-hair; 6, a short
stunted spine; 8, a short broad seta, a short curved spine,
and a sense-hair; 9, a long broad seta and a sense-hair;
11, a short broad seta and a sense-hair; 12, a sense-club, a
short curved spine, and a short broad seta; 18, a short broad
seta and a sense-club; 14, a long seta and a short broad
seta; 15, a sense-club and two short broad seta?; 16, a long
seta, a sense-club, and a short broad seta; 17, a sense-club,
and abroad, pointed, knife-like process; 18, along sense-
club, and a hyaline lamella armed with teeth and extending
almost the entire length of the segment; 19, 20, and 21
(ankylosed, the suture between 19 and 20 obscurely indi-
cated), a blunt digitiform process at the inner apical angle,
a seta, a blunt stunted spine slightly below the middle, and a
stunted spine and a knife-like process still lower down ; 22
and 23, (ankylosed, suture indistinct), two seta? and a sense-
hair; 24 two seta?; and 25 (very short), four seta' and a
sense-club.

First basal segment of right fifth leg of male subquadrate.
Second basal segment about as "wide as the first and about
twice as long, provided at the outer apical angle with an in-
conspicuous hyaline process. First segment of outer ramus
considerably narrower than the second basal segment, less
than twice as long as wide; armed at the outer apical angle
with a stout spine, serrate on the inner margin, and on the
inner margin below the middle with a hyaline process. Sec-
aond segment slightly narrower than the first ; produced at
the inner apical angle into a hook-like process, which i^
armed on the outer margin, near the base, with two sharp
slender spines, and provided on both margins with a hyaline
lamina having an appearance of transverse st nation. The
hook is fully three times as long as the segment itself.

Inner ramus of right iifth leg three-segmented, the first
segment irregular in form, about twice as long as wide;
armed on almost the entire outer ma ruin with a few tine
hairs, and at the beginning of the distal third with a slender
plumose seta. Second segment somewhat wider than the

North American Centropagidae. 241

first, and rather more than twice as long as wide ; armed on
the outer margin with a few hairs and a moderately stout
plumose seta. Third segment about as wide as the second,
with margins sulcate ; outer margin armed with two stout
plumose setae, the proximal third with a few fine hairs ; inner
margin and apex each armed with two stout plumose seta?.

First basal segment of left fifth leg subquadrate, having
near the inner apical angle a large tubercle bearing a few
rather long hairs. Second basal segment somewhat narrower
than the preceding and not twice as long as wide ; armed at
the outer apical angle with a prominent hyaline process.
First segment of outer ramus subquadrate, rather more than
twice as long as wide ; armed on the inner margin, at the be-
ginning of the distal third, with a small process provided with
hairs, and at the outer apical angle with a short blunt spine
and a long stout movable spine serrate on the inner. margin.
Second and third segments ankylosed, forming one very long
narrow segment, slightly narrower than the first and more
than twice as long ; provided for the greater part of the inner
margin with hairs, and armed on the outer margin with three
spines, the upper two similar to the larger one of the preced-
ing segment, the third sometimes serrate on both margins ;
provided at the inner apical angle with a narrow digitiform
process about half as long as the segment itself and serrate
on the outer margin.

Inner ramus of the left fifth leg very similar in every re-
spect to that of the right leg.

First basal segment of fifth leg of female of the ordinary
form. Second basal segment about as wide as the first and
barely twice as long as wride ; outer half of the distal margin
produced in the form of an irregularly triangular flap extend-
ing over the margin of the first segment of the outer ramus.
First segment of outer ramus quadrate, about twice as long
as wide ; armed at the outer apical angle with a stout spine
serrate on the inner margin. Second segment somewhat nar-
rower than the first and not quite twice as long as wide ;
armed with hairs on both margins and at the outer apical
angle with one short spine and a longer, stouter one serrate

242 Illinois State Laboratory of Natural History.

on the inner margins ; inner apical angle produced in the form
of a moderately curved hook armed on both margins with
spines or teeth. Third segment narrower than the second
and fully three times as long as wide ; hairy on the upper
part of both margins, and armed on the outer margin, at the
beginning of the distal third, with two spines, one stout and
serrate and the other short and smooth; outer apical angle
armed with three spines, two short and smooth, the other
long and serrate on the inner margin ; inner margin sulcate,
and armed with two stout plumose setae ; apex armed with
two setre, the inner seta plumose on both margins, the outer
plumose on the inner margin and provided on the outer with
a hyaline lamina.

Inner ramus of fifth leg of female three- segmented. First
segment hairy on the outer margin ; outer apical angle armed
with a moderately stout plumose seta. Second segment sub-
quadrate, more than twice as long as wide ; hairy on both
margins ; armed at the outer apical angle with a plumose seta.
Third segment somewhat longer and broader than the second ;
margins sulcate, both hairy at the upper part ; armed with six
stout plumose seta', two apical and two on each margin.

Length of female 2.2 — 2.6 mm.; that of male 2.05 — 2.4
mm.

The above description was prepared from specimen- of
]j. macrurus sent by Professor Sars to the Illinois State Labor-
atory of Natural History, and from specimens of L. grimaldii
kindly sent by him to me. Nothing further need be said about
L. macrurus, the type of the genus, except in regard to syn-
onymy and distribution.

The original description of the species appeared in the
" Forhandlinger i Yidenskabs-Selskabet i Christiana " (Sars
'02). De Guerne ('86) described it under the name of ( 'entro-
pages grimaldii ; Nordqvist, in "Die Cahmiden Finlands" ('88 ),
made this a synonym of L. macrurus; and de Guerne and
Richard, in their "Revision" ('89b), acknowledged the cor-
rectness of Nordqvist's view. Recently, however, Professor
Sars, in his "Pelagic Entomostraca of the Caspian Sea"
('97), re-established de Guerne's form as a new species of

North American Centropagidce. 243

Limnocalan us, L. grimaldii de Guerne. Except for a difference
in size and in the proportions of the segments of the fifth legs
of both sexes, which segments are somewhat less robust in
the fresh-water form than in the one from the Caspian Sea,
and but for a slight though noticeable difference in the lateral
aspect of the head, the two forms exactly correspond. It
does not seem to me that such slight differences warrant the
establishment of a new variety, much less of a new species.
With the exceptions just noted, the details of structure men-
tioned in the foregoing description are equally prominent in
both forms, as are those noted in the following discussion of
the published figures of the species.

The best illustrations of L. mqcrurus are given in "Die
Calaniden Finlands " (Nordqvist, '88) and in the "Revision
des Calanides d'eau douce" (de Guerne et Richard, '89b),
although in neither publication are they strictly correct. 1 )e
Guerne and Richard's figures of the fifth pair of legs of the
female do not show the projection of the second basal seg-
ment over the first segment of the outer ramus, nor the hairs
on the inner margin of the second segment of this ramus and
on the third segment of the inner ramus, nor the serrations on
the spine at the outer apical angle of the last segment of the
outer ramus. Nordqvist says that the outer ramus has three
segments but figures it with two. The inner ramus he repre-
sents as smooth on the outer margin of all its segments, and
gives the ordinary form to the outer of the two setae on the
apex of the last segment of the outer ramus, while de Guerne
and Richard picture it with a hyaline lamina on both margins
and a few fine spinules on the inner margin. Neither is cor-
rect with regard to this seta, since it is plumose on the inner
margin and has a hyaline lamina on the outer one.

Both de Guerne and Richard's and Nordqvist's figures of
the fifth pair of legs of the male fail to show the hairs on the
inner margins of the inner rami, the hyaline processes on the
outer margin of the second basal segment of the left leg and
on the first segment of the right outer ramus, and the serra-
tions on the hook of the last segment of the left outer ramus.
Further, Nordqvist fails to figure the hyaline process on the

244 Illinois State Laboratory of Natural History.

second basal segment of the right leg, the two spines on the
outer margin near the base of the hook of the second seg-
ment of the right outer ramus, the serrations of the apical
spine of the second segment of the left outer ramus, and the
process on the inner margin of the first segment of the same
ramus. De Guerne and Richard omit the tubercle on the
inner apical angle of the first basal segment of the left leg,
the hairs on the inner margin of the second segment of the
left outer ramus, and the hyaline lamina on the process of
the second segment of the right outer ramus, which is figured
by Nordqvist as being on the outer margin only, while it is
really on both. Nordqvist also fails to show the spines at the
base of the outer margin of this hook.

I have had no opportunity to examine specimens of the
marine genus Centropages, but the drawings of the fifth pair
of legs of the female of L. macrurus and of C, hamatus are
so similar that it is hardly to be wondered at that de Guerne
regarded the two forms as belonging to the same genus. The
fifth pair of the legs of the males also show the same general
structure in the two genera, although they differ materially
in detail.

L. macrurus is the only species of the family Centropagida
which is common to Europe and America. This is probably
due to the fact that it occurs in both fresh and salt water,
and thus the Atlantic offers no barrier to its distribution. It
has been recorded from Sweden, Norway, and Finland, from
the Kara and Baltic Seas and the Gulf of Finland, and from
the ocean off Spitzbergen ; and it is probably widely distributed
in the countries of northern Europe and Asia. In America it
was first recorded from Lake Michigan (Forbes, '82), and
later, under the name of L. macrurus auctus, from Lake
Superior (Forbes, '90). Marsh ('93 and '95) found it in
Green Lake, Wisconsin, in Lake St. Clair, Michigan, and in
Lake Huron.

North American Centropagidce. 245

Limnocalanus sinensis Poppe.

Limnocalanus sinensis, de Guerne et Richard, 89b, p. 79, PI. IV.,

Fig. 4, 15, 15a, 16.
Linmocalwius sinensis. Herriek and Turner, '95, p. JO.

Body six- segmented, slender, more attenuate at the an-
terior than at the posterior part ; suture between' head and
thorax distinct. Second thoracic segment about as long as the
other five, which differ but little in length. Last two thoracic
segments distinct, the last segment somewhat produced pos-
teriorly and armed on each side with a short blunt spine.
First abdominal segment barely three times as long as the
second, which is but slightly longer than the fourth ; third
segment about one and three fourths times as long as the
second. Furcal rami more than twice as long as the third seg-
ment and barely four times as long as broad; somewhat
sparsely hairy within. All of the furcal seta? in both sexes dis-
tinctly plumose, the innermost seta much more slender than
the others and placed on the dorsal surface of the ramus, almost
directly opposite the base of the outer one. In the male the
first and fifth segments are subequal, each slightly longer
than the second and third, which are also about equal.
Fourth segment the shortest, about three fourths as long as
the second. Furcal rami fully three times as long as the
fourth segment, about four and a half times as long as
broad, and armed as in the female.

Antenna; 25-segmented, hardly extending to the base of
the furca. Plight antenna of the male moderately swollen
from the 12th to the 18th segments inclusive. The armature
of the segments anterior to the 10th segment is as follows:
1 1 has a sense-club and a short seta ; 12, a sense-club, a short
seta, and a short curved spine; 13, a sense-hair and a sense-
club; 14, a sense-hair, a sense-club, and a long plumose
seta; 15, a sense-hair, a sense-club, and along spine; 1(5, a
sense-hair, a sense-club, and a long plumose seta; 17 a
broad knife-like process and a sense-club; 18, a short
stunted spine, another spine somewhat longer, and a hya-
line lamina armed with teeth about half as long as the lamina
is broad ; 19, 20, and 21 (completely ankylosed), a short

246 Illinois State Laboratory of Natural History.

•stunted spine, a long plumose seta, two processes, and a
hyaline lamina armed with teeth about as long as the lamina
is wide and occupying about a third of the margin slightly
below the middle ; 22 and 23 (completely ankylosed), a short
seta, a short stunted spine, and a long plumose seta ; 24, two
long plumose setre ; and 25 (very short), three long plumose
seta- and a sense-club.

First basal segment of right fifth leg of male not characteris-
tic. Second basal segment irregular in form, about two and a
half times as long as wide, armed on the anterior aspect, below
the inner proximal angle, with a stout sharp spine, and at the
middle of the inner margin with a number of exceedingly short
hairs or spines. First segment of outer ramus narrower than
second basal segment, about one and three fourths times as
long as wide ; armed at the outer distal angle with a straight
sharp spine serrate on the inner margin. Second segment
produced in the form of a long stout sub-sigmoid hook, wid-
est some distance below the base and tapering gradually to a
rather blunt point ; inner margin of broadest part roughened
by a number of irregularly disposed ridges, otherwise both
margins perfectly smooth.

Inner ramus of right fifth leg three-segmented, the first
segment subelliptical, more than twice as long as wide, and
hairy at the middle of the inner margin. Second segment
considerably broader than the first, bulging out at the middle
and armed here with a few rather long hairs ; inner apical
angle armed with a rather short plumose seta. Third segment
subelliptical, more than twice as long as wide ; armed with six
stout plumose setre, two apical and two on each of the
lateral margins.

First basal segment of left fifth leg not characteristic.
Second basal segment about one and three fourths times as
long as wide ; armed at the outer distal angle with a plumose
seta, and at the middle of the inner margin with a few very
short hairs or spines; produced at the inner apical and
proximal angles into smooth hemispherical processes, the
lower of which is the larger. First segment of outer ramus
subquadrate, about twice as long as wide, produced at the

North, American Centropagidce. 247

middle of the inner margin into a smooth rounded process,
and armed at the outer apical angle with a stout straight
spine serrate on the inner margin. Third segment ahout
twice as long as its greatest width, dilated at the middle of
the inner margin and armed here with a few rather long
hairs ; outer margin armed with three spines similar to the
one on the preceding segment, and at the apex with a long,
narrow, slightly curved process, perfectly smooth, and some-
what longer than the segment from which it springs.

Inner ramus of left fifth leg three-segmented. First seg-
ment subquadrate, slightly more than twice as long as wide ;
provided at the middle of the inner margin with a hemispher-
ical process armed with a few scattered hairs. Second seg-
ment somewhat broader than the first and about as long ;
armed at the inner proximal angle with a small sharp spine,
and at the middle of the inner margin with two irregularly
roughened processes provided with hairs ; a long plumose seta
on the inner margin just below the lower of the two processes.
Third segment slightly narrower and shorter than the second,
both margins sulcate, armed with six stout plumose setae
arranged about as in the corresponding segment of the inner
ramus of the right leg.

First basal segment of fifth leg of female subquadrate.
Second basal segment about as wide as the first and approxi-
mately one and three fourths times as long as broad ; hairy
at the middle of the inner margin and armed on the outer
apical angle with a plumose seta. First segment of outer
ramus subquadrate, about one and three fourths times as long
as broad ; armed on the inner margin, near the proximal
angle, with a smooth hemispherical process, and on the outer
apical angle with a stout spine, serrate on the inner margin.
Second segment slightly narrower at the base than the first,
but widening distally and produced at the inner apical angle
into a stout hook-like process armed on the inner margin
with six or seven strong teeth, largest near the middle of the
hook, and near the proximal end with five or six smaller teeth.
On the outer margin of the hook and opposite the smaller
teeth of the inner margin are a number of rather minute

248 Illinois State Laboratory of Natural History.

teeth. Third segment about half as wide as the second and
approximately three times as long as its greater width ; inner
margin silicate and armed with live stout parallel plumose
setae; outer margin armed with two strong straight spines,
the upper at about the beginning of the distal third, the lower
at the apical angle, and both serrate on the inner margin.
Just within the apical spine are a short blunt process and a
long, narrow, awl-like process almost twice as long as the
segment.

Inner ramus of fifth leg of female three-segmented, the first
segment subelliptical, somewhat less than twice as long as
wide, and hairy at the middle of the inner margin. Second
segment a little wider than the first, about twice as long as
wide, hairy at the middle of the inner margin; outer apical
angle armed with a stout plumose seta. Third segment about
as wide as the first, margins sulcate ; armed with six stout
plumose seta?, two apical and two on each side.

Length of female about 1.65 mm. ; that of the male
1.60 mm.*

The above description is based on specimens kindly sent
me by Herr S. A. Poppe. On examination I found a few
minor differences between the specimens sent me and the
original figures. These differences I note below. The second
thoracic segment instead of being only as long as the two
succeeding ones is about as long as the remainder of the
thorax. The innermost f ureal, seta is plumose instead of
smooth — as figured in the original drawings. In the fifth pair
of legs of the male the spines on the outer ramus of the left
leg were found to be serrate on the inner margin instead of
smooth. The spine or seta on the outer apical angle of the
second basal segment of this leg is plumose. The inner
margin of this segment is hairy or minutely spinose. Neither
the short hook-like spine at the inner proximal angle of the
second segment of the left inner ramus, nor the stout straight
spine (serrate on the inner margin) at the outer apical angle
of the right outer ramus is figured or described in de Guerne
and Richard's "Revision." I was unable to find the hairs

* Measurements as given in de Guerne and Richard's" Revision " (89b).

North American Ceniropagidce. 249

which Poppe figures on the inner margin of the second seg-
ment, and on the outer margin of the third segment, of the
outer ramus of the fifth leg of the female.

This species differs so much from L. macrurus, that it
might almost be regarded as the type of a new genus, but
Poppe has not considered the differences as of generic value,
nor have de Guerne and Richard. Unlike L. macrurus, the
inner rami of the fifth pair of legs of the male although both
three-segmented differ from one another, and the right outer
ramus is composed of two segments instead of three. In the
female the differences are not so striking, for while the outer
rami are noticeably unlike, the inner rami are very similar.

This species was found in Lake Sitai, China, and in the
Whangpoo River, which flows from it, the waters of both of
which are perfectly fresh. To my knowledge it has not yet
been recorded from any other locality.

Epischura Forbes.

Scopiphora ( ?), Pickering, "44, p. 62.
Epischura, Forbes, *82a. p. 647.
Epischura, Herrk-k, '83a. p. 384.
Epischura, Ilerrick, '87, p. 13.
Epischura, Herrkk and Turner, '85. p. 81.
Epischura, de Guerne et RiehanV89b, p. 141.

Cephalothorax more or less distinctly six- segmented. Ab-
domen (furca included) composed of five segments in the fe-
male and of six in the male ; in the female, of the ordinary form
(nevadensis, nordenskibldi) or flexed to the right and provided
with a process on the right side of the second segment (hiaix-
tris) ; in the male, straight or very slightly flexed (nordenski-
oldi) or strongly flexed to the right (lacustris, nevadensis) ; in
the males of all species, second, third, and fifth segments pro-
vided on the right side with processes. Furcal rami hairy
on the inner margin, provided in both sexes with three plu-
mose terminal setae, one slender simple seta at the inner
apical angle, and a stout spine at the outer apical angle.

First pair of antennae 25-segmented. Right male antenna
geniculate between the 18th and 19th segments; segments

250 Illinois State Laboratory of Natural History.

19 — 21, and 22 and 23 ankylosed ; antepenultimate segment
unarmed ; segments preceding geniculation very slightly
swollen. Second pair of antenna! about as in Diaptomus.

All the swimming legs biramose, the outer ramus three-
segmented, the inner, one-segmented. Fifth pair of legs of
the female alike, uniramose, three-segmented, the first seg-
ment of the ramus being, however, really the second basal
segment ; armed at the outer apical angle with a hair or deli-
cate spine. Third segment armed with a varying number of
spines (5 — 7).

Fifth pair of legs of the male unlike, uniramose, modified
into a grasping organ. Eight leg two- (lacustris, nevadensis)
or three-segmented (nordenskioldi); last segment almost
always flexed. Left leg three-segmented, the first segment
produced on the inner margin to form a strong hook-like
process ; last segment variously armed on the outer margin
with a number of spines, and provided on the inner margin
with fine long hairs.

Female generally bears spermatophore, and does not carry

eggs m egg- sac.

Inhabits* deep fresh water lakes.

As will be seen from the above, the doubtful E. fiuviatilis
Herrick has not been considered in this description, but only
the three recognized species, lacustris, nevadensis, and norden-
skioldi.

The species of this genus seem not to be fully differentiated
from each other. This is illustrated by the variable armature
of the fifth pair of legs of the females, nevadensis having
sometimes one and sometimes two spines at the outer apical
angle of the second segment and either six or seven spines on
the last segment, and nordenskioldi also varying in the latter
respect, having sometimes five and sometimes six spines.
All female specimens of lacustris observed, were constant in
the armature of the fifth legs, but in the left fifth leg of the
male the second segment, although generally unarmed, was
sometimes provided at the outer apical angle with a small
spine.

This genus, confined so far as known to North America,

North American Centropagidce. 251

and represented in different sections by different species, is
found from Newfoundland on the north and east to Wash-
ington on the west, and as far south as central Illinois and
Indiana.

KEY TO THE SPECIES OF EPISCHUBA.

Based on the Characters of the Female.

1 (2). Abdomen flexed to the right ; second segment armed

on the right side with a process. Furcal setae and
spines very broad. Fifth leg with last segment twice
as long as the first ; last segment armed with seven
spines. lacustris.

2 (1). Abdomen straight; second segment unarmed. Fur-

cal seta? and spines of ordinary width.

3 (4). Fifth legs very robust, first segment almost as wide

as long ; second segment sometimes armed with two
spines; third segment armed with six (occasionally
seven) spines. nevadensis.

4 (3). Fifth legs slender, first segment considerably longer

than wide ; second segment armed with a single small
spine ; third segment armed with five (sometimes six)
spines. nordenskioldi.

Based, on the Characters of the Male.

1 (2). Abdomen straight, abdominal processes small and

inconspicuous. Eight leg three-segmented, the first
segment armed on the inner margin with a hook ; sec-
ond and third segments armed at the outer apical angle
with a small spine. Process on first segment of left
leg but slightly curved. nordenskioldi.

2 (1). Abdomen flexed to the right; abdominal processes

large. Eight leg two-segmented.

3 (4). First segment of right leg with subtriangular toothed

plate on the inner margin, and a hair at the outer
apical angle. First segment of left leg very stout and
strongly curved ; second segment unarmed.

nevadensis.

252 Illinois State Laboratory of Natural History.

4 (3). First segment of right leg entirely unarmed. First
segment of left leg with comparatively slender process ;
second segment armed at the outer apical angle with a
small spine. lacustris.

Epischura nordenskioldi Lilljeborg.

Epischura nordenskioldi, de Guerne et Richard. 'e9b, p. 04, PI. I.

Fig. 36; Pi. II., Fig. If), 23.
Epischura nordenskioldi, Herrick and Turner, '95, p. 85, Pi. XI.. Fig.

2, 5, 9.
Epischura nordenskioldi. Schrneil. '9S. p. 183.

About medium size, body rather robust, widest in front of
middle. Cephalothorax six-segmented, the first two segments
confluent and together somewhat longer than the remainder;
third segment slightly longer than either of the last three,
which are subequal ; last two segments distinct, the last
segment produced on each side at the posterior angle into
a bluntly-rounded lobe armed at the tip with a minute
spine. Abdomen (including furca) five-segmented, slender.
a little less than half as long as the cephalothorax ; first two
segments indistinctly confluent below ; third segment slightly
longer than the fourth. Furcal rami about twice as long as
broad and ciliate on the inner margin ; armed at the apex
with three slender plumose setae fully three times as long as
the ramus itself, at the outer apical angle with a short stout
spine, and on the dorsal surface, near the inner margin, with
a delicate smooth seta. Abdomen of male (furca included)
six-segmented, the second, third, and fifth segments armed on
the right side with prehensile processes ; flexed to the right but
slightly or not at all. First segment somewhat broader than
long, slightly produced along the left margin into a process
ending at the posterior angle in a lobe-like expansion. Sec-
ond segment slightly narrower and longer than the first ; pro-
duced on the right side in the form of a subtriangular plate,
somewhat longer than w7ide and pointing obliquely backward.
The process is armed at the tip with a small sharp spine,
on the inner margin, near the apex, with two or three rather
large teeth, and within these with a number of smaller

North American Centropagidce. 253

ones. Third segment slightly shorter than the preceding;
process very simple, small and inconspicuous, bluntly pointed,
extending almost straight backward ; armed on outer margin,
near the tip, with a slight, blunt protuberance. Fourth seg-
ment unarmed, about half the length of the first. Fifth
segment about as long as the fourth ; armed with a narrow
triangular plate, broadest anteriorly and bluntly rounded at
the apex. Dextral margins of the fourth and fifth segments
tuberculate. Furcal rami about as in the female.

Antenna? 25-segmented, extending almost to the base of the
furca. Eight antenna of the male geniculate between the
18th and 19th segments ; segments preceding the geniculation
slightly or not at all swollen.

Eight fifth leg of the male three-segmented. First seg-
ment irregular in form, about twice as long as wide, armed
on the outer margin, near the distal angle, with the usual deli-
cate hair ; inner margin provided with a curious, smooth,
bluntly-pointed hook-like process extending downward almost
parallel to the margin. Second segment irregular, about
twice as long as wide ; outer margin smoothly convex, armed
near the distal angle with a small spine ; outline of inner
margin sinuous. Third segment long and narrow, with a
broad basal portion about half as wide as the segment is long ;
curved inward slightly at the tip and armed here, on the outer
margin, with a minute spine.

First segment of left fifth leg with a subquadrate main por-
tion produced on the inner margin into a long, smooth broad
hook but slightly curved ; armed at the outer distal angle
with the usual hair. Second segment somewhat narrower
than the first, subquadrate, about twice as long as wide ; outer
distal angle armed with a small sharp spine; inner margin
sometimes with indications of minute teeth or serrations at
about the middle. Third segment curved inward slightly,
about as broad as the second and fully four times as long as
broad ; armed on the outer margin with four rather small
sharp spines, the first at about the middle, the second midway
between this and the apex of the segment, the other two near
the apex and nearer together than the upper ones ; armed on

254 Illinois State Laboratory of Natural History.

the distal part of the inner margin with long delicate hairs.
This segment is much simpler than the corresponding seg-
ment of lacustris and nevadensis.

Fifth pair of legs of the female imiramose, three-segmented.
First segment subquadrate, somewhat longer than wide,
armed near the outer distal angle with a hair or delicate
spine. Second segment somewhat narrower than the first
and slightly longer ; armed at the outer apical angle with a
small sharp spine. Third segment slightly narrower than
the second and barely one and a half times as long ; armed
with five or six spines*, two (one) outer, one inner, and three
apical. Of the outer spines, the upper one is at about the mid-
dle of the segment and the lower one is directly opposite the
inner spine. Of the apical spines, the middle one is spinu-
lose on both margins and the outer one on the inner margin. +

Length of female 1.9 mm. ;t that of male 1.1 mm.

The above description was prepared from specimens kindly
sent me by Dr. Lillejeborg, the measurements, however, with
the modification explained in the foot-note, being those given
in the original description. The material was a part of that
collected by Dr. C Xystrom, a member of the Xordenskiold
expedition to Greenland in 1871, and was not in the best
state of preservation, owing no doubt to the length of time
since its collection.

Figures of this species may be found in de Guerne and
Richard's "Revision" ('89b), and imperfect copies of these
in Herrick's "Synopsis" (Herrick and Turner '95). The
fifth pair of legs of the male are correctly represented in the
"lievision" except that the spine at the outer apical angle of
the right leg is not shown ; indeed it is not mentioned in the
description. The spine figured on the outer margin of the

* The armature of this --eminent differs somewhat in different specimens. See on
a subsequent page the discussion in regard to the fifth leg of the female.

t Having only a few specimens to study. I could not satisfactorily determine
whether the other spines were also spinulose or not. but I am quite positive with re-
gard to the two mentioned. I think it likely that they are armed as in lacustris.

i It is quite evident that a mistake was made in regard to the measurements given
in the original description: " Length of female, caudal seta' excepted, about 3.9 mm.,
and of male 1.1 mm." In the specimens I examined there was no such difference in
length in favor of the female; in fact the single entire female I had the opportunity
to measure was 1.333 mm. in length, while the average length of five males was con-
siderably above this— 1.698 mm. I have hesitated to substitute these measurements
because of the limited number examined, and have altered Lillejeborg's figures to
what I think they were intended to he.

North American Centropagidce. 255

•

second segment of the right leg, which Schmeil ('98) says he
could not find, was present in all the specimens examined by
the writer. In one of the two specimens of females examined
the last segment of the fifth leg was armed with five spines,
as shown in the original figures, while the other had six.
I think that six may perhaps be found to be the rule, in
which case the species approaches nevadensis and laeustris
more closely, the former having six and sometimes seven
spines, and the latter constantly seven. The fact that none
of the other writers, Lilljeborg, de Guerne and Richard, and
Schmeil, have mentioned the existence of a sixth spine would,
however, militate against this assumption.

The male of nordenskioldi is very easily distinguished from
the males of the other two species. The fifth pair of legs,
while of the same general type as in the rest of the genus, are
less modified and yet very characteristic. But for the fact
that it is, as a rule, difficult to make out, the hook-like process
on the first segment of the right leg would alone serve to
distinguish nordenskioldi. Further, the right leg is three-
segmented instead of two ; the last segment is armed on the
outer margin, at the apex, with a small spine ; and the hook
on the first segment of the left leg is comparatively simple.'
The abdomen is also less modified than that of nevadensis
and laeustris. Instead of being quite strongly flexed to the
right it is almost or entirely straight, while the processes are
small and inconspicuous, there being some difficulty in dis-
cerning the one on the fifth segment.

The fifth pair of legs of the female also serve, though not
so readily, to distinguish this species. They differ from those
of laeustris in that the last segment is armed with only five or
six spines, instead of seven, and in the relative length of the
segments. From the fifth legs of nevadensis they may be
distinguished by the difference in proportions, those of neva-
densis being much more robust than those of nordenskioldi,
which are intermediate between the other two. The different
arrangement of the spines on the last segment, the occasional
absence of the sixth spine on this segment, and the presence,
at least occasionally, of a second spine at the outer apical

256 Illinois State Laboratory of Natural History.

angle of the second segment of the leg of nevadensis, will all
assist in determining the species.

De Guerne and Richard (89b) make the statement that tin-
females always have the spermatophore — which they describe
as curved in a semicircle around the abdomen — attached. ( hi
none of the females examined by the writer was this structure
present. It may of course have been torn off, although
even then the statement that it is always present seems to
me too strong, since in E. lacustris and E. nevadensis the
female, even when mature, is very often found without a
spermatophore.

Epischura nevadensis Lilljeborg.

Epischura nevadensis , de Guerne et Richard, "89b, p. 93. PI. II., Fig.

17.24; PJ. III., Fig. 21.
Epischura nevadensis columbice, Forbes/93. p. 254. PI. XLL, Fig. 19-21.
Epischura nevadensis, Herrick and Turner, '95. p. 84. PI. XL, Fig.

1, 6, 8.
Epischura nevadensis columbice, Herrick and Turner. '95, p. 84. PJ.

XL, Fig. 4, 10.
Epischura nevadensis, Schmeil, '97, p. 183.

Of medium size and somewhat oval in form, broadest
before the middle. Front armed on each side with a hook-
like process pointing downward. Cephalothorax six-seg-
mented, the second segment the longest, about twice as long
as the first or last, which are subequal, the remaining three
segments subequal, each about a fourth the length of the
second. First two segments somewhat confluent, as are the
last two; last segment, seen from above, not produced and
entirely unarmed. Abdomen (furca included) composed of
five segments, the first two confluent and together almost as
long as the two following, which are subequal and slightly
longer than the furca. Furcal rami subquadrate, very short
and broad, and provided on the posterior part of the inner
margin with a few fine hairs ; armed at the outer apical angle
with a stout pointed spine, and at the inner apical angle with
a slender smooth seta, posterior margin armed with three long
delicately plumose setae, of which the inner is the longest,
the other two being about equal. In the male the abdo-

North American < 'entrap a g idee. 257

men is asymmetrical, flexed to the right, and consists of six
segments (furca included). The segments vary but little
in length, the furca being, however, the shortest, the fifth,
second, and first increasing in length in the order of their
mention, the third and fourth subequal, each slightly longer
than the first. Seen from above, the first segment is pro-
duced slightly to the left at its posterior margin. Second,
third, and fifth segments armed with processes on the right
side. The process on the second segment is a broad thin
lamina about as long as the segment is broad, smooth on the
convex anterior margin and for about the distal fourth of its
posterior margin (which is almost straight), but for the re-
maining three fourths of this margin provided with minute
irregular teeth having a tendency to point toward the abdo-
men; apex acute and slightly recurved. The process on the
third segment springs from the posterior part as a broadly
rounded smooth hyaline lamina slightly longer than broad.
Fourth segment unarmed. Fifth segment provided with two
processes, the anterior one (pointing forward and upward)
consisting of a narrow irregularly triangular plate with an
acute apex and smooth margins, the posterior one having the
form of a truncated triangle, armed at the apical margin with
three or four large equal teeth and one or two much smaller
ones. Posterior to this process the right margin of the seg-
ment is armed with a row of bead-like tubercles which, near
the suture between the furca and this segment, lengthen to
form two or three blunt spines. Furcal rami slightly longer
proportionally than in the female, but similar in other respects.

Antenna; 25 - segmented, long and slender, extending
slightly beyond the posterior end of the third abdominal seg-
ment in the female and beyond the fourth segment in the
male. Right male antenna geniculate between the 18th and
19th segments; segments 19, 20 and 21, and 22 and 23
ankylosed ; antepenultimate article unarmed.

Right fifth leg of male two-segmented. First segment
irregularly pentagonal, the longest base forming the outer
margin, which is armed near the distal angle with a delicate
seta; basal half of inner margin armed with a broad irregu-

258 Illinois State Laboratory of Natural History.

lar hyaline plate which near its middle is somewhat produced
and provided with a number of delicate serrations. Second
segment consists of a broader basal portion and a narrow
terminal part, the latter constituting about three fourths the
entire length, and extending upward to the middle of the
inner margin of the preceding segment ; apex produced at
the inner margin, forming a kind of hook.

Left fifth leg uniramose, three-segmented. First segment
armed near the outer apical angle with a delicate seta and
produced on the inner margin into a large plate-like hook
almost as broad as the segment and strongly curved inward.
Second segment irregular in shape, slightly longer than broad,
and unarmed.* Third segment or terminal hook contorted,
about twice as long as the second segment; basal portion
broad, with a projecting inner angle ; inner margin sinuous,
the lower curve densely provided with fine long hairs ; outer
margin armed with three short, sharp unequal spines increas-
ing in size from above downwards ; the attenuate apex pro-
vided with a spine considerably larger than the others.

Fifth leg of female uniramose, three-segmented. First
segment subquadrate, with flaring sides; armed near the
outer apical angle with a rather delicate smooth seta. Sec-
ond segment subquadrate, about one and a half times as long
as the first and about two and a half times as long as broad ;
armed at the outer distal angle with a short sharp spine
(occasionally with two subequal spines). Third segment
(terminal spines excluded) about as long and wide as the
second ; outer margin armed with a short sharp spine at
about the beginning of the distal half (another spine occa-
sionally present a short distance above this); apex provided
with three spines, the two outer ones subequal and the mid-
dle one considerably larger ; inner margin armed with two
spines near the apex of the segment, the upper about half
the size of the lower, and the margins of both denticulate.

Length of female 2-2.5 mm.; that of male 1.7-2.1 mm.

The above description is based on type specimens of E.

i mi one or two specimens I noticed <iu>te a larsje tubercle, with a roughened up,
projecting from the anterior aspectof tins segment near the outer proximal ai

Out did not ti nt 1 it at all constant.

North American Centropagidce. 259

nevadensis Columbia Forbes; on other specimens collected in
the same localities — Swan Lake and Flathead Lake, Montana ;
and on specimens from Gamble's Lake and Lake Pend
d'Oreille, Idaho, from Lake Tahkemitch and Tsiltcoos Lake,
Oregon, and from Lake Union and Lake Washington, Wash-
ington, sent to the State Laboratory by Messrs. Evermann
and Meek of the U. S. Fish Commission. I had also a large
number of the Nevada form kindly sent me by Prof. Lillje-
borg, but, unfortunately, there was not a single mature indi-
vidual in this lot, and for this reason I cannot say on my own
responsibility that E. nevadensis Lilljeborg and E. nevaden-
sis Columbia Forbes are identical. A careful examination of
the material at hand, however, inclined me to that belief, and,
moreover, Professor Schmeil, both in a personal letter and
later in the "Bibliotheka Zoologica " (Schmeil, '97) says that
they are, after having examined authentic specimens from
both localities. He states also that Professor Forbes was
perfectly justified in establishing his Columbia, as a new
variety, since Lilljeborg's descriptions and figures are inac-
curate in several respects. In the following paragraph are
given the points in which my observations differ from those
of Forbes and of Lilljeborg.

In all the specimens examined the segments of the fifth leg
of the female are proportionately longer and narrower than
figured by Lilljeborg. This fact may be due to his having
.made his drawings from an individual not perfectly matured.
This difference was noted by Forbes in his description of
Columbia ('93). The appendage near the outer distal angle
of the first segment of this leg is correctly drawn as a seta by
Lilljeborg, while Forbes's figure represents it as spine-like.
The fact that a second spine is occasionally found at the outer
distal angle of the second segment must have been observed
by Lilljeborg, since his drawings show it, although no mention
of it is made in the original description of nevadensis (de
Guerne et Richard, '89b). Forbes refers to it in his descrip-
tion of Columbia? but does not figure it. A seventh spine on
the outer margin of the last segment was correctly said by
Forbes to be occasionally present. Lilljeborg does not seem

260 Illinois State Laboratory of Natural History.

to have found this spine, but Schmeil confirms Forbes's state-
ment. The inner two spines on the last segment are serrate
on both margins, but this fact is shown in none of the figures,
nor is it mentioned in the literature referred to. The first
segments of the fifth pair of legs in the male are each provided
with a rather delicate seta near the outer distal angle. This
is shown in the published figures, but Lilljeborg mentioned
only the one on the left leg. The ordinary appearance of the
lamina of the second segment of the right leg is best shown in
Forbes's figures.

This species is quite common in the western United States,
having been found to occur in considerable quantities in col-
lections from Nevada, Idaho, Oregon, Washington, and Mon-
tana, and further collections will no doubt show a still more
general distribution. It occurred in collections with Diap-
tomus ashlandi Marsh and with I), minutus Lilljeborg.

Epischura lacustris Fokbes.

Scopiphora vagans (?), Pickering. *4-l, p. 62.

Epischura lacustris. Forbes, '82a, p. 648, PI. VIII., Fig. 15, 16, 21-23.

25-27; P). IX., Fig. 8.
Epischura lacustris, Herrick, '84, p. 131, PI. Q, Fig. 15.
Epischura lacustris, de Guerne et Richard, "89b, p. 90, PJ. IV.. Fig.

3, 9, 10.
Epischura lacustris, Forbes, '90, p. 704, PL I., Fig. 1-5; PI. II., Fig. 7.
Ejrischura lacustris. Forbes, '93, p. 255.
Epischura lacustris, Marsh, "93, p. 200, PI. IV., Fig. 6.
Epischura lacustris, Marsh, '95. p. 10, PI. II., Fig. 1-6; PI. III., Fig

1-6.
Epischura lacustris, Herrick and Turner, '95, p. 82. PI. XIII., Fig.

15.

Of medium size. Body elliptical, widest before the middle.
Cephalothorax composed of six segments, the first two sub-
equal and together somewhat longer than the remaining four.
Third, fourth, and fifth segments subequal and together about
equal to the first. Sixth segment slightly longer than any of
the three preceding ; not produced laterally. Abdomen flexed
to the right, the first segment very short. Second segment the
longest and about equal to the remainder of the abdomen

North American Centropagidce. 261

(furca included) ; produced on the right side into a slight
semicircular process. Third segment and furcal rami sub-
equal, each slightly longer than the fourth segment. Furcal
rami very broad and delicately hairy within ; armed at the
outer apical angle with a short, sharp broad spine (the one
on the right ramus the larger), and within this with three
delicately plumose apical setpe, the outer of which, at the base
and for a considerable part of its length, is even broader than
the spine but gradually tapers and ends in a delicate flagellum,
while the other two sets are much narrower than the outer
seta but about as long. At the inner apical angle is a much
smaller delicate smooth seta. Abdomen of male much
more strongly flexed to the right than that of female, com-
posed of six segments (furca included), the second, third,
and fifth produced on the right side. First segment short,
about twice as broad as long. Second segment somewhat
longer than the first, the process about as long as the segment
is wide, with a smooth anterior margin and an irregularly
serrate inner margin with a hooked tip. Third segment about
as long as the first ; process about as long as the segment,
..of nearly the same width throughout, the tip bluntly rounded
and armed anteriorly with a hemispherical tuberculate
cushion or pad, and on the posterior margin, almost opposite,
with another similar process. Fourth segment slightly longer
than the third, and unarmed. Fifth segment slightly shorter
than the fourth and armed with two processes, the anterior
of which is perfectly smooth, pointing forward and to the
right, the posterior one pointing almost straight to the right,,
armed on the anterior margin with a number of large teeth
(8 — 10), its posterior margin smooth at the tip but minutely
denticulate for the basal three fourths. Furcal rami armed
about as in the female but with no such difference in the width
of the apical setae and with narrower spines.

Antennas 2 5 -segmented, extending to the posterior margin
of the fourth abdominal segment. Right male antenna slen-
der, geniculate between the 18th and 19th segments; seg-
ments 19 — 21, and 22 and 23 ankylosed ; antepenultimate
segment without special armature.

"2i)"2 Illinois State Laboratory of Natural History.

Left fifth leg of male uniramose, three-segmented. Firsl
s< gment subquadrate, produced on the inner margin into a
long, broad, strongly curved hook-like process about twice as
long as the main part of the segment and armed at the tip
with a broad blunt spine; provided at the outer apical angle
with a rather stout hair or spine. Second segment about as
long as the first but much narrower; margins parallel, the
inner margin concave ; usually unarmed but sometimes pro-
vided at the outer apical angle with a minute sharp spine.
Third segment irregularly triangular in form and about one
and a half times as long as the second, somewhat produced
at the inner proximal angle ; armed at the tip with a short
broad spine, on the outer margin with three spines, dividing
it approximately into thirds, and on the inner margin with a
close row of long delicate hairs.

Eight fifth leg uniramose, two-segmented. First segment
irregular in form, the outer margin almost straight, the inner
produced on the lower half into a large lamella or rlat
process* ; usual seta at the outer apical angle wanting. The
second segment consists of a broader basal and a narrower
terminal part which is always rlexed inward and upward;.*
inner margin slightly produced at the tip.

Fifth leg of female uniramose, three-segmented. First
segment barrel-shaped, armed at the outer apical angle with
a delicate spine. Second segment about half as wide as the
first and about three times as long as wide : armed at the
outer distal angle with a minute spine. Third segment
slightly narrower than the second and about one and a half
times as long; armed on the outer margin with three spine>
(the upper two smooth, the lower one spinulose) ; on the
apical margin with three spines (the outer two spinulose on
their opposed margins and the inner one on both), and on th-
inner margin with one spine, spinulose on the inner margin.

Length of female 1.784 mm. ; that of male 1.370 mm.

The above description was prepared from type specimens,
from Dr. Forbes's slides, from specimens taken in the same

*In one or twn specimens I thought I saw indications of several teeth, similar to
those in E. nevadensis, but could not fully satisfy myself of their presence.

North American Centropagidce. 263

Ideality as the type, — Normal, 111., — and from other speci-
mens collected at various times and places in Illinois, Indiana,
and Michigan.

This species, the type of the genus, was first described in
the "American Naturalist" (Forbes, '82a), and de Guerne
and Richard, Forbes, Herrick, and Marsh have since published
descriptions and figures. Scopiphora vagans Pickering is, as
de Guerne and Richard, Herrick, and Marsh have said,
probably identical with Epischura lacustris, but this can never
be definitely determined since the following quotation is all
that has been published concerning S. vagans.

"Genus Scopiphora, Pickering. Body small. Eye single,
in the anterior margin of the shield. Antenna; large, and as
long as in the preceding genus ^Cyclops], and has the same
motions in the water. Abdomen terminating in two styles
each with three setie; a brush under the last or last three
joints. Ovaries none. Legs spiny.

" S. vegans (Pickering) MSS."*

This is, of course, too meager a description upon which to
establish a genus, and the writers mentioned above, as well
as Dr. Schmeil ('98), have considered it insufficient and
allowed Forbes's name to stand. Herrick explains the "brush"
as some parasitic growth. May it not rather have been the
fifth, and perhaps the fourth, pair of legs projecting straight
backward under the abdomen which caused this appearance?

In the following three paragraphs are noted the points in
which my observations differ from those of previous writers
as shown by their descriptions and figures.

The abdomen of the male is very complicated in its seg-
mentation, and in the original description (Forties, '82a) was
described as having processes on the second, third, fourth,
and fifth segments. All figures published previous to the
appearance of " A Preliminary Report on the Aquatic In-
vertebrate Fauna of the Yellowstone National Park, etc."
(Forbes, '93), including those of de Guerne and Richard's
" Revision," were incorrect. In Forbes's paper attention was
called to the fact that the fourth segment was without a

* See Pickering, '44.

'2(')4 Illinois State Laboratory of Natural History.

process but that the fifth had two as in all the other species,
and in the same year Marsh in his " Cyclopidae and Calanidae
of Central Wisconsin" ('93), published the first correct figure
of the abdomen, but seems to have been unaware of it, since
in his "Cyclopidae and Calanidae of Lake St. Clair" ('95) he
says,'' Forbes has recently called attention to the fact that the
fourth abdominal segment of the male is without a process
and that the fifth bears two processes." His figure in this
paper also ('95) is correct.

The armature of the fifth leg of the female is nowhere
represented with exact correctness. The first segment is cor-
rectly figured by Forbes ('90) and by de Guerne and Richard
in their " Revision," with a spine at the outer apical angle, but
this is wanting in Marsh's figure ('95). The second segment
is correctly shown in all the illustrations. The third segment,
which has three outer spines, three apical ones, and one inner
spine, is represented in all the figures without the upper spine
on the outer margin. The armature of the spines themselves
is nowhere correctly shown, the differences being evident by
comparing the specific description with the drawings.

The left fifth leg of the male is usually represented with the
outer apical angle of the first segment unarmed ; de Guerne
and Richard, however, figure this correctly. The second seg-
ment is often armed with a spine at the outer apical angle,
but this is wanting in all of the figures ; nor are the three
spines on the outer margin of the third segment shown, there
being in most cases only one but sometimes two. The right
leg is correct in all the figures.

The spermatophore is very persistent, and a female is rarely
found without one or several. In this species it is a long tube-
like sac extending upward and to the left under the abdomen,
differing considerably from the same appendage in E. neva-
densis, in which it extends downward and backward, and
when in position has somewhat the appearance of a keel. It
is also much longer in E. lacustris than in E. nevadensis.

/•.'. lacustris is quite common in the North Central States,
being found in the deeper, clearer lakes in connection with
Limnocalanus macrurus Sars, Diaptomus sicilis Forbes, 1>.

North American Centropagidce. 265

ashlandi Marsh, D. pallidus Herrick, or D. siciloides, I), on
gonensis, and 1>. nlinutus, Lilljeborg, and sometimes with two
or more of these species. It has been found in Illinois,
Indiana, Ohio, Minnesota, Michigan, Wisconsin, and also at
East Portland, Oregon.

DOUBTFUL SPECIES.

Epischura fluviatilis Heerick.

Epischurafluviatilis, Herrick, '83a, p. 381. PI. V.. Fig. 10-20.
Epischura fluviatilis, Herrick, "84, p. 133. PI. Q, Fig. 14-16.
Epischurafluviatilis, Herrick, '87, p. 13, PI. II., Fig. 21-24.
Epischurafluviatilis, de Guerne et Richard, ?89b, p. 92, PI. IV., Fig.

13. 20.
Epischurafluviatilis, Forbes. "93. p. 254 (foot-note).
Epischurafluviatilis,. Herrick and Turner, '95, p. 83, PI. XIII., Fig.

14-16.
Lamellipodia [Epischura] fluviatilis. Sehrneil, "98, p. 183.

Of small size, body rather slender ; color greenish- blue.
Cephalothorax imperfectly six-segmented. Abdomen three-
segmented, differing in no way from that of Diaptomus except
in the number of f ureal seta?. In the male the second abdom-
inal segment bears on its left side a peculiar process con-
sisting of two parts forming a clasping organ, the inner part
of which is about as long as the third segment and armed at
the apex with two small spines, the outer part being slender,
curved, and about twice as long as the inner.

Antennae 25-segmented, extending somewhat beyond the
end of the thorax. Eight male antenna geniculate between
the 18 and 19th segments; last six segments not ankylosed,
enlarged portion not greatly swollen.

Swimming legs biramose, the outer ramus consisting of
three segments, the inner ramus of one segment. Basal seg-
ments of the two legs fused beyond the last.

Fifth pair of legs of male uniramose, the two basal seg-
ments entirely fused. Eight fifth leg three-segmented, the
first two segments subquadrate and subequal, about three
times as long as wide and entirely unarmed. Third segment
slightly longer and broader than the second, tapering to a

266 Illinois State Laboratory or' Natural History.

blunt point and armed on the outer margin with three spines.

Left fifth leg very peculiar, consisting of a single lamelli-
form subcircular segment, armed on the flat surface with two
opposable claws forming a forcipate structure.

Fifth pair of legs of female uniramose, three-segmented
(two basal segments). First segment about twice as long as
broad. Second segment narrower than the preceding and
about twice as long ; armed at about the middle of the outer
margin with a spine. Third segment curved inward, some-
what longer and narrower than the second, ending in a sharp
point, and armed on the outer margin with two spines divid-
ing it approximately into thirds.

Mulberry Creek, Cullman county, Alabama.

Length, about 1.103 mm.

The above description was compiled .from drawings and
descriptions found in Herrick's writings (Herrick, '83a, '84,
and '87, and Herrick and Turner, '95), since all attempts to
obtain material from Cullman county, Ala., or from any
other part of that State, were unsuccessful.

A brief discussion of the published figures and descriptions
will not be superfluous in connection with' a doubtful species.
In the American Naturalist, Vol. 17 (Herrick, '83a), is pub-
lished the original description of E. fluviatilis, and a figure
representing apparently a ventral view of the last thoracic
segment and abdomen, and the fifth pair of legs of the male.
In this drawing the process on the third segment is on the
right side, making it sinistral in the animal as Herrick says
it is ; but in his " List of Fresh-water and Marine Crustacea
of Alabama" ('87) he gives another figure, which is just as
apparently a ventral view of the same thing. In ttris latter
figure, however, the process is sinistral, making it dextral in
the animal, and also making the left leg three-segmented
and the right leg one- segmented. Two other figures (Her-
rick, '84 and Herrick and Turner, '95) also show the process
on the right side, but there is nothing to indicate whether
they are dorsal or ventral views.

Now, in regard to the synonymy. If the process is on the
left side, as is maintained in all of Herrick's descriptions, this

North American Centropagitke. 267

species cannot belong to the genus Epischura, as has already
been pointed out by Forbes ('93, p. 254) and Schmeil ('98),
since the process cannot be homologized with the similar
process in Epischura proper. If, however, the process is
dextral, as shown in three out of the four figures published,
it might be more easily homologized with the process in the
other species of the genus. It would also be more likely that
the left leg was three-segmented and the right one especially
modified into a clasping organ if E.fluviatilis belonged to this
genus, although even then the fact that the second segment
of the left (right ?) leg is not at all produced inwardly and the
structure of the right (left ?) leg is radically different would
present difficulties. The fifth legs of the female are very
similar to those of Epischura, but partake slightly of the
characters of Heterocope. Schmeil says ('98) that, judging
from analogy with other genera, there is one basal segment
too many in the fifth pair of legs of both sexes. Herrick, in
the " American Naturalist" (Herrick, '83), gives a drawing of
a swimming leg of E.fluviatilis, with its one-segmented inner
ramus, which, if the upper, incomplete part shown is to be
regarded as another segment, certainly gives it, as Schmeil
says, one too many segments. If, however, it is an adhering
part of the thoracic segment, it will differ from a swimming
leg of E. lacustris only in that in lacustris the first basal seg-
ments instead of being fused their entire length, as in fluvia-
tilis, are fused for about the basal two fifths only. The fifth
legs of both sexes are similar in arrangement to the above,
although on account of the absence of an inner ramus it is
less evident. I believe that the appendage figured at the'
outer apical angle of the furca is intended for a spine, rather
than a seta as Schmeil supposes it to be. From this it will
be seen that the drawings and descriptions conflict, and Dr.
Schmeil was perhaps justified in proposing to establish a new
genus, Lamellipodia, to receive this species. It seems to me,
however, that it would be better to wait until material col-
lected in the same locality and described and figured by a
more careful observer has determined whether or not this
species is a good one, and I have hesitated, therefore, to
adopt a new name for a form the description of which, to use
Marsh's words in regard to Scopiphora vagans Pickering, " is
manifestly inaccurate in some particulars, and maybe in all."

268 Illinois S%(tc Laboratory of Natural History.

ADDITIONS TO THE BIBLIOGRAPHICAL LIST
PUBLISHED IN ARTICLE III.

Birge, E. A.
'97. The Vertical Distribution of the Limnetic Crustacea of Lake
Mendota. Biol. Centralbl., XVII. Bd., pp. 371-374; Abstract, Zool.
< 'entralbl.. IV. Jahrg., Xo. 18 u. 19, pp. 606, G07.

Erlanger, It. v.
"97. I'ber die Chromatinreduktion in der Entwickelung der mann-
lichen Gesehleehtszellen. Zool. Centralbl.. IV. Jahrg., No. 8, pp.
265-278.

Forbes, S. A.
'85. On the Food Relations of Fresh-AVater Fishes: a Summary
and Discussion. Bull. 111. State Lab. Xat. Hist., Vol. II., Art. VIII.,
pp. 475-538.

Fric, A., und Vavra, V.
'97. Untersuchungen iiber die Fauna der Gewiisser Bohmens. III.
Untersuchung zweier Bohmerwaldseen, des Schwarzen Sees und
des Teufelsees. Arch. d. naturw. Landesdurchf. v. Buhmeu. Bd.
X. 74 pp., 33 Fig.; Abstract, Zool. Centralbl., V. Jahrg., No. 5, pp.
158, 159.

Fuhrrnann, O.

*'97. Recherehes sur la faune des lacs al pines du Tessin. Rev. Suisse
de Zool., T. XV.. pp. 489-543.

Loude, Ad.

"'92. Xotatki Karcynologiezka. Kosmos (Lemberg) T. 17. pp.
443-448, 561-565. ( Fide Steuer. '97a.)

Richard, J.
'96. Sur la faune de quelques lacs eleves du Caucase d*apres les re-
coltes de M. Kavraisky. Bull, de la Soc. zool. de France, T. XXL.
pp. 183-185.

Schacht, F. W.
'97. The North American Species of Diaptomus. Bull. 111. State
Lab. Xat. Hist.. Vol. V.. Art, III., pp. 97-207. Pis. XXI.-XXXV.

Scott, Th.

*'98. Diaptomus Jiircus G. S. Brady, in Loch Lochy, Mouness. Ann.
Scott, Xat. Hist., Jan., 1898. p. 55.

Scott, Th., and Duthie, R.
*'97. An Account of the Examination of some of the Lochs of Shet-
land. Fifteenth Ann. Rep. Fisheries Board, for Scotland, pp.
327-333.

All articles except those marked with an asterisk are in the Library of the Mate
Laboratory of Natural History or in that of the University.

Nortli American Centropagidce. 269

Scott, Th., and Scott, A.
'97. Notes on Sunarestes paguri Hesse, and some other rare Crusta-
cea. Ann. Nat. Hist., Vol., 20, pp. 489-494. 2 Pis.

Steuer, A.
'97. Copepoden und Cladoceren des siissen Wassers aus der Umge-
bung von Triest. Verhandl. d. k.-k. zool.-bot. Gesellsch. Wien,
Jahrg. 1897. 16 pp., 1 PI.

'97a. Ein Beitrag zur Kenntniss der Cladoeeren-und Copepoden-
fauna Karntens. Verhandl. d. k.-k. zool.-bot. Gesellsch. Wien,
Jahrg. 1897. 49 pp., 6 Fig.

'97b. Liste aller bisher in Rarnten gefundenen Cladoceren und
Copepoden. "Carinthia" II., Nr. 4. Klagenfurt.

Szekely, B.

»'82. Tanulrnauyok a Diaptomus petefejludcsonek elso phasisairol a
blestoderrna fellepescig. Kolozsvar, 1882. (Fide Steuer, '97a.)

INDEX.

(Synonyms in italics..

Calanus, 237.
Canthocainptus. 225.
Centropages, 244.

hamatus, 244.
Centropages. 235.

grimaldii. 238, 242.
Centropagidae, 225, 227, 244.
Copepoda, 225. 227. 228.
Cyclops. 225.234, 235. 263.
Diaptomus, 225, 226. 227. 228, 230,
234. 235, 236, 237, 250, 265.

ashlandi, 260. 265.

minutus, 260, 265.

oregoneusis, 229. 265.

pallidas. 265.

sanguineus. 234.

sicilis, 229, 264.

siciloides. 229. 265.
Entomostraca. 225, 228.
Epischura, 225, 226, 227, 228, 237.
249, 267.

fluviatilis, 226, 250, 265.

lacustris. 22S. 229, 249, 250. 25 1 ,
252, 254, 255, 256, 260, 267.

nevadensis. 229, 249, 250, 251,
254,255,256,262,264.

nevadensis columbice, 256, 258.
259.

Epischura — Continued.

nordenskioldi. 249. 250, 251.
252.
Euryteuiora. 225.

herdmani. 226.
Heterocope. 225, 267.
Lamellipodia, 267.

fluviatilis. 265.
Limnocalanus, 225, 226, 227. 228,
235.

grimaldii. 226. 229. 236. 239. 243.

macronyx (?). 226.

inacrurus. 226.227. 229. 235, 236,

237. 238,264.
macrurus ductus, 239, 244.
sinensis. 226, 229, 235, 236, 237.

238, 245.
Osphranticum, 225. 226. 227, 228,

229, 234. 235, 237.

labronectum, 227. 230.
Potamoichetor. 229, 230.
Potomoichetor, 229.

fucosus, 230. 233.
Tt mora. 225.

affinis, 225.
Temorell". 225.

affinis, 225.
Scopiphora, 249, 263.

vagans. 260, 263, 267.

BULLETIN

OF THE

Illinois Qtate I aboratory

OF

NATURAL HISTORY,

Urbana, Illinois.

VOLUME V

ARTICLE V.— PLANKTON STUDIES. II. ON PLEODORINA
ILLINOISENSIS, A NEW SPECIES FROM THE PLANK'-
TON OF THE IILINOIS RIVER.

By C. A. KOFOID, Ph. D.

Illinois State Laboratory of Natural History,

URBANA, ILLINOIS.

September, 1898.

State Laboratory of Natural History.

LABORATORY STAFF.

Professor Stephen Alfred Forbes, Ph. D.,

Director of State Laboratory and State Entomologist.

Charles Arthur Hart,

Systematic Entomologist and Curator of Collections.

Frank Smith, A. M.,

Assistant Zoologist.

Charles Atwood Kofoid, Ph. D.,

Zoologist, and Superintendent of Biological Station.

Ernest Browning Forbes, B. S.

Entomological Assistant.

Wallace Craig, B. S.,

Zoological Assistant.

Mary Jane Snyder,

Secretary.

Henry Clinton Forbes,
Business Agent and Librarian.

Lydia Moore Hart,
Artist.

Article V. — Plankton Studies. II. On Pleodorina illinois-
ensis, a New Species from the Plankton of the Illinois
Hirer. By C. A. Kofoid.

The genus Pleodorina was discovered in 1893 by Shaw
('94) at Palo Alto, California, and in May of the following-
year the species Pleodorina californica, upon which the genus
was founded, was detected by Mottier ('94) in water from a
shallow stagnant pool near Bloomington, Imliana. During
the same summer the form also occurred in the Illinois River
and its adjacent waters (Clinton, '94), and it has been found in
the plankton of these situations in succeeding years from
June to September. The distribution of the species in this
continent is thus quite extended, and it is not at all improb-
able that continued investigation of fresh- water plankton will
demonstrate that this genus has a cosmopolitan distribution
similar to that of some other genera of the family Volvocinece
to which it belongs.

On June 16, 1898, a form which may be referred to the
genus Pleodorina was found in the Illinois River in water
entering the stream in large part from Cook's Slough and
Quiver Lake. Owing to high water (ten feet above low-water
mark) prevailing at the time, a considerable portion of the
habitat of the form in question consisted of submerged terri-
tory, with shallow warm water abounding in growing aquatic
and semi-aquatic vegetation.

This Pleodorina could not be found in Quiver Lake collec-
tions made on the 7th of June, but on the 16th it was present
in the river in small numbers, increasing until the 20th, when
a maximum was reached. From this time the numbers
decreased until the 27th, when, following a rise in the river,
the species seemingly disappeared entirely from the plankton.
It was also found sparingly in Thompson's Lake during this
period, a large area of slightly submerged territory being at
this time tributary to the lake.

Associated with this species in great abundance was Eudo-
rina elegans, in all stages of asexual reproduction, and Pando-
rina mormn was also present in smaller numbers and in like

274 Illinois State Laboratory of Natural History.

condition. Volvox, Euglena, Phacus, Lepocinclis, Traehelo-
monas, Dinobryon, Synura, Mallomonas, Uroglena, Melosira,
and Fragillaria occurred in varying frequency, but only a single
specimen of Pleodorina californica was found in collections
containing the species described in this paper. The animal
plankton was represented in the main by rotifers, Polyarthra
being most abundant, while Synchceta, Euchlanis, Pterodina,
Brachionns, and Anurcea were also present. Difflugia,
Codonella, Bosmina, Cyclops and nauplii complete the list
of the more common associates of this Pleodorina in the
plankton.

Pleodorina illindisensis n. sp.

The species here described consists of an ellipsoidal eoeno-
bium or colony of 32, rarely 16 and still more rarely 64,
biflageUate cells. The shape is quite constant, occurring in
the youngest colony and continuing throughout the asexual
cycle until the daughter colonies abandon the gelatinous
matrix of the maternal organism. Among the large number
examined only a few specimens were seen which approached
a spherical form. Measurements of twrelve seemingly full-
grown colonies from material freshly killed in 2% formalin
showed a range of 101 to 137 /< in long diameter, and an
average of 113 j(. The transverse diameter ranged from 84
to 102 f-i, and averaged 94 /<. Individuals in which the
gonidia have begun to divide show a considerable swelling of
the hyaline gelatinous envelope. One specimen containing
2- and 4-cell stages measured 178x155 //, and when
the young colonies are ready to escape, the parent may meas-
ure as much as 200x175 )t. At the time of escape the
young colonies measure 46x38 /'. The measurements of
the colonies approach very closely those given by Butschli
('80-89, p. 840) for Eudorind; viz., 100-150 n ; and the
colonies of this genus found in association with the form here
described exhibit dimensions almost, if not quite, identical
with those above recorded for the Pleodorina.

The colony (PL XXXVI., Fig. 1) contains, as a rule, 32
cells arranged, as Henfrey \'5i\) first noted for Endorina, in

On Pleodorina Illinolsensis. 275

five circles, two of which are polar and contain four cells
each, while eight cells are found in each of the remaining
three circles, one of which is equatorial and the other two lie
between the latter and the polar circles. The cells resemble
those of Eudorina in that they are situated in the periphery
of the hyaline gelatinous matrix and are not closely crowded
together, the degree of separation depending upon the age of
the colony and varying considerably in different cases.
Their inner ends do not approach the center of the colony as
is the case in Pandorina. No trace of any protoplasmic
connection between the cells of a colony could be detected in
the living organisms, nor in material killed in formalin or in
chromo-aeetic acid and afterwards stained in fuchsin, hema-
toxylin, or Bismark brown. Specimens treated by Zograf's
method (1% osmic acid followed by 4% crude pyroligneous
acid) or by 1% osmic acid followed by picrocarmine, showed
no connection between the cells.

The colony is surrounded by a common gelatinous sheath
(sh.) increasing in thickness (3.5 to 12 /<) with the age of the
organism. This membrane or sheath is of equal thickness in
all regions and consists of two parts : an outer, thin, denser,
more highly refractive layer (o.l.) ; and an inner homogeneous
one (/./.), which shows no traces of the concentric structure
found in Pandorina. It is within this latter layer that
the increase in thickness takes place in the older colo-
nies. It is limited centrally by a thinner and less highly
refractive layer (m.m.) which encloses the common matrix
(m.) in which the cells of the colony lie. Frequently among
the older organisms there occur upon the posterior end of the
colonies blunt, pseudopodia-like protuberances (PL XXXVI.,
Fig. 4) of the sheath, of irregular form and of no constant
number. Their position and the fact that they are often,
though not always, found in old colonies from which some of
the daughter colonies have already apparently escaped, sug-
gest that they may mark the place of exit of the young indi-
viduals from the parent. Similar protuberances were ob-
served upon Eudorina and Pandorina, under similar con-
ditions, in the collections in which the Pleodorina under

276 Illinois State Laboratory of Natural History-.

discussion was found. Wills ('SO) found that the daughter
colonies of Volvox globator escaped through a rift in the pos-
terior hemisphere of the parent, and Klein ('89) observed the
same phenomenon in Volvox aureus. The escape of the
daughter colonies in Pleodorina has not been observed by me.

The sheath stains deeply in an aqueous solution of methylen
blue, more deeply, in fact, than the enclosed matrix, the outer
layer taking the deeper stain. It also shrinks to about one
fourth its former thickness. This shrinkage, together with
that of the central matrix, causes the sheath to wrinkle along
lines which bound hexagonal areas from whose centers the
cells now project, thus giving the appearance of a division of
the surface of the colony into regular polygons. The sheath
shows no trace of the layer of radial rod-like structures
found by Klebs ('86) in Pandorina, but iodine or methylen
blue demonstrates a finely granular condition like that
described for Eudorina. The sheath is traversed by the pairs
of flagella which arise from the outer ends of each of the cells.

The matrix (m.) is a gelatinous substance of some consist-
ency, filling the colony inside of the inner membrane. In
the living colonies, in those which were killed in the
various reagents mentioned above and afterwards stained,
and in disintegrating material, no traces of any divisions can
be detected in this substance that are not due to wrinkling
caused by shrinkage. Methylen blue or iodine causes the
matrix to show a faintly reticulated or vacuolated appearance
due to different densities of staining. That the substance of
the matrix has considerable consistency even in the swollen
condition found in the maternal colonies, is shown by the
fact that the flagella of the young forms, before rotation
begins, can be seen to penetrate the matrix of the parent very
slowly. Their ends are often blunted or even knob-like and
their lateral motion is very limited. The movement of the
young colonies through the matrix is a very slow and gradual
one, showing the gelatinous consistency of the substance in
which they are imprisoned.

The striking feature in the structure of this species, as in
the case of V. californica (Shaw, '94), is the presence of two

On Pleodorina illinoisensis. 277

distinct types of cells in the colony (PI. XXXVI., Fig. 1),
the vegetative (v. c.) and the gonidial (g. c.) cells. The
presence of these two types of cells at once places this new
species in the genus Pleodorina rather than in Eudorina —
which it otherwise closely resembles.

The vegetative cells (v. c.) are four in number and consti-
tute the anterior polar circle, being always directed forward
in locomotion, as in the other species of the genus. Their
number remains the same in the smaller colonies of sixteen
cells and in the larger ones of sixty-four. The diameter of
these cells ranges from 9.5 to 16.8 /■<, twelve cells averaging
12.25 //. The size of these cells varies even in the matured
colonies, measurements at this stage ranging from 9.(5 to
15.6 //. At birth the cells of the young colonies vary in
diameter from 3.5 to 5 )i in different parents. In the
daughter colonies while still in the maternal matrix, no dis-
tinction in size between the vegetative and gonidial cells can
be detected, nor can this distinction be made in the younger
free-swimming colonies, it being thus impossible at this
stage to distinguish the young P. illinoisensis from the simi-
lar stages of Eudorina elegans with which they were asso-
ciated. AVhen the young colonies have attained dimensions
of 46x38 //, the vegetative cells measure 4 /< and the gonidia
4.8 //. A like similarity between the two kinds of cells in the
young colonies exists, according to Shaw ('94), in 1'. cali-
fornica.

In structure the vegetative cells (PI. XXXVI., Fig. 2) are
in most particulars similar to the gonidia, described below.
They sometimes appear to be a trifle lighter green in color—
a difference which may be due to their smaller size. The
principal differences lie in the smaller number of pyrenoids
and the larger size, both absolute and relative, of the stigma
or eye-spot.

As to the fate of the vegetative cells, the evidence at hand
is insufficient and conflicting. In three colonies in which
the daughters were moving about in the maternal matrix,
some having already escaped, the vegetative cells showed
very evident signs of degeneration, the contents being

278 Illinois State Laboratory of Natural History.

shrunken and irregular. In the larger number of instances
of this stage under observation the cells appeared normal,
showing no trace of degeneration or division. In one instance
only have I found a specimen in which the vegetative cells
had divided beyond question. This was a colony in which
the gonidia had completed their division but had not escaped.
Three of the vegetative cells were in the two-cell stage and one
was undivided. In two instances matured colonies have been
found in which four smaller daughter colonies (of eight and
sixteen cells respectively) were present at one pole.

The gonidial cells (PL XXXVI. , Fig. 3) constitute the
remainder of the colony. They usually number 28, rarely
12 or 60, and occupy the parts behind the anterior polar
circle of vegetative cells. These cells in most instances can
be easily distinguished by their larger size. In form they are
spherical, though some specimens in preserved material are
slightly flattened on their inner ends. In diameter they range
in seemingly full-grown colonies from 15 to 25 yu, averaging
in twelve specimens 1 9.2 yu. Their dimensions just before their
division, that is in colonies in which division has begun, also
show the extreme range quoted above, the smaller diameter
having been found in a sixteen-cell colony. As a rule the
gonidia are all of the same size, but occasionally specimens
have been found in which one or more dwarf cells occur
among them. These are irregular in their distribution and
can be distinguished at once from the vegetative cells by
their position. Similar dwarf cells were found in both Pan-
dorina and Eudorina. In matured colonies gonidial cells are
frequently found which fail to divide. The gonidia are of a
light green color, a trifle darker than the vegetative cells.
Their color in general is similar to that in Eudorina, and is
sonnwhat lighter than that in Yolvox and Pandorina, with
which they are associated.

A distinct cell membrane (c. m.) is found about each of the
cells. In the living condition and in the material preserved
in formalin it forms a highly refractive hyaline layer, about
1 // in thickness, outside of the green contents of the cell. It
stains very faintly in hematoxylin and assumes a deep brown

On Pleodorina illitioisensis. 279

tint with long-continued action of iodine and sulphuric acid.
In the case of diseased colonies hereafter mentioned the cell
membranes persist, often retaining their original form and
shape, after the' entire disappearance of the contents.

The greater part of the cell contents consists of what seems to
be one large chromatophore (PL XXXVI., Fig. 2, chr.), which
occupies all of the cell except the centrally placed nucleus
with its enveloping protoplasm, and a slender column {p. c.)
passing from this region to the anterior end of the cell. In
many cells a faintly marked notch or furrow (fu., Fig. 1) is to
be detected on one side of the chromatophore at the anterior
end of the cell. This seems to mark the line of contact of
the sides of the chromatophore which has surrounded the
nucleus. In the 2- and 4-cell stages of the gonidial cells
the nucleus and the protoplasmic mass are plainly seen
to occupy one side of the cell (PI. XXXVII., Fig/ 7, 8),
but in the cells of the young colony it again occupies a central
position. The chromatophore is uniformly of a bright chloro-
phyll-green, and shows a finely granular structure under high
magnification. In the youngest colonies each cell contains
but a single spherical pyrenoid (pr.), which occupies a lateral
position in the chromatophore, in the inner hemisphere of the
cell. In the older colonies the number of pyrenoids increases,
as many as twelve having been found. They are scattered
irregularly through the chromatophore, and may occur in
any part of it. A similar increase of pyrenoids is reported
by Shaw ('94) for P. californica. In the vegetative cells the
number of pyrenoids is often but 2-4, and is, as a rule, less
than that of the gonidial cells. In a very few instances as
many as eight have been found, and in one old colony the
vegetative cells seemed to be packed full of pyrenoids. In the
young colonies the pyrenoids have a diameter of about 1 m,
and in the older colonies of 2.5 /'.

The nucleus (n.) lies in about the center of the cell in the
midst of a mass of protoplasm enclosed by the chromatophore.
In mature gonidial cells before division it has a diameter of
7-8 M, and contains a sub-central nucleolus (ncl.) whose
diameter is 3 /<. The nucleolus stains deeply with picro-

280 Illinois State Laboratory of Natural History.

carmine, and is by tins means easily distinguished from the
pyrenoids, which it resembles in appearance and size. The
nuclear membrane is detected with difficulty. It encloses a
faintly stained nuclear reticulum (/•.). In the younger cells
the nucleus is much smaller (4-5 /<), the nucleolus is rela-
tively larger, and the reticulum is not evident. In the living
cell the nucleolus alone can be seen in the midst of the
grayish protoplasmic mass at the center of the cell. The
protoplasm is continued from this central region peripherally,
in the axis of the cell as a slender column (p. <■.), to the
anterior end, where it includes the stigma and bases of the
two flagella. A protoplasmic mantle enclosing the chromat-
ophore was not demonstrated.

The stigma or eye-spot (s.) lies at the anterior end of the
cell, near its axis, and is often so placed that an equilateral
triangle may be drawn with it and the bases of the two flagella
as apices. It is of a bright reddish brown color, though in
some of the posterior cells the color is often very faint, giving
the stigma the appearance of a slightly tinged oil-globule.
It is of an elongated hemispherical shape when seen from the
side, and has a circular outline when seen from above. Its
upper end often projects slightly so as to elevate the cell
membrane. The application of killing agents and alcohol
soon removes its color, and even in formalin this fades out in
the course of a few days, leaving merely a colorless, highly
refractive structure. The larger stigmata have a diameter of
2.5 /< and a depth of 2.8 //, and are to be found in the cells
in the anterior part of the colony, especially in the four vege-
tative cells of the anterior polar circle. Posteriorly the stig-
mata are less prominent, and are often not to be found at all
as brightly colored spots but merely as pale globules whose
position alone affords a clue to their real character.

This specialization of the stigmata in the anterior end of
the colony occurs also in Eudorina, Pandorina, and Volvox,
and Shaw ('9-i) states that in V. californica the stigmata,
which are present in the posterior part of the young colonies
(in gonidial cells), become less conspicuous and disappear as
the colony enlarges and the differentiation of the cells pro-

On Pleodorina illinoisensis. 281

ceeds. This prominence of the stigmata in the anterior end,
together with the facts that this end is always directed fore-
most in locomotion and that the species showing this differ-
entiation are positively phototactic in the vegetative condition
when the differentiation is prominent, all point toward the
l)articipation of the stigmata in the function of light percep-
tion. An interesting phenomenon occurs at the time of the
division of the gonidia, for the stigma of the mother cell
persists and is passed on through the five successive cell
divisions to the outer end of one of the cells of the daughter
colony, situated in the margin of the cup which arises from
the plate of cells and closes to form the ellipsoidal daughter
colony. Inasmuch as this cup always closes from the inside
out, that is with the opening directed outward, it is evident
that the stigma must traverse the distance between the outer
end of the mother cell and its inner end, which corresponds
to the outer ends of the cells of the daughter colony. New
stigmata arise in the cells of the daughter colony, but being at
first very small are thus quickly distinguishable from the
persisting stigma. The ultimate fate of this persisting stigma
has not been traced.

No contractile vacuole was observed in the living cells, and
careful search with a Zeiss ^.,-inch oil-immersion lens for
this structure in preserved and stained material has led to no
positive identification of a vacuole. The bleached stigma
and what seem to be the enlarged bases of the flagella are the
only areas discernible in the anterior end of the cell which at
all resemble a contractile vacuole. Shaw ('94) finds in picro-
nigrosin material a single vacuole in the anterior end of the
young cells of P. calif or n tea.

The flagella (,/'.) are two in number for each cell, and unite
with the cell at the anterior end adjacent to the stigma. The
ttfo flagella have the same proportions, and in adult colonies
they measure 40 u in length. In the young colonies they
are relatively longer. They are visible on the young colonies
shortly after the cup closes, and persist upon the maternal
colony during the early divisions of the gonidia.

The locomotion of the colonies of Pleodorina illinoisensis

282 Illinois State Laboratory of Natural History.

is of the type prevailing among other spherical or ellip-
soidal genera of the Volvocinece ; viz., rotation about the
principal or long axis of the colony, either from right
over to left or the reverse, frequently with one direction
predominating, progression being usually along the line
of the axis, the same end of the colony always leading.
In P. illinoisensis the vegetative pole always leads in loco-
motion in horizontal, oblique, and vertical movements, and
is therefore the anterior pole of the colony. Under normal
conditions, when under observation, this species is rarely quiet
during the period of growth. While still within the matrix of
the mother colony the ceasless rotation with its frequent rever-
sals begins. Colonies in the life cell, while favorable condi-
tions prevail, can be seen in active movement, jostling one
another and their neighbors in their seemingly aimless wan-
derings. When an object is met which does not yield to their
persistent rotation, their movements may slacken for a time
to be resumed shortly in some line of less resistance. The
rotation of this species is prevailingly from right over to left
as the following tables show, which indicate the number and
direction of the reversals of rotation in ten individuals in one
minute.

Direction

1

2

3

4

5

6

7

8

9

10

Total

Right over to left . .
Left over to right . .

2
2

1
0

1
0

2

1

1
1

2
2

1

1

5
4

4
3

3
2

22

1(5

A few days later a second set of observations was made
with the following result :

Direction

1

2

3

4

5

6

7

8

9

10

Total

Right over to left . .
Left over to right . .

3 +
2-

5±

5±

3±

2±

3±

3±

4 +
3-

3 +
3-

5 +
5-

3 +
2-

2 +
2

4 +
3-

35

30

In the majority of instances where the direction of rotation
was observed it was from right over to left, the ratios being
22 to 16, and 35 to 30. These tables give some idea of bhe
frequency of change in direction and its variation in different
individuals, but do not show the duration of the directions of

On Pleodorina illinoisensis. 283

rotations. This is indicated in a general way in the second
table by the pins and minus signs, which show the direction
in which the rotation was of longer and shorter duration.
In conclusion it may be said that both directions of rotation
occur, though that from right over to left is more frequently
met with, or, in other words, is of longer duration.

With regard to locomotion in P. californlca, Shaw ('94)
says that "the movement of the plant in the water was fol-
lowed in the case of a few individuals bearing well-developed
gonidia. In swimming through the water the vegetative pole
is directed forward and the plant revolves to the right (in
observed cases) on the axis connecting the vegetative and
reproductive poles. The path is parallel to this axis in up-
ward vertical as well as in horizontal movement. " The
polarity of this genus thus expressed physiologically in the
movements of the colony is accompanied by a corresponding
structural differentiation of the cells composing the organism.

In Gonium, according to Fresenius ('56), the motion of the
colony resembles that of a wheel, progression taking place in
the line of the axis of rotation. According to Butschli
('83-'87, p. 858), locomotion is accomplished by the rotation
of the plate-like colony around its shorter axis, the direc-
tion of rotation being to the right in some individuals and to
the left in others. Pfeffer ('84), on the other hand, describes
the rotation during the forward movement as alternately
from the right and the left. Migula ('90) calls attention to
the wavering, often backward, and irregular movements of
this genus, and also notes its rotation about an axis through
the middle of the colony. This rotation is either to the righl
or to the left, no predominance being mentioned. Polarity
is thus marked in the activity of the Gonium colony, though
not expressly marked in its structure except as it appertains
to the individual cells.

In Stephano$i>h«T<i the polarity in structure is but slightly
marked in the colony, being indicated in some colonies by
the asymmetrical position of the cells, but there is a physio-
logical differentiation in that one pole of the colony leads in
locomotion. In this genus also, according to Colin ('52), the

284 Illinois State Laboratory of Natural History.

rotation is in either of the two directions and is subject to
frequent change. No predominant direction was noted by
him.

In Pandorina the only structural expression of polarity is
found in the greater development of the stigmata in the cells'
in the anterior end of the colony. In other particulars the
poles are not differentiated. Braun ('51) maintains that in
this genus the rotation is constantly around the long axis of
the colony in the direction of the hands of a clock, when the
motion is toward the observer. Nageli {fide Biitschli, '83-87,
p. 858), on the other hand, observed rotation in both direc-
tions. My own observations upon Pandorina morum show
beyond question that the direction of rotation is not constant,
as the following table demonstrates.

Direction

1

2 3

4 5 6

7

8

9

10

Total

Right over to left.
Leftover to right.

6+
6-

12+ 5±
12-|4=fc:

1- 2=t 3d=

2+ 2=fc 4=fc

7=b
6=fc

1 +
2-

1+ 3=fc 41
1- 3±J42

The table gives the direction and number of changes in
direction in rotation of ten colonies, each observed for one
minute. The plus and minus signs indicate the estimated
predominance in duration. According to the table the in-
stances of direction observed are approximately equal for the
two directions, though that from right over to left showed
the greater duration. The younger and smaller colonies
showed much the greatest activity and exhibited more
frequent changes in direction than the older colonies. In all
observed cases the same end continues to lead in locomotion,
physiological polarity being thus fully developed in this genus.

In the case of Eudorina the structural polarity of the
vegetative colonies is no more marked than it is in Pandorina,
though according to Carter ('58) there is in the monoecious
sexual colony a differentiation, in that the four cells at one
pole divide to form spermatozoa, while the remaining twenty-
eight become egg-cells. It should be noted in this connection
that no such colonies were observed by Goroschankin ('75)
in the sexual generation. The literature at hand presents no

On Pleodorina illinoisensis. 285

precise statement as to locomotion in this genus. As ob-
served by me, it closely resembles that described above for
Pleodorina illinoisensis; viz., rotation around the long axis of
the colony, the same pole constantly leading in progression.
The direction of rotation is frequently reversed, though it was
predominantly from right over to left in the cases observed.
A functional polarity thus exists in this genus.

In Volvox, according to Klein ('90), there is a polar differ-
entiation as regards the stigmata that is even more marked
than it is in the genera previously mentioned. He finds that
the cells of the pole directed forward in locomotion each
possess a stigma which is especially large and intensely
colored ; that the color fades out and the stigmata become
smaller and paler as the equator is approached ; and that
beyond this they are usually represented merely by a color-
less oil-drop, which in some cases may even disappear. The
posterior hemisphere is also marked by the development
there of the gonidia, as was first shown by Colin ('56), and
occasionally ellipsoidal colonies are found whose long axis
connects the anterior and posterior poles. Locomotion in
Volvox is accomplished, as elsewhere in the family, by the
rotation of the colony about its principal axis. Wills ('80)
observed the predominance of the rotation to the right and
its occasional brief reversal. Klein ('89) states that this
preference is found in V. globator, but that it is not shown by
V. aureus. In this latter species the changes are frequent and
are often separated by a brief pause. Backward motion is
rarely seen and lasts but a short time. In the case of Volvox
the axis of rotation is slightly oblique, the center of the
colony remaining in the line of progress, but the axis of
rotation being inclined from above the line at the anterior
pole to below it at the posterior one.

We thus find that Pleodorina illinoisensis, which exhibits
both a structural and physiological polarity, shares with
most, if not all, of the genera of the family to which it
belongs, the physiological differentiation which is expressed
in locomotion, and also, in observed cases, exemplifies the
extreme form of a predominance of rotation in one direction.

28(5 Illinois State Laboratory of Natural History.

We also find that the structural differentiation shown in the
decadence of its posterior stigmata obtains in varying degrees

in the other spherical and ellipsoidal genera of the family —
least in Pandorina, most in Volvox. The gemis Pleodorina
agrees with Volvox in having a structural polarity based upon
tlic division of the colony into vegetative and gonidial regions,
but the differentiation is simpler. Of the two species of Pleo-
dorina, the one here described exhibits the simplest possible
differentiation of the colony consistent with the symmetry
of the organism; viz., the differentiation of the anterior
polar circle of four cells as vegetative members of the colony.
Of the two species of the genus it thus stands nearer Eudo-
rina, while its sister species P. californica approaches more
closely to Volvox both in the number of cells and in the
extent of the differentiation.

The discovery of this additional species of the genus Pleo-
dorina thus supports the opinion expressed by Shaw ('(.»4),
who founded the genus, that it was intermediate between
Eudorina and Volvox but nearer the former. Judging merely
from the asexual stage, P. illinouensis affords additional evi-
dence of the close relationship of Pleodorina and Eudorina.

Throughout the preparation of this paper the writer has
had constantly in mind the possibility that the form here
described is merely a stage in the life cycle of Eudorina. A
number of facts lend support to this hypothesis: (1) the
occurrence of Pleodorina illinoisensis with Eudorina elegans;
(2) their marked similarity, aside from the four vegetative
cells, in structure and measurements ; (3) the impossibility
of separating the youngest free-swimming colonies of the
two forms; (4) a considerable variation in the size of
the vegetative cells in Pleodorina, grading toward the
condition in Eudorina; (5) some evidence that in certain
cases ;it least the vegetative cells may divide, one case of a
2-cell stage having been seen in the hundreds, if not thou-
sands, of specimens examined, and one instance noted in
which a maternal colony containing thirty-two daughter
colonies had at one pole four colonies which were slightly
smaller than the remaining twenty-eight; and (6) the occur-

On Pleodorina illinoisensis. 287

rence of pleomorphism in the family Volvocinecs, Klein ('89
and '90) citing no less than twenty-four "combinations" in
the case of Volvox aureus. It may then be that the form here
described as Pleodorina illinoisensis is only a " Pleodorina
stage" of Eudorina.

The abrupt disappearance of this supposed new species
from the plankton prevented the carrying out of breeding
experiments designed to test its validity, and it seems that
the matter must remain undecided for the present. In the
absence of satisfactory proof that the form here described is
but a phase of the life cycle of Eudorina it has seemed best
to the writer to make the above suggestion and to take the only
course open in publication, namely, the description of the form
as a new species, inviting the criticism of subsequent investiga-
tion. The dilemma here presented is by no means an isolated
one in plankton work, nor is it new to the family Volvocinece :
witness the long confusion which existed over the two species
of Volvox, aureus and globator, which has been at last cleared
up by the excellent work of Klein ('89, '89a, '90) and Overton
('89). Another instance is often presented when Pandorina
and Eudorina both occur in the same collections and the
plankton statistician must decide to which genus each speci-
men observed must be referred. Typical specimens of each
can be found, but all individuals do not conform to the type,
or they may present conditions in which the conformation is
obscured by some phase of the life cycle.

The asexual reproduction of Pleodorina illinoisensis (PI.
XXXVII.) resembles that of other species of the genus in that
it is accomplished by the repeated division of the gonidial
cells, resulting in the formation of daughter colonies in the
maternal matrix. These escape later from the parent organ-
ism, and by growth attain the adult condition with the differ-
entiation of the four vegetative cells. Five successive cell di-
visions, pervading all the cells of the parent organism except the
vegetative cells, are necessary for the completion of the process,
and result in the 2-, 4-, 8-, 16-, and 32-cell stages of the form-
ing colonies. The firsttwo of these divisions result in the forma-
tion of a quadrangular plate of cells — a form which is retained

288 Illinois State Laboratory of Natural History.

through the two succeeding divisions, which produce the 8-
and 16-cell stages. The cupping of this plate, which results
in the formation of an ellipsoidal colony, is apparent as early
as the 4-cell stage (PI. XXXVII. , Fig. 9) and continues
through the later stages (Fig. 11, 13), so that hy the time
the 16-cell plate is formed it has almost the curvature of a
saucer. With the formation of thirty-two cells the closure
of the cup proceeds and is soon completed. The orifice of
the cup is directed outward in all cases, and thus the ends
of the cells of the daughter colony which are formed from the
outer end of the maternal gonidial cell come to lie in the
inner side of the cup, and are the inner ends of the cells of
the daughter colony. In the matured colonies the young
usually lie with their long axes parallel to the surface of the
parent. I have not, however, heen ahle to identify the point
of closure of this cup with this region or positively with any
other.

The sequence and position of cleavage planes which produce
the quadrangular plate of the 16-cell stage is, in the main,
similar to that described hy Goroschankin ('75) and Braun
(75) for Eudorina and Volvox. Beyond this stage there is
some doubt as to the agreement. A full discussion of the
subject is beyond the scope of the present paper, for which the
following brief description must suffice. The first cleavage
plane (I) divides the gonidial cell into two hemispheres along
the axis of the cell, and the daughter nuclei, with the sur-
rounding protoplasm, are placed close together in the center
of the opposing faces of the new cells (PI. XXXVII., Fig. 7).
The second plane (II) is at right angles (Fig. 8-9) to the first
and also passes through the regions representing the axis
of the ancestral cell. In this instance also the nuclei are
gathered near the center of the young colony, which exhibits
to an appreciable extent the curving indicative of the later
formation of the cup. The 8-cell stage results from the
divisions of each of the quadrants of the 4-cell stage by a
plane (III) which is parallel to one of the previous planes
and perpendicular to the other, meeting the latter at a point
about midway between the center and the circumference. By

On Pleodorina illinoisensis . 289

a subsequent adjustment of the cells the four more centrally
placed ones come to form a sort of a Greek cross whose angles
are filled by the other four (PL XXXVII., Fig. 10, 11). The
16-cell stage is formed by four additional planes, each of
which divides one of the cross-cells and its corner neighbor.
The location of these planes may be described in the same
terms as the last excepting that they meet the radial planes, I
and II, at about one fourth the distance from the circum-
ference toward the center. The cupping of the plate soon
advances to such an extent that it consists of a square of four
centrally placed cells, upon each of the four sides of which
there overhangs a row of three cells, of three grades of eleva-
tion (PI. XXXVII., Fig. 12, 13). The succeeding division and
the completion of the cup (PL XXXVII., Fig. 14) result in the
young colony's assuming the ancestral form. Throughout
these divisions the number of pyrenoids in the daughter cells
grows steadily less. But one can be found in each cell in the
32-cell stage, while in the 16-cell stage two are readily recog-
nizable in each cell. In the earlier stages and before division
the number often varies, and the pyrenoids are frequently so
crowded that enumeration is difficult if not impossible. It
seems not improbable that these structures also must undergo
some division during the process of cell multiplication. Dur-
ing the processes of division the nuclei continue to occupy
a position near the inner ends of the cells (in the new colony),
and it is only after the divisions have been completed that
they come to occupy their usual positions at the center of the
cells — perhaps as a result of the growth of the chromatophore.

No stage of sexual reproduction has been positively identi-
fied for this species.

A peculiar condition of the colonies of this species, also
occurring in Pandorina and Eudorina, deserves passing-
notice. It occurred with considerable frequency in all three
genera and resulted in each case in the destruction of the
entire colony affected. The early stages of the disease, if it
be such, are indicated by the homogeneous condition of the
cells and the fading out of the color, together with a flattening
of the cell contents into a disk- or lozenge-shaped mass (PL

290 Illinois State Laboratory of Natural History.

XXXVI., Fig. 4). In the subsequent stages this mass assumes
a yellow and then a brownish color, takes on an irregular shape
(PI. XXXVI., Fig. 5), and disintegrates, leaving the empty cell
walls occupying the matrix. In spite of the suggestion in the
above description there was never any trace of the formation
of spermatozoa in the colonies presenting these phenomena,
neither was there any indication of encystment. There was
no indication of either a fungous or an algal parasite, and it
seems not improbable that the occurrence of these diseased
forms may have been due to some unfavorable local condition
in the water tributary to the habitat of the genera affected.

The following brief synopsis of the prominent characters
of this genus and its two species will serve as a convenient
diagnosis for their determination.

Pleodorina Shaw. — Colony consists of a spherical or ellip-
tical coenobium of greenish biflagellate cells of two types,
vegetative and gonidial, in the anterior and posterior parts
of the colony respectively, which lie in the periphery of a
hyaline gelatinous matrix and are surrounded by a common
hyaline envelope. Cells each with one reddish stigma, which is
more prominent in the anterior part of the colony. No con-
necting filaments between the cells. Non-sexual reproduc-
tion by gonidia, which are formed by increase in size of a
part of the cells of the colony. Daughters escape from
parent as small colonies of biflagellate cells which at this
stage are all similar. Sexual reproduction not known.

P. californica Shaw. — Number of cells in colony 64 or 128.
Maximum diameter of colony 175-340 //. Vegetative cells
constituting approximately one half the colony. Gonidial cells
2-3 times diameter of vegetative cells. Known habitat : ponds,
ditches, and streams in California, Indiana, and Illinois.

V. illinoisensis n. sp. — Number of cells in colony usually
32, rarely 10 or 64. Dimensions of colony range from
46x38 H to 200x175 /<•. Vegetative cells always four in
number. Gonidial cells approximately 1.1 — 2 times diam-
eter of vegetative cells. Known habitat: submerged lands
along the Illinois Paver. Types deposited in collections of
Illinois State Laboratory of Natural History and United
States Nationn 1 Museum.

Illinois Biological station. Havana, 111.. July 25, 1898.

On Pleodorina illinoisensis. 291

BIBLIOGRAPHY.

Braun, A.

'51. Betrachtungen liber die Erscheinung der Verjungung in cler
Natur, insbesondere in der Lebens- mid Bildungsgeschicbte der
Pflanze. XVI+364 pp., 3 Taf. Leipzig.

'75. Uber einige Yolvoeineen. Ber. d. Gesellsch. natnrforsch.
Freunde zu Berlin, 1875, pp. 9-18.

Butschli. 0.
'80-'89. Protozoa. Bronn's Klassen und Ordnungen des Thier-
reiehs, Bd. 1., Th. I.-1II. 2035 pp., 79 Taf. Leipzig und Heidelberg.

Carter, H. J.
'58. On Fecundation in Eudorina elegans and Cryptoglena. Ann.
Mag. Nat. Hist., Ser. 3, Vol. II., pp. 237-253, PI. VIII.

Clinton. G. P.
'94. Pjeodorina in Illinois. Botan. Gazette, Vol. XIX., p. 3S3.

Colin, F.
'52. Uber eine neue Gattung aus der Familie der Volvocineen.
Zeitschr. f. wiss. Zool., Bd. IV., pp. 77-110, Taf. VI.

'56. Observations sur les Volvocinees. Ann. d. Sei. Nat., Botan.,
IV. Ser..T. V., pp. 323-332; also, with some changes, in 34 Jahresber.
d. Schles. Gesellsch. f. vaterl. Cultur f. 1856, pp. 39, 40, 77-83.

Fresenius, G.

'56. Uber die Algengattungen Pandorina, Gonium und Raphidium.

Abhandl. der Senckenberg. uaturforsch. Gesellsch., Bd. II. , pp.

187-200, Taf. VIII.
Goroschankin, J.

'75. Genesis im Typus der palmellenartigen Algen. Versuch einer
vergleichenden Morpbologie der Familie der Volvocinea (German
title of Russian article). Mittheil. der kais. Gesellsch. uatur-
forsch. Freunde in Moskau, Bd. XVI. 40 pp., 2 Taf.

Henfrey, A.

'56. Notes on some Fresh-water Confervoid Algae New to Britain.
Trans. Micr. Soc. London, N. S., Vol. IV., pp. 49-54, PI. IV.

Klebs, G.

'86. Uber die Organisation der Gallerte bei einigen Algen und
Flagellaten. Untersuch. a. d. botan. Inst, zu Tubingen, Bd II., pp.
333-418, Taf. III., IV.

Klein, L.
'89. Morphologische und biologische Studien liber die Gattung
Volvox. Pringsheim's Jahrb. f. wiss. Botan., Bd. XX., pp. 133-211,
Taf. X.— XII.

292 Illinois State Laboratory of Natural History.

'89a. Xeue Beitriige zur Kenntniss der Gattung Volvox. Ber. d.

deutsch. botan. Gesellseh., .Tahrg. 1889, Bd. VII.. pp. 42-53. Taf.

111.
'90. Vergleiehende Untersucbungen iiber Morphologie und Biologie

der Fortpflanzung bei der Gattung Volvox. Ber. d. naturf. Ge-

sellsch. zu Freiburg i. B., Bd. V., pp. 20-120, Taf. II— VI.

Mijjula, W.
'90. Beitrage, zur Kenntniss ties (ionium peetorale. Botan. Centralbl..
Bd. XLIV.. pp. 72-76, 103-107, 143-1 4G, Taf. 11.

Mottier, D. M.
'94. Pleodorina in Indiana. Botan. Gazette, Vol. XIX., p. 383.

Overton, E.
'89. Beitrag zur Kenntniss der Gattung Volvox. Botan. Centralbl.,
Bd. XXXIX., pp. 65-72, 113-118, 145-150, 177-182, 209-214,241-240,
273-279, Taf. I.-III.

Pfefler, W.
184. Looomotorisdie Richtungsbewegungen durch ehemische Reize.
I'ntersueh. a. d. botan. Inst, zu Tubingen. Bd. I., pp. 363-482.

Shaw. W. R.
'94. Pleodorina. a new genus of the Volvocinese. Botan. Gazette, Vol.
XIX., pp. 279-283, PI. XXVII.

Wills, A. W.

'80. On the Structure and Life History of Volvox globator. Mid-
land Naturalist, Vol. III., pp. 209-214, 233-237, PI. VII.. VIII.

On Pleodorina illinoisensis.

293

EXPLANATION OF PLATES.*

ABBREVIATIONS.

A., anterior pole.
chr., chromatophore.
c. m., cell membrane.
/., rlagellum.
/it., furrow.
g. c, gonidial cell.
i. I , inner layer of sheath.
hi., matrix.
»n. m., matrix membrane,
n., nucleus.

wcZ., nucleolus.

0. £., outer layer of sheath.
P.. posterior pole.

p. c, protoplasmic column,
pr., pyreuoid.
/•.. reticulum.
s., stigma.
s/(„ sheath.
v. c, vegetative cell.

1. II, 111, cleavage planes.

Plate XXXVI.

Fig.

1.

Fig.

2.

Fig.

3.

Fig.

4.

Fig.

5.

Fig.

6.

Pleodorina illinoisensis, lateral view of colony. X 500.

Lateral view of vegetative cell. X 1500.

Lateral view of gonidial cell. X 1500.

Lateral view of matured colon}', showing posterior lobes.

X 185.
Diseased cell, early stage. X 1250.
Diseased cell, later stage. X 1250.

Plate XXXVII. '

FlG. 7. Pleodorina illinoisensis, top view of 2-cell stage.

Fig. S. Top view of 4-cell stage.

Fig. 9. Lateral view of 4-cell stage.

Fig. 10. Top view of 8-cell stage.

Fig. 11. Lateral view of 8-cell stage.

Fig. 12. Top view of 16-cell stage.

Fig. 13. Lateral view of 16-cell stage.

Fig. 14. Top view of 32-cell stage.

* Figures drawn by C. A. Kofoid and inked by Miss 1.. M. Halt.
1 Figs. 7-11 magnified loon diameters.

Plate XXXVI.

State Laboratory of Natural History.

LABORATORY STAFF.

Professor Stephen Alfred Foubes, Ph. D.,

Director of State Laboratory and State Entomologist.

Charles Arthur Hart.

Systematic Entomologist and Curator of Collections.

Frank Smith, A. M.,
Assistant Zoologist.

Charles Atwood Kofoid. Ph. I)..

Zoologist, and Superintendent of Biological Station.

Ernest Browning Forbes, B. S.,

Entomological Assistant.

Wallace Craig, B. S.,

Zoological Assistant.

Mary Jane Snyder.
Secretary.

Henry Clinton Forbes,
Business Agent and Librarian.

Lydia Moore Hart,
Artist.

Article VI. — A List of the Protozoa and Rotifera found in
the Illinois River and Adjacent Lakes at Havana, III.*
By Adolph Hempel.

INTRODUCTORY.

The material studied in the preparation of this paper was
collected at the Biological Experiment Station established on
the Illinois River, at Havana, April 1, 1894, by the Univer-
sity of Illinois and the Illinois State Laboratory of Natural
History. The work of collecting the material began April
7, 1894, and was carried on almost entirely at nine substa-
tions, designated as A, B, C, D, E, F, G, K, and L. The
first three are in Quiver Lake, which is an arm of the river
on its east side, about two miles above Havana. A is at the
head of the lake ; B, at a wet, springy place on the eastern
shore, about half a mile from the head ; and C, about a mile
and a half from the head, including both the east and west
shores at this point as well as the middle of the lake, where
the towing-net was hauled, the depth here at low water being
about four feet. D is about half a mile above Havana, on the
east bank of the river, and E about two and a half miles north
of the town, in the main river, opposite C, collections being
taken especially from the west shore and the middle of the
river, where the depth at low water was about nine feet. About

*I3efore Mr. Hernpel had completed that part of his manuscript relating to the
Protozoa, he left to accept a position in the Muse t Paulista, in Sao Paulo, Brazil, and
the entire manuscript was placed in my hands by Dr. Forbes to be prepared for pub-
lication. At first I was reluctant to undertake the work, but realizing the value of
the paper as planned by Mr. Hernpel to students and teachers of Illinois natural
history, I have spared no effort to put it in the most useful form for this class of
workers.

On account of the limited time and area represented in this list, it can only be
regarded as a preliminary one, not sufficient for permanent generalizations on sea-
sonal or local distribution, but rather as a history of these groups at the Station
during the two years covered by Mr. Hempel's work. It seemed undesirable, for (he
same reason, to attempt to give keys to the species listed. I have, however, for the
Protozoa, carefully compiled from Butschli a synopsis of the distinctive characters of
the larger subdivisions represented in the list, and have drawn up from Butschli,
Leidv, and Kent condensed generic descriptions, following, as did Mr. Hernpel, the
order given by Butschli. The chlorophyll-bearing forms, such as Volvox and Euglena,
are retained among the Protozoa since they are included by Biitschli, but it is proper
to state that they are now regarded as plants by :i large number of authors. For the
Rotifera.l have compiled a synopsis of the families from Hudson and (fosse, and
Mr.IIempers generic diagnoses are mostly from the same source.

Under each species in the list is a brief account of the important points in its
history for the two vears. These accounts were drawn up from Mr. Hempel's records,
and may prove of especial value to students at the Station. Aside from these sum-
maries and the additions previously mentioned, the manuscript remains substantially
as Mr. Hempel left it, and will be found to contain much interesting and useful
information for the student of microscopic life. CHAS. A. HART.

301

302 Illinois State Laboratory of Natural History.

half a mile below Havana, west of the river, is situated
Phelps Lake, which is merely a shallow depression something
over half a mile long and less than a quarter of a mile wide,
surrounded by woodland, and usually filled with water to a
depth of one or two feet ; near its upper end F is located.
G is in the southern part of Thompson's Lake, a large per-
manent body of water, about five miles long and over half a
mile wide, with a depth at low water of about four feet, lying to
the west of the river above Havana. K is located near the
middle of Flag Lake, which is a large but very shallow body
of water, about three miles long and half a mile wide, lying
between Thompson's Lake and the Illinois River, and full of
coarse "flags" — Scirpus, Sagittaria, etc., — Nymphced, Nelumbo,
and Ceratophyllum. L is situated in Dogfish Lake, which
opens into the west side of Quiver Lake, and is about a mile
long and a quarter of a mile wide, and somewhat shallower
than Quiver Lake at C. Collections were also made in the
"Pumpkin Patch," a small marshy bay communicating with
Quiver Lake at its head, and in Matanzas Lake, just east of
the river, about three and a half miles south of Havana.

Studies of the Protozoa and Rotifera at the Biological Sta-
tion were begun respectively in the latter part of April and
of May, 1894. This work was carried on at the Station
throughout the season until September 10, and all subse-
quent catches from that date to April 1, 1896, were examined
and a record was kept of the Protozoa and Rotifera found in
them. The period of time thus covered was about two years,
the interval between the collections varying from a week to
two months. The results of this work form the basis of the
present article. Several species which were first noticed later
than April, 1896, are incorporated in their proper place. The
list is intended primarily as a record of the Protozoa and
Rotifera found in the general collections made at the various
substations, and in but few instances were data obtained from
other sources. Doubtless the number of species recorded
would be considerably greater if the time had been spent in
endeavoring to list as many forms as could be found, regard-
less of substations. As it was, there were two difficulties

Protozoa and Rotifera at Havana, III. 303

which materially interfered with the making of full and satis-
factory substation lists. The first obstacle was the imperfect
preservation of many forms in the material put up for exami-
nation, the identification of this material being thus largely
restricted to those forms which possessed structures suffi-
ciently hard to preserve without distortion. The second was
due to changes in the list of substations under examination :
A and B had to be abandoned, because of extreme low water,
in August, 1894; Phelps Lake, in which was substation F,
became entirely dry by the 18th of that month, and work
there was suspended until January, 1895, when a rise in the
river refilled the lake bed; and in the spring of 1895 D was
abandoned and two new substations, K and L, situated in
Flag and Dogfish Lakes respectively, were added to the list.
My thanks are due to my instructor, Dr. S. A. Forbes, for
his interest in my work and for counsel and guidance while
the work was in course of preparation; to Prof. Frank
Smith and to Dr. C. A. Kofoid for suggestions and help in
technique and research ; to Mr. C. A. Hart, who has kindly
undertaken to revise the manuscript and prepare it for the
printer; and to Miss Lydia M. Hart, who has contributed the
figures.

METHODS OF COLLECTION AND PRESERVATION.

During the first season, in making collections in the river
and in other places comparatively free from vegetation, a tow-
net of No. 12 silk was used, both surface and oblique hauls
being taken at intervals of from seven to ten days. The col-
lections along shore and among plants were secured by means
of a Birge net, or cone-dredge, at different intervals varying
from fourteen to twenty-five days. Many kinds were ob-
tained by squeezing out the water from vegetation ; while
large forms, such as Megalotrocha and Conochilus, were picked
out with forceps and pipette. In 1896 Dr. C. A. Kofoid,
Superintendent of the Station, introduced the use of a pump
in making collections. This method has many advantages
over the earlier ones, as by means of it collections can easily
be made from any desired depth, or from among weeds where
a tow-net could not be hauled.

304 Illinois State Laboratory of Natural History.

Several methods were followed in the preservation of the
tows. Some of the material was killed in 50% alcohol and
then transferred to 70% alcohol; another part was killed in
95% alcohol ; and picro-nitric acid, followed hy 70% alcohol,
was extensively used. Flemming's fluid as employed by
Rousselet ('93), and a solution of potassium permanganate
recommended by Zacharias ('94, p. 88) were also used. A
second paper by Rousselet ('95), in which he describes the
method of killing with | % osmic acid and then preserving
in a 2.5% solution of formalin, was received in time to be
used in connection with the work in 1895. In 1896 nearly
all the qualitative catches were killed and preserved in 2%
formalin. Good results were obtained in almost all cases. If
one is limited in time and can have but one killing agent,
formalin comes nearest being the ideal all-around killing fluid.
By far the best results, however, are obtained with osmic acid,
according to the process worked out by Rousselet ; but the
use of this agent requires much time and patience.

PROTOZOA.

The Protozoa present a very attractive field for study,
including a large number and great variety of species. We
find here a more marked difference in structure and form
than among the Rotifera; yet all the Protozoa are either
simple one-celled animals or colonies of single-celled individ-
uals.

They exhibit a great variety of structural detail, and range
in length from 6 mm. to ,.005 mm. Many of the forms are
marine, but a great number occur in fresh or stagnant
water. Notwithstanding their diversity of structure, the
Protozoa have, as a rule, the protoplasm or body substance
differentiated into an inner part, called the endoplasm, and
an outer envelope, called the ectoplasm. This differentiation
may be temporary, as in the Rliizopoda, or permanent, as
in the Flagellata and Infusoria. A single nucleus is usually
present, though some species have more than one. The
Infusoria are characterized by the presence of a paranucleus,
or micronucleus, in addition to the larger nucleus, or mega-

Protozoa and Rotifera at Havana, III. 305

nucleus. One or more contractile vacuoles are usually
present except in the Sporozoa and Cystoflagellata, in which
none have as yet been discovered.

As a pool dries up, the Protozoa it contains assume a
spherical shape and secrete about themselves a chitinous shell,
when they are said to be encysted, the spheres being called
cysts. In this condition they can readily withstand drought,
and when rain comes and fills up the pool they revive,
break through the chitinous envelope, and assume their former
shape. Encystment may also take place just before spore
formation.

Protozoa occur abundantly in every pond or wayside pool
as well as in the larger bodies of water, and one might
naturally think that they would be favorites with the zoologists
and be thoroughly well studied ; but in the United States
there are only a few persons who have given much attention
to them. Among these may be mentioned Prof. Joseph
Leidy, Prof. D. S. Kellicott, and Dr. A. C. Stokes, each of
whom has done much to awaken interest in these small forms
and to bring them into notice.

In order to get a good idea of the structure of the Protozoa
we may now consider some typical forms of the various
groups.

The lowest of the Protozoa, belonging to the class Sarcodina,
are the subclass Rhizopoda, or root-footed animals, so called
because they send out a number of root-like processes of pro-
toplasm, known as pseudopodia, by means of which they
move from place to place. Among the forms included under
this head are Amoeba, Difflugia, Arcella, and Euglypha.
Amoeba consists of a small portion of protoplasm differen-
tiated into a granular endoplasm and a clear transparent
contractile ectoplasm, and having a nucleus and contractile
vacuole. As already indicated, the animal moves along by
thrusting out processes of protoplasm in the direction of loco-
motion. As these pseudopodia are thrust out at one part of
the body they are drawn in at another part. Because of
this peculiar movement the Ameeba has no constant form, its
shape changing continually. Aside from locomotion the

30(1 Illinois State Laboratory of Natural History.

pseudopodia also serve in obtaining food, for when they come
in contact with a diatom, for example, they flow around it
and entirely enclose it. Then the soft parts are digested,
and as the Amoeba moves along the undigested hard parts are
extruded. The structure of Difflugia is essentially the same
as that of Amoeba, with the exception that the Difflugia builds
for itself a small shell or lorica, using sand, diatoms, and
particles of other foreign matter. Arcella secretes a homo-
geneous chitinous shell, which is usually free from all foreign
substance. Euglypha secretes chitinous plates and then
unites them to form its shell.

The subclass Heliozoa includes a number of the Sarcodina
characterized by having numerous thread-like pseudopodia.
These are not continuously thrust out and retracted, but have
a permanent form. The Radiolaria constitute another
subclass of the Sarcodina, but as it includes only marine
forms it is unnecessary to consider it here. The prevailing
mode of reproduction among the Sarcodina is division,
although budding and spore formation also occur.

The class Sporozoa is composed of a number of Protozoa
which reproduce by means of spore formation. The occur-
rence of fission or budding among any members of the
group has not as yet been demonstrated. All of them are
parasitic, living in the intestines or in other organs or tissues
of higher animals, and therefore show a marked degeneration
of structure. Gregarina may be taken as a type. It is more
or less oval in outline, with the protoplasm differentiated
into a well-marked endoplasm and ectoplasm. The body is
constricted at about one third of its length from the anterior
end. A nucleus is present, but pseudopodia and the con-
tractile vacuole are wanting.

In the class Mastigophora the members of the order Flagcl-
lata are characterized by the possession of one or more flagella
which serve as organs of locomotion, and also aid the animal
in securing food, since by means of them a constant current
of water is directed towards the mouth. The well-known
Euglena may be considered as a type. The body is elongate
and more or less cylindrical, and is highly flexible and very

Protozoa and Rotifcra at Havana, III. 807

variable in shape. The endoplasm and ectoplasm are well
differentiated. From the anterior end of the body projects a
long slender flagellum, just below which is the mouth opening.
Near the base of the flagellum is the red stigma, sometimes
called the eye-spot. A little behind this pigment spot is the
contractile vacuole. This empties into a sort of vestibule.
The posterior extremity of the body is, in some species, pro-
longed into a short spine-like process. A large nucleus is
present. The endoplasm usually contains a number of starch
bodies.

The order Dinoflagellata includes Peridinium and ( 'eratium,
which have a hard covering or shell of modified cellulose.
Contractile vacuole and nucleus are present. There are two
rlagella ; one extending out in front of the animal, while the
other encircles the body and lies in an equatorial groove.

The members of the class Infusoria have more or less of
the surface of the body covered with fine cilia. These are
permanently present in the subclass Ciliata, but in the sub-
class Suctoria are found only in the young. In the holotri-
chous Ciliata they are comparatively uniform, and usually
invest the entire body surface. By some authors these forms
are all grouped under the name Holotricha. A large part
of them, however, constitute a group sufficiently distinct
from all other Ciliata to be ranked as a separate order, the
Gymnostomata. The mouth is naked, and closed except when
in use, the food being swallowed. In the remaining Ciliata,
constituting the order Trichostomata, the mouth usually
remains open, and the food is swept into it by the action of
cilia or undulating membrane.

The holotrichous Trichostomata form the suborder Aspiro-
tricha, which is well represented by Paramecium aurelia, the
slipper animalcule. Its body is elongate, pointed posteriorly,
and rounded and slightly narrower anteriorly. The entire
surface is covered with fine cilia. On the ventral surface is
an anterior oblique groove, at the posterior end of which the
oral opening is situated. The nucleus is large. Two con-
tractile vacuoles are present, which usually assume a stellate
appearance upon contracting The ectoplasm or cuticula is

308 Illinois State Laboratory of Natural History.

provided with a number of rods called trichocysts. These
are used for defense, and are comparable with the nemato-
cysts in Hydra.

The suborder Spirotricha, which includes the remaining
ciliates, is characterized by the presence of a spiral or nearly
circular wreath of cilia — the adoral wreath — leading to the
mouth opening, and partly or entirely enclosing a usually
well-marked area known as the peristome-field. This sub-
order comprises four quite well-marked divisions, Heterotri-
cha, Oligotricha, Hypotricha, and Peritricha, distinguished
largely by the ciliary structure and distribution.

The Heterotricha have the body clothed with short, fine
cilia and an adoral circle or spiral of longer cirrose cilia at
the anteiior end, around the peristome-field. Stentor polymor-
phus may be taken as typical of this group. The body is
variable in form, but may be described as trumpet shaped,
expanded anteriorly and attenuated posteriorly. It is some-
times found in large attached colonies, and at other times
is free-swimming. The body is covered with longitudinal
rows of very fine cilia, while those around the peristome are
modified into strong flattened structures. The left margin of
the peristome is involuted, forming a little pocket, at the
bottom of which is the oral opening. The endoplasm usu-
ally contains a number of granules. The ectoplasm is
supplied with a layer of fine longitudinal contractile fibrils,
called the myophan. The contractile vacuole is large and
the nucleus large and moniliform.

The Oligotricha are a rather small group of short, rounded
to obconic forms, with the peristome-field occupying the
the anterior end, as in Stentor, and surrounded by a nearly
or quite completely circular adoral wreath. The ciliation of
the body varies in amount. A lorica is sometimes present.

The Hypotricha differ from the other groups in that they
are usually flattened and have the locomotor cilia upon the
ventral surface. These cilia are frequently modified into
strong styles or uncini. The dorsal surface is smooth or
furnished with a few rows of stiff cilia. The oral and anal
openings are distinct. Usually the peristome-field is on the

Protozoa and Rot if era at Havana, III. 309

anterior part of the ventral surface, triangular, and partly
surrounded by the adoral wreath. Stylonichia may be re-
garded as typical of this group. Its body is elongate, rounded
at the ends, and persistent in shape. The cilia form a con-
tinuous border around the ventral margin. The peristome-
field is placed anteriorly on the left side of the ventral surface.
It is well supplied with cilia and with a band-like undulat-
ing membrane. A number of the frontal cilia are modified
into styles. There are several claw-like caudal setse, and some
anal spines. The contractile vacuole is single ; the nuclei
two in number, usually oval.

In the Peritricha the cilia are usually limited to an adoral
wreath at the expanded end. Sometimes a circlet is present
at the opposite end. The well-known Vorticella, or bell ani-
malcule, is a good example of this group. The body is
spheroidal or more or less bell-shaped, and the ectoplasm is
prolonged posteriorly into a stalk, by means of which the
animal is attached. The myophan fibrils of the body unite
and form a large contractile muscular fiber extending through-
out the length of the stalk. The cuticular surface is some-
times transversely striated and otherwise ornamented. The
right limb of the adoral ciliary wreath descends into the
pocket or vestibulum, at the bottom of which the oral opening-
is situated. Contractile vacuoles one or several ; nucleus
band-like, large.

The subclass Suctoria is the most highly differentiated of
the Infusoria. This is especially seen in the matter of repro-
duction, for many of them reproduce by internal budding.
Tolcophrya may be considered as a type of this group. The
body is usually persistent in shape, more or less oval, and
fastened by the attenuate posterior end to a rigid stalk. In-
stead of cilia, the adult forms have a number of fine hair-
like tentacles, either scattered irregularly over the anterior
surface or arranged in several fascicles. These tentacles are
slightly movable and may be extended or retracted, serving
to capture prey and to convey food substance into the body ;
for, notwithstanding their slender form, particles of food from
the mass being fed upon may be seen passing within these

310 Illinois State Laboratory of Natural History.

tentacles to the body of the Tokophrya. The nucleus is large
and usually oval in shape; the contractile vacuoles are one
to several in number. All the members of this genus repro-
duce by internal budding. The young Tokophrya is provided
with an equatorial circle of cilia, by means of which it swims
rapidly through the water, later fastening itself to some
object, when the cilia disappear and the form of the adult
begins to be assumed.

METHOI/S OP CAPTURE AND STUDY.

All of the methods of capture suggested on a later page for
the Rotifera will answer equally well for the Protozoa. Of
course, infusions of hay or grass will furnish certain kinds.
The method of keeping water from ponds and ditches in
watch-glasses as described for the Rotifera, if duly attended
to, will not fail to give satisfactory results. Considerable
attention should be given to the examination of small
Crustacea, aquatic insect larvae, pond snails, small turtles,
and crayfishes, as many Protozoa are likely to be found upon
them. Vorticella may be found on the roots of Lemna, or on
fixed aquatic plants.

Whenever possible, Protozoa should be studied alive.
Good results were obtained in the preservation of Tokophrya
quadripartlta by the following process. A small colony was
transferred to a drop of water upon a slide and a cover-
glass placed over it, the cover-glass being raised by little
supports of wax so that it did not touch the zooids. A drop
of an aqueous solution of corrosive sublimate was then added
and allowed to remain about half a minute, when it was
washed out and 30% alcohol substituted, this being grad-
ually changed to 70%. Next, the zooids were stained for
about twenty minutes in Kleinenberg's hematoxylin and then
decolorized with acidulated alcohol, consisting of .5% hydro-
chloric acid in 70% alcohol, which in turn was well washed
out with pure 70% alcohol. Then the alcohol was gradually
changed to 95%, after which clove oil was substituted and
allowed to remain until the zooids were clear. Finally they
were mounted in balsam. All the changes from water to

Protozoa and Rotifera at Havana, III. 311

balsam were made on the slide by the irrigation process, that
is, by placing a drop of the liquid on the slide at the edge of
the cover-glass, and then drawing it under the cover-glass
by means of blotting-paper. The Tokophrya was attached to
Opercularia, and many of the latter genus were killed well
expanded, thus suggesting the idea that this method could
probably be used with good results for other Vorticellidce.

GEOGKAPHICAL DISTRIBUTION.

There is probably no place on earth, unless it be a sandy
desert or a subterranean stream, where Protozoa may not be
found. No stream is too clear or pond too muddy for them
to thrive in. They are found in the warm waters of the
tropics and in the icy waters of the northern countries. The
United States stands next to Europe in the number of recorded
species. A considerable number are also found in Australia.
There are many cosmopolitan species, which is not so re-
markable when we consider that the light cysts may very
readily be carried long distances by air currents.

FOOD RELATIONS.

But little attention has been paid to the food of the Proto-
zoa, and it is very desirable that students should make and
record careful observations along this line.

In general it is known that Amosha, Arcella, Diffiugia, Vor-
ticella, Opercularia, and the like, feed largely on diatoms and
desmids, diatoms especially seeming to be a favorite food
of such forms as Vorticella and Opercularia. Euglena has
been found within the body of Opercularia, and Tokophyra
and Acineta are predaceous, living upon other Protozoa.

Individuals of the latter genus have been seen to kill and
devour Vorticella. Schewiakoff ('93) says that' rotifers,
daphnids, and Chcetonotus also serve as food for Protozoa.
No doubt many of the species that possess chlorophyll derive
some nourishment from gases, as plants do ; while other
forms absorb organic matter in solution in the water. It is
probably true that plants constitute a larger proportion of
their food than animals, but the data on this point are so
meager that no general statement can be made.

312 Illinois State Laboratory of Natural History.

On the other hand, the Protozoa play an important part in
the food of other organisms. Many rotifers feed freely upon
them, and even young fishes have been found with Difflugia
in their stomachs. Euglena, Volvox, Pandorina, Difflugia,
and Codonella are among the forms observed in the stomachs
of rotifers ; but so few observations on this subject have been
recorded, that very little information can be gathered at
present.

LOCAL DISTRIBUTION.

In the waters from which our Station collections were made
the Protozoa were not so abundant nor so widely distributed
as the rotifers. In all, ninety-three species are recorded, one
of which (Difflugia fragosa) is here described for the first
time. Species which could not be identified with certainty
are not included in the list.

The most widely distributed form was Difflugia globulosa,
which appeared at every substation and was present in
nearly every month of the year. Other species of Difflugia
and species of Arcella were found during a considerable part
of the year, including the summer months. Dinobryon
sertularia was very abundant, occurring from December to
June; Euglena viridis was observed throughout the summer
months ; Volvox globator was found in every month except
February; Coleps hirtus was present from May to October ;
and Codonella cratera was frequently seen from April to
September. All through the summer months many species
of Vorticella, Epistylis, and Opercularia were taken in thetow-
ings or upon the backs of turtles and the larger Crustacea,
but few of them could be definitely determined.

A number of the species here recorded were found in
aquaria started with dried mud from the bed of Phelps Lake.

I have found it very difficult to make a sharp distinction
between the littoral or shore forms, and the so-called pelagic
or limnetic forms found in the open waters. These waters
were so shallow— the average depth at the various substations
ranging from two to twelve feet— and so full of vegetation,
that the only species that seemed entitled to be considered as

Protozoa and Eotifera at Havana, III. 313

pelagic were those that evidently preferred clear open water,
free from vegetation.

Thirty-five of the species here treated were found in open
water, either in surface, hottom, or oblique towings. They
are as follows :

Arcella vulgaris Ehrbg. Euglena acus Ehrbg.

Arcella vulgaris discoides. Euglena oxyuris Schmarda.

Leidy. Euglena torta Stokes.

Arcella vulgaris angulosa Trachelomonas acuminata

Leidy. Schmarda.

Arcella dentata Ehrbg. Phacus longicauda Ehrbg.

Difflugia globulosa Duj. Phacus pyrum Ehrbg.

Difflugia pyriformis Perty. Volvox globator Ehrbg.

Difflugia acuminata Ehrbg. Pleodorina californica Shaw.

Difflugia lobostoma Leidy. Cryptomonas ovata Ehrbg.

Difflugia corona Wallich. Peridinium tabulatum Ehrbg.

Difflugia aculeata Ehrbg. Ceratium brevicorne Hempel.

Difflugia tuberculosa Paramecium aurelia 0. F.

Hempel. Mull.

Difflugia fragosa n. sp. Stentor polymorphus 0. F,
Actinophrys sol Ehrbg. Mull.

Actinosphaerium eichhornii Stentor coeruleus Ehrbg.

Ehrbg. Stentor barretti Barrett.

Kaphidiophrys pallida Halteria grandinella 0. F.

Sclmlze. Mull.

Dinobryonsertularia Ehrbg. Codonella cratera Leidy.

Euglena viridis Ehrbg. Tintinnopsis illinoisensis
Euglena spirogyra Ehrbg. Hempel.

To these might be added Diditiium nasutum 0. F. Mull.,
mentioned by Zacharias ('94a), and Trachelomonas <-<tu<lata
Ehrbg, both of which were found in aquaria started with mud
from the bottom of Phelps Lake.

One peculiar fact noted was the occurrence of a number of
Rhizopoda in the surface towings. Prof. Frank Smith ('94)
lists three species as occurring in surface collections in Lake
St. Clair; Dr. C. A. Kofoid lists eight species from the waters

814 Illinois State Laboratory of Natural History.

of Lake Michigan ; while at Havana nine forms were found.
These are as follows :

Arcella vulgaris Ehrbg. Difflugia globulosa Duj.

Arcella vulgaris discoides Difflugia pyriformis Perty.

Leidy. Difflugia lobostoma Leidy.

Arcella vulgaris angulosa Difflugia corona Wallich.

Leidy. Difflugia aculeata Ehrbg.
Arcella dentata Ehrbg.

These forms appeared in the surface collections frequently,
being at times quite a constant factor in the catches.

CLASSIFICATION.

Many different classifications of the Protozoa have been
proposed, but the arrangement given by Butschli ('80-'89)
has been followed throughout in the construction of this
list. Kent's " Manual of the Infusoria" ('80-'82) was mainly
used in the determination of the species of that class. For
the species described since the publication of Kent's Manual
and Leidy' s lihizopods ('79) citations are given, by date, to
the works containing the original descriptions, and these titles
may be found in the list of literature appended to this paper.

SYNOPSIS OF THE HIGHER GROUPS OF PROTOZOA.*

I. Class Sarcodina. Forms that move about by a simple
protoplasmic movement, by a flowing motion, or by the
formation of protoplasmic processes (pseudopodia).
1. Subclass Rhizopoda. Form usually protean; pseudo-
podia lobose or slender, more or less temporary struct-
ures without axial support, often restricted by a shell
to a part of the body surface.
Order Rhizopoda. (Includes all the recent forms of this
subclass.)
1. Suborder Amoebcea. Naked; pseudopodia lobose
or filiform. Two families ; one mostly marine.
Amcebidce. Pseudopodia usually lobose, never form-
ing a network.

♦Compiled from Butschli ('80-89).

Protozoa and Rotifer a at Havana, III. 315

2. Suborder Testacea. Shelled forms; pseudopodia
lobose or filiform. Four fresh-water families.
Arcellidce. Shell homogeneous or incrusted with
sand grains or other foreign material ; pseudo-
podia lobose.
Euglyphidce. Shell built of round or hexagonal
plates ; pseudopodia filiform at tip.

2. Subclass Heliozoa. Body usually globose; pseudo-
podia thread-like, constant, radiating in all directions.

1. Order Aphrothoraca. Naked, or with gelatinous
envelope.

2. Order Chalarathoraca. Coated with silicious bodies
of a definite form, spicular, discoid, etc.

3. Order Desmothoraca. Skeleton shell nearly or quite
spherical, latticed, with numerous openings.

3. Subclass RadAolaria. Body globose, with a silicious
shell; pseudopodia filiform, radiating in all directions.
Marine.

II. Class Sporozoa. Parasitic forms, multiplying exclusively

by spore formation.

III. Class Mastigophora. Provided with one or more vibra-

tile anterior or lateral flagella ; body not ciliated.

1. Order Flagellata. One or more anterior, rarely
lateral, flagella, not encircled by a membranous
collar; body naked or loricated.

2. Order Choanoflagellata. One anterior flagellum,
encircledby one or two thin membranous raised col-
lars.

3. Order Dinoflagellata. Two flagella, anterior or
lateral (if we consider the advancing pole in loco-
motion as the anterior end), one directed longitudi-
nally, the other transversely, and usually encircling
the body more or less ; body with a shell or armor ;
no definite mouth.

4. Order Cystqflagellata. Large, phosphorescent ma-
rine forms.

IV. Class Infusoria. Clothed with cilia, entirely or in part ;
cilia variously differentiated and modified.

316 Illinois State Laboratory of Natural History.

1. Subclass Giliata. Cilia persistent through life; food
taken through a mouth, except in some parasitic forms.

1. Order Gymnostomata. Mouth usually closed when
not in use, without undulating membrane or well-
developed ciliary structures ; food taken by swal-
lowing ; throat, if present, without ciliary structures,
usually surrounded by a wall of more or less indu-
rated parallel longitudinal rods. Three families.

2. Order Trichostomata. Mouth or throat rarely closed,
provided with well-developed undulating membrane
or ciliary structures, food usually drawn in or
engulfed.

1. Suborder Aspirotricha. Body invested with fine
and comparatively uniform cilia, no anterior
spiral adoral wreath.

2. Suborder Spirotricka. A spiral to nearly circular
adoral ciliary fringe bordering a differentiated
peristome-field and ending at the mouth ; cilia of
fringe often broad or lamellate.

1. Section Heterotricha. Entire surface usually
rather uniformly ciliated, the adoral series larger
than the rest, and more or less spirally arranged.
Four families.

2. Section Oligotricha. Body more or less globular
or obconic ; peristome-field wholly on the anterior
end, adoral wreath nearly or entirely a closed cir-
cle ; ciliation well developed to wanting ; in some
instances loricated. Four families.

3. Section Hypotricha. Body usually flattened;
ventral cilia modified into seta? or styles, back
usually with rows of stiff bristles ; peristome-
field about in the plane of the ventral surface,
adoral wreath bordering its left and anterior
sides, and sometimes a part of its right side.
Four families.

4. Section Peritricha. Solitary or united in social
colonies ; cilia confined to the adoral wreath encir-
cling the expanded terminal peristome-field ; a

Protozoa and Rot if era at Havana, III. 317

second circlet of cilia sometimes present at the
opposite end of the body. Three families.
2. Subclass Suctoria. Cilia present only in the free-
swimming young ; food absorbed by tubular tentacles ;
reproduction by budding, rarely by division. Eight
families.

Class SABCODINA.

Subclass RHIZOPODA.

Order BHIZOPODA.

Family AMOEBID^.

Amoeba Bory.

Body naked, with pseudopodia ; contractile vacuole and
nucleus present ; reproduction by bipartition in the active
condition.

1. A. proteus Bosel.

This species appeared only in towings from the river chan-
nel at E in September.

2. A. radiosum Ehrbg.

A few examples of this interesting form were taken in the
tow-net in Phelps Lake in July.

Pelomyxa Greeff.

Amoeba-like, naked, usually quite large (up to 2 mm. in
diameter), moving by means of short, broad pseudopodia, and
commonly more or less slug -like when in motion. Nuclei
very numerous.

3. P. villosa Leidy.

This was found sparingly in June, July, and August : in
July with the preceding species in towings from Phelps Lake ;
and on the other occasions at C in bottom towings and in col-
lections from the vegetation along the east shore.

318 Illinois State Laboratory of Natural History.
Family ARCELLIDiE.

ARCELLA EHEBG.

Shell chitinous, usually round, convex above, concave be-
neath with a large round opening at middle ; color yellow or
brown, its surface smooth or thickly pitted ; usually several
nuclei and contractile vacuoles.

4. A. vulgaris Ehrbg.

This species occurred in small numbers in the towings
throughout the year, except during the winter months, and in
summer was occasionally found in collections from the vegeta-
tion along shore. It seems remarkable that none were found
in towings from Thompson's Lake except a few which
appeared in March, 1895.

5. A. vulgaris discoides Leidy.

This variety was usually found in company with the typ-
ical form, in about the same numbers and similarly distri-
buted. A single finding in midwinter at C is recorded, also
its occurrence in Matanzas Lake.

6. A. vulgaris angulosa Leidy.

Not so common as the preceding forms, but similarly dis-
tributed.

7. A. dentata Ehrbg.

This form was very rare, and was seen but twice ; once dur-
ing August, and again in September, in towings from sub-
station C.

DlFFLUGIA LecLERC.

Shell variously shaped, sometimes chitinous, but usually
composed principally of small grains of sand and other for-
eign substances. Pseudopodia narrow, long, sometimes
branching, rounded at the ends. Nucleus usually single.

8. D. globulosa Duj.

This was widely distributed, occurring at all the substa-
tions, usually in the towings, and much less frequently in the
Birge-net collections. It was never very common, but con-

Protozoa and Rotifer a at Havana, III. 319

tinuecl to appear throughout the year, becoming very scarce
during cold weather.

9. D. pyriformis Perty.

Although this was even less common than the preceding
species, its occurrences were quite uniformly distributed
through the entire year, and it was recorded from all the
principal substations. It was also found in Matanzas Lake.
It appeared usually in the towings, rarely in shore collections.
In February a few were taken in a towing at C, underneath a
foot of ice.

10. D. pyriformis vas Leidy.

Not common ; taken only in July and August in towings
from substations K and L (Flag and Dogfish lakes).

11. D. pyriformis compressa Carter.

In July and August a few appeared in towings from Thomp.
son's and Dogfish lakes.

12. D. urceolata Carter.

No individuals of this species were found in any of the
collections, but in November a quantity of dried mud was
collected from the bed of Phelps Lake, which was entirely
dry at this time, and several small aquaria were started by
placing some of this mud in jars of filtered water. Several
examples of U. urceolata appeared in these aquaria, as well
as other forms which will be mentioned in their proper place.

13. D. acuminata Ehrbg.

Like D. pyriformis, this was scarce, but generally dis-
tributed through the year and at the various substations. It
also occurred under the ice at C in February, and in Matan-
zas Lake. With one exception it was found only in the tow-
ings.

14. D. lobostomata Leidy.

This species was very generally distributed. It was found
almost entirely in the towings, associated with D. globulosa.
In the fall it became common and even abundant, but was
noticeably sparser in winter. This species was among those
collected from under the ice at C in February. It is also
recorded from Matanzas Lake.

320 Illinois State Laboratory of Natural History.

D. lobostomata may be easily mistaken at first for D. globu-
losa. It is smaller than globulosa, however, and long in
proportion to its width. I have, found both species in the
stomachs of rotifers.

15. D. corona Wallich.

This beautiful and attractive species was moderately com-
mon throughout the year, less common in winter, appearing
in collections from nearly all of the substations, usually in
towings, but often also in shore collections.

Schewiakoff ('93) identifies this species with D. lobostoma,
but in my judgment the two species are distinct. D. corona
is larger and more spherical than lobostoma, and the fundus
always bears one or more spines. In corona, the border of
the mouth has quite a number of lobes or crenulations, while
in lobostoma there are usually but three or four lobes present.
Among all the specimens of D. lobostoma that I have ex-
amined there was but one which had more than three lobes ;
and, on the other hand, I have never seen a corona with so
small a number of lobes.

16. D. aculeata Ehebg.
Centropyxis aculeata Ehrbg.

The record of this species shows it to be much scarcer than
the two preceding, although occurring pretty uniformly
through the year. It was found both in towings and shore
collections, and seems to prefer weedy waters.

17. D. tuberculosa Hempel ('96).

Found in three out of six towings taken on one occasion in
Matanzas Lake in August. But few individuals were found.
In the following season a few examples were taken in the
river channel at E in September and October. It is easily
recognized and remembered by its irregular outline and
by the presence of tubercles.

18. D. fragosa, n. sp. (Fig. 1, 2.)

This form was found several times, and seems to be new.

Protozoa and Rotifera at Havana, III.

321

Fig. 1, Difflugia fra-

gosa, n. sp. Lateral

view.

Fig. 2, Difflugia fra-

gosa n. sp. View

showing mouth

opening.

Shell composed of fine sand grains, irregular in form,
about one and a half times as long as
wide, widest at fundus, thence tapering to
the mouth where it is slightly constricted ;
mouth irregular, slightly notched. The
peculiarity of this species is the presence
upon the fundus of from one to eight
ascending processes or
spines, rounded at tip.
These originate at about
the middle of the shell,
giving an irregular out-
line to the shell when

seen from above. Pseudopodia simple, fine,

and few in number.

Length .23 mm., width .15 mm.

It appeared occasionally from August to November of the

second year in towings, mostly from the river at E, with a

few from lake substations (G and C).

Family EUGLYPHID.3E

Etjglypha Duj.

Shell uniaxial, formed of round or hexagonal silicious
plates in overlapping rows ; mouth opening usually toothed.
Pseudopodia not anastomosing.

19. E. alveolata Duj.
Rare, occurring only in a towing from C in May.

Subclass HELIOZOA.

(Sun Animalcules).

Order APHROTHORACA.

ACTINOPHRYS EHRBG.

Body soft, spherical, with numerous radiating fine fila-
mentous pseudopodia ; endosarc finely granular ; ectosarc
vacuolated; division between the two not well marked.
Nucleus single, central ; usually a large contractile vacuole
in the periphery.

y

322 Illinois State Laboratory of Natural Hisiory.

20. A. sol Ehrbg.

This occurred only during the warmer half of the year,
from Jun^ to October, largely in collections from among
vegetation, where it was on one occasion quite common. A
few were found in lake towings.

ACTINOSPEUERIUM STEIN.

Body spherical, with numerous long tapering radiating
pseudopodia ; protoplasm vacuolated, vacuoles of the ectosarc
larger than those of the endosarc, the division between endo-
sarc and ectosarc distinctly marked. Nuclei numerous ;
contractile vacuoles located at the periphery.

21. A. eichhornii Ehrbg.

This interesting and fine species was seen only a few times,
appearing in towings from the river and Dogfish Lake from
July to September.

Order CHALARATHORACA.
Raphidiophrys Archer.

Isolated, or united into colonies. Body spherical, with
numerous fine, long, straight, radiating pseudopodia ; division
between endosarc and ectosarc not distinct. One or more
nuclei. Surface layer densely filled with fine, straight or
curved spicules, tangentially arranged.

22. R. pallida Ehrbg.

Found in small numbers in towings from substation C, in
Quiver Lake, during July and August.

23. R. elegans Hertw. Less.

Bare, occurring only in September, in towings from C.

Class MAST IGOPH OKA.

Order FLAGELLATA.

Suborder MONADINA.

Family HETEROMONADIDiE.

Subfamily Dendromonadinje.

Anthophysa Bory.

Zooids minute, obliquely pyriform, united into round
clusters of fifty to sixty, which are borne upon the extremities

Protozoa and Rotifera at Havana, III. 323

of a clickotomously branching pedicel; anterior extremity
prolonged into a spine-shaped process on one side. Flagella
two, one much shorter than the other. Nucleus and con-
tractile vacuole usually conspicuous.

24. A. vegetans 0. F. Muller.

A number of colonies were found in an aquarium started
with mud from the dry bed of Phelps Lake.

Subfamily DiNOBRYONiNJE.

DlNOBRYON EHRBG.

Animals in transparent loricse, which are united into
branching colonies. Free-swimming; zooids with a long and
a short flagellum, an anterior pigment spot, and two lateral
chromatophores.

25. D. sertularia Ehrbg.

Very common and often extremely abundant in the tow-
ings, especially from waters containing vegetation, during the
period from December to June.

26. D. sertularia divergens Imhof.
Observed in May, in towings from substation C.

27. D. sertularia angulatum Seligo.
Abundant in the towings from Dogfish Lake in Apri

28. D. sertularia undulatum Seligo.
Common in the river towings from E during April.

Suborder EUGLENOIDINA.
Family ETJGLENIDiE.

EUGLENA EHRBG.

Animals free-swimming, generally oval to elongate, usually
obtuse anteriorly, and more or less prolonged and attenuate
posteriorly. A well- developed mouth and flagellum at the
anterior end, and near this end a red pigment spot. Color
usually green.

In the latter part of summer Euglena is universally abun-
dant, even in the smallest pools and ditches. At certain

324 Illinois State Laboratory of Natural History.

times of day, except in case of a storm, these and related
species appear in vast numbers at the surface of the water,
forming the "water-bloom." In the vicinity of the Station,
this frequently formed green, brown, or red patches along the
shores, or drifted down the main channels in long streaks or
broad areas, not dense enough to be evident when close at
hand but very noticeable if viewed obliquely from a short
distance. On small pools the water-bloom often becomes a
dense green, paint-like, scum. It frequently consists in great
part of some single species. Euglena is readily eaten by
rotifers and by some Protozoa. The rotifer Eosphora au/rita
was found in the water-bloom.

29. E. viridis Ehrbg.

During the warmer season, from May to September, this
was frequent to abundant in the towings from most of the
substations, and very abundant in the water-bloom that was
examined. This species is highly changeable in shape.

30. E. spirogyra Ehrbg.

A few were found in a towing from Phelps Lake in July.
This pretty species preserves its form better than the pre-
ceding, is slightly thicker in proportion to its length, and its
surface is marked with oblique rows of small bead-like eleva-
tions.

31. E. acus Ehrbg.

Occurred from July to September, in small numbers, in
towings from the river and several lakes. It is very slender,
ending posteriorly in a sharp point, and is persistent in
shape.

32. E. oxyuris Schmarda.

Frequent and often common during about the same period
as that recorded for viridis; occurring from June to October.
It is elongate, obliquely striate, often spirally contorted. A
fine species, persistent in shape, and easily recognized.

33. E. torta Stokes ('85).

This small species was observed but once, namely, in a tow-
ing taken from Phelps Lake in July. It agreed in all par-
ticulars with Dr. Stokes's description, and the species appears

Protozoa and Rotifera at Havana, III. 325

to be well defined and valid. It is elongate, with three longi-
tudinal spiral furrows or elevations.

Amblyophis Ehrbg.

Very similar to Euglena in structure and colors, but with
the posterior end rounded, not at all acuminate.

34. A. viridis Ehrbg.

Found infrequently in the river channel at E in August
and September.

Trachelomonas Ehrbg.

Differs but little from Euglena, except that it is enclosed
in a lorica or shell, varying in shape from elongate-oval to
spherical, and with a minute anterior opening, through which
the flagellum issues.

85. T. caudata Ehrbg.

This appeared in large numbers in aquaria started with
dried mud from the empty bed of Phelps Lake. Within two
days after starting the aquaria the Traclielomonas began to
develop. At first they had no loricae, and were scarcely dis-
tinguishable from Euglena viridis. After a short time the
lorica began to appear, first around the central and an-
terior parts of the body. At this stage, before the posterior
part of the lorica had become fully formed and hardened, the
animals while swimming about would occasionally contract
the body, drawing the posterior part into the lorica.

In the second year's work a few were found in August and
September in towings from the river at E.

36. T. acuminata Schmarda.

Phelps Lake, with its shallow water and lack of vegetation,
seemed to be well fitted for the development of the Euglenida
during the first season of our work, since more species were
found here than at any other of the substations. T. acuminata
was scarce, appearing in the lake in July and August. It is
also recorded from Matanzas Lake.

37. T. armata Ehrbg.

A single occurrence is recorded, namely, at C in July.

326 Illinois State Laboratory of Natural History.

38. T. urceolata Stokes.

Rare ; found during September in towings from the river
at E.

39. T. torta Stokes ('88).

Observed only in September, in towings from the river and
Dogfish Lake. Not common.

40. T. hispida Stein.

Found in towings from Dogfish Lake in September.

Family CHLOROPEL.TIDID.ffi.

PHACUS Nitzsch.

Persistent in shape, ellipsoidal to pyriform, mostly com-
pressed and leaf-like, with a posterior, pointed, tail-like pro-
longation ; cuticle indurated, longitudinally or spirally
striated; mouth and throat asymmetric, opening dorsally;
body green, with anterior pigment spot.

41. P. triqueter Ehrbg.

Scarce ; found in September in towings from the river
channel.

42. P. pyrum Ehrbg.

Found but once, namely, in a towing from the river chan-
nel in October.

43. P. longicauda Ehrbg.

This fine and attractive species was present in small num-
bers from June to September, and was generally distributed.
A single occurrence in October is also on record.

Suborder ISOMASTIGODA.
Family CHRYSOMONADIDiE.

Synura Ehrbg.

Individuals oval to elongate, each contained in a membra-
nous lorica, commonly united into free-swimming subglobose
colonies ; llagella two, subequal ; one or more colored eye-
spots.

Protozoa and Rotifera at Havana, III. 327

44. S. uvella Ehrbg.

This species was seen only occasionally at first, a few being
observed in April and a single one in July. In October and
November it became common in the river towings, and from
December to March was more or less abundant at all the sub-
stations under examination, reaching its maximum in Janu-
ary.

Family VOLVOCIDiE.

Pandorina Bory.

Colonies free-swimming, spherical to oval, consisting usu-
ally of 16, rarely 32, individuals closely joined at a common
center.

45. P. morum Bory.

Observed only during the second year's work, from April
to September, and again from January to March. It was
quite common, but was not found in Phelps Lake. This spe-
cies forms an important element in the food of large rotifers.

Volvox Linn.

Colonies spherical, large, consisting of many thousand
similar zooids forming an enclosing wall about a large cen-
tral gelatinous mass.

46. V. globator Linn.

Abundant and well distributed in the field studied, except
in Phelps Lake, where it was only seen once. In midwinter
it became rare. It was abundant near the field laboratory in
Quiver Lake during July, and though many were taken here
in the bottom towings, none appeared in the surface towings
made during the day.

Pleodorina Shaw.

Colonies more or less oval, consisting of about 128 individ-
uals of two kinds, the large ones about one polo and the
small ones about the other, enclosing a central gelatinous
mass.

328 Illinois State Laboratory of Natural History.

47. P. californica Shaw ('94).

Occurred from July to October in both years, often in
great abundance, in towings and among vegetation in the
river and deeper lakes.

Family CRYPTOMONADID^.

Cryptomonas Ehrrg.

Free-swimming, ovate or elongate, anterior end oblique,
with a peristome-like excavation, in which is the oral open-
ing, leading to a distinct pharynx ; two flagella issuing from
beneath a lip-like anterior marginal prolongation ; two lateral
brown to green chromatophores.

48. C. ovata Ehrbg.

This was found in both years, but only in September and
October. Except a record from substation L it was taken
only in the river at E, where it was found excessively abundant
in both months.

Order CHOANOFLAGELLATA. (Collared Monads.)

Family CRASPEDOMONADIDiE.

Subfamily CoDONOSiGiNiE.

Diplosiga Frenzel.

Individuals attached singly, without pedicel ; two concen-
tric anterior membranous collars, the inner one small.

49. D. frequentissima Zach. ('94).

Taken abundantly in April, 1896, and in smaller numbers
during the following month in towings from the river chan-
nel at E. These minute individuals were attached to the rays
of Asterionella, a colonial diatom.

ASTROSIGA Kent.

Individuals united into stellate colonies by the attachment
of their pedicels at a common center.

Protozoa and Rotifer a at Havana, III. 329

50. A. radiata Zach. ('94).

One example observed by Dr. Kofoid in plankton from the
river at E, in May.

Subfamily Salpingcecin^:.
SALPINGCECA James-Clark.

Loricated, solitary, attached directly or by pedicel.

51. S. minuta Kent.

This extremely small form was found attached to the
loricae of Dinobryon sertulari'a from the river, in May.

Order DINOFLAGELLATA.

Suborder DINIFEBA.

Family PERIDINID-ffi.

Peridinium Ehrbg.

Free-swimming, covered with an ornamented shell en-
circled by an equatorial groove, dividing the shell into two
similar halves, the anterior formed of thirteen or fourteen
plates, the posterior of seven, two of which, nearest the pos-
terior extremity, are each often drawn out distally into a
horn-like prolongation. A moderately wide longitudinal
groove extends back from the equatorial groove at the middle
of the ventral surface. Two fiagella, one of which lies in the
equatorial groove.

52. P. tabulatum Ehrbg.

Found in July and August, but only in Thompson's and
Matanzas lakes, abundantly in the former situation though
not in any of the intervening waters.

CERATIUM Schrank.

Differing from Peridinium especially in the form and
structure of the shell. This is somewhat flattened dorso-
ventrally, with a broad uncovered area on the ventral surface ;

330 Illinois State Laboratory of Natural History.

the two ends and two lateral plates just back of the equa-
torial groove drawn out into horn-like processes, often much
longer than the width of the shell, usually the left process
not developed, so that there are but three in all; the two
halves similar in size and texture, the anterior with six plates,
the posterior with four.

53. C. hirundinella 0. F. Mull.

A few individuals were noted in towings from the river and
Thompson's Lake in August and September of the second
year only.

54. C. brevicorne Hempel ('96).

A few were taken in the river channel at E in August and
September, also in each of six successive towings in Matan-
zas Lake in August.

Class INFUSORIA.

Subclass CILIATA.

Order GYMNOSTOMATA.

Family ENCHELIDiE.

Subfamily HoLOPHRYiNiE.

Lacrymaria Ehrbg.

A distinct circle of large cilia around the mouth ; body
narrowed anteriorly and more or less bottle-shaped, moder-
ately elastic.

55. L. truncata Stokes ('85a).

Taken only once, in a Birge-net collection amongst vege-
tation at the mouth of Dogfish Lake, in August.

Subfamily Colepin^.

CoLEPS Nitzsch.

More or less barrel-shaped, axis slightly curved ; persistent
in shape ; covered with quadrangular plates in checker-board
arrangement, with intervening spaces in which arise rows of

Protozoa and Rotifera at Ha ran a, III. 331

long cilia. A circle of cilia surrounds the large terminal
mouth opening.

56. C. hirtus Ehrbg.

This lively and interesting little species was taken mostly
from June to September in both years, with scattering oc-
currences in May, October, and December. It was not very
common, although widely distributed.

Subfamily Cyclodininje.

Didinium Stein.

Obovate or obconic, anterior end feebly convex to distinctly
concave, the mouth borne on a prominent conical elevation ;
ciliation reduced to an anterior and a median circle, the
latter sometimes wanting.

57. D. nasutum 0. F. Mull.

One or two examples of this very peculiar protozoan were
found in the aquaria started with dried mud from Phelps
Lake. It is a fine species of striking form and very quick
movements.

Family TEACHELIIDiE.
Subfamily AMPHiLEPTiNiE.

AMPHILEPTUS Ehrbg. (Swan Animalcules.)

Elastic, ovate, anterior part more or less flattened and
produced like an elephant's trunk, along the lower edge of
which (oblique in side view) extends the slit-shaped mouth ;
surface entirely and finely ciliate ; contractile vacuoles single
or multiple.

58. A. anser Ehrbg.

Found in August in a Birge-net collection from among
plants at the mouth of Dogfish Lake.

DlLEPTUS Dim.

Elongate, with a very long, slender tiexible snout, along the
ventral edge of which is a band of trichocysts, ending at the

332 Illinois State Laboratory of Natural History.

round mouth-opening at the base of the snout. A row of
cilia extends along each side of the band of trichocysts and
around the mouth; ciliation of body fine and uniform.

59. D. anser 0. F. Mull.

Taken once, in August, with the Birge net, in vegetation
on the west side of the river at E.

Family CHLAMYDODONTID-ffi.

Subfamily Nassulinje.

Nassula Ehrbg.

Oval or somewhat elongate, ends equally rounded ; mouth
circular, situated on the ventral surface back of the anterior
extremity, left side more or less constricted beside the mouth ;
a row of stronger cilia extending from the mouth along the
constriction ; body finely and evenly ciliated, usually highly
colored, with a pigment spot at the constriction.

60. N. ornata Ehrbg.

Found once, in an aquarium started with dried mud from
Phelps Lake.

Order TEICHOSTOMATA.

Suborder ASPIROTEICHA.

Family PARAM^ECIIDiE.

Paramecium 0. F. Mull. (Slipper Animalcule.)

Ovate to elongate, flexible ; densely, finely, and evenly
ciliated ; peristomal groove feebly or moderately excavated,
narrowing posteriorly, and ending in the oval mouth, which
is in the middle part of the ventral surface ; one or two
stellate contractile vacuoles.

61. P. aurelia 0. F. Mull.

Very few individuals of this common species were found,
possibly because of the lack of stagnant water at any of the
substations. A few were taken among vegetation and in
towings in August, and examples appeared in towings in
October and January, all in the main river.

Protozoa and Rotifera at Havana, III. 333

Suborder SPIROTRICHA.

Section Heterotricha.

Family PL.AGIOTOMID.ffi.

CONCHOPHTHIR^US &TEIN.

Colorless, not elastic, strongly compressed, in lateral view
oval; mouth usually near the middle of the ventral edge,
which is here sinuated because of the more or less excavated
trough-like peristome-field ; ciliation uniform, cilia rather
long, usually a few larger ones along the anterior edge of the
peristome-field and at the posterior extremity.

62. C. anodontae Ehrbg.

Among the gills of Unio anodontoides from the river in
July. Found also in other Unionidas.

Spirostomtjm Ehrbg.

Colorless or green, elongate, often very much so, very
elastic and flexible, rarely compressed ; peristome-field nar-
row and long, extending from near the anterior end nearly
straight to the mouth, with a zone of adoral cilia upon its
left margin, turning obliquely into the mouth ; ciliary stria-
tion very distinct, and slightly oblique ; dorsally a long,
canal-like extension from the large contractile vacuole at the
posterior end.

63. S. teres C. & L.

Found only once, in August, in a towing from Quiver Lake.

Family STENTORID-ffi.

Stentor Oken.

Fixed or free-swimming at will ; trumpet-shaped when ex-
panded, tapering to the attached posterior end, the anterior
end broad and flattened, occupied entirely by the peristome-
field, which is encircled by the adoral zone of cilia ; this takes
a slightly spiral course on the ventral edge of the peristome-
field, descending into the pharynx; ciliation of body very

334 Illinois State Laboratory of Natural History.

fine, in longitudinal rows, often with intervening bristles ;
body more or less contracted when free-swimming ; when
attached, often protected by a tubular gelatinous sheath.

64. S. polyxnorphus 0. F. Mull.

Not very common at any time, occurring now and then
from April to July in towing and vegetation collections taken
in lakes. In an aquarium in the zoological laboratory of the
University this species was very abundant, large colonies
more than half an inch in diameter being formed, consisting
of a gelatinous substance in which the animals were fixed.

65. S. roeselii Ehrbg.

Not common; found in towings and among vegetation in
the river and in Quiver Lake.

66. S. barretti Barrett.

A few examples seen in March from the river at E. This
is closely allied to S. roeselii, but to me the two appear dis-
tinct.

67. S. cosruleus Ehrbg.

Found in some catches from along the shores of Quiver
Lake in May, in one of which it was common. This form
also occurred in aquaria at the University laboratory. Small
glass jars were filled with water containing some of them,
and after these had stood for several weeks the inner surface
of the jars was fairly lined with the Stentor. They reproduce
very rapidly, and with a little care a constant supply for
laboratory use can be kept on hand.

68. S. igneus ? Ehrbg.

A Stentor was found several times in the towings, which I
have doubtfully referred to this species. It was found once
in Dogfish Lake in August, and afterwards in towings from
the river at E from November to -January, being abundant in
December.

69. Stentor sp.

A small green species was found in a weedy bay — the
"Pumpkin Patch" — at the head of Quiver Lake; but was
not definitely determined.

Protozoa and Rotifera at Havana, III. 335

Section Oligotmcha.

Family HALTERIIDiE.

Strombidium C. & L.

Free-swimming, colorless, yellowish, or green, usually

persistent in shape, globose, pyriform, or urceolate, usually

narrowed or pointed behind ; anterior end convex, encircled

by the adoral zone, the oral end of which follows a ventral

excavation back to the mouth-opening towards the middle of

the body ; without cilia except a few on the ventral surface,

either irregularly scattered or in a short oblique row.

70. S. claparedi Kent.

Rare ; taken in September and December in the river and
Thompson's Lake.

Halteria Duj.

Free- swimming, colorless, persistent in shape, more or less
globose, anterior end feebly convex, adoral zone about as in
Strombidium, to which the genus is closely allied. Surface
with a number of long stiff bristles or springing hairs, irregu-
larly scattered or gathered into an equatorial zone. By
means of these bristles the animal progresses with a succes-
sion of quick springing or leaping movements, as indicated
by the name of the genus.

71. H. grandinella 0. F. Mull.

This peculiar species was of frequent occurrence from June
to September, and a few were seen in January and February.
It was very generally distributed.

Family TINTINNID^.
Tintinnopsis Stein.
Lorica chitinous, usually campanulate, structureless ; nu-
merous foreign particles imbedded in its outer surface, mostly
grains of sand.

72. T. illinoisensis Hempel ('96).*

Found in April and May, in company with Codonella cra-
tera, in towings from the Illinois River, Thompson's Lake,

♦Subsequent studies by Dr. Kofoid indicate that this form is not specifically dis-
tinct from Tintinnidiumjluviatile Stein.

D

36 Illinois State Laboratory of Natural History.

and Quiver Lake. In the following year it was again noted
in small numbers, during August and September, in towings
from the river at E.

CODONELLA HAECKEL.

Lorica indurated, short-urceolate in form, composed of
hexagonal or circular areolets, ea,ch with a darker central dot ;
structure usually more or less obscured by a covering of
foreign particles, a slight constriction at the base of the
neck of the lorica ; peristomal cilia often altered into leaf-like
lamellae.
73. C. cratera Leidy.

Difflugia cratera Leidy.
Few species among the Infusoria attract so much attention
as this. It was frequent to abundant in towings from the
deeper and more permanent bodies of water under examina-
tion, continuing apparently throughout the year. At Thomp-
son's Lake it was abundant in December, and again in
February was found in a towing from under eighteen inches of
ice. On one occasion in the latter part of August six tow-
ings were taken in different parts of Matanzas Lake and
examples of C. cratera were found in all but one of these
towings. This lake is fed almost entirely by springs, and con-
sequently the water is in places comparatively cool during the
summer, thus affording a congenial habitat for species that
thrive best in cold waters. One towing was taken near the
point where the water from a large spring enters the lake, and
contained an abundance of this form. The species serves
as food for such rotifers as Asplanchna and Asplanchnopus.

Section Hypotricha.

Family OXYTRICHID^].

Subfamily Pleurotrichin^;.

Stylonychia Ehrbg.

Free-swimming, persistent, obovate or elliptic, peristome
not greatly narrowed ; anterior styles usually eight, occupy-

Protozoa and Rotifera at Havana, III. 337

ing a more or less circular area ; five claw-like "ventral styles
and five straight anal styles ; three long caudal sets at the
posterior extremity.

74. S. mytilus Ehrbg.

This species seems to avoid the open water, as it did not
occur in the towings, although it was not uncommon in oc-
casional shore collections among vegetation in June and
again in December.

Section Pekitricha.

Family VORTICELLID^S.

Subfamily Urceolarinje.

Trichodina Ehrbg.

Free-swimming, more or less short-cylindrical, elastic and
flexible, especially the peristome end, which bears a well-
developed adoral zone; posterior end forming an adhesive
disc, bearing a complicated attachment-ring of radiating
structure which is encircled by a posterior ciliary wreath,
used in creeping and swimming, margin of disc forming a
thin transparent edge. Parasitic on the surface of Hydra
and other invertebrates.

75. T. pediculis Ehrbg.

Frequent on Hydra viridis, in towings from Dogfish Lake

(substation L) in April.

Subfamily VORTlCELLiNiE.

SCYPHIDIA DlJJ.

Not forming colonies ; individuals elongate-cylindrical, at-
tached by a posterior disc which does not bear a ring of
cilia ; peristome moderately well developed. Parasitic upon
mollusks.

76. Scyphidia sp.

A species of this genus was observed on the siphonal
papilla? of Unio parvus, but was not determined.

338 Illinois State Laboratory of Natural History.

VORTICELLA Linn. (Bell Animalcule.)

Inverted bell-shape, attached singly by a slender pedicel
containing a highly contractile central thread ; peristome end
usually very wide ; nucleus usually band-like. Many species
of this genus were found, but few of them could be deter-
mined with any certainty.

77. V. campanula Ehrbg.

Found in July among Lemnacece and other vegetation in
Quiver Lake and the river, and once again in December in a
river towing.

78. V. microstoma Ehrbg.

A few were noted in July, taken from among Lemnacece
upon the river at E.

79. V. similis Stokes ('87).

Common in July on roots of Lemnacece in the very weedy
bay of Quiver Lake known as the " Pumpkin Patch."

CARCHESIUM Ehrbg.

Animals like Vorticella, but forming tree-like colonies, the
individuals borne upon the tips of a single branching stalk,
with a contractile central thread. At the forkings of the
stems the contractile thread of one branch is continuous with
that of the stem below, while that of the other is not con-
nected, thus permitting the independent extension and con-
traction of the separate zooids.

80. C. polypinum Linn.

This was also found on the roots of Lcmnaee<e in the
" Pumpkin Patch" in July. The colonies found were rather
small. It was not common.

81. C. lachmanni Kent.

This species was abundant about the field laboratory in
Quiver Lake in May. It was first noticed in some breeding-
cages used in rearing aquatic larva?. It multiplies very
rapidly in foul or stagnant water. Some were placed in
glass jars in the laboratory, and in a few days the entire
inner surface of the jars was coated with a dense grayish
layer.

Protozoa and Rotifera at Havana, III. 339

82. C. granulatum Kell.

Many large colonies of this species were found in May upon
an Asellus taken from the west side of the river at E.

ZOOTHAMNIUM BoRY.

Similar to Vorticella and forming branching contractile
colonies ; but in this genus the contractile central thread
is continuous throughout, dividing with each branching of the
stem, whereby the act of contraction involves the entire
colony.

83. Z. arbuscula Ehrbg.

This interesting and beautiful form was met with twice in
the towings ; in June from Quiver Lake, and in August from
the river at E. A number were found on the latter occasion.
The colonies are usually large and symmetrical, and when
once seen will be remembered.

Epistylis Ehrbg.

Animals forming colonies, borne on a rigid, noncontractile
tree-like pedicel ; individuals bell-shaped, more or less elon-
gate to cylindrical ; adoral zone encircling a slightly raised
disc within the peristome margin, its oral end descending at
one side, through an excavated vestibule, to the mouth open-
ing; anterior end not so flexible as in Vorticella.

Several species were found, but only two could be definitely
determined.

84. E. plica tilis Ehrbg.

Found at various times, especially in May, at a number of
different places, twice in river towings, but usually attached
to various insect larvae, and on the shells of water-snails,
such as Physa and Vivipara. Tokophrya quadripartita was
sometimes found associated with it.

85. E. flavicans Ehrbg.

This species was noted as abundant on plants on two occa-
sions in summer, and was found to be quite generally dis-
tributed, though not very abundant, in towings taken in the
winter time.

340 Illinois State Laboratory of Natural History.

RHABDOSTYLA Kent.

Similar to Epistylis, but not forming colonies.

Several undetermined species of this genus were found on
various Entomostraca, on a rotifer (Polyarthra platyptera),
and on small aquatic worms.

Opercularia Goldf.

Forming colonies as in Epistylis, individuals more or
less narrowed at the anterior end, peristome not laterally
expanded ; adoral disc very strongly elevated, while the sur-
rounding peristomal ring is deeply excavated and the vesti-
bule conspicuously wide and very deep ; the adoral disc is
therefore borne upon a column, on which it is usually
obliquely placed, looking like a ciliated lid to the anterior end.

86. O. nutans Ehkbg.

Found in May on a Planorbis from Quiver Lake at C.

87. O. rugosa Kell. ('84).

Common among vegetation ; a few found in bottom towing
in Quiver Lake. Observed in May and July in the river and
in Quiver and Thompson's Lakes. This is a fine species, and
can be easily recognized by its thick pedicel and sessile
zooids. Schewiakoff ('93) marks the species with an interro-
gation point, but I see no reason for it.

88. O. irritabilis Hempel ('96).

This fine large species was found at a variety of places
from May to July, during which time it was common and
aften abundant, always occurring attached to the surface of
some animal, especially young musk-turtles (Aromochelys
odoratus). It was also found upon the backs of snapping
turtles (Chelydra serpentina), and on two kinds of crayfishes,
Cambarus diogenes and C. blandingii acutus. Its food consists
partly of diatoms and Euglena.

The species is similar to Operculariq articulata Ehrbg., but
differs from it in the shape of the body, the character of the
peristome border and pharynx, and the elevation of the
ciliary disc.

Protozoa and Rotifera at Havana, III. 341

Tokophrya quadripartite was found common in company
with this species, as was also a small Opercularia, which may
prove to be only a variety of irritabilis. The zooicls of this
small form measured .08 mm. in length and .042 mm. in
width, but otherwise seem to agree with those of irritabilis.

COTHURNIA EHRBG.

Animal similar to Epistylis, but more elongate ; contained
in a lorica which is subcylindrical, of variously modified
shapes, often expanded at middle and narrowed near the
opening, attached posteriorly, either directly or by a short
pedicel ; sometimes closed when the animal is retracted
within it. Nucleus elongate, band-like.

89. C. curva Stein.

Found upon Urnatella gracilis in July, in bottom towings
from the river at E.

Vaginicola Lam.

Animal similar to that of Cothurnia ; lorica sac-like, nar-
rowed at the opening, attached lengthwise by the ventral
surface and flattened, the opening turned upwards.

90. V. gigantea D'Udek.

A few individuals were found in September among vegeta-
tion in Thompson's Lake.

Subclass SUCTOKIA.

Family ACINETID^E.

Tokophrya Butschli.

Solitary, not loricated, globose to elongate, attached pos-
teriorly by a rigid pedicel ; reproducing by the formation of
ciliated embryos within the body of the parent.

91. T. cyclopum C. & L.

In May and July a few were found on Cyclop* in towings
from Quiver Lake and the river.

92. T. quadripartita C. & L.

This was the commonest of the Suctoria in our collections.

342 Illinois State Laboratory of Natural History.

It occurred principally in May and June, in collections from
a number of substations, and was usually found associated
with Epistylis plicatilis and Opercidaria irritabilis, attached
to small animals taken among vegetation. It is recorded
from Cambarus diogenes, C. blandingii acutus, Chelydra ser-
pentina, Aromochelys odoratus, and larvae of Hexagenia.

AciNETA Ehebg.

Solitary, ovate or elongated, basally or entirely within a
cup-like lorica with a rigid pedicel ; reproduction as in Toko-
jthrya.
93. A. mystacina Ehrbg.

In the aquaria started with dried mud from Phelps Lake
this species was quite common. It is very voracious, living
upon Ciliata. Several specimens were observed while thus
eating, and the passage of food particles through the tentacles
was easily seen.

ROTIFERA.

The researches and investigations of morphologists during
recent years have led to a clearer and fuller acquaintance
with the details of animal structure, thus stimulating study
along related lines. The field of the systematist has thus
been broadened and extended. With a thorough knowledge
of the anatomy of the animal body rather than a mere ac-
quaintance with its external appearance, he is now better able
to trace the relationships of the various subdivisions of the
animal kingdom, and to place each form in the group to
which it properly belongs. At the same time has come the
study of cecology — the relation of organisms to each other
and to their environment. Nothing can be more fascinating,
or of more value in solving the general problems of life than
this study of interrelations and dependences ; but it cannot
be carried on rightly unless our knowledge of the morphology,
habits, etc., of the forms under observation is as complete as
science can make it. Nor should this study be confined
solely to animals of large size and easy of access ; it must be

Protozoa and Rotifera at Havana, III. 34

o

extended until it includes the minutest creature ; for it is
through these simple, minute organisms that we may arrive
at the relations which exist between the inorganic and the
organic.

The Rotifera constitute one of these groups of minute
animals. It is a somewhat small group, consisting of about
six hundred known species, one hundred and seventy of
which have been found in the United States. They range in
length from .05 to 2.5 mm. The body is usually elongate,
sac-like or more or less oval, and is commonly provided with
two circles of cilia on the corona or frontal border of the head,
which, as the name indicates, have the appearance of two
small wheels. These cilia are used in locomotion, and also
assist the animal in obtaining food, since by their rapid vibra-
tion a stream of water is directed towards the mouth or buc-
cal orifice, carrying with it particles of food material. The
word rotifer is, however, misleading, since in many cases the
circles of cilia or ciliary discs are so modified that they have
lost all resemblance to a wheel. Sometimes but a single disc
is present ; again, there may be merely a row of cilia around
the anterior border of the animal ; and in rare cases the cilia
are even entirely wanting. Some of the Rotifera have the
body covered with a very thin chitinous external cuticula,
while a great many have a hard, inflexible carapace or lorica.
A number of species inhabit tubes, which they either secrete
or build up from surrounding debris and pellets of excreta.

Members of this group are readily recognized by the pres-
ence of the mastax, a more or less irregularly three-lobed
muscular organ, containing the teeth, jaws, or tropin, as
they are variously called. These are composed of chitin, are
hard and durable, and are true masticatory organs. Although
some of the rotifers have no cilia, all of them agree in having
a mastax and trophi, and as these structures are peculiar to
the Rotifera they afford a ready means of identification.

The mastax is usually situated in the anterior part of the
body, just behind the buccal orifice or lips, and a short
oesophagus connects it with a large stomach lying in the pos-
terior dorsal part of the animal. Many rotifers have the

344 Illinois State Laboratory of Natural History.

power of protruding the tropin through the buccal orifice,
and they may often be found nibbling at algae and other
aquatic plants. Although the tropin are used by many
rotifers to crush their food, there are some large forms, like
Asplanchna, that swallow their food entire, as is shown by the
uninjured rotifers, protozoans, and algre found in their
stomachs.

The chitinous jaws or tropin (Fig. 3) consist typically of
two hammer-like lateral parts, the mallei, bearing one to
seven comb-like apical teeth, and working upon the two
halves of a divided central part, the incus. The mallei are
usually separable into an apical part bearing the teeth, the
uncus, and a basal part, the manubrium. The two divisions
of the incus are the rami and its basal projection is the ful-
crum. These inner and outer pairs vary greatly in relative
development, the mallei in some groups disappearing entirely.
Hudson and Gosse recognize seven types of tropin, as shown
in the figure below. Dr. Hudson's summary of the distin-
guishing features of these types is given on the next page.

un+wa

Fig. 3, Diagram of trophi: A, malleate; B. sub-malleate: C.virgate; D,
forcipate; E. raalleo-ramate ; F, incudate; G, uncinate; ET, ramate.
f, fulcrum; i, incus; wia, manubrium: r, ramus; un, uncus. (After
Hudson, from the Cambridge Natural History.)

Protozoa and Rotifer a at Havana, III. 345

Malleate (A). Mallei stout; manubria and unci of nearly
equal length; unci 5- to 7 -toothed; fulcrum short; as in
Brachionus urceolaris.

Sub-malleate (B). Mallei slender; manuhria about twice
as long as the unci; unci 3- to 5-toothed; as in Eucklanis
defiexa.

Virgate (C). Rami as well as mallei rod-like ; as in Furcu-
lar'ia.

Forcipate '(D). Mallei rod-like; manubria and fulcrum
long ; unci pointed or evanescent ; rami much developed and
used as a forceps; as in Diglena forcipata.

Malleo-ramate (E). Mallei fastened by the unci to rami;
manubria 3 loops soldered to the unci; unci 3-toothed; rami
large, with many stria? parallel to the teeth ; fulcrum slender ;
as in Melicerta ringens.

Incudate (F). Mallei evanescent; rami highly developed
into a curved forceps; fulcrum stout; as in Asplanchna
ebbesbornii.

Uncinate (G). Unci 2 -toothed; manubria evanescent;
incus slender ; as in Stephanoceros eichkornii.

Ramate (H). Rami sub-quadrantic, each crossed by two
or three teeth ; manubria evanescent ; fulcrum rudimentary ;
as in Philodina roseola.

The oesophagus, connecting the mastax and stomach, is
lined with cilia, which by their vibratory motion cause a con-
stant stream of water to flow towards the stomach, carrying
particles of food with it.

The stomach is a large sac with thin walls, and usually
contains a number of oil or fat globules. This may be
demonstrated by killing rotifers with osmic acid, when the
oil globules will be turned black by the acid. It is astonish-
ing to see how much may be crammed into the stomach of a
rotifer. I have frequently found specimens of Asplanclniojuts
with six or seven other rotifers in its stomach, and I once
found a rotifer that had just made a meal of half a dozen
small crustaceans (Chydorus) .

There are at least three sets of glands within the body of
a rotifer. One pair, the supposed salivary glands, are

34C) Illinois State Laboratory of Natural History.

globular in shape and situated at the sides of the mastax.
Another pair, the so-called liver or gastric glands, more or less
kidney-shaped, are situated behind the mastax and on the
anterior part of the stomach, and, as their name implies, are
supposed to secrete a digestive fluid for the stomach. The
third pair are located in the foot, and are called the foot
glands. They are usually tubular, more or less elongate in
form, and secrete a sticky substance by means of which the
rotifer anchors itself to weeds, sticks, or other objects.

No true circulatory or respiratory organs are present,
although there is an excretory system. This consists of
a pair of tubes or canals, one on each side of the body,
running almost its entire length, and connected posteriorly
with a contractile vesicle which, in turn, opens into the
cloaca. Upon each lateral canal are a number of small cup-
like structures, the vibratile tags, each one probably pro-
vided with cilia or flagella by means of which the fluid of the
body is caused to flow into these vibratile tags and thence
into the lateral canals, thence passing to the exterior by
way of the contractile vesicle and cloaca. While it is prob-
able that all rotifers are provided with a contractile vesicle,
this has not been demonstrated for every species.

All rotifers, especially the more highly organized kinds, are
well provided with muscles for the extrusion and retraction
of head and foot, and for the working of the skipping ap-
pendages where such exist. These muscles are transversely
striated, and the striae can be distinctly seen in such forms as
Triarthra, Polyartkra, and Pedalion.

A nervous system and various sense organs are also
present in rotifers. The sense organs consist of various
styles or seta; on the head and, usually, a brush of fine setae
on each side at the lumbar region. The brain is rather large
and is visually situated in front of and above the mastax.
From this brain nerve fibers extend to the various sense
organs. There are also from one to three so-called eyes,
which are usually ruby-colored or black, and are situated
either on the posterior part of the brain or on the frontal
border of the head. They probably serve more for the

Protozoa and Botifera at Havana, III. 347

perception of light than for the formation of images. While
the eyes are absent in the adults of some species, they may
always be found in the embryonic or young forms.

Rotifers are dioecious and dimorphic ; that is, the sexes are
represented by separate individuals, and the males differ
greatly from the females in size and organization. Descrip-
tions of rotifers apply only to the females, as the males are but
little known and may be found for only a few days once or
twice a year. The male is usually inferior in size to the
female, and consists of a transparent sac with a circle of cilia
around the anterior border. It has no internal structures
except a sperm sac and copulatory organ, eats nothing, and
disappears in a few days.

Rotifers are usually oviparous, although there are forms,
like Rotifer and Asplanchna, that are viviparous. There are
three kinds of eggs. One of these is the ordinary egg, from
which the female hatches, and which is sometimes encased
in a spiny or roughened shell. Another form, from which
the males are hatched, is smaller and smooth-shelled. These
two are the so-called summer eggs. The third is the "lasting"
or "ephippial" egg, which is larger than either of the other
forms and has a hard, thick shell, well able to withstand
drought and frost. The eggs are usually carried about at-
tached to the posterior part of the lorica just above the foot.

Experiments were long ago made which show that the adult
rotifer can be revived after it has been subjected to a severe
drying process. Interesting results were obtained by us by
starting aquaria with earth from the bottoms of dried-up
ponds and lakes. Within two days after filtered water had
been placed on the dried mud, full-grown specimens of Brach-
iomis with eggs were found, which goes to prove that the
rotifers had been dried with the mud and had revived when
the water was added. Further experiments along this line
might be profitably carried on to ascertain just how long
rotifers can remain in this condition without having their
vitality impaired, and to find out whether they will survive
after being subjected to the hard frosts of a severe winter.

348 Illinois State Laboratory of Natural History.

METHODS OF CAPTURE AND STUDY.

Eotifers should be widely studied, not only because they
are interesting but because they are so easily accessible to
nearly every one. Eepresentatives of the group are found in
every pool, pond, river, or other body of water. They seem
to be little dependent upon the coarser aquatic vegetation,
since they are equally abundant in waters with or without
vegetation. No pond or mud hole is too insignificant to be
populated by some of these forms. If one wishes to study
them at times other than their usual season, or desires to
have material for class use, all that is necessary is to collect
some of the bottom of a dried-up pond and keep it until ready
for the material. Then a small quantity may be put into a
glass jar with some filtered water, and in twenty-four hours
the forms will begin to appear. Such an aquarium may be
kept up almost indefinitely by placing it in a moderately
cool room in the sunlight, and renewing the water from time
to time as it evaporates.

This work of starting aquaria from the bottom of dried-up
bodies of water should be extensively practiced, as the ob-
server will in this way meet many forms which he would not
otherwise find ; not only rotifers but numbers of Protozoa and
microscopic plants as well.

Another method of obtaining material is to collect water
from various sources and start a number of cultures by plac-
ing small quantities of the water in watch-glasses, or other
small dishes, keeping a sharp lookout that the water does
not dry out. If these dishes are examined from time to time
they will be found to have developed certain forms of Protozoa,
one species or another predominating in each of the dishes.
After a time, if the student has been faithful, the chances
are that he will be rewarded by finding in several of the
dishes an almost pure culture of some particular species.
This method was tried by Prof. Frank Smith in the zoological
laboratory of the University of Illinois during the winter of
1894 with good results, pure cultures of Distyla ohioensis,
Ilji<hitiiia senta, Stentor coeruleus, Stylonychia mytilus, and
other species being obtained.

Protozoa and Rotifera at Havana, III. 349

If there are marshes, weedy lakes, or river banks in the
neighborhood, many rotifers may be obtained by gathering
quantities of the weeds and allowing them to remain for a
day or two in a glass jar with water. An examination of the
water will then usually reveal the presence of the rotifers.
Sometimes it is merely necessary to gather handfuls of the
weeds and press out the water, which may be immediately
examined. Other forms may be found by searching care-
fully the roots of Lemnacece, and the fronds of Utricularia or
Ceratophyllum. Many fixed forms may be obtained by care-
fully examining the under sides of the leaves of water lilies
and pondweed (Potamogeton). If catches are to be made in
large bodies of water free from vegetation, a tow-net made of
fine bolting-cloth (No. 12) will be indispensable.

The requisites for the examination of material and the
study of rotifers are a compound microscope, several large
and small pipettes, watch-glasses, slides and cover-glasses,
and several killing and fixing agents. Of course the best
results are obtained by studying the rotifers while alive ; but
if for any reason this cannot be done the material may be
preserved and studied later. If the living subjects under
examination are too lively and energetic they may be quieted
down by adding to the water, very gradually, a 2% solution
of cocaine or chloral hydrate.

If material is to be preserved, good results may be obtained
by killing either in 50% alcohol or picronitric acid*, either
of which, after one or two hours should be replaced by 70%
alcohol, and this, again, by 80% or 90%, in which the
material may be indefinitely preserved. Permanent mounts
may be made from material preserved in this way by gradu-
ally substituting glycerine for the alcohol, and then mount-
ing the objects in glycerine in a cell on a slide. By far the
best method of preservation thus far devised is that given by
Mr. C. F. Eousselet ('95). He first narcotizes the rotifers

*The formula for picronitric acid is as follows :

Water 100 volumes

Nitric acid (25£ N205) 5

Picric acid as much as will dissolve in mixture.

Filter before using.

850 Illinois State Laboratory of Natural History.

with a " cocaine- spirit mixture," made according to the fol-
lowing formula :

2% solution of cocaine 30 parts.

Methylated spirit 10 parts.

Water 60 parts.

Just before the cilia stop vibrating the rotifers are killed
with a \% solution of osmic acid, in which they are kept for
about half a minute, after which they are thoroughly washed
in water from a few minutes to half an hour and are then
permanently preserved in a 2^% solution of formalin.
This is an aqueous solution of formaldehyde and as prepared
for sale has a strength of 40%. The species which have
gelatinous tubes are more satisfactorily preserved in a mix-
ture of equal parts of a -fo% solution of corrosive sublimate
and a \ ;% solution of common salt, since formalin extends
the tubes to two or three times their natural length. In
place of cement cells for permanent mounting, Mr. Eous-
selet uses slides with concave centers and fastens the cover-
glass by means of Miller's caoutchouc cement.*

GEOGRAPHICAL DISTRIBUTION.

The Rotifera are cosmopolitan in their range, being found
in all parts of the world. They inhabit mostly fresh water,
but a number of species are foilnd in the sea. Some of the
species, such as Rotifer vulgaris and Hydatina senta, appa-
rently occur in all parts of the world. There seems to be
something about the organization of the rotifer that enables
it to thrive under a great variety of conditions. The same
forms are found in both rivers and muddy ponds in the
United States, in clear streams of Europe or even in Alpine
lakes, in the rivers of Egypt, and in the reservoirs of India.
Climate and temperature seem to have little effect upon
the distribution of rotifers.

FOOD RELATIONS.

The rotifers play an important part in the economy of
nature, since they evidently take a prominent position among

*I find that Brown's transparent rubber cement answers this purpose very well.

Protozoa and Rotifera at Havana, III. 351

the forms which, in the matter of food relations, bridge the
gap between plants and animals. Many of the smaller forms
like Metopidia, Colurus, Monostyla, and also Dinocharis and
Euchlanis are frequently found chewing the ends of fine fila-
mentous algae. At one time a Mastigocerca was observed
feeding on a piece of alga. It would puncture the outside,
and appropriate the immediate contents of a cell ; then it
would creep along, make another puncture, and continue its
meal. Diatoms also serve as food, and a Notliolca was found
that had its stomach crammed full of the rays of Asterio-
nella. Asplanchna priodonta and also A. brightwellii seem
to be omnivorous. I have frequently found Pediastrum, Vol-
vox, Codonella crater a, Difflugia globulosa, Anurcea tecta and
A. cochlearis in their stomachs. One Asplanchna herrickii
was observed that had just made a meal of two Brachionus
mllltaris; while an Asplanchnopus myrmeleo was found with
its stomach gorged with Chydorus.

On the other hand, the larger species of Rotifera doubtless
form a considerable portion of the food of mollusks, min-
nows, buffalo fish, carp, suckers, and the like. Specimens of
Anurcea cochlearis were found in the stomach of a young
"croppie" and in that of a young catfish. It is possible that
the smaller Crustacea also live upon rotifers. This was es-
pecially indicated in Phelps Lake (substation F). There
were times when the water of this lake was swarming with
Entomostraca and the rotifers were very scarce, yet in a few
weeks there would be very few Entomostraca and a great
abundance of rotifers. Possibly the periodical disappearance
'of the rotifers was due to lack of food, but the disappearance of
the Crustacea seems explainable only on the supposition that
they depended on the rotifers for food. At one time a towing
was taken at this substation in which there was such an abun-
dance of Pediastrum — an element in the food of rotifers — that
the water was colored green, and in this same towing there
was an abundance of rotifers and very few Entomostraca.

SEASONAL DISTRIBUTION.

While our seasonal histories of the Protozoa show but
little tendency to a concentration in any particular part of

352 Illinois State Laboratory of Natural History.

the year, the species of Rot if era, on the other hand, often
have a well-marked period of abundance, with scattering
occurrences at other times. The season of abundance varies
greatly even in species of the same genus. Some are summer
and some winter species ; some have shorter and some longer
periods. In general the group is well represented throughout
the entire year. No towing was taken by us at any time that
did not contain some rotifers. In 1894 they were most
abundant from June to September, while comparatively few
species were listed in October. The December records show
an increase in such forms as Brachionus, Anuraa, and
Notholca. On February 23, 1895, towings were taken at
substation G, under eighteen inches of ice, which were re-
markable for the abundance of life they contained. Eight
species of rotifers were found in this catch, three of which
included individuals with eggs attached.

The forms which were common enough to show definite
indications of their seasonal distribution are given in the fol-
lowing list, which can be greatly improved — perhaps in some
cases disproved — by more extensive and systematic observa-
tions. The period of greatest abundance is given in italics.

Floscularia ornata : Sept.

Megalotrocha semibullata : July, Aug.

Conochilus : Jan., Feb -July, Aug., Sept.

Rotifer: July-Sept., Oct.-June.

Philodina : June-Sept., Oct.

Asplanchnidse : Jan., Feb., Apr.-Sept., Nov., Dec.

Synchaeta pectinata : Sept.-May, June, Aug.

S. stylata : July-Sept., Oct.

Polyarthra platyptera : Dec-Mar., Apr.-Nov.

Triarthra longiseta : Feb., Apr.-Sept., Dec.

Ploesoma lynceus : May, June, July-Oct., Nov., Dec.

Notommatida; : June, July-Sept., Oct.

Mastigocerca bicristata : May, June-Sept., Oct.

Coelopus : June-Aug.

Dinocharis pocillum : Mar.-July, Oct.-Jan.

Salpina eustala : June, July-Sept., Oct.

Euchlanis : Apr.-June, July-Sept., Oct. -Dec.

Protozoa and Rotifer a at Havana, III. 353

Cathypnidae: Mar.-May, June-Oct., Nov.-Dec.

Colurus : Mar., Apr., June-Sept., Oct.

Metopidia : Mar., June, July-Sept., Oct., Dec.

Pterodma patina : June-Oct., Nov.-May.

Brachionus pala : May-July, Aug. -Apr.

B. dorcas : Oct., Nov., Dec-Apr., May.

B. punctatus : June-Sept.

B. urceolaris : Jan., Feb., Mar., Apr.

B. bakeri, angularis, and militaris : Feb.-May, June-Sept.,

Oct., Dec.
Schizocerca : June-Sept.

Noteus quadricornis : May, June, July-Sept., Oct., Nov.
Anursea tecta and cochlearis : Jan., Feb., Mar -Aug., Sept.-

Dec.
A. aculeata : Jan.-June, Nov., Dec.
Notholca acuminata: Oct., Nov., Dec-Apr., May.
Pedalion mirum : May, July-Sept., Oct.

LOCAL DISTRIBUTION.

The Rotifera were widely distributed, being well repre-
sented at all of the substations. One hundred and eight
forms were observed and identified. The five lakes under
examination reflect their peculiarities in the species records.
Thompson's, Quiver, and Dogfish lakes have well-defined
shores, never become dry, and are more or less permanently
supplied with aquatic vegetation. Their rotifer fauna was
much the same. Phelps and Flag lakes, on the other hand,
were very shallow, margined by mud flats which grew in size
as the water dried up under the summer sun, the latter lake
being substantially a reedy swamp. Species found in the
other three lakes were often not present in these two, while a
few forms were conspicuously more abundant in one of these
than in the other three.

It is difficult to distinguish littoral and pelagic forms in
this list. At most of the substations the water was compara-
tively shallow, its average depth where the tow-net was used
ranging from abou^, one and a half feet in Phelps Lake to
nine feet in the river at E. Because of this shallowness

354 Illinois State Laboratory of Natural History.

the forms preferring life amongst vegetation and near the
shores or bottom doubtless often mingled with those inhabit-
ing the clear open water, the same forms being usually found
in both surface and bottom towings. The amount of aquatic
vegetation present was an important item in the question.
In Phelps and Thompson's lakes and in the river at E there
was comparatively little visible plant life, while at D — in the
river — and in Quiver and Dogfish lakes aquatic plants of all
kinds flourished ; indeed, Quiver Lake was almost entirely
choked up during the first summer and autumn with Cerato-
phyllum, Elodea, Spirogyra, and the like. There was, how-
ever, a slight current in Quiver Lake, which kept a narrow
channel free from weeds, so that it was possible to take tow-
ings at C during the entire season. On the whole it seems
most satisfactory to consider those forms found near the
shore or among vegetation as littoral, and those taken in
open water free from vegetation as pelagic. Of the species
studied the following twrenty-four are in this sense pelagic :

Conochilus dossuarius Hudson.

C. unicornis liousselet.

Asplanchna ebbesbornii Hudson.

A. brightwellii Gosse.

A. priodonta Gosse.

A. herrickii de Guerne.
Synchaeta pectinata Ehrbg.
S. stylata Wierz.
Polyarthra platyptera Ehrbg.
Triarthra terminalis Plate.
Plcesoma lynceus Ehrbg.
Brachionus mollis Hempel.

B. pala Ehrbg.
B. dorcas Gosse.

B. dorcas spinosus Wierz,
B. punctatus Hempel.
B. variabilis Hempel.
B. angularis Gosse.
B. angularis bidens Plate.
Anuria tecta Gosse.

Protozoa and Rotifera at Havana, III. 355

A. aculeata Ehrbg.

A. cochlearis Gosse.

Notholca acuminata Ehrbg.

Pedalion mirum Hudson.

Among these pelagic forms the most abundant were As-
planchna brightwelli,Synchata pectinata, Polyarthra platyptera,
Triarthra terminalis, Brachionus pala, and Anurcea cochlearis.
Brachionus militaris was probably the most abundant form
of the littoral species.

Of all the substations under examination, C yielded the
greatest number of species. There were two reasons for this.
In the first place, a variety of conditions prevailed here.
There was dense floating vegetation on each side of the lake,
and at the same time a tolerably clear channel through the
middle. Again, a greater number of collections were made
here than at any other substation on account of the location
of the field headquarters at this point. A and B were not
satisfactory locations since they had to be abandoned early
in the season. F was a constant source of surprise, and the
catches made there were very interesting in regard to both
numbers and variety. This was a very fruitful substation
until August, when it completely dried up. D yielded noth-
ing unusual, and the catches there were essentially the same
as those among vegetation at the other substations. E was
a typical river situation, and was satisfactory in every way.
Next to C it yielded the largest number of species and, as
might have been expected, all of the pelagic forms were found
here. G was in a lake typical of the larger and more per-
manent lakes of the river bottoms, and contained a remark-
able variety and number of organisms. Unfortunately its
usefulness to us was reduced by the fact that it was difficult
of access, and was consequently visited only at long in-
tervals— usually a month, but sometimes longer.

AFFINITIES AND CLASSIFICATION.

There has been much discussion about the affinities of the
Rotifera. Dr. C. F. Hudson ('75) thinks that such forms as
Pedalion link them with the Crustacea, while, on the other

356 Illinois State Laboratory of Natural History.

hand, forms like Trochosphara seem to indicate that they are
derived from the Annelida. The nervous and excretory sys-
tems are very similar to those of the turbellarian worms,
which fact seems further to strengthen the theory that the
rotifers are related to the Vermes. In the present state of
our knowledge it seems best to class them as a separate group
under the head of Vermes.

The entire group has been divided into four well-marked
orders, mainly with reference to locomotion. These are the
Rhizota, lixed when adult; the Bdelloida, "that swim with
their ciliary wreath and creep like a leech;" the Ploirna,
" that swim with their ciliary wreath and (in some cases)
creep with their toes ;" and the Scirtopocla, "that swim with
their ciliary wreath, and skip with arthropodous limbs."

In the preparation of the following list I have depended
largely upon the superb monograph of Hudson and Gosse
('86), from which most of the descriptive matter is taken,
and have in the main followed their classification, except in
a few cases where it has been shown that they are in error.
It seems unnecessary to give the synonymy of any forms de-
scribed in the monograph, except perhaps in a few special
cases regarding which there are differences of opinion ; -but
for all forms in this list that have been described since the
publication of Hudson and Gosse's Supplement ('89), a cita-
tion is given to the work containing the original description.

Other rotifers were found, as yet either unidentified or un-
described. Owing to limited time and opportunity they were
not worked up, and are not included in this list.

SYNOPSIS OF THE FAMILIES OF ROTIFERA.

I. Order Rhizota. Fixed when adult, usually inhabiting a
gelatinous tube ; foot transversely wrinkled, not re-
tractile within the body, ending in an adhesive disc
or cup.
Flosculariidcs. Coronal cup usually produced into
setigerous or ciliate lobes; buccal orifice central;
ciliary wreath a single half circle above the buccal
orifice; tropin uncinate. (Fig. 3, G.)

Protozoa and Rot if era at Havana, III. 357

Melicertidce. Corona not produced into setigerous
lobes; buccal orifice lateral; ciliary wreath a mar-
ginal continuous curve, bent on itself at the dorsal
surface, so as to encircle the corona twice, with the
buccal orifice between its upper and lower curves,
and having also a dorsal gap between its points of
flexure; trophi malleo-ramate (Fig. 3, E) ; usually
inhabiting tubes made of pellets.

II. Order Bdelloida. Swimming with their ciliary wreath

and creeping like a leech; foot wholly retractile
within the body, telescopic, ending almost invariably
in three toes.

Philodinidce. Corona a pair of circular lobes trans-
versely placed ; ciliary wreath a marginal continu-
ous curve, bent on itself at the dorsal surface so as
to encircle the corona twice, with the buccal orifice
between its upper and lower curves, and having also
two gaps, the one dorsal, between its points of flex-
ure, the other ventral, in the upper curve, opposite
the buccal orifice; trophi ramate. (Fig. 3, H.)

Adinetidce. Corona a flat surface, facing ventrally;
ciliary wreath the furred ventral surface of the
corona; tropin ramate (Fig. 3, H) ; frontal column
soldered to dorsal surface, and ending in two hooks.

III. Order Bloima. Swimming with, their ciliary wreath and
(in some cases) creeping with their toes.

1. Suborder Illoricata. Integument flexible, not stiff-
ened to an inclosing shell, except in Pla'soma; foot,
when present, almost invariably furcate, but not
transversely wrinkled ; rarely more than feebly tele-
scopic, and partially retractile.

Microcodonidce. Corona obliquely transverse, flat, cir-
cular ; buccal orifice central; ciliary wreath a mar-
ginal continuous curve encircling the corona, and
two curves of larger cilia, one on each side of the
buccal orifice; trophi forcipate (Fig. 3, D) ; foot
stylate.

Asplanchnida. Corona subcorneal, with one or two

358 Illinois State Laboratory of Natural History.

apices ; ciliary wreath single, edging the corona ;
intestine and cloaca absent.
Synchaetidce. Corona a transverse spheroidal segment,
sometimes much flattened, with styligerous promi-
nences ; ciliary wreath a single interrupted or con-
tinuous marginal curve, encircling the corona ;
mastax very large, pear-shaped ; tropin forcipate
(Fig. 3, D) ; foot minute, furcate.
Triarthridce. Body furnished with skipping append-
ages ; corona transverse ; ciliary wreath single, mar-
ginal; foot absent.
Hydatinidce. Corona truncate, with styligerous promi-
nences ; ciliary wreath two parallel curves, the one
marginal, fringing the corona and buccal orifice ;
and the other lying within the first, the styligerous
prominences being between the two ; tropin malleate
(Fig. 3, A) ; foot furcate.
Notommatidre. Corona obliquely transverse ; ciliary
wreath of interrupted curves and clusters, usually
with a marginal wreath surrounding the buccal ori-
fice ; tropin forcipate (Fig. 3, D) ; foot furcate.
2. Suborder Loricata. Integument stiffened to a wholly
or partially inclosing shell ; foot various. Corona
and ciliary wreath various in shape, tropin of different
types, but, except in the Pterodinidte, these struct-
ures are never as in Rhizota or Bdelloida.
Division I. Foot jointed, stylate or furcate ; not trans-
versely wrinkled nor wholly retractile.
Rattid'uhe. Body cylindric or fusiform, smooth, with-
out plicae or angles ; contained in a lorica closed all
around, but open at each end, often ridged ; tropin
long, asymmetric ; eye single, cervical. Variously
asymmetrical.
Dinocharidce. Lorica entire, vase-shaped, or depressed ;
sometimes faceted, often spinous ; head distinct,
with a chitinous covering ; foot and toes often greatly
developed ; tropin symmetrical.
Salpinidce. Body more or less completely enclosed in

Protozoa and liotifcra at Havana, III. 359

a firm lorica, which is open at each end, and divided
down the back by a fissure whose sides are united
by membrane ; two furcate toes always exposed.

EuchlanicUe. Lorica of two dissimilar plates, one dor-
sal, one ventral, united so as to form two confluent
cavities, of which the upper is much the larger ; foot
jointed, furcate.

Cathypnidce. Body enclosed in a lorica which is open
at each end, and consists of two plates ; the dorsal
more or less elevated ; the ventral nearly flat, the
two divided by a deep lateral longitudinal sulcus,
covered with flexible membrane ; toes two or one,
always exposed.

Coluridce. Body enclosed in a lorica, usually of firm
consistence, variously compressed or depressed,
open at both ends, closed dorsally, usually open or
wanting ventrally ; head surmounted by a chitinous
arched plate or hood ; toes two, rarely one, always
exposed.
Division II. Foot transversely wrinkled, wholly retract-
ile, furcate or ending in a ciliated cup ; sometimes
absent.

Pterodinidce. Lorica entire, various ; corona and cili-
ary wreath as in the Philodinida; ; trophi malleo-
ramate (Fig. 3, E) ; foot jointless, toeless, ending in
a ciliated cup or absent.

Brachionidce . Lorica box-like, open at each end, gene-
rally armed with anterior and posterior spines ; foot
long, excessively flexible, ending in two toes.

Anurceidce. Lorica box-like, broadly open in front,

behind open only by a narrow slit ; usually armed

with spines or elastic setse ; foot wholly wanting.

IV. Order Scirtojioda. Swimming with their ciliary wreath,

and skipping with arthropodous limbs ; foot absent.

Pedalionidce. Arthropodous limbs six; head truncate ;
corona of two concave lobes ; ciliary wreath as in
Philodinidce ; trophi malleo-ramate (Fig. 3, E).

360 Illinois State Laboratory of Natural History.

Order I. EHIZOTA.

Family FLOSCTJLAEXDiE.

Floscularia Oken.

Frontal lobes short, expanded, or wanting ; setae very long
and radiating, or short and cilia-like ; foot terminated by a
non-retractile peduncle, ending in an adhesive disc.

1. F. ornata Ehrbg.

Infrequent. Found during September on Ceratophyllum at
substation L in Dogfish Lake.

Family MELICERTID^.

LiIMNIAS ScHRANK.

Provided with a tube, which is usually dark colored, but
not made of pellets. Corona distinctly two-lobed ; dorsal
gap wide ; dorsal antenna minute.

2. Li. ceratophylli Schrank.

This fine form was first found in an aquarium started with
dried mud from the bed of Phelps Lake, and in September
was discovered on Ceratophyllum and Potamogeton' from
Thompson's Lake. While the rotifer was expanded a con-
stant stream of fine particles kept moving away from
it, the movement being quite uniform and the direction defi-
nite, as if the stream were shot out of the nozzle of a hose.

Cephalosiphon Ehrbg.

Corona nearly circular; dorsal gap distinct; dorsal an-
tenna obvious ; ventral antennae absent, two dorsal hooks
enclosing the dorsal antenna.

3. C. limnias Ehrbg.

Infrequent, occurring in September on vegetation from
Thompson's Lake.

CEciSTES Ehrbg.

Corona a wide oval, indistinctly two-lobed ; dorsal gap
minute ; dorsal antenna absent ; ventral antennae obvious.'*'

Protozoa and Rotifera at Havana, III. 361

4. O. intermedins Davis.

Infrequent, occurring during August on Ceratophyllum from
Thompson's Lake.

5. O. mucicola Kell.

A few examples of this species were found in Dogfish Lake
during September, 1895, on Rivularia.

Megalotrocha Ehrbg.

Forming spherical colonies of many individuals ; corona
kidney-shaped or four-sided, with a deep ventral sinus; trunk
with two or four opaque warts on breast.

6. M. alboflavicans Ehrbg.

Colonies of this rotifer were found in Quiver Lake during
June and August, 1894, the clusters being attached to Cera-
tophyllum. In September of the same year young free-
swimming clusters were taken in the tow-net from the Illinois
River. The young have a small corona and well- developed
eyes, and might easily be mistaken for Conochilus were it not
for the presence of the opaque warts. In November a quantity
of vegetable matter was taken from the shores of Quiver Lake
and put into an aquarium, and in a few days several of the
colonies were found attached to the plants. During Septem-
ber of the following year it was found in Dogfish Lake.

7. M. semibullata Hudson.

This interesting form was not discovered until July of the
second year, when it was occasionally found in the weedy
waters of Flag Lake. It increased rapidly until the follow-
ing month, when it was very abundant. The colonies seemed
to hang by slender threads to stems of rushes and other
aquatic plants, and when disturbed would swim through the
water with a revolving motion. I was one day watching
some of these colonies, when one of them, coming very near
the surface of the water, was pounced upon and quickly de-
voured by a water beetle, Dineutes.

TROCHOSPHiERA SEMPER.

Solitary, free-swimming ; body a perfect sphere ; buccal
orifice on the spherical surface ; principal wreath dividing the

362 Illinois State Laboratory of Natural History.

sphere into two hemispheres, and passing ahove the buccal
orifice ; dorsal gap in the wreath at the pole opposite to
buccal orifice; secondary wreath a fragment on the under
side of the buccal orifice ; ventral antennae extremely minute ;
no tube.

8. T. solstitialis Thorpe.

The occurrence of this rare and remarkable form in this
country was reported for the first time by Dr. C. A Kofoid
('96a). It was found by him in the Illinois River and Flag
Lake in June, July, and August, 1896.

CONOCHILUS EHRBG.

Clusters of several or many individuals, free-swimming;
corona horse-shoe shaped ; gap in the ciliary wreath ventral.

9. C. dossuarius Hudson.

This species was found in all the bodies of water under
observation. It was present during the greater part of the
year from January to September, reaching its maximum in
March. Many clusters were taken with a tow-net in Thomp-
son's Lake, in February, 1895, under eighteen inches of ice.
These specimens appeared larger and more vigorous than
those seen during the summer. It is readily recognized by
the small number of individuals composing the cluster; by
the presence of the two antennae, which stand out on the
arched ventral surface like tall chimneys on a building ; and
by the fact that eggs are almost invariably found in connec-
tion with the colonies.

10. C. unicornis Rousselet ('92).
C. leptopus Forbes, '93.

This rotifer was found only in May and June. During this
time only a few were taken in the tow-net at C, although it
was common in the river at D and E, and was taken in both
surface and oblique towings at the latter substation.

Order BDELLOIDA.

Family PHIL.ODINID.ffi.
Rotifer Schrank.

Eyes two, situated within the frontal column. (Tropin,
Fig. 3, 4.)

Protozoa and Eotifera at Havana, III. 363

11. R. macrurus Schrank.

In June one specimen was found in a surface towing from
C, in Quiver Lake.

12. R. vulgaris Schrank.

A few were found during July in the surface towings from
the river at E. In March it was also found in the oblique
towings from the same place.

13. R. tardus Ehrbg.

This species was comparatively rare. In June it was found
among the vegetation on the west shore of Quiver Lake at C,
and in June, September, and October it occurred in the tow-
ings from the river at E.

14. R. neptunius Ehrbg.
Actinurus neptunius Ehrbg.

This peculiar and interesting form was found in the river
at E from May to October, in Matanzas Lake in August, and
in Thompson's Lake in September. Although it was not
common at any time, still it was persistent during the months
mentioned, and was found in both surface and oblique tow-
ings. It is rather remarkable that it was not found among
the vegetation.

Philodina Ehrbg.

Eyes two, placed above the brain.

15. P. macrostyla Ehrbg.
Philodina tuberculata Gosse.

One specimen of this rotifer was taken in August among
the vegetation on the west shore of Quiver Lake, at the
mouth of Dogfish Lake.

16. P. megalotrocha Ehrbg.

This form was well distributed, being found in Quiver and
Phelps lakes and in the river (substations C, F, D, and E).
It was taken in surface and oblique towings and among vege-
tation. There was hardly a collection made at these substa-
tions from June to September in which it did not occur, and
it was also found once in October at E.

364 Illinois State Laboratory of Natural History.

Callidina Ehebg.

Eyes wanting.

17. C. elegans Ehebg.

This species was found once, in September, in towings
from Dogfish Lake.

Order III. PLOIMA.

Family ASPLANCHNIDiE.

ASPLANCHNA GosSE.

Body sac-like, foot wanting; corona with two apices;
tropin (Fig. 3, F), two plates working together like the jaws
of an insect, not inclosed within a mastax. Viviparous.

18. A. ebbesbornii Hudson.

This large species was found once during June, in a surface
towing from the river at E, in company with A. priodonta.
So far as I know, it has not been previously recorded from
the United States. It is a fine, attractive form', and not
easily confused with other species of this genus.

19. A. brig-htwellii Gosse.

This form was the most abundant representative of its
genus in the field studied by us. It was widely distributed
among the various substations, and present during nearly the
entire year, reaching its maximum in July and August. It
appropriates almost everything in the way of food: Asteri-
onella, Codonella cratera, Difflugia globulosa, Anwrcea cock-
It, iris and A. tecta have all been found in stomachs of
individuals of this species.

20 A. priodonta Gosse.

This species was found from April to September in both
years. In 1894 it was most abundant in May and June, and
in 1895 the maximum was reached in August. It occurred
mostly in towings from the Illinois River and from Thomp-
son's Lake, but was also found in Quiver and Dogfish lakes.
This form, like most of the members of this genus, is dis-
tinctively pelagic. None were found among vegetation. Like

Protozoa and Rotifera at Havana, III. 365

the preceding species it is omnivorous. Asterionelld, Pedi-
astrum, Volvox globator, Codonella cratera, Anurcea tecta, and
A. cochlearis were common in its food.

21. A. herrickii de Guerne.

The record of this species presents a similar history for
each of the two years. It appeared in April and May, reach-
ing its maximum in May ; was not seen at all in June, and
but once in July; and in August and September it occurred
extensively, but was not common. Like A. priodonta, it
was found in the river and more permanent lakes, — Quiver,
Dogfish, and Thompson's, — but not in the two shallower
lakes, Phelps and Flag — liable to dry up more or less in late
summer.

Professor Forbes, in studying this species, found several
small parasites within the body. They were apparently one-
celled, very changeable in shape, and seemed to have three
flagella-like pseudopodia.

Two specimens of Brachionus militaris were found in the
stomach of one example of this Asplanclina, and Anurcea
cochlearis, Volvox globator, and Bosmina also serve as food
for it.

22. A. g-irodi de Guerne.

Taken only in towings from Flag Lake, during April, 1896.

ASPLANCHNOPUS DE GUERNE.

Like Asplanclina, but with a ventral retractile foot, ending
in two toes.

23. A. myrmeleo Ehrbg.

Notommata myrmeleo Ehrbg.
This fine large rotifer was present in small numbers from
May to September. It occurred in collections from Quiver
Lake, Dogfish Lake, and the Illinois Paver, and was found
both in the open water and among vegetation. Individuals
can be easily recognized in the water without a lens by their
large size and sluggish movements. They are great eaters,
and their stomachs are almost invariably filled with other
rotifers and crustaceans, sometimes so gorged with food that

366 Illinois State Laboratory of Natural History.

the body walls are greatly distended. Monostyla and Chy-
dorus seem to be their favorite food.

This form has not been previously listed from the United
States.

Sacculus Gosse.

Corona with one apex ; tropin inclosed in a mastax, virgate,
with unequal mallei ; alimentary canal very large, having
eight caeca ; eggs attached after deposition.

24. S. viridis Gosse.

This species was scarce, appearing only in surface towings
taken at the mouth of Quiver Lake during May, 1896.

Family SYNCELffiTIDiE.

Synch^ta Ehrbg.

Form usually that of a long cone whose apex is the foot ;
front furnished with two ciliated auricles ; ciliary wreath of
interrupted curves ; foot small, furcate.

25. S. pectinata Ehrbg.

This was abundant and widely distributed, being found at
all of the substations. It was not found in July, and was
noticeably scarcer in June and August. At all other times
of the year it was common and often abundant, especially in
May and November. The records for each of the two years
were substantially alike. This is a very pretty gem in the
water, very quick in its movements, darting hither and
thither, and consequently difficult to study, but after its
characters are once made out it will long be remembered.

26. S. sty lata Wierz. ('92).

Found only in the Illinois River and Quiver Lake, from
July to October, and again in March; most abundant in
October in the river.

This was also found by Jennings ('94) in Lake St. Clair.

Family TRIARTHRID^.

POLYARTKRA EHRBG.
Body small, sac-like; skipping appendages, when present,
in clusters on the shonMus; eye single, occipital; mastax
large and pear-shaped ; tropin forcipate.

Protozoa and Rotifera at Havana, III. 367

27. P. platyptera Ehrbg.

This is one of the four species that were present during
every month of the year. It seems to thrive best in cold
water, for it was most abundant during December, January,
and March, and reached its minimum in June. It was found
in all the bodies of water under observation. Many indi-
viduals were larger than the dimensions given by Hudson and
Gosse, some of them measuring .2 mm. in length. Rhabdo-
styla was found parasitic on many that were taken in Phelps
Lake.

28. P. platyptera euryptera Wierz. ('91).

Rare ; found in September, in towings from the Illinois
River.

29. P. aptera Hood ('93).

In November, 1894, a quantity of dried mud from the
bottom of Phelps Lake was taken to the University, and, as
has been previously stated, aquaria were started by putting
filtered water upon this mud. This species was found at two
different times in these aquaria, but was not observed at any
of the substations.

TltlARTHRA Ehrbg.

Body sac-like ; spines single, two lateral, one ventral ; eyes
two, frontal ; mastax of moderate size ; tropin malleo-ramate.

30. T. longiseta Ehrbg.

Not especially common but generally present in both years
in the river and lakes studied except Flag Lake, during the
period from April to September. A very few were also seen
in both years in December and February.

Plate ('85) describes a new rotifer, calling it T. term 'mails.
He says: "The attachment of the posterior spine is not
ventral but terminal, just in front of the anal opening, and
the spine cannot be flexed anteriorly. The spines are smooth,
although I found one individual in which they bore very small
spinules, as in T. longiseta."

Many of the individuals taken here had smooth spines,
while others had them notched. The posterior spine was

368 Illinois Stat,' Laboratory of Natural History.

inserted on the posterior part of the body. It is my belief
that terminalis and longiseta are identical.

As far as known, this is the first time the species has been
recorded for the United States.

Pedetes Gosse.

Body ovate, tailed; toes absent; eyes two, frontal; two
leaping styles articulated to the breast.

31. P. saltator Gosse.

One specimen was found in an aquarium started with dried
mud from the bottom of Phelps Lake. The species was
probably not abundant, since several aquaria had been
started before this specimen was discovered.

Family HYDATINIDiE.

Hydatina Ehrbg.

Not loricate ; body conical, tapering towards the foot ; foot
short and confluent with the trunk; eye absent.

32. H. senta Ehrbg.

This large, fine form was rare. It was seen only in March
and July, 1895, in the main river at E.

Plcesoma Herrick ('85).

With a lorica composed of two ovate valves united above
and partially united below; foot springing from middle of
ventral margin.

33. P. lynceus Ehrbg.

Euchlanis lynceus Ehrbg.
Plcesoma lenticular 'e Herrick.
Gomjihoijastrr areolatus Yorce.
Gastropus ehrenbergii Inihof.
Gastroschiza lynceus Bergendal.
Gastroschiza foveolata Jagerskiold.
Bipalpus lynceus Wierzejski and Zach arias.
Plcesonvi lynceus Jennings ('94a.

Not common. Found in all the more permanent waters
from May to December, but most frequently from July to

Protozoa and Rot if era at Havana, III. 369

October. It seems to be most at home creeping among the
vegetation, such as was so abundant at substation C in
Quiver Lake.

A very fine rotifer, arresting the attention by its unusual
activity and attractive lorica.

Family NOTOMMATIDiE.

Taphrocampa Gosse.

Body fusiform or cylindrical, annulose, furnished with two
furcate toes ; trophi forcipate ; cilia very limited or wanting.

34. T. annulosa Gosse.

Infrequent, being found only at substation C in Quiver
Lake, among vegetation and in open water, from July to
September of the first year.

NOTOMMATA GOSSE.

Body cylindrical, not annulose, furnished behind with a
projecting tail; evertile and protrusile ciliated auricles on
the head ; brain large, usually containing opaque chalk
masses ; trophi virgate. Numerous species, in some of which
one or more of these characters may be lacking.

35. N. aurita Ehrbg.

Infrequent ; taken among vegetation in the Illinois Biver
in July.

36. N. cyrtopus Gosse.

Infrequent, occurring during February in towings from the
Illinois Biver.

37. N. tripus Ehrbg.

Occurred only during June and July, in both surface and
bottom towings from Quiver Lake.

38. N. lacinulata Ehrbg.

This form was found once, in July, when a few were taken
among the vegetation at the mouth of the "Pumpkin Patch ;"
a bay full of wild rice and other vegetation, communicating
with the west side of Quiver Lake, near the head of the lake.

370 Illinois State Laboratory of Natural History.

FURCULARIA Ehrbg.

Body generally laryiform, cylindrical, with a tendency to
enlargement in the lumbar region ; front conical, broad, and
deep ; eye single, frontal, sometimes wanting ; incus forci-
pate, much developed, protrusile ; toes two, furcate, usually
conspicuous.

39. F. forficula Ehrbg.

This species was scarce, being taken only in May, 1896,
in surface towings at the mouth of Quiver Lake.

40. F. longiseta Ehrbg.

This rather peculiar form was found only in Quiver Lake.
In July and August, and once in March, a few were taken.
It occurred both among vegetation and in the towings.

EOSPHORA Ehrbg.

Body oblong, head dilated and furnished with protrusile
auricles; foot very distinct, with telescopic joints and fur-
cate toes; eyes three, one large, cervical, two minute, frontal.

41. E. aurita Ehrbg.

One morning in July, 1894, we saw a large quantity of red
scum on the river. Upon examining it several specimens of
this rotifer were found. In September of the same year it
was again found, on the west shore of Quiver Lake, among
vegetation.

DiGLENA Ehrbg.

Body subcylindric but very versatile in outline, often swell-
ing behind and tapering to the head; eyes two, minute,
situated near the edge of the front ; foot furcate, fcrophi forci-
pate, generally very protrusile.

42. D. grandis Ehrbg.

This large form was found only in Quiver Lake in 1894,
once in August, and again in October.
!:S. D. catellina Ehrbg.

This species was found in small numbers during August in
the red scum at the mouth of Quiver Lake.

Protozoa and Rotifera at Havana, III. 371

44. D. biraphis Gosse.

This species was rare, being found only in bottom towings
from Quiver Lake in July.

Family R ATTITUDE.

Mastigocerca Ehrbg.

Body fusiform or irregularly thick, not lunate ; toe a single
long style, with accessory stylets at its base ; lorica often
furnished with one or more thin dorsal ridges.

45. M. carinata Ehrbg.

This form was not very common. It was mostly found, in
both years, at substation C in Quiver Lake, from June to
September, the maximum being in July, when it was also
seen in the river. A single occurrence in this lake in Decem-
ber is also noted. At one time I watched a Mastigocerca
feeding on some Spirogyra. It would puncture the side of a
filament with its sharp trophi and eat the green contents of
the cell ; then it would creep along, open another cell and
appropriate its contents ; and so on, until satisfied.

46. M. elongata Gosse.

Found but once, in a towing taken below the surface of
Quiver Lake in June.

47. M. bicornis Ehrbg.

I found this species several times in the towings during
June and July, and again in November, mostly in Quiver
Lake, but in June also in oblique towings from the river at E.

48. M. stylata Gosse.

This form was scarce, being found only in towings from
the Illinois Eiverin August, 1895.

49. M. bicristata Gosse.

This species and M. carinata were the commonest represen-
tatives of the genus at the Station. M. bicristata was found
but once in the river, in September, but appeared in moderate
numbers in Quiver Lake from May to August, and in Thomp-
son's Lake from August to October.

The specific characters as given by Gosse are, "Two equal
subparallel carina?, running nearly the whole length of the

372 Illinois State Laboratory of Natural History.

dorsum." The two carina? of the specimens taken at Havana
extend a trifle more than two thirds the length of the dorsum.
The carina are high, thick at base, and very conspicuous.
The length of the specimens averages greater than that given
by Mr. Gosse. I found them as long as .58 mm., includ-
ing the toe, which is nearly half the entire length. The
toe is slightly curved and ends in a spine, with two smaller
accessory spines.

50. M. lata Jennings ('94).

This species was met with in June and several times during
October, in surface towings, and also in towings taken below
the surface, from Quiver Lake. It is easily recognized by
the indentation on the right side of the body next to the foot
joint, and by the flattened truncate column of the corona.

CCELOPTJS GOSSE.

Body cylindrical, curved ; foot bulbous, inclosed ; toes,
one broad plate with another laid upon it in a different plane.

51. C. porcellus Gosse.

This curious and interesting form was found in towings
and among vegetation from Quiver Lake from June to
August, and in surface towings from the river in June.

52. C. tenuior Gosse.

This form was taken in Quiver Lake in the same months
as the preceding, and was generally found in company with
it, although in smaller numbers.

Family DINOCHARID^J.

DlNOCHARIS EhEBG.

Lorica vase-shaped, faceted, with projecting plates, or
armed dorsally with spines ; head retractile within a chiti-
nous cap ; eye single ; foot and toes very long, the former
bearing spines.

53. D. pocillum Ehrbg.

The records of this species for both years show a seasonal
distribution quite the reverse of that characterizing its rela-
tives, which are generally commonest in the warmer months,

Protozoa and Rotifera at Havana, III. 373

from June to October. This was most frequently seen,
though never very numerous, from December to June, with
occasional appearances in October and November and in
July. Found in the towings, mostly in Quiver Lake, and
not at all in Phelps, Flag, or Thompson's lakes.

SCARIDITJM EHRBG.

Lorica vase-shaped or pear-shaped ; very thin, transparent,
smooth, without spines or projecting plates ; head with a
chitinous cuticle, except in front ; eye single ; foot without
spurs ; toes very long.

54. S. longicaudum Ehrbg.

But few specimens of this rotifer were taken. It is re-
corded from the deeper lakes, from July to October.

Family SALPINID-ffi.

Salpina Ehrbg.

Lorica an oblong box, furnished with spines, but widely
open at each end, split down the back ; head and foot pro-
trusile ; toes furcate, long, straight ; tropin submalleate ; eye
single, cervical.

55. S. eustala Gosse.

In both years this species was present from June to Sep-
tember, with a single occurrence in October. It was found
in the Illinois River and the deeper lakes, but was not abun-
dant.

Our specimens agree with the description given by Mr.
Gosse, but average smaller, the largest individual measuring
.23 mm. in length.

r&i

Family ETJCHLANXDiE.

EUCHLANIS Ehrbg.

Dorsal plate with the median portion arched ; ventral plate
nearly flat, usually with a flange on each side ; eye single.
Members of this genus were frequently seen eating diatoms

374 Illinois State Laboratory of Natural History.

and tine filamentous alg;e. They would grasp the threads of
alga? with the rami and chew them preparatory to swallowing.

56. E. dilatata Ehrbg.

This species was present from July to September in the
river and deeper lakes, being found at the same substations
as the foregoing species and reaching its greatest abundance
in July. It was the only member of its genus found in Dog-
fish Lake, where it continued to occur until December, long
after it had disappeared at the other substations. It was
also found once in April in this lake.

57. E. triquetra Ehrbg.

Not so abundant as the preceding species ; found only in
the Illinois River and Quiver Lake, from June to October.
This is the most conspicuous and beautiful representative of
this genus. It may very readily be distinguished by the
curious "three-winged" shape of the lorica.

58. E. deflexa Gosse.

This was found only in towings from Quiver Lake during
the period from May to September.

59. E. pyriformis Gosse.

Of infrequent occurrence, during November, in towings
from Flag Lake.

Family CATHYPNID^.

CATHYPNA Gosse.

Lorica subcircular horizontally, usually much arched verti-
cally ; lateral inangulation wide and deep ; toes two, furcate.

60. C. luna Ehrbg.

This species was present from April to December, and at
all of the substations except B. Its maximum of abundance
was reached in July and August. The records for the first
and second year are very similar.

61. C. leontina Turner ('92).

Seasonal distribution about the same as that of C. luna.
It was found in the Illinois River and deeper lakes, and was
present both in towings and among vegetation. It was com-
monest about July.

Protozoa and Rotifera at Havana, III. 375

Distyla Eckstein.

Lorica of the form of a long ellipse, open and membranous
before, closed behind, depressed, higher before than behind ;
lateral inangulation feeble ; toes two ; selvage-like thicken-
ings of the lorica around the foot.

62. D. gissensis Eckstein.

Found but once, in a towing from Phelps Lake in July.

63. D. ohioensis Herrick ('85).

Excepting a rare occurrence in April, this species was
present only from July to November. It was found in Quiver
and Dogfish lakes.

64. D. stokesii Pell ('90).

Cathypna stokesii Pell *
This little species was found four times in towings from
Quiver Lake ; once in July, again in September and in Octo-
ber, and again in March. The entire surface of the lorica is
finely stippled.

65. D. hornemanni Ehrbg.

Occurred only in towings from Thompson's Lake, during
September.

MONOSTYLA Ehrbg.
Like Cathypna, but with only a single toe.

66. M. lunaris Ehrbg.

This form was found in January and April, but principally
from June to November. It occurred upon vegetation and
in towings from the Illinois River, and from all the lakes
studied except Phelps Lake.

67. M. cornuta Ehrbg.

Taken in limited number among plants and in towings in
the Illinois River and in Quiver Lake, from July to October.

Individuals have been observed nibbling and eating bits of
algfe, like the species of Euchlanis.

68. M. bulba Gosse.

This species was as abundant among the vegetation as in
the open water, and was found in all the bodies of water

♦Jennings ('94) has pointed out that this species belongs to Distyla rather than
to Cathypna.

376 Illinois State Laboratory of Natural History.

except the two shallower lakes, Phelps and Flag. It was
present from April to November, and was most common dur-
ing the period from July to September.

69. M. quadridentata Ehrbg.

This was found at all of the substations except that in
Phelps Lake. It occurred from May to December and was
uniformly present, though never very abundant, throughout
the warmer months, from June to October.

70. M. closterocerca Schmarda.

Scattered occurrences at various times and places char-
acterize the record of this rather rare species. A maximum
in September is feebly indicated. It was found in all the
deeper lakes.

71. M. mollis Gosse.

Rare, being taken only in to wings from the Illinois River
in August.

Family COLTJRIDiE.

COLURUS Ehrbg.

Body subglobose, more or less compressed ; lorica com-
posed of two lateral plates, open in front, united dorsally,
gaping behind, and generally open ventrally ; frontal hood in
the form of a hook, not retractile ; foot permanently extended ;
of distinct joints, terminated by two furcate toes.

72. C. deflexus Ehrbg.

Occurred only in oblique towings from Quiver Lake, during
March.

73. C. bicuspidatus Ehrbg.

This species was not common at any time, and was found
only in the Illinois River and deeper lakes. It was present
from July to October, also once in April, frequenting both
vegetation and open water.

74. C. obtusus Gosse.

This attractive minute species was found in Quiver Lake
and once in the Illinois River. It was taken among vegeta-
tion and in towings from June to September.

Protozoa and Rotifera at Havana, III. 377

METOPIDIA Ehrbg.

Lorica usually depressed, entire, with an opening at each
end for the protrusion of the head and foot ; frontal hood in
the form of a hook ; foot and toes as in Colurus ; eyes usu-
ally two.

75. M. solidus Gosse.

Of rare occurrence. Found in towings from Quiver Lake
in September.

76. M. acuminata Ehrbg.

No member of this genus was common at any time. The
present species was taken only in March, July, and Decem-
ber, in towings from the deeper lakes — Dogfish and Thomp-
son's.

77. M. oxy sternum Gosse.

Rare. Found in towings from Quiver Lake and the Illi-
nois Eiver from September to December.

78. M. rhomboides Gosse.

This species was more numerous than any other member
of the genus. It was found in towings from the Illinois
Piiver and deeper lakes during August and September, and
also once in December.

79. M. triptera Ehrbg.

This species was found in Quiver Lake during July and
August, and in Thompson's Lake in July.

80. M. bractea Ehrbg.

Found sparingly among vegetation and in towings from
Quiver Lake in July of both years.

81. M. oblonga Ehrbg.
Metopidia elliptica Turner ('92).

Found sparingly among vegetation in Quiver Lake and in
the river in June and July of the first year. Length of lorica
.105 mm.

Family PTERODINID^J.

Pterodina Ehrbg.

Lorica entire, greatly depressed, of two oval, but nearly
circular, plates united at their edges ; foot wholly retractile,

378 Illinois State Laboratory of Natural History.

transversely wrinkled, jointless, toeless, ending in a ciliated
cup.

82. P. patina Ehrbg.

This species was present throughout the entire year, and
was found in the river and in all the deeper lakes. As to
the shallower lakes, it was rare in Flag and not found at all
in Phelps. It occurred both in towings and among vegeta-
tion. Its period of abundance is evidently from June to
October.

83. P. valvata Hudson.

Very rare, being found only once — among vegetation in
Quiver Lake, in June, 1894.

Family BRACHIONID^J.

BRACHIONUS Ehrbg.

Lorica without elevated ridges, gibbous both dorsally and
ventrally ; foot very flexible, uniformly wrinkled, without
articulation ; toes very small.

84. B. mollis Hempel ('96).

This active species was found, during July and August, in
towings from the Illinois River, Phelps Lake, and Flag Lake,
but was not common except in Phelps Lake, where it was
abundant.

85. B. pala Ehrbg.

This species was present all the year round, and was found
at nearly all of the substations. It was very abundant at
times, especially in April, August, September, November,
and December.

There seem to be several varieties of this species. Some
individuals have no posterior spines ; others have the two
prominences which guard the foot developed into spines, and
also have two other posterior spines. There are still others
in which these posterior spines are remarkably developed, so
that they are twice the length of the occipital spines.

This is undoubtedly a pelagic species, since it was found
in surface and bottom towings, and but once among vegeta-
tion near the shore.

Protozoa and Rotifera at Havana, III. 379

86. B. dorcas Gosse.

This is a winter species, as the records of both years show.
It was found in towings from the Illinois River and from all
the various lakes in which collections were made, from
December to April, with a few scattering occurrences just
before and after this period, becoming very abundant in
April.

Like the preceding species, this one was found only in
towings, and is recognized as a pelagic form.

87. B. dorcas spinosus Wierz. ('91).

But few specimens of this variety were found. It occurred
in towings from the Illinois River and Quiver Lake during
May, 1894, and in towings from the river and Thompson's
Lake taken in January, March, and May, 1895. This indi-
cates a seasonal history like that of the typical form.

88. B. punctatus Hempel ('96).

This was moderately common, and appeared from June to
September. It occurred only in the open water, and was
taken in most of the waters studied.

I have had the opportunity to study living examples of this
rotifer since the publication of my description ('96), which
was drawn up from dead specimens somewhat inflated by
the preserving fluid, and is consequently not as accurate as
it might be. I find that in the live specimens the dorso-
ventral diameter is less than was at first supposed, the
rotifer being flatter than the illustration represents it.

89. B. urceolaris Ehrbg.

This also seems to be a winter species, occurring from
January to April. It was found only the second year, in
towings from the river and from all the lakes studied except
Phelps Lake, and though usually not very common, it was
very abundant in Thompson's Lake in March.

90. B. rubens Ehrbg.

This species occurred from December to March in small
numbers in towings from the river and from all the lakes but

380 Illinois State Laboratory of Natural History.

Phelps Lake. It also appeared in the river at E in August
and September, 1894, becoming very abundant in August.

This is a very difficult species to work with, since it varies
greatly. Specimens were found ranging from .17 to .25
mm. in length. The pectoral edge is slightly more notched
in our specimens than in the typical form.

91. B. variabilis Hempel ('96).

This is a very restless active species, most common from
April to July, but present also in most of the other months
of the year. It was found only in the open water, but at
nearly all of the substations, and was very abundant in
Phelps Lake at the time when the Station work first began.

92. B. bakeri Ehebg.

This is preeminently a summer species, making its first
appearance in our collections in May, becoming common
from June to August, and disappearing again in October. It
occurred in all the waters studied except Flag Lake, and was
found among vegetation as well as in the open water.

This is also a variable species.

93. B. bakeri brevispinus Ehrbg.

Infrequent. Found in towings from the Illinois River
during April, 1896.

94. B. anguiaris Gosse.

This species was common and often abundant in summer.
It occurred from April to September, with occasional appear-
ances in October, December, February, and March, its time
of greatest abundance being in July and August. It was
found in all of the waters of the Station except Flag Lake.

Comparatively few specimens were found that had the
characteristic bluntly angled lorica. The majority of them
were more or less smooth; and in many instances there were
minute dots or tessellations on the surface of the lorica. In
connection with this species was found the following variety
with two posterior spines.

Protozoa and Rotifera at Havana, III. 381

95. B. annularis bidens Plate ('85). (Fig. 4, 5.)

B. caudatus Barrois et Daday ("94.)
This form was present from April
to September, most abundantly in
July and August. It was found at the

#same substations as
the preceding species.
Dr. Plate, in describ-
ing this form, gives it
specific rank. Barrois
and Daday have re-
cently described a form

_,. . _ under the name B. cau-

Fifir 4 Brach-

ionus caudatus datus. A careful com- Fig. 5. Brachionus bidens

Barrois&Daday. pariSOn of the figures of Plate'

the two forms shows that they are identical. As Plate says :

"The animal is closely related to B. angularis Gosse, with

which it corresponds in size and shape of the lorica; and

differs from it alone in that the surface of the lorica is not

roughened by angular ridges but is entirely smooth, or, at

most, very finely punctate." The opening for the protrusion

of the foot is characteristic in both forms. I found individuals

grading from angularis to forms that had the two posterior

spines even more developed than in caudatus. I see no

reason why this form should not be recognized as a variety

with the name proposed by Plate.

96. B. militaris Ehrbg.

This is also a summer species, occurring in both years
from June to October, and found but once outside this period
— in December. It was most abundant from July to Sep-
tember, and was found in all the bodies of water studied,
although it was rarer in the two shallower lakes. It was
equally abundant among vegetation and in open water. Not-
withstanding the short period of its occurrence this was the
most abundant species of the genus. Collections made
among vegetation during the summer months were almost a
"pure culture" of it. It became abundant very suddenly and
disappeared with equal abruptness.

382 Illinois State Laboratory of Natural History.

SCHIZOCERCA DADAY.

Foot long, ending in a fork of two unequal branches, each
terminated by a pair of unequal toes.

97. S. diversicornis Daday.

This species did not make its appearance in our collections
until 1895, and then it was quite rare. It was well dis-
tributed, however, being taken in towings from the Illinois
River and from the three more permanent lakes. It occurred
from July to September.

98. S. diversicornis homoceros Wierz. ('91).

Not so abundant as the preceding, being found but twice;
once in Phelps Lake in June, 1894, and again in Thompson's
Lake in August, 1895 ; on both occasions in the towings.

NOTEUS Ehrbg.
Lorica faceted, and covered with raised points; gibbous
dorsally, flat ventrally; foot obscurely jointed; toes moder-
ately long ; eyes wanting.

99. N. quadricornis Ehrbg.

This beautiful creature was found many times in the tow-
ings or among vegetation, but it was never abundant. It is
evidently a summer species as it was present only from May
to November. Found in the Illinois River and in the three
deeper lakes.

Family ANUR^EID-ffi.

ANTJRiEA GOSSE.

Lorica an oblong box, open widely in front, narrowly in
rear ; dorsal surface usually tessellated ; spines present ; the
egg, after extrusion, carried attached to the lorica.

100. A. hypelasma Gosse.

This species was found only in towings from Thompson's
Lake and among vegetation in Quiver Lake, in July, 1895.

101. A. tecta Gosse.

This species was present very uniformly throughout the
year, but was not at any time common. It was found in the
river and in all of the lakes except Flag Lake.

Protozoa and Rotifera at Havana, III. 383

102. A. aculeata Ehrbg.

This is a winter species. It was present in towings from
all the substations from November to June, reaching its
greatest abundance in May.

103. A. aculeata valg-a Ehrbg.

Found in towings from the Illinois River and Thompson's
Lake during April, 1895.

104. A. cochlearis Gosse.

This was the commonest representative of its genus, and
was present every month in the year, most abundantly from
April to September. It was found in towings from all of the
substations.

105. A. serrulata Ehrbg.

Found once — in a towing from the Illinois River in Decem-
ber, 1895.

NOTHOLCA GOSSE.

Lorica ovate, truncate and six-spined in front, sometimes
produced behind ; dorsal surface marked longitudinally with
alternate ridges and furrows ; extruded eggs not usually
carried.

106. N. acuminata Ehrbg.

This is clearly a winter species, being present during both
years in towings at nearly all of the substations from October
to May. It reached its greatest abundance during March
and April. It was found both among vegetation and in open
water.

107. N. longispina Kell.

Found only in towings from the Illinois River in Janu-
ary, 1895.

Order IV. SCIRTOPODA.

Family PEDALIONLDiE.

Pedalion Hudson.

Limbs arranged around the body in pairs, and parallel to
its longitudinal axis ; two stylate ciliated appendages on the
posterior dorsal surface.

384 Illinois State Laboratory of Natural History.

108. P. mirum Hudson.

This curious and interesting species was taken several
times in the towings during the summer. It was first seen in
the river at E in May, and was rather common there from
July to October. During this period it was also taken in
Phelps and Thompson's lakes.

Protozoa and Rotifera at Havana, III. 385

LITERATURE CONSULTED.

Anderson, H. H.
'89. Notes on Indian Rotifers. Journ. Asiatic Soc. Bengal, Vol.
LVIIL, Pt. II., pp. 345-358, PI. XIX.-XXI.

Barrois, Th., et Daday, E. v.
'94. Contribution a l'Etude cles Rotiferes tie Syrie et descriptions tie
quelques especes nouvelles. Rev. Biol, du North de la France, T.
VI., pp. 391-400, 401-409, 410, PI. V. 15 fig. in text,

Bergh, R. S.
'82. Der Organismns der Cilioflagellaten. Morph. Jahrb., Bd. VII.,
pp. 177-288, Taf. XII.-XVI.

Biedermann, Richard.
'93. Uber die Structur der Tintinnen-Gehause. Inaugural Disserta-
tion zur Erlangung der Doctorwiirde an tier Christian-Albrecbt
Universitat zu Kiel. 42 pp., 3 Taf.

Butschli, O.
'80-'89. Protozoa. Bronn's Klassen und Ordnungen ties Thier-
Reichs, Bd. I., Th. I.-III. 2035 pp., 79 PL

Caiman, W. T.
'92. On certain New or Rare Rotifers from Forfarshire. Ann.
Scottish Nat. Hist., 1892, pp. 240-245, Pi. VIII.

Daday, E. v.
'87. Monographie der Familie der Tintinnodeen. Mitth, zool. Stat.
Neapel, Bd. VII., pp. 473-588, Taf. XVIII.-XXI.

Entz, Geza.
'85. Zur niiheren Kenutnis der Tintinnotlen. Mitth. zool. Stat. Nea-
pel Bd. VI., pp. 185-214, Taf. XIII., XIV.

Fol, Hermann.
'81. Contribution a la Connaissance de la Familie des Tintinnodea.
Arch, des Sci. phys. et nat., III. Per., T. V., pp. 5-24, Pi. I.

Forbes, S. A.
'93. A Preliminary Report on the Aquatic Invertebrate Fauna of
the Yellowstone National Park, Wyoming, and of the Flathead
Region of Montana. Bull. U. S. Fish Comm,, 1891, pp. 207-258, PI.
XXXVII.-XLII.

Guerne, Jules de
'88. Excursions zoologiques dans les iles de Fayal et tie San Miguel
(Aeores). Campagnes scientifiques du yacht monegasque l'Hiron-
delle, HI. Ann. (1887). 110 pp., 1 PI., and 9 fig. in text.

386 Illinois State Laboratory of Natural History.

Heinpel, Adolph.
'96. Descriptions of New Species of Rotifera and Protozoa from the
Illinois River and Adjacent Waters. Bull. 111. State Lab. Nat. Hist..
Vol. IV., Art. X., pp. 310 317, PI. XXII.-XXVI.

Herrick, C. L.

'85. Notes on American Rotifers. Bull. Sci. Lab. Denison Univ.,
Vol. I., pp. 43-62, PI. II.-IV.. X. + l.

Hood, John.
'93. Three New Rotifers. Journ. Quekett Micr. Club, Ser. II.. Vol.
V.. pp. 281-283, PI. XII.

Hudson, C. T.

'75. [Classification and Affinities of the Rotifera.] Nature, Vol.
XII., p. 413.

Hudson, C. T., and Gosse, P. H.

'86. The Rotifera or Wheel-Animalcules, Vol. I., vi + 129 pp., PI.
l.-XV. ; Vol. II., 144 pp., PI. XVI.-XXX. London.

'89. Ibid. Supplement, vi + 64 pp , PI. XXXI.-XXXIV. London.

Janson, Otto.

'93. Versuch einer Ubersicht fiber die Rotatorien-Familie der Philo-
dinaeen. Beilage zum Abhandl. d. Naturw. Vereins zu Bremen.
Bd. XII. 82 pp., 5 PI.

Jennings, H. S.
'94. A List of the Rotatoria of the Great Lakes and of some of the
Inland Lakes of Michigan. Bull. Mich. Fish Coram., No. 3. 34 pp.,
2 PI.

'94a. Rotifers related to Euchlanis lynceus Ehrbg. Zool. Anz.,
XVII. Jahrg., pp. 55, 56.

Johnson, Herbert P.
'93. A Contribution to the Morphology and Biology of the Stentors.
Journ. Morph., Vol. VIII., pp. 467-562, PI. XX1II.-XXVL

Kellicott, D. S.
'84. Observations on Infusoria, with Descriptions of New Species.
Proc. Am. Soc. Micr., 1884, pp. 110-125, PI. III.

'87. Notice of some Fresh-water Infusoria, with Remarks on Collect-
ing and Preserving these Delicate Animals. The Microscope, Vol.
VII., pp. 225-233. 4 fig.

'88. Partial List of Rotifera of Shiawassee River at Corunna, Mich.
Proc. Am. Soc. Micr., Vol. X., pp. 84-96. 3 fig. in text.

Kent, W. Saville.
'80-'82. A Manual of the Infusoria. Vol. I., pp. x + 472; Vol. II.,
pp. 473-913; Vol. III., 79 PI. London.

0

Protozoa and Rotifer a at Havana, III. 387

Kofoid, Charles A.
'96. A Report upon the Protozoa observed in Lake Michigan and
the Inland Lakes in the Neighborhood of Charlevoix during the
Summer of 1894. Bull. Mich. Fish. Comm., No. 6, App. II., pp.

76-84.

'96a. On the Occurrence of Troehosphaera solstitialis in the Illinois
River. Science, Vol. IV., N. S., pp. 935, 936.

Leidy, Joseph.
'79. Fresh-water Rhizopods of North America. Rep. U. S. Geol.
Surv. Terr., Vol. XII. xi +324 pp., 48 PI.

McMurrich, J. Playfair.

'94. Text-book of Invertebrate Morphology, viii + 661 pp., 291 rig.
New York.
Pell, A.

'90. Three New Rotifers. The Microscope, Vol. X., pp. 143-145. 3 fig.

Plate, Ludwig.
'85. Beitrage zur Naturgeschichte der Rotatorien. Jenaische Zeit-
schr., Bel. XIX.. pp. 1-120, Taf. l.-III.

Rousselet, C. F.
'92. On Conochilus unicornis and Euchlanis parva — two New Roti-
fers. Journ. Quekett Micr. Club, Ser. II.. Vol. IV., pp. 367-370,
PI. XXIV.

'93. On a Method of Preserving Rotatoria. Ibid., Ser. II., Vol. V.,
pp. 205-209.

'95. Second Note on a Method of Preserving Rotatoria. Ibid.,
Ser. II., Vol. V., pp. 5-13.

Schewiakoff, Wl.
'93. Uber die Geographische Verbreitung der Siisswasser-Protozoen.
Mem. l'Acad. Imper. des Sci. de St.-Petersbourg, Ser. VII., T. XLL,
No. 8. 201 pp., 4 Taf.

Shaw, "W. R.
'94. Pleodorina, a New Genus of Volvocineae. Bot. Gazette, Vol.
XIX., pp. 279-283, PI. XX VII.

Smith, Frank.
'94. List of the Protozoa and Mollusca observed in Lake St. Clair in
the Summer of 1893. Bull. Mich. Fish Comm., No. 4, pp. 42-44.

Stokes, A. C.
'85. Some apparently undescribed Infusoria from Fresh Water.

Am. Nat, Vol. XIX., pp. 18-27. 8 fig.
'85a. Some New Infusoria from American Fresh Waters. Ann. and
Mag. Nat, Hist.. Ser. V , Vol. XV., pp. 437-449, PI. XV.

388 Illinois State Laboratory of Natural History.

'87. Notices of New Fresh-water Infusoria. VI. Am. Monthly
Micr. Journ., Vol. VIII., pp. 141-147. PI. VIII.

'87a. Microscopy for Beginners, xiii + 308 pp., 178 fig. New York.

'88. A Preliminary Contribution toward a History of the Fresh-
water Infusoria of the United States. Journ. Trenton Nat. Hist.
Soc, Vol. I., pp. 71-319, PI. I.-XIII.

Turner, C. H.
'92. Notes upon the Cladocera, Copepoda, Ostracoda, and Rotifera
of Cincinnati, with Descriptions of New Species. Bull. Sci. Lab.
Denison Univ., Vol. VI., Pt. II., pp. 57-74, PI. I., II.

Wierzejski, A.
'91. Liste des Rotiferes observes en Galicie. Bull. Soc. Zool. France,
T. XVI., pp. 49-52. 4 fig.

'92. Rotatoria (Wrotki) Galicyi. Rozpr. Wydz. mat.-przyr. Akad.
Umiej. w Krakowie, T. XXVI., pp. 160-265, Tab. IV.-VI.

Zacharias, Otto.
'93. Faunistische und biologische Beobachtungen am Gr. Ploner See.
Forschungsber. aus der Biol. Station zu Plon, Th. I., pp. 3-44, PI. I.

'94. Faunistische Mittheiluugen. Ibid., Th. II., pp., 57-90, Taf. I.,
II. 2 fig. in text.

'94a. Beobachtungen am Plankton des Gr. Ploner See's. Ibid., Th.
II., pp. 91-137.

'95. Faunistische Mittheiluugen. Ibid., Th. III., pp. 73-96, Taf.
I., II.

'95a. Fortsetzung der Beobachtung fiber die Periodicitiit der Plank,
ton wesen. Ibid., Th. III., pp. 129-144.

'95b. Quantitative Untersuchungen fiber das Limnoplankton. Ibid.,
Th. III., pp. 1-64.

BULLETIN

OF THE

Illinois Qtate I aboratory

OF

NATURAL HISTORY,

Urbana, Illinois.

VOLUME V.

ARTICLE VII.— FIRST SUPPLEMENT TO THE CHECK-LIST

OF THE COCCI DM. ■

BY T. D. A. COCKERELL.

Illinois State Laboratory of Natural History,

IKP.ANA, ILLINOIS.

January, 1899.

State Laboratory of Natural History.

LABORATORY STAFF.

Professor Stephen Alfred Forbes, Ph. I>..
Director of State Laboratory and State Entomologist.

< !harles Arthur Hart,
Systematic Entomologist and Curator of Collections.

Frank Smith, A. M..

Assistant Zoologist.

Charles Atwood Kofoid, Ph. D..
Zoologist, and Superintendent of Biological Station.

Ernest Browning Forbes. B. S.
Entomological Assistant.

Wallace Craig, B. S.,

Zoological Assistant.

Mart Jane Snyder.
Secretary.

Henry < Jlinton Forbes.
Business Agent and Librarian.

Lydia Moure Hart.
Artist.

Article VII. — First Supplement to the Chick-List of the
Coccidce. By T. D. A. Cockerell, New Mexico Agricul-
tural Experiment Station.

Since the publication of the Check-List* in 1896 no less
than three hundred and twenty-two species have been added.
A few of these are old species which had been accidentally
omitted or improperly reduced to synonyms, but the number
of actually new species is very great, and bears witness to
the activity of coccidologists. Forty species, given as valid
in the Check-List, are here reduced to varieties or synonyms.

As before, I have included a number of names of species
(mostly by Green) which I know to be either in press or

«

awaiting very early publication.

The group Idiococcina has been abandoned and merged
into Coccbuc. The Coccince could very well be divided into
two subfamilies and perhaps four tribes, as follows :

(A.) Cocc'uuc. Newly hatched larva with rows of dorsal spines,
and the last antennal joint usually short.
(1.) Coccini. Anal ring hairless. (Coccus, etc.)
(2.) Eriococcini. Anal ring hairy, hairs normally 8.
(Eriococcus, etc.)
(B.) Dactylopiince. Newly hatched larva without dorsal
spines, last antennal joint usually long.
(1.) Spluerococcini. Anal ring hairless. (Sphcerococcus.)
(2.) Dactylopiini. Anal ring hairy, hairs normally 6.
(Dactylojnus, etc.)

Species which were in the original list, here repeated to
indicate varieties, synonyms, etc., have the original numbers.

Since the Check-List was written, the following new writers
have described and named Coccidte. To facilitate corre-
spondence I give their addresses :

Bogue, E. E., Stillwater, Oklahoma.

Cooley, R. A., Agricultural College, Amherst, Mass.

*Article XI.. Vol. V.. of this series.

390 Illinois State Laboratory of Natural History.

Charmoy, D. d'Emmerez de, Port Louis, Mauritius.

Ehrhorn, E. M., Mountain View, Sta. Clara Co., Cal.

Fuller, Claude, Department of Agriculture, Cape Town,
S. Africa.

Hunter, S. J., Lawrence, Kansas.

Ihering, H. von, S. Paulo, Brazil.

King, G. B., Lawrence, Mass.

Leonardi, G., Portici, Italy.

Lidgett, J., Myrniong, Victoria, Australia.

Newell, W., Ames, Iowa.

Pergande, Theo., Dept. Agriculture, Washington, 1). C.

Tinsley, J. D., Mesilla Park, New Mexico.

I may also permit myself to mention that my own address
is now Mesilla Park, New Mexico. (Not Mesilla, nor Las
Cruces.)

Mouopblebinn'.

Callipappus, Gut-r.11 >

798. farinosus, Full.

799. bufo, Full.

Protortonia, Towns.12 '
S00. mexicanorum, Ckll.

801. primitiva, Towns.

Icerya, Sign.

39. purchasi, Mask.

v. maskelli. Ckll.
r. crawii, Ckll.
42. seyehellarum, Westw.
v. albolutea, Ckll.

802. formicarum, Newst.
s. g. Proticerya. Ckll.

803. littoral is. CM.
v. mimosas, < 'Ml.

Crypticerya, Ckll.

804. nudata, Mask.

805. ewarti, Newst.

806. hempeli, Ckll.

807. townsendi, Ckll.
v. plqcheae, Ckll.

Margarodiiiae.

Margarodes, Guild.

57. formicarum, Guild.
v. rileyi, Giard.

808. trimeni, Giard.
s. g. SpTiceraspis, Giard.

809. capensis, Giard.

Ortheziinae.

Orthezia, Bosc.

810. delavauxi. Thieb.

811. artemisise, Ckll.
S12. cheilanthi, Tinsl.

813. graminis, Tinsl.

814. montioola, Ckll.

815. garryae, Ckll.

Ortheziola, Sulc.

816. signoreti, JIaller.

817. fodiens, Giard.

(1.) Mr. Fuller states that Colostoma australe, immune and rubiginosum, of Maskell.
belong to Callipappus.

(•2.) The name Ortonia is preoccupied.

A Check-List of the Coccidce.

391

Coccinae.

Coccus, L.(3,)

818. opuntiae, Licht. MS., Ckll.
? s. of tomentosus, Lam.
v. newsteadi, Ckll.

819. acacias, Mask.

Eriococcus, Targ.

820. forrnicieola, Newst.

821. thy mel rate, Newst.

822. devoniensis, Green.

823. greeni, Newst.

824. gilletti. Tinsl.

825. arenosus, Ckll.

826. tinsleyi, Ckll.

827. adenostornae, Ehrh.

828. spiniger, Mask.

829. simplex, Mask.

v. dealbata, Mask.
84. paradoxus, Mask,
v. simplex, Mask,
v. indiea, Mask.

830. exiguus, Mask.

831. graminis, 3Iask.

832. elegans, Full.

833. apiomorpha', Full.

834. hakeae, FmW.

835. imperfectus. Full.

836. tricarinatus, .FmW.

837. agonis, Full

838. cypreaeformis, Full.

OUiffia, Full.

839. eucalypti, .F«W.

Rhizococcus, Sign.

840. tripartitus, Full.
100. casuarinae, Musk.

v. mancus, Mask.

Lachnodius, Mask.
203. eucalypti, Mask.

841. lectularius, Mask.

842. hirtus, Mask.

Dactulopius, Costa.
S43. syringre, Mask.

844. edgeworthia.1, Ckll.

845. hirsutus, Newst.

846. prosopidis, Ckll.

847. gutierreziae, CAW.

848. dasylirii, Ckll.
175. sorghiellus, Forbes.

v. kingii, Ckll.

v. neomexicanus, Tinsl.

849. lichtensioides, Ckll.

850. pseudonipae, Ckll.

851. claviger, King & Tinsl.

852. quaintancii, Tinsl.

853. azalea;, Tinsl.

854. cockerelli, A"mi</ tO Tinsl.

855. bainbusae. Green.

856. rimulae, Green.

857. lauigerus, i^W.

858. macrozamiae, F«W.

859. similans, Lidgett.
194. graminis, 3Iask.

v. orientalis, Mask.
205. calceolarias, Mask.

v. minor, Mask.
177. virgatus, CAW.

s. ceriferus, Newst.

s. talini, Green.

Phenacoccus, Ckll.

860. comari, Kunow.

861. solenopsis, Tinsl.

862. americanae, King & Ckll.
140. helianthi, Ckll.

v. gossypii, Towns. & Ckll.
1121. minimus, Tinsl.

Riper si a, Sign.

863. europaea, Newst.

864. tumida, Newst.

865. filicicola, Newst.

866. montana. Newst.

867. kingii, CAW.

868. lasii, CAW.

869. flaveola, CAW.

870. blanchardii, King & Ckll.

871. cuneiformis, Green.

872. myrmecophila, Mask.

(A.) Mr. E. E. Greeu informs me that Coccus laniger.W. F. Kirb., is Waiieriitnajloriger.

39'2 Illinois State Laboratory of Natural History.

1122. minima, Tins/, and King.

873. villosa, Ehrh.

s. g. Apterococcus, Newst.

121. fraxini, Newst.
s. g. Cryptoripersia. Ckll.

874. arizonensis. Ehrh.

S. g. Pseudoripersia, Ckll/4-1
89. turgipes, Mask.

Tylococcus, Newst.

875. madagascariensis, Newst.
Ceroputo, Sulc.

876. pilosellse, Sulc.
Rhizcecus, Kunck.

877. eloti, Giard.

Solenococcus, Ckll.'3-'

878. koebelei, Ckll.

879. ornatus, Green.

880. coloradensis. Ckll.

Cerococcus, Comst.

881. corticis, Towns. tfc Ckll.

Porococcus, Ckll.

882. tinctorius, Ckll.

883. pergandei, Ckll.

Carpochloroides, Ckll.

884. viridis, Ckll.

Capulinia, Sign.

885. jaboticabae, von Uier.

Mallococcus, Mask.

(Mallophora, Mask., preocc.)

886. sinensis, Mask.

Ourococcus, Full.

887. cobbii, Full.

888. eucalypti, Full.

889. casuarinse, Full.

Kermicus, Newst.

890. wroughtoni, Newst.
s. g. Chcetococcus, Mask.'0'

318. bambusae, Mask.

891. graminis. Mask.

Sphcerococcus, Mask.

892. rugosus, Mask.

v. elongatus. Mask.

893. pulehellus, Mask.

894. social is, Mask.

319. acacias, Mask.

v. melaleuca', Full.

895. leaii, Full.

896. tepperi. Full.

897. ethelae, Full.

898. morrisoni, Full.

899. obscuratus, Mask.
323. inflatipes, Mask.

v. simplicior, Mask.

900. populi, Mask.

901. parvus, dlask.

1120. sylvestris, C%K. rf- A'zwgi.

Olliffiella, Ckll.

902. cristicola, C%«.

Cylindrococcus, Mask.

903. gracilis, Full.
331. amplior, Mask.

s. Crocidocysta froggatti,
Rubs.

Asterolecaiiiinae.

Lecaniodiaspis, Targ.

904. tessellatus, Ckll.

905. artemisirc, Ckll.
900. mimosa1. Musk.

907. radiatns. Ckll.

908. manihotis, Towns.

909. atherosperniM'. Mask

910. melaleucae, F«W.

(4.) New subgenus. Well distinguished by the very peculiar legs, as figured by
Maskell, Trans. N. X Inst.. Vol. XXV.

(5.) New name for Solenoplwra, preoccupied. A Solenoph&ra ( ?) dryandrai «:is pub-
lished without description by Puller; the author now wishes to withdraw it.

(6.) Chcetococcus has only 8 (sometimes 6?) hairs <jii the anal ring; Kermicus proper
has 17. Otherwise they hardly diff< r The larva is Dactylopiirb

A Check- List, of the Coccidce.

393

Asterolecanium, Targ.

912. algeriense, Newst.

913. ilicis, JVeivst.

914. petrophilse, Full.

915. hakea', Full.

254. bryoides, Mask,
v. stellata, Mask.

255. bambusse, Boisd.

v. bambusulae, Ckll.

Tachardiinse.

Tachardia, Blanch.

916. nigra, Towns. & Ckll.

917. fulvoradiata, Ckll.

Bracliyscelinae.

Apiomorpha, Riibs.'7 '

918. helmsii, Full.

919. maliformis, Full.

920. cucurbita, Full.
300. karschi, Bubs.

v. rletcheri, Full.
292. thorntoni, Frog.

v. nux, Full.
283. conica, Frog.

s. regularis, Tepp.

s. similis, Riilis.
275. munita, Schrad.

s. corn if ex, Bubs.

v. tricornis, Frog.
297. strombylosa, Tepp.

s. crispa, Full.
294. urnalis, Tepp.

v. schraderi, Full.

921. excupula, Full.

Ascelis, Schrad.

922. melaleuese, Full.
Opisthoscelis, Schrad.

923. conica, Full.
Cystococcus, Full.

924. echiniformis. Full.

LeeaniiiiEe.

Kermes, Auctt.

925. austini, Ehrh.

926. pettiti, Ehrh.

927. ceriferus, Ehrh.

928. kingii, Ckll.

929. nivalis, King & Ckll.

930. pubescens, Bogue.

931. boguei, Ckll.

932. cockerelli, Ehrh.

933. nigropunctatus.£'Ar/*,d'- Ckll.

934. concinnulus, Ckll.

935. grandis, Ckll.

Aclerda, Sign.

936. distorta, Green.
1123. berlesii, Buffa.

Lecanopsis, Targ.

937. lineolatae, King & Ckll.

Lecanium, Illig.

938. ceratoniae, Qenn.

? s. of hesperidum, L.

939. perlatum, Ckll.

446. hesperidum, Linn.

s. patelliformis, Curt.1*'
v. alienum, Dovgl.{9>

447. minimum, Newst.
v. pinicola, Mask.

449. tessellatum, Sign,
v. swainsonse, ( 'kll.
v. perforatum, Areivsl.(4~>0.)

940. flaveolum, Ckll.

941. ventrale, Ehrh.

942. impar, Ckll.

943. rhizophorse, Ckll.
941. chilaspidis, Ckll.

945. erythrina1, con Iher.

946. perconvexuin, Ckll.

917. tuberculatum, Towns.&Ckll.
94S. townseudi, Ckll.
486. scrobiculatum, Mask.

1 7. ) The changes in the synonymy are made on the authority of Mr. Fuller,
is.) So given on Mr. Newstead's authority.
(9.) So given on Mr. Green's authority.

394 Illinois State Laboratory of Natural History.

v. leve, Mask.

v. pingue, Mask. (485.)

949. stracliaui, (JklL

950. castilloae, Ckll.
469. viride, Green.

v. africanum, Newst.

951. flcus, Mask.

952. globulosum, Mask.

953. no tat urn. Mask.

954. mirificum, Mask.

955. macrozamiae, Full.m

956. melaleucaj, Mask.

957. casuariniv, Mask.
487. baccatuui, Mask.

v. martnoreum, Full.

958. tubuliferum, Ckll.

959. turgidum, Ckll.

960. parvicorne, Ckll.
s. g. Pseudokermes. Ckll.

961. armatuin, CAW.
s. g. Eulecanium, Ckll.

528. quercitron is, Fitch.

s. kermoides, Tyrrell.
498. berberidis, <SV7<r.

«. major, Mask.

962. nigrofasciatum, Pergande.

963. magnoliarum, C&ZJ.

964. pubescens, Ehrh.

965. crawii, 2i%rft

966. kiugii, CAM.

967. maclurarnm, Ckll.

968. caryarum, Ckll.

969. perditum, C/.7/.

970. subaustrale, Ckll.

Ceroplastes, Gray.

409. irregularis, Ckll.

v. rubidus. Ckll.
426. rubens, Mask.

v. minor. Mask.
407. rusci, Linn.

s. caricse, Fonsc.

s. testudineus, Costa.

s. testudinata. Targ.

971. nerii, Newst.

972. angulatus, Ckll.

973. coloratus, Ckll.

974. minutus, Ckll.

975. roseatus, Towns. & Ckll.

976. confluens. Ckll. eft 77/,*/.

977. person at us, Newst.

Inglisia, Mask.

978. fossilis, Mask.
400. foraminifer, Mask.

v. loranthi, Full.

979. malvacearum, Ckll.

Platinglisia, Ckll.

980. noacki, Ckll.
Ctenochiton, Mask.

981. aztecus, Towns. & Ckll.

982. nuytisiae, Full <u->

Ceronema, Mask.

983. dryandrrc. Full.

984. japonicum, Mask.

Pulvinaria, Targ.

985. salicis, BouchJ.
361. bigeloviao, Ckll.

v. marmorata, Ckll.

986. amygdali, Ckll.

987. acericola, Walsh <ft Eiley.
359. innumerabilis, Hathv.

s. acericorticis, Fitch.
v. occidentals, Ckll.
v. tiliaa, King & Ckll.

988. rhois, Ehrh.

989. cellulosa, Green.

990. tbompsoni. Mask.
372. maskelli, Olliff.

v. viminarise, Full.
v. nuytisiae, Full.

991. lloccifera, Westw.

(10. 1 Mr. Filler tolls me this is probably a variety of L.frenchii.
(11.) Mr. Fuller no longer considers this valid.

A Cheek-List of the Coecidce.

395

s. g. Philephedra, Ckll.

992. ephedra', Ckll.

s. g. Protopulvinaria. < 'kll.
378. pyriformis, Ckll.
s. newsteadi, Leon.

Lichtensia, Sign.

993. mimosa:', Towns, and Ckll.

994. crescentise, '7,7/.

995. hakearum, Full.w

Pseudophilippia, Ckll.
990. quaintancii, '77/

Conchaspinae.

Conchaspis, Ckll.

997. socialis, Green.

998. newsteadi. '7.7/.

Diaspinne.

Aspidiotus, Bouche.

548. lied era1., Vail ,13)
? s. capparis, T"a//.
s. nerii. BoucM.
s. affinis, Tarij.
s. ceratoni:r. Sign,
s. erica', Boisd.
s. denticulatus. Targ.
s. genista, Westw.
s. gnidii, Sign,
s. corinocarpi, Colve'e.
s. ilicis, Sign.
s. lentisci, Sign,
s. olea, ColvSe.
s. villosns, Targ.
s. aloes, Bo is (7.
s. budleia, Sign.
s. cycadicola, Boisd.
s. epidendri, BoucM.
s. myrsina1, Sign,
s. obliquus. Costa,
s. bouchei, Targ.
s. palmarum. BoucM.

s. vrieseia, Sign,
s. carpodeti, Mask.
999. transparens. Green,
v. simillimns, Ckll.

1000. persearum, Ckll.

1001. britannieus, Newst.

1002. fraxini, "AUum," Henry.

1003. maculatus, Newst.

1004. excisns, Green.

1005. putearius, Gr< , ,,.

1006. moorei. Green.

1007. artocarpi, Green.

1008. bilobis. Mask.

1009. implicatus, Mask.

1010. virescens, Mask.

1011. dryandra, Full.

1012. niveus, Full.
626. eucalypti, Mask.

v. comatus, Mask.
g. Morganella, Ckll.

1013. inaskelli. Ckll.

s. ornatns, Mask.
g. Targionia, Sign.

1014. bigelovia, ( 'kll.

1015. dearnessi, Ckll.

1016. yuccarum, Ckll.
g. Odonaspis, Leon.

(Spatheaspis, Leon.)

1017. inusitatus, Green.

1018. bambasarum, Ckll.
560. secretns, Ckll.

v. lobulatus, Mask.

1019. canaliculars, Green.
g. Selenaspidus , Ckll.

603. articulatus, Morg.
v. celastri, 3Iask.
g. Phaulaspis, Leon.

1020. hakese, Mask.
g. Chentraspis, Leon.

622. unilobis, Mask.
g. Aspidiella, Leon.
612. saccbari, ' 7,7/.

i 12. ) Described as a doubtful Lecaniodiaspis.

(13.) The synonymy, except the lirst name
names cited as synonyms doubtless represent a
is the type of subg. Evaspidiotus, Leonardi.

I have specimens from Fuller.
i- after Berlese and Leonardi. The
i least several good varieties. A.hedera

396 Illinois State Laboratory of Natural History.

s. g. Pseudaonidia, (Jkll.

620. trilobitifonnis, Green.

s. tlarutyi, d'Emmerez cle
Charmoy.
s. g. Diaspidiotus (Berl. & Leon.),
Ckll.
579. perniciosus, Comst.
v. androinelas. Ckll.
v. albopunctatus, C'/r//.(785.)
V v. eucalypti, Full:u-<

1021. fernaldi, Ckll.

v. albiventer. Hunter.

1022. osborni, Newell & Ckll.

1023. coniferaruni. Ckll.
584. ancylus. Putn.

v. serratus, Xewell & Ckll.

587. seseuli, W. G. Johns,
v. solus, Hunter.

589. juglans-regire, Comst.
v. kafka, Ckll.

1024. jatrophu'. Towns. & Ckll.

1025. subsimilis, GJcll.
s. g. Hemiberlesia . Ckll.

(Aspidites, Berl. it' Leon..
preocc.)
568. rapax, Comst.

s. evonymi, Targ.

1026. ulmi, W. G. Johns.

1027. tricolor, Ckll.

588. cydonise, Comst.
v. tectus, Mask.

1028. crawii, Ckll.

1029. greenii, Ckll.

1030. cupressi, Ckll.

Chrysomphalus, Asbni.

1031. reniformis, Ckll.
606. dietyosperuii. Morg.

v. mangiferse, Ckll. (607.)

1032. longissimus, Ckll.

1033. agavis, Towns, and ('III.

1034. koebelei. Towns, and < 'hi I.

1035. albopietus. Ckll.

o. leonis, Towns, end ('III.

1036. rhizophorse, <'kll.
s. g. Melanaspis. Ckll.

1037. setiger. Mask.
103S. lilaoinus, Ckll.

1039. calurus. Ckll.
8. g. Myceiaspis. Ckll.

604. personatus, Comst.
s. g. Aonidiella, Berl. it Leon.
570. aurantii, Af".sA:.

Pseudodiaspis, Ckll.

1040. larrea. C3fcK.

1041. dentilobis, Ckll.

Comstockiella, Ckll.

63S. sabilis, Comst.

v. mexicanus, Ckll.

Cryptophyllaspis, Ckll.
619. occultus, Green.

Maskellia, Full.

1042. globosa, Full.

Xerophilaspis, Ckll.

1043. prosopidis, CAM.
Gymnaspis, Xewst.

1044. sechmese, Newst.

1045. bullata, Green.

Greeniella. Ckll.

772. eornigera, Green.

Aonidia, Sign.

1046. loranthi, Green.

1047. obseura, Green.

1048. messuaa, Green.

1049. ebeni. Green.

1050. planchonioides. Green.

1051. elaeagnus, Mask.

1052. banksia, .Fh//.

1053. distinetissima. JVeios£.

(14.) I do not think Fuller's eucalypti belongs to perniciosus. Mr. Puller kindly sent
me two slides of it. but on these are apparently three different things; the one which
1 suppose to lie ( ucalypti is immature.

A Check-List of the Coccidce.

397

Poliaspis, Mask.

(Maskelliella, Loon.)

1054. pini, Mask.

1055. nitens, Full.

1056. intermedia, Full.

Fiotinia, Targ.

757. fioriniae, Targ.
s. palmae, Green,
s. pinicola, Mask.
v. minor. Mask.
755. aeaciae. Mask.

v. bilobis, Full.
757. rubra, Mask.

• v. propinqua, Mask.

1057. casuarina\ Mask.
105S. sign at a, 31ask.
1059. tenuis. Mask.
10G0. similis. Green.

1061. bambusae, Mask.

1062. nephelii, Mask.

Ischnaspis, Dougl.

680. longirostris, Sign.

s. riliformis, Dougl. (752.)

Leucaspis, Sign.

1063. japonica, Ckll.

Parlatoria, Sign.

1064. aflinis, Newst.
666. these, Ckll.

v. euonymi, Ckll.
668. proteus, Curt.

s. orbicularis, Targ.
v. pergandei, Comst. (667.)
v. virescens, Mask.
v. palmae, Mask.

1065. eingala, Green.

1066. mytilaspiformis. Green.

1067. aonidiformis. Green.

1068. sinensis, Mas/.:

1069. perpusilla, Mask.

1070. viridis, Full.

1071. dryandras, Full.
Pseudoparlatoria, Ckll.

1072. noacki, Ckll.

1073. serrulata, Towns. & Ckll.

Mytilaspis, Sign.'15 '

675. pomorum, Bouche.
v. saliceti, Bouche.

1124. confusus. Horvath.

s. abietis, Sign nee Schr.

1074. eeratonia\ Genn.

1075. minima, Newst.

1076. ampelodesma^, Newst.

1077. serrifrons, Leon.

1078. maehili, Mask.

676. erawii, Ckll.

v. canaliculata. Mask.
678. eitricola. Pack.
v. tasmania1, Mask.

1079. perlonga, Ckll.

1080. mexicana, Ckll.

1081. argentata. Ckll.

1082. bambusicola, Ckll.

1083. eocculi, Green.
685. pallida, Green.

v. maskelli, Ckll.
689. pallens, Mask.

v. alba, Mask.
692. spin if era, Mask.

v. major. Mask.

1084. acacia1, Mask

v. albida, Mask.

1085. banksise, Mask.

1086. melaleucas Mask.

1087. maideni, Mask.

1088. defecta, Mask,
v. tincta, 3Iask.

Pinnaspis, Ckll.

705. pandani, Comst.

v. alba, Ckll.

Hemichionaspis, Ckll.
718. aspidistras, Sign.

(15 ) Leonardi has separated from Mytilaspis groups which lie treats as genera, named
Phatilomytilus, Coccomytilw and Trichomt/Ulus. I have proposed the subg. Opuntiaxpin for
J/, philococcus.

398

Illinois State Laboratory of Natural History.

v. braziliensis, Sign. (720.)
r. these, Musk, i 734.)
!>. lata, Ckll. (716.)
722. minor. Musk.

Chionaspis, Sign.'16

712. salicis. LinnS1'' •■
s. alni. Sig7i. (70S.)
s. fraxini, Sign. (713.)

1089. striata, Newst.

1090. berlesii. Leon.

1091. quercus, Comst.

1092. caryse, Cooley.
1125. platani, Cooley.

725. furfurus, Fitch.

». ulini, CA7Z.

v. fulva, A7h<7.
72<i. salicis-nigrae, PFafeA.

s. bruneri, CkllSl%)
728. pinifolise, Fftcft.

v. heteropliylla1. Cooley.

v. semiaurea. Ckll.

730. spartinse, ( 'omst.

v. natalensis, Mask.

731. lintneri, Comst.
v. betulse, Cooley.

733. prunicola, Mask. ''•'
i?. these, Mask.

1093. agonis, i*V/.

1094. ethelse, F><//.

1095. xantliorrhaa'. FwZZ.

1096. saccharifolii, Zehntner.

1097. tlepressa. 7.'lnitn>r.

1098. howardi, Cooley.

1099. lounsburyi, Cooley.

1100. simplex. './••

1101. chinensis, CAW.

1102. latissima, '7.7/.

1103. aucubse, Cooley.

1104. wistaria', ( 'ooh y.
■1105. cockerelli, Cooley.

Aulacaspis, Ckll.

658. rosa\ Bouch/.

v. spinosa. Mask.

659. boisduvalii, Sigrra.
/-. cnaculata, C/7/.

1100. montana. Ckll:

1107. miranda, Ckll.

1 108. ? elegans. Leon.

Diaspis, Costa.

1109. gennadii, Leon.

1110. olea-. Colv ■ .
651. amygdali, Tryon.

v. rubra. Mask.

1111. persimilis, Ckll.

1112. baccharidis. Towns. & Ckll.

1113. phoradendri, Ckll.

1114. erawii, Ckll.

1115. fagrsese, Green.

1116. loranthi, Green.
s. g. Epidiaspis, Ckll.

1117. pirieola, Dei Guercio.
s. fallax. Horvath.

1118. snowii. Hunter. -'

Howardia, Berl. & Leon.
719. biclavis. ( >/*/*>/.

Protodiaspis. Ckll.

1119. parvulus, r/7/.

(16. 1 /'/,. nacaspift, Cooley and Ckll., will be a new genus to include P. nyssat, chiru
eugenice, etc, hitherto placed in Chionaspis. Mr. Cooley and the present writer agree
that these forms have no genetic relationship with genuine < 'hionaspis except through
Aulacaspis and Diaspis. 1 leave Mr. Cooley to publish the generic characters and
classify the species.

(17.)" Mr. i !ooley is responsible for the synonymy.

(18.) According to W r. Cooley,

(19.) Mr. Cooley finds that specimens of C. prunicola from Mr. Maskell are Dia
amygdali. It is jus) possible that Maskell accidentally mixed the ZWaspts with a*genu-
ine Chionaspis, however, and that prunicola may still be valid.

(80.) This could very well pas> for Aspidiotw cmcylus, did it not have a Diaspis male
scale! D. pirieola, in Europe, was long confounded with Aspidiotus ostreatformis.

BULLETIN

OF THE

Illinois Qtate Laboratory

OF

NATURAL HISTORY,

Urbana, Illinois.

VOLUME V.

ARTICLE VIII.— A STATISTICAL STUDY OF THE PARA-
SITES OF THE UNIOFTIDM.

BY H. M. KELLY, A. M.

Illinois State Laboratory of Natural History,
URBANA, ILLINOIS.

March, 1899.

State Laboratory of Natural History.

LABORATORY STAFF.

Professor Stephen Alfred Forbes, Ph. D.,

Director of State Laboratory and State Entomologist.

Charles Arthur Hart,

Systematic Entomologist and Curator of Collections.

Frank Smith, A. M.,

Assistant Zoologist.

Charles Atavook Kofoid, Ph. D.,

Zoologist, and Superintendent of Biological Station.

Wallace Craig, B. S.,

Zoological Assistant.

Mary Jane Snyder,

Secretary.

Henry Clinton Forbes,
Business Agent and Librarian.

Lydia Moure Hart,

Artist.

Article VIII. — A Statistical Study of the Parasites of the

Union id<e. By H. M. Kelly.

The studies on the quantitative occurrence of parasites in
different species of the Unionidce which form the hasis of the
present paper were made at the Illinois Biological Station, at
Havana, early in the summers of 1896 and 1897 and con-
tinued both seasons at Mt. Vernon, la., and at Lewisburg and
Phcenixville, Pa.«, the material used being secured in the
above mentioned localities and examined while fresh. It
was the purpose of the investigation to determine, if possible,
under what conditions infestation would be found to vary in
a series of closely related species of a given locality or of
several localities, and to what extent this variation could be
regarded as a specific characteristic.

The Illinois, Iowa, and Pennsylvania waters from which
collections were made are indicated in Table I., and for the
purposes of this paper may be briefly characterized as fol-
lows : (1) The Illinois Paver at Havana is a large sluggish
stream with alluvial banks and largely muddy bottom, full
of organic matter of various origin. (2) Spoon River, a
tributary of the Illinois, is at Bernadotte and Duncan's
Mills, where collections were made, small, with rapid current
and rocky bottom. It drains a purely agricultural region,
and is subject to frequent and sudden Hoods. (3) Quiver
Creek, near Havana, is a smaller tributary to the Illinois,
draining a sandy plain. (4) Thompson's Lake is a shallow
body of water about six miles long and one mile wide, lying
in the low alluvial flood plain of the Illinois River, with very
muddy bottom and little change of water except as affected
by change of level in the river, with which it is connected.
(5) The Cedar River, near Mt. Vernon, la., is a rapid shallow
stream with shifting sandy bottom for the most part, draining

400 Illinois State Laboratory of Natural History.

a rolling prairie region. (6) iVbbey Creek is a small, slug-
gish, and muddy tributary of the Cedar, flowing through a
wooded region of rich black soil. (7) The Schuylkill River
at Phoenixville, Pa., is rapid and shallow, with a rocky bed.
Its waters are largely contaminated with the sewage of the
populous region through which it flows, with manufacturers'
wastes, and with the acid pumpings of anthracite coalmines.
(8) Pickering Creek, a tributary of the Schuylkill, is an
uncontaminated, swift-flowing stream, constant in volume,
and draining a restricted rocky area. (9) French Creek, a
near-by branch of the Schuylkill, is of similar size, but
traverses a country of clay soils, and is subject to frequent
inundations. (10) The West Branch of the Susquehanna
River is, upon most of its course, a large but shallow mountain
stream with rapid current. It is quiet for some miles at
Lewisburg, Pa., where it crosses one of the fertile valleys of
the Appalachian system.

Fifteen hundred and thirty-seven individual unios from the
above localities, belonging to forty-four species, were person-
ally examined by me with reference to their parasites; and
with the (lata thus obtained I have incorporated the results
of an examination of seventy- seven individuals, belonging to
eighteen species, made by Dr. C. A. Kofoid in 1895 and
1896, which were placed at my disposal. It is unfortunate
that my material did not furnish equal representation for
eaeh host species, and that the examination extended over
such a long period of time. For control on both these point>
an effort was made to examine, if possible, about twenty indi-
viduals of each species which were all taken at the same time
from the same locality and under the same conditions.

Whenever it was practicable individuals of or above the
adult average in size and age were chosen for examination.
Only ninety-seven of the sixteen hundred and fourteen indi-
viduals examined could be regarded as immature, and these
were well distributed among the several species. The inclu-
sion of records for these younger and smaller individuals
would presumably reduce somewhat both the probability of
and capacity for infestation. However, in the case of

A Study of the Parasites of the Unionidce. 401

Tahle I. Geographical Distribution of Ltnionid.e Examined.

NAMES OF SPECIES.

z

p

_ o

£ Ms

£.—

■ a.

<'

Si

Illinois.

Iowa.

Pennsylvania

_Z

a •
re'

99

0

S5

<

re

rj

•a

o

s

re

<

re

*-i

re
re
W

o
o

B

•a

PS

iT> a:

c

Q
So

g

<
re

>

a
re

o

re

XI

re
S
c
«*^

sH

< B
re

2

a

r-
re

5 =

re

2

(D

re

/
c

_re
re "

-s ~

Quadrula multiplicata Lea.
tuberculata Bar.
metanevra Kaf.
lachrymosa Lea.
asperrima Lea.
pustulata Lea.
granifera Lea.
pustulosa Lea.
plicata Say.
trigona Lea.
rubiginosa Lea.
ebena Lea.
Unio gibbosus Bar.

complanatus Sol.
heterodon Lea.
Alasmodonta confragosaSay
complanataBar
rugosa Bar.
marginata Say
undulata Say
tappanianaLea
Strophitus edentulus Lea.
Anodonta imbecilis Say.

suborbiculata Say
grandis Lea.
corpulenta Coop.
Obliquaria reflexa Raf.
PJagiola securis Lea.
elegans Lea.
donaciformis Lea.
Lampsilis parvus Bar.
ellipsis Lea.
higginsii Lea.
ligamentiniis Lam
luteolus Lam.
nasutus Say.
anodontoides Lea
rectus Lam.
ochraceus Say.
ventricosus Bar.
alatus Say.
l?evissimus Lea.
gracilis Bar.
tenuissimus Lea

28
41
36
29
21
20

1
87
89
27
40
23
35
137

4
35
64
IS
51

3

1
36
49
20

8
45
32

5
48
37
31
14

1
91
25

4
62
49

1

108

60

4
89

5

26

18

2

21
20

1
29
45
22

1
23
25

2
21

2

3

2

1

1

1

1

3

3

2

3

1

2

4

3

2

4

2

3

1

1

6

2

1

2

2

3

1

3

3

2

2

1

3

4

2

3

3

1

4

3

2

3

1

2
34

29

28
8
5
1

30
36

38

10

62
1

U\ 20
1 2

41

34
11

]

8
1

37

17

1

8

30

20
3

1
1

12

47

35

26

5

25

21

25

3

1

24

11

2

18
2

2

1

3
1

20

5

10

5

3
3

20
13

6

11

2
2

65
2

10

3

1

49
10

4
2

9
37

1

10

38

1

40

2

3

3

16

40

56
19

33
5

~68

5

45
3

47

fi

12
2

Totals j Individuals.
1 Species.

1614

44

iiil
32

160
24

50

2

30

2

195
23

16
3

402 Illinois State Laboratdry of Natural History.

Quadrula pustulosa* where the highest proportion of under-
sized individuals is included in the tabulation, — twenty out
of eighty-seven, — it appears that the infestation of these
younger hosts did not differ materially in kind or degree
from that of the larger individuals.

The sex of fourteen hundred and eighty-three individuals
of the sixteen hundred and fourteen examined was deter-
mined by microscopical examination, seven hundred and
eighty-two being males and seven hundred and one females.
In one hundred cases the determination of sex was not
attempted. In the thirty-one remaining, it was indetermin-
able by microscopic examination, all but five being infested by
Bucephalus or other cercaria forms to the utter destruction of
the proper reproductive tissue. From the shape of the shells
eight of these thirty-one individuals were pronounced males
and two females. Others, also belonging to species in which
the shells of the two sexes are normally characteristic, had
shells of such shape as to render the sex problematical and
to suggest that infestation by Bucephalus or other cercaria,
when early acquired and long continued, may so alter the
form of the shell of the female as to cause it to resemble that
of the male or, if acquired later, may produce an intermediate
form. Moreover, females infested with Bucephalus or other
cercaria rarely (in but three observed cases) carried glochidia,
though examined when the marsupia of other females of their
species were normally inflated with young. This is especially
noteworthy in Lampsilis gracilis, in which determination of
the sex of the clam by the form of the shell is usually certain.
Of the eighty-nine individuals of this species examined,
thirteen were infested with Bucephalus or other cercaria. Of
these, seven appeared to be males, one was a female with
glochidia in the gill, three were doubtfully regarded as females
although no germinal tissue was discernible, while the sex of
two was problematical.

In thirty-eight of the forty-four species examined the niirn-

* For the convenience of those who have not followed the recent changes in
unionid nomenclature a list of the names mentioned in this article is given in the
lirst column below, each name being followed in the second column by the one

A Study of the Parasites of the Unionidce. 403

ber of infested males and females for each species did not
differ materially. The exceptions are as follows :

Unio heterodon, 4 males, 0 females.

Anodonta suborbieulata, 18 males, 2 females.

Plagiola securis, 5 males, 0 females.

Lampsilis parvus, 0 males, 31 females.

Lampsilis lsevissimus, 4 males, 0 females.

Lampsilis tenuissimus, 5 males, 0 females.

The disparity of the sexes in these few species has no
significance, however, in this connection, for in no case where
both sexes were liberally represented in the host species
could a different capacity for infestation be established for
the two sexes. The only seeming exception, in the case of

previously in common use. The specific names remain the same, except that comu-
tus becomes reflexa, and plana is now considered a form of grandis.

Quadrula multiplicata Unio multiplicatus

tuberculata tuberculatus

metanevra metanever

lachrymosa lachrymosus

asperrima asperrimus

pustulata pustulatus

granifera graniferus

pustulosa pustulosus

plicata plicatus

trigona trigonus

rubiginosa rubiginosus

ebena ebe'nus

Unio gibbosus gibbosus

complanatus complauatus

heterodon , heterodon

Alasmodonta confragosa Margaritana confragosa

complanata complanata

rugosa rugosa

marginata marginata

undulata .....' nndulata

tappaniana Unio tappanianus

Strophitus edentulus Anodonta edentula

Anodonta imbecilis imbecilis

suborbieulata suborbieulata

grandis plana

corpulenta eorpulenta

Obliquaria reflexa Unio cornutus

Plagiola securis securis

elegans elegans

donaciformis donaciformis

Lampsilis parvus parvus

ellipsis ellipsis

higginsii higginsii

ligamentous ligamentous

luteolus luteolus

nasutus nasi it us

anodontoides anodontoides

rectus rectus

ochraceus ochraceus

ventricosus venlricosus

alatus alatus

lsevissimus lsevissimus

gracilis gracilis

tenuissimus tenuissimus

404 Illinois State Laboratory of Natural History.

infestation by Bucephalus, has already been explained as the
result of the unsexing of the host.

Though this study was instituted primarily with the
trematodes alone in mind, record was made of all parasites
whose presence did not appear to be accidental. I have
presented in Table II. a concise record of these parasites and
of the species and number of their hosts, while the relations
of the one to the other are set forth in the discussion which
follows.

Aspidogaster conchicola von Baer, the most common parasite
of the Uiiionidcv, is confined for the most part to the peri-
cardial and nephridial cavities of the host. In four hundred
and thirty-five cases- it was found in the pericardium only,
in seventy in the kidneys only, and in one hundred and
thirty-four cases both cavities contained the parasite. In
only one host species showing any considerable degree of
infestation, Lampsilis parvus, — where twenty out of thirty-
one individuals examined were parasitized, — were the flukes
restricted wholly to one cavity (the pericardium), and here
the small size of the host may perhaps account for such
restriction. As a rule, though there are many exceptions,
flukes appear in both chambers only when the parasites are
very numerous ; and as the number in the pericardium is
usually much larger than that in the kidneys, and as the
pericardial infection is the more frequent, it would seem that
only in excessive parasitism is the nephridial cavity invaded.
A single Aspidogaster was found encysted in the lateral wall
of the visceral mass of the host. In four cases only, in all
of which the pericardium was ruptured in opening the shell,
were individuals of this species detected in other than the
usual localities, and then their positions were always such as
to suggest escape from the broken pericardium. This para-
site was most frequently found in the adult stage, but eggs
and embryos in abundance and young of varying sizes were
found when the parasitism was considerable. The presence
of the mature trematode in the pericardium and of eggs
within the nephridia is not infrequent.

Cotylaspis in sign is Leidy is found adherent to the surface

A Study of the Parasites of the Unionidce. 405

of the host in the angle between the inner gill and the
visceral mass. Its range is usually restricted to this axilla,
and the number infesting one host is small. In one case,
however, — that of Anodonta corpulenta, recorded by Dr.
Kofoid. — where the number reached the unparalleled extreme
of ninety-two, the flukes extended well out upon the inner sur-
face of the gill ; and in another, under my own observation,
some of them were crowded down upon the abdominal surface.
In A. suborbiculata, in which Cotylaspis attains its maximum
average, thirty-eight to each host, not only are the axillge and
the adjacent surfaces of both inner gill and visceral mass
invaded, but some are usually found within the tubes of the
inner gill, and occasionally even in those of the outer gill.
Such migration from the usual seat of infestation to immedi-
ately adjacent regions is perhaps to be expected in cases of
overcrowding such as are instanced. In a single Lampsilis
ellipsis, one Cotylaspis unmistakably occurred in the peri-
cardium along with twenty-three specimens of Aspidogaster.
Since Cotylaspis normally frequents the region of the nephrid-
ial openings, an invasion of the pericardium by way of the
nephridia might not be impossible. All the Cotylaspis found
were adults varying little in size. Eggs were not infrequently
observed in the surface slime collected in the vicinity of the
parasites.

Four forms of Distomidce have been found, probably of as
many different species, all immature, and none sufficiently
developed for specific determination. One of these forms —
referred to in the table as "Free Distomata" —is found in
loose salmon-colored masses either upon or slightly w;thin
the tissue of the mantle, along or. near the dorsal fold. In
Quadrula, Unio, Plagiola, and Lampsilis this parasite is most
frequently located immediately between the cardinal teeth,
less commonly between the lateral teeth, or, again, upon
the sides, extending over the external surface of the mantle
on a line parallel to its attachment to the viscera. In
the genera Strophitus and Anodonta the distribution of this
parasite is lateral, as just described, often extending over the
mantle surface like a large widely-open inverted V, with its

406 Illinois State Laboratory of Natural History.

apex just below the umbo and its arms reaching even beyond
and below the anterior and posterior adductor muscles.*
This trematode has not in my experience been found singly,
the number associated having varied from four to many
hundreds. They are habitually loosely adherent by their
suckers to the mantle surface and to each other, but may be
slightly insinuated within the loose tissue of the mantle,
especially when found between the hinge teeth. The position
of this parasite is usually marked by rusty stains in and
upon the nacre, by malformation of the shell or of the hinge
teeth, and not infrequently by a number of dark, poorly
formed pearls. Though these conditions of the superimposed
shell do not always accompany infestation by this trematode,
and though similar abnormalities are found without its pres-
ence being discerned, yet these malformations are very con-
stant where the mass of the parasites is considerable, and
the size and location of the ferruginous stain or injury corre-
spond to those of the infesting colony. When but few are
present and there is no injury to the nacre, the irritation is
no doubt too slight or too recent for much interference with
the normal secretion of the mantle. A malformation char-
acteristic of the presence of this parasite but unaccompanied
by it, would seem to imply desertion for another host. Such
implication is strengthened by the fact that in the case of
some of the host species, individuals are frequently found in
which none of these salmon-colored masses of trematodes are
present, but which nevertheless present malformations of
considerable size in which the rusty, altered, and diseased
nacre is covered with a normal layer of later deposit. The
parasite is, moreover, uniformly immature, no matter at
what season it is observed.

The other three species of Distomum were found encysted
in the following situations respectively: (1) in the peri-
cardium of a single individual in each of the species Qiiadrula
riibiginosa, Plagiola elegans, and Lampsilis anodontoides ;
(2) in the ventral muscular margin of the mantle in four

*H. L. Osborn ("98. Zool. Bull., Vol. I.. Xo. tl) describes in like manner this para-
site and its mode of infestation in Anodonta plana (= grandis) and Stropltit»i>
edentulus from Chautauqua Lake, X. Y.

A Study of the Parasites of the Unionidcel 407

individuals of Lampsilis ligamentinus ; and (3) within the
ovary of a single specimen of Lampsilis ventricosus. These
are evidently all immature forms, the clam serving them only
as an intermediate host.

Bucephalus pvlymorphus von Baer and two other cercaria
forms were found within the viscera of the host. These
usually occurred in such abundance as to obliterate totally
the normal tissue of the sexual glands, rendering the whole
abdomen as granular as fish roe, or fibrous with the sporo-
cysts of the Bucephalus. Extensive infestation with the
latter parasite also involves the nephridia, which may be
much swollen, their ducts being nearly obliterated by the
tangled fibers of sporocysts. This unsexing of the host, and
the accompanying changes in the . form of the shell have
already been referred to.

Various species of Atax are common ectoparasites of the
Unionidce. Their favorite situations are upon the body
surfaces, between the gills or between the gills and abdomen,
between the labial palps, or among the papillae fringing the
mantle edges at the inhalent siphon. Their eggs are laid
either in the body wall, the gills, or the mantle.

Dr. Kobert H. Wolcott, to whom a part of the Atax
material collected in the course of this study was sent, kindly
furnished the determinations of the species of this genus
included in the following table, which indicates the host
species from which these different parasites were derived,
and also the total number of individuals of each species of
A tax found in a given host species.

Conchophthirus hirtus Ehrbg. and C. anodontce Ehrbg.,
ciliated Infusoria, inhabit the slime investing the body sur-
faces. In the accompanying tables no attempt is made to
separate the two species.

Chaetogaster limned von Baer, an oligochaate, is also found in
the slime of the various surfaces and in the kidneys.

The frequent presence of leeches and planarians upon the
shell and on the mantle edges, at times indeed within the
branchial chamber, was regarded as accidental, and they are
consequently not included in the accompanying tabulations.

408 Illinois State Laboratory of Natural History.

HOST SPECIES.

73 So
!>

£-3

(5 -1
O '

--SO

£.»

O *-»>

<D o

— . D°

eg-

\tnx lndistinc-
tus Wolcott.

Atax serratus
Wolcott.

Atax stricta
Wolcott.

#g

P-

Quadrula tubereulata. .

363

12

5

115
43

4

lachrymosa .
asperrima .. .

,

marj^inata
Anodonta imbecilis.. . .
suborbiculata
corpulenta . .

11

18

8

5

3
37
16

Obliquaria reflexa .....

10

Lampsilis anodontoides

26

8

1

636

ventricosus. .
alatus

14

6
G
6

78

Jaevissimus. . .

Sp. ?

3

30

82

8

1

Table II. is an exhibit of the results of all the examinations,
the booty of the table giving the number of individuals of the
various host species examined, and the number of such hosts
infested by each of the nine parasites named in the head-
ings. The footings of the columns and the subjoined per-
centages give the number and per cent, of species and
individuals infested. On the right, one column gives the
number of kinds of parasites found in each host species, and
another the total number of individuals in the species
examined which were infested to any degree. A comparison
of the data in these two columns, note being taken of the
number of individuals examined in the several species, as
given in the first column, shows a marked variation among
the different host species in the number of kinds of parasites
harbored and in the number of individuals of each species
infested. It is seen that Aspidogaster is by far the most
widely distributed and abundant parasite ; that Cotylaspis,
Atax, and Conchophthirus must be classed as very frequent;
that the free distomid and Bucephalus are less common ; and
that the remaining three parasites occur but occasionally.
It is remarkable that at least two sufficiently examined

A Study of the Parasites of the Unionidce.

409

Table II. Specific

Distribution of Parasites

•

HOST SPECIES.

No. of Hosts Infested with

- 2
r 0

Names.

— ?

on

£ =

&?

28
41
36
29
21
20

1

87
89
27
40
23
35
137

4
35
64
18
51

3

1
36
49
20

8
45
32

5
48
37
31
14

1
91
25

4
62
49

1

108

60

4
89

5

>

O

crq
P

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Quadrula multiplicata

3
33
12

21

21

5

1

28

62
3

10
7
9

37
1
9

10

3

23

12

7

9

16

1

50

36

8
5

3

12
1

2

20

5
4
2
4
3
3
6
4
3
4
1
5
4
2
5
6
5
4

38
28
22
21
18

1
59
70
10
15

7

21

120

1
12
36
13
47

asperrinia

ii

1

13

pustulata

1
6
5
4
2

9

6

1

1

trigona . .

4

1

3

1

1

i

1

1

17

113

1

2

6

8

33

3

heterodon

Alasuiodonta conf ragosa . . .
coraplanata. . . .

ragosa

marginata

undulata

tappaniana ....

Anodonta imbecilis ....

3
2

1
3

1

1
21

9
39

1
1

4

9

6
25
20

8
37

3

5
17

18

5

40

3

6

3

1

15

1

32

13

10

28

19

5

21
6
2

1

33

i

i
2

6
5
4
5
6
4
1
5
5
3
4
1
6
6
3
6
7
1
5
5
2
6
3

26
46
20

8
43
19

2
10
22
21
14

1
51
17

3
54
44

1
94
57

3
86

5

suborbiculata

grandis. . .

5
21

corpulenta

1

Plflonolft SPCliris

elegans

3
21
20
12

3

1

47

7

1

3

1

4
1

Ijaninsilis parvus

2
11

1
13

4

1
18
21

1

10

1

ligamentous

lnteolus

"3

4

5

12
2

20
12

9

1

2

15

18

ii

1

"3

2
3

38
32

1
72
48

2
57

1

alatns

30

49

3

77
5

24
27

58
4

1

...

10

26

trronili.c .

46
3

1

13

11

644
37

297
24

146
14

8
5

17

8

60
15

586
35

398
30

40

5

1197
42

Percentage of individ. infested
Percentage of species infested.

40
84

18
55

9
32

0.4
11

1

18

4
34

36

80

25

i;8

2

11

74
95

410 Illinois State Laboratory of Natural History.

species, Alasmodonta rugosa and Lampsilis ligamentinus,
show no infestation with the generally prevalent Aspidogaster,
and this is especially noteworthy in the case of the latter,
whose infestation with other parasites is both frequent and
severe.

Table III. brings into comparison the number of kinds of
parasites found infesting individuals of each host species and

Table III. Degree of Infestation of Individual Hosts.

host SPECIES.

Names.

Quadrula multiplicata . . .
tuberculata

metanevra

lachrymosa

asperrima

pustulata

pustulosa

plicata

trigona

rubiginosa

ebena

Unio gibbosus

complanatus

Alasmodonta confragosa.
complanata

rugosa

marginata .

Strophitus edentulus

Anodonta irnbecilis

suborbiculata .
corpulenta
Obliquaria reflexa

Plagiola elegans

donaciformis .

Lampsilis parvus

ellipsis

ligamentinus

luteolus ,

anodontoides
rectus .......

ventricosus. .

alatus

gracilis

Totals 1577

X -
SS D

B £

28
41
36
29
21
20
87
89
27
40
23
35

137
35
64
18
51
36
49
20
45
32
48
37
31
14
91
25
62
49

108
60
89

CD «■

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4
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4
5
6
5
4
6
5
4
6
4
5
5
3
4
6
6
6
7
5
5
6

Percentage of Individuals
Infested.

o

<t>
TO

CD

a>

39
93
78
76

100
90
68
79
37
38
30
60
88
34
56
72
92
72
94

100
96
59
21
59
68

100
56
68
87
89
87
95
97

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29
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33
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43
33
35
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42
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39
47

6
39

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11

6

4
11
10
57
11

4
40
31
37
22
45

Co
9?

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15
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20

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20
19
33
23

er

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30 20

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12

6

27
13

5 |0. 6

A Study of the Parasites of the Unionidce. 411

the number harbored by each species considered as a unit.
In this table and in the succeeding one the data regarding
host species in which less than fourteen individuals were
examined are not included. While the comparisons between
the species included are thus rendered the more reliable, it
will be seen that the general conclusions deduced from Tables
III. and IV. only confirm the findings of the more general
statistics of Table II. While nine kinds of parasites are here
listed for the Unionidce, no species of the family was found
to harbor more than seven, and the average was but four or
five. Moreover, in but four species — Quadrula laehrymosa,
Q. ebena, Q. pustulata, and Anodonta suborbiculata — were
individuals found with the maximum variety of parasites
listed for its species, and in these the maximum variety is
four or less. It is perhaps futile to imagine what variety of
parasites an individual host might successfully sustain, but
it is noticeable that in this table the mean individual infesta-
tion lies closer to the species minimum than to its maximum.
A close inspection of the data of all examinations further
confirms the inference that the individual host is unable to
realize the maximum capacity of its species for infestation,
since in no case is the presence of an unusual number of one
parasite accompanied either by like severe infestation by
another or by a considerable variety of parasites. It is true
that one individual of Lampsilis gracilis with sixteen speci-
mens of Aspidogasier in the pericardium and six in the
nephridia, harbored also two of Cotylaspis and one each of
Atax and Bucephalus, and that one Lampsilis ventricosiis
infested with thirty-one specimens of Aspidogasier contained
large numbers of Bucephalus ; but these are exceptional
cases, and even in these individuals, when we consider the
size of the host and the established maximum capacity of
their species, the extreme limit can hardly be said to be
reached. The ectoparasites probably require but little from
their hosts, but they rarely occur in numbers upon clams
exhausted by Bucephalus.

Table IV. gives the percentage of the hosts which were
infested with Aspidogasier, Cotylaspis, and Atax, the most

412 Illinois State Laboratory of Natural History.

abundant parasites, and also the maximum, minimum, and
average number of these parasites found in the hosts. The
frequency of occurrence of any one of these parasites in
relation to the total infestation of a species is to be learned
by a comparison of Tables III. and IV. Thus in a total of
fifteen hundred and seventy-seven examinations, — in which
seventy-four per cent, were in some measure infested (Table

Table IV. Comparison of Infestation by Different Parasites.

host SPECIES.

Names.

Quadrula uiultiplicata.
tuberculata. .
metanevra.. .
Jachrymosa. .
asperrima . . ,

pustulata

pustulosa.. . .

plicata

trigona

rubiginosa

ebeiia
Unio gibbosus

coraplanatus

Alasmodonta confragosa.
complanata
rugosa

marginata.
Stropbitus edentulus. . . .
Anodonta imbecilis

suborbiculata .

corpulenta

ObHquaria reflexa

Plagiola elegans

donaciformis.. . .
Lampsilis parvus

ellipsis

ligamentinus. .

luteolus

anodontoides .

rectus

ventrioosus . . .

alatus

gracilis

Totals 1577 41

2S
41
36
29
21
20
87
89
27
40
23
35

137
35
64
18
51
36
49
20
45
32
48
37
31
11
91
25
62
49

108
60
89

Percentage of

hosts infested

with

CD Oi

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tiq

P

CO

11

80
33
72
100
25
32
70
11
25
30
26
27
26
16

18
17

51
100
82
9
03
57
65
86

i2

76
14

28
82
87

o
o

29
3

55
11

15

14
35
90

88

7
79
14
16
29
43
22
45
52

18

11
56
33
24

44
80
57
40

3
1
3

33
50
76

8
20
75
71
41
83

3

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22
48
61
65
67

Number of

parasites in

one host.

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26

63

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134

63

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64 1-77

37

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1-6
1-9
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31

Average No. of

parasites in

one host.

CO o,
T> O

OS

p

2

6

2

12

6

2

2

4

3

4

6

2

3

27

11

3
3
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8
1
4
2
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18

16

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a
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p

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1

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3S
12

1
23
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Eggs
3
8
2

2

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4
2
3
4
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3
50

A Study of the Parasites of the Unionidte. 413.

III.), — forty-one per cent, were parasitized by Aspidogaster,
eighteen per cent, by Cotylaspis, and thirty-seven per cent,
by Atax — as shown in Table IV. It may be seen from the
tables under discussion, as well as from Table II., that there
is a marked difference between the several host species in
capacity for infestation in both kind and degree.

The range in number of parasites infesting one host, and
their average number, may depend to some extent upon the
size of the host, — Anodonta suborbiculata and A . corpulenta
showing high numbers and Strophitus edentula and Anodonta
imbecilis low, — and this applies with force in case of occupa-
tion of the pericardial and nephridial cavities by Aspidogaster,
where the volumes of the organs closely limit the possible
number of invading parasites. But size is not the sole
determining factor, else Lampsilis lutcolus and L. anodontoi-
des, L. ligamentinus and L. alatus, Quadrula multiplicdta and
Lampsilis ventricosus, and Quadrula plicata and La mpsilis gra-
cilis should harbor similar, rather than so widely different,
numbers of parasites, and little Lampsilis parvus should not
show such large infestation and such a wide range in the
number of parasites harbored.

The tables seem to indicate in the different species a
general correspondence between the frequency of infestation,
the variety of parasites, and the average number of individual
parasites harbored by a given host. Thus Quadrula tuber-
culata, Anodonta suborbiculata, A. corpulenta, Lampsilis
ellipsis, L. ventricosus, L. alatus, and L. gracilis, all figuring
largely in the tables, are frequently parasitized, carry a large
variety of parasites, and, in proportion to their size, a high
average number individually ; while the statistics concerning
Quadrula nmltlplicata , Q. trigona, Q. ebena, Unlo gibbosus,
Obliquaria refiexa, and Plagiola elegans show a like uniformity
in infrequent infestation, little variety in kinds of parasites,
and a low average number harbored by the individual host.

In the light of the latest views upon the natural classifica-
tion of the Union id, c it may be said that closely related
species exhibit somewhat similar capacities for infestation.
In general the species of Anodonta and also those of Lamp-

414 Illinois State Laboratory of Nut anil History.

silis are of large parasite capacity; those of Unio (restricted)
and of Plagiola are of low capacity; while within the genera
Quadrula and Alasmodonta we find wide extremes of infesta-
tion. Within the limits of the above genera this correspond-
ence is more or less evident between members of groups of
closely related species, especially when taken in considerable
numbers in similar situations. For example, we may note
the correspondence between Lampsilis ligamentinus and
L. luteolus; Quadrula ebena, Q. trigona, and Q. rubiginosa;
Lampsilis alatus and L. gracilis; and Quadrula lachrymosa
and Q. asperrima.

Seasonal changes have been found to modify the distribu-
tion of the parasites in the case of Atax and Conchophthirus
only. As the water grew colder in late October and Novem-
ber, the examinations of Unionida from the Cedar River
gave relatively fewer adult Atax and more abundant eggs.
The presence of these eggs was regarded as potential infesta-
tion, and therefore these data may properly be included in
the tabulation. The reliability of the tabulations may be
somewhat vitiated by the fact that Conchophthirus is much
more plentiful in the warmer months, during which the
greater part of my collections were made.

Tabi-E V. Geographical Distribution

OK

Parasites.

LOCALITIES.

Illinois.

Iowa.

Pennsylvania.

<'J-

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DO

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o
o

g=

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2

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495
23

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3

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6

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Free Distomata ......

Encysted Distomata. .

Bucephalus

X

y

X

V

X
X
X

X

X
X

X
X
X
X
X
X
X
X
X

X
X

X

X

X

V

X
X
X
X
X
X

X
X
X

x

X

X
X
X
X

X
X

X
X

X
X

X

X

X
X

Kinds of parasites

9

6

5 5

9

1

3

4

5 3

A Study of the Parasites of the Unionidce. 415

Table V. indicates the range of the different parasites in
the several localities supplying the material. In all proba-
bility the blanks opposite the more usual parasites are due to
the absence of the proper host species or to the examination
of an insufficient number of these species rather than to
peculiarities in the localities themselves, for the variety of
parasites listed for any situation varies with the number of
individuals and the variety of species examined from each
locality. Thus the absence of Atax from the Schuylkill and
its occurrence in the tributary French and Pickering creeks
may be accounted for by the fact that with the exception of
a single occurrence, this parasite was never found by me, in
any locality, in the particular species examined from the
Schuylkill. Again, an examination of twenty individuals of
Anodonta corpulenta from Abbey Creek, la., made since these
tabulations were completed, has increased the list of unionid
parasites from that stream to six, adding Aspidogaster, Coty-
laspis, free Distomata, Bucephalus, and Conchophthirus, the
smaller number of parasites reported in the table being due
in a large degree to the particular species of Unionida
previously examined from the stream. An examination of
Table VI. shows, however, that there is quite a great varia-
tion in the infestation of the same species in different local-
ities. This variation is the greatest, as would be expected, in
the host species least frequently parasitized, and especially
in the case of those parasites that are infrequent or unusual
in a given host. Again in the case of the larger streams as
compared with the smaller ones, whenever a given host is
especially plentiful and Unionida in general are abundant
the infestation is relatively larger and a greater variety of
parasites occur. For example, in the Illinois and Cedar
rivers, both large streams, a large proportion of the Unionida
are excessively parasitized, but in the Spoon River, a smaller
stream, only such species are extremely infested as are
abundant or dominant, as, for example, Quadrula tubercidata,
Unio gibbosws, and Lampsilis gracilis. The fact that Unio
complanatus from the Schuylkill River is but slightly parasit-
ized in comparison with individuals from its tributaries,

416 Illinois State Laboratory of Natural History.

Table VI. Comparison ok

Local

In

KES

rATION

2
C

s ^

5
a

17
21

Pehcentage Infested with

HOST SPECIES.

O
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90
64
20
67
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x t?

29
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:,o
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!»4
70
86
80

Quadrula tuberculata.

Illinois Riv
Spoon Riv.

1

Quadrula pustulosa.

Illinois Riv
Spoon Riv.
Cedar Riv.

29
28
30

13

3

Quadrula plicata.

Illinois Riv
Spoon Riv.
Cedar Riv.

45

8
36

76
63
61

|

Unio gibbosus.

lllinoisRiv.
Spoon Riv.

25
10

2U
40

• ■

4

10

Unio complanatus.

Susquehanna Riv.
Schuvlkill Rir.
Pickering Cr.
French Cr.

17
20
14
20
11

8
37

8

59
15
43
30

27

5

5

Alasniodonta complanata.

lllinoisRiv.
Spoon Riv.
Cedar Riv.
Abbey Cr.

18

18

38
27

67

so
75

55
3

"70
«;o

19

3

5

Alasmodonta marginata.

Pickering Cr.
French Cr.

30
20

27

10

5

Strophitus edentulus.

lllinoisRiv
Cedar Riv.

12
14

25
21

33

7

25

8
29

8

7

17
29

Anodonta grandis.

Spoon Riv.
Cedar Riv.

3

5

100
100

33

33

SO

65
60

100

100
75
40

Anodonta eorpulenta.

lllinoisRiv.
Thompson's L.

20
10

90
90

95
100

5

85
90

Plagiola elegans.

lllinoisRiv.
Cedar Riv.

25
20

12

4

8
5

4

15

4

Plagiola donaciformis.

lllinoisRiv.
Cedar Riv.

21

13

3

11

67
54

5

5

5

5

Lampsilis ellipsis.

lllinoisRiv.
Cedar Riv.

100
S2

100
73

67

73

. . .

. .

it

. . .

Lampsilis ligamentous.

lllinoisRiv.
Cedar Riv.

24
65

50
2

37
17

4
11

. . .

6

8

18

Lampsilis luteolus.

lllinoisRiv.
Quiver Cr.

10
10

30

20

10
,10

"io

!)0
30

Lampsilis anodontoides.

lllinoisRiv.
Spoon Riv.
Cedar Riv.

20
4
9

100

55

5

75

60
50

22

11

. . .

11

Lampsilis rectus.

lllinoisRiv.
Cedar Riv.

10
37

20
14

60
57

00
70

30
38

30

. * .

8

3

Lampsilis ventricosus.

lllinoisRiv.
Quiver Cr.
Cedar Riv.

10
40
56
20
18
40
16
33

60
18
29
95
94
s:i
94
85

60
5

29
80
11
83

30
48
63

00

43

82
95
77

T)5

39

2

Lampsilis alatus.

lllinoisRiv.
Cedar Riv.

22

13

25
24

Lampsilis gracilis.

lllinoisRiv.
Spoon Riv.
< 'odar Riv.

7 s :

7:.

00

3

36

::

A Study of the Parasites of the Unionidce. 417

French and Pickering creeks, and from the Susquehanna
River, may be due to the very peculiar conditions, referred to
on page 400, which exist in the Schuylkill. Again, in
Alasmodotita marginata the extensive amount of parasitism
in the material from Pickering Creek as compared with that
from French Creek, is explained by the fact that this is an
abundant and dominant species in Pickering Creek, while it
is relatively infrequent in French Creek.

Some attempt was made to discover whether purely local
conditions in the habitat, such as the character of the bottom
and association with other species of Unionidce, bear any
relation to the character and degree of infestation. The
examination of representatives of nine species taken at one
time from a restricted locality below a bar in the Illinois
River, where Unionidce were unusually abundant and at least
twenty-nine species represented, gave results which did not
differ materially or in any one direction — save in the slightly
larger infestation to be expected because of the hosts'
unrivaled opportunities for infestation — from those obtained
from the same species collected in other localities.

A purely qualitative examination of the food of the various
species of Unionidce showed no differences that could be
correlated with their capacities for infestation. The nature
of the food would hardly determine to any appreciable degree
the parasites of other organs than those closely connected
with the alimentary canal, and least of all those whose lodg-
ment would be effected by mere entrance to the branchial
chamber.

In conlusion, the results arrived at by the foregoing studies
may be summed up as follows : The host species seem to
exhibit unlike capacities for infestation, both as to the num-
ber of individuals and the kinds of parasites present. It
appears that the differences shown are attributable only in
a minor degre'e to the age and size of the host, the size of the
stream, and the density of the unionid population. They
are not sufficiently accounted for by the seasonal variation,
— which is shown to exist to some degree al least in the case
of certain parasites,— nor by the very slight difference in

418 Illinois State Laboratory of Natural History.

general structure between the various host species. The
evidence therefore seems to indicate that the capacity for
infestation in each host species is to a large extent a specific
characteristic.

I am indebted to Prof. S. A. Forbes, Director of the Illinois
State Laboratory of Natural History, for opportunities of
study and of publication; to Dr. C. A. Kofoid, Superin-
tendent of the Illinois Biological Station, for many sugges-
tions of value; and to Mr. C. A. Hart, of the Laboratory and
Station staff, Dr. H. A. Pilsbry, of the Philadelphia Academy
of Sciences, and Mr. C. T. Simpson, of the United States
National Museum, for assistance in the determination and
nomenclature of the Unionidce.

Just before going to press the nomenclature and systematic
arrangement of the host species have been revised by Mr.
Hart to bring them into accord with the more natural classi-
fication which is now being elaborated for this group.

Cornell College, Mt. Vernon, Ia.
January, 1899.

BULLETIN

OP THE

[llinois Qtate I aboratory

OF

NATURAL HISTORY

Urbana, Illinois.

VOLUME V.

ARTICLE IX. PLANKTON STUDIES. III. ON PLATY-
DORLNA, A NEW GENUS OF THE FAMILY VOLVOC-
IDsE, FROM THE PLANKTON OF THE ILLINOIS RIVER.

By C. A. KOFOID, Ph. D.

Illinois State Laboratory of Natural History,

UKBANA, ILLINOIS.

December 28, 1899.

Article IX. — Plankton Studies. III. On Platydorina, a
new Genus of the Family Volvocidce, from the Plankton of
the Illinois River. By C. A. Kofoid.

The family Volvocidce is well represented in the plankton
of fresh- water ponds and streams. Indeed, with the possible
exception of Stephano splicer a, all of the colonial forms in-
cluded in the subfamily Volvocince — Spoiidylomorum, Gonium,
Stephanosphcera, Pandorina, Pleodorina, and Volvox — are
pelagic in habit and are found only in the fresh-water
environment. For the past four years, during the summer
and autumn months, a colonial form belonging to this sub-
family has occured in plankton collections from the Illinois
River and its adjacent waters, to which I have given the
name of Platydorina caudata. It appears as early as June 15,
and becomes abundant in the months of August and Septem-
ber, diminishing in numbers in October, and disappearing
in November. It thus attains its greatest development
toward the close of the maximum period of summer heat,
when the temperature of the water in which it is found often
reaches 36° C. This species has occurred in all the waters
examined in the course of the operations of the Illinois
Biological Station; viz. in the Illinois River, in Thompson's,
Quiver, Flag, Mantanzas and Phelps Lakes, at Havana, 111.,
and in the Illinois River and Meredosia Lake at Meredosia,
111. During the summer and fall of 1899 it was also found
in abundance near Urbana, 111., in Salt Fork, a small stream
tributary to the Embarras River — a confluent of the Wabash.
'It was not equally plentiful in all these localities, but showed
a decided preference for shallow water free from vegetation,
reaching its maximum development when the turbid water
was but a few feet, or even less than a foot, deep. In such
situations the shallowness of the water and the absence of
vegetation conduce to a maintenance of the high temperatures
which seem to favor its multiplication. The bottom of the lakes
in question is usually composed of soft mud, rich in decay-
ing organic matter and often covered by a mat of Oseillaria,
but otherwise quite free from vegetation. At Havana

420 Illinois State Laboratory of Natural History.

we have found Platydorina in greatest numbers in Phelps
Lake, which in 1896, '97, and '98 afforded the conditions
above described. It was likewise abundant in Thompson's
Lake in the late summer and early fall of 1897 and '98, when
the lake was at a low level and contained little vegetation.
In the shallow open waters of Matanzas Lake it was much
more abundant than in Quiver Lake, where there was usually
a large amount of vegetation. At the time of the maximum
abundance of Platydorina in Salt Fork in September the
stream was reduced by drouth to a series of stagnant pools
with no vegetation. In the early part of August it was full
of alga; and other aquatic vegetation, and Platydorina was
then present in considerable numbers, although not so abund-
ant as it was in the following month.

On August 2, 1888, Professor H. Garman, while conduct-
ing a biological survey of the aquatic life, in the vicinity of
Quiney, 111., in the bottoms of the Mississippi Paver (see
Garman '90), found a specimen of this interesting species in
the waters of Libby Lake. He records and sketches it in
notes now on file at this Laboratory, but published nothing
concerning it.

The occurrence of this new genus in the waters of the
Wabash, Illinois, and Mississippi river systems and its
recurrence in our collections for several successive years
indicate its wide distribution and firm establishment in the
Mississippi Valley in waters of some permanency. It has
not yet been noted in temporary pools.

The associates of Platydorina in the plankton have varied
with the season, the locality, and the year. It may be said, in
a general way, that the plankton in which it occurs is charac-
terized by an abundance of flagellates, of rotifers,— especially
Brachionid<e, — and of immature Copepoda. A water-bloom
composed largely of Euglena, Traehelonionas, Carter ia, and
other green flagellates, often appears at the surface of waters
where Platydorina is abundant. Goniinn is frequently
associated with it in large numbers, as are also Pandorina,
Eudorina, and Pleodorina, though these three genera may also
be plentiful in the early summer, when Platydorina may

On Platydorind. 421

be absent or rare. Pleodorina califomica was extremely
abundant in Salt Fork in August, but had almost entirely
disappeared by the time that Platydorina had reached its
maximum. A few specimens of Volvox, which, in this locality,
is common in the spring months, were also noted, while
perhaps the most interesting associate in Salt Fork was
Ceratium kumaonense, discovered by Carter ('71) in Hindostan.
Other chlorophyll-bearing associates frequently seen are
Pediastrwm, Scenedesmtts, Actina strum, and Closterium.
Among the diatoms, Melosira, Fragillaria, and Surirella,
were to be seen; and among the Peridinidce, Peridinium
tabulatum was almost always represented.

The zooplankton associated with Platydorina is not less
varied than the phytoplankton. The Protozoa were usually
represented by Arcella, Difflugia, and occasionally by pelagic
Anuxba; by Symira, Mallomonas, Dinobryon, and Uroglena ;
and by Codonella and Coleps. Among the Rotifera the order
Ploima was well represented ; Triarthra and the Brachionides
—notably Brachionus militaris, B. angularis, B. punctatus, and
B. bakeri, and its varieties — were most common during the
summer months, while the Synchcetidm increase in numbers in
the early autumn. Polyarthra was frequently abundant, and
Rotifer, PliilodiiKt, Asplanchna, Euchlanis, Cathypna, Distyla,
Monostyla, and Pterodina, were often represented by one or
more species. The paucity of Entomostraca stands in sharp
contrast with the abundance of rotifers, the former group
being represented by relatively few species and few adult
individuals. The nauplii of Cyclops were, however, as a rule
abundant, but only occasional specimens of adult Cyclops,
Diaptomus, Bosmina, Chydorus, Ceriodaphnia, Daphnia, and
Cypridopsis were to be seen.

Platydorina caudata n. g., n. sp.

The species here described consists of a horse-shoe shaped
ccenobium or colony (PL XXXVIII., Fig. 1) of 16 or 32
biuagellate cells, the anterior end corresponding to the toe of
the horse-shoe and the truncate posterior end to the heel, the

422 Illinois State Laboratory of Natural History.

latter carrying 3 or 5 prolongations or tails formed by the
gelatinous substance of the ccenobium. The colony is plate-
like, and flat except that the plate is slightly twisted in a left
spiral. This spiral is scarcely noticeable in a face view
(Fig. 1) except by focusing with a high-power objective, but
it can be easily detected in a side view (Fig. 3). It varies
from one eighth to one thirty-second of a turn of the spiral,
and in twenty-five colonies especially examined on this point
it was invariably a left spiral, with the location of the twisting
always in a definite relation to the colony, the right anterior
and the left posterior regions of the colony in face view being
high, while the left anterior and the right posterior are low.
Kepeated examinations of specimens, both living and pre-
served, indicate that this spiral form is a constant feature of
structure ; that it is not reversed in direction ; and that it is
subject to but slight variation in the degree of the torsion.
No movement within the colony which would produce or vary
the spiral was noted in living individuals. The form of
Platydorina seems to be as constant and as characteristic as
that of other genera of the family.

The size of the colony varies with the age, with the number
of cells present, and also, perhaps, with the locality and the
season. Colonies of 32 cells in which the first division lead-
ing to the formation of daughter colonies is taking place,
average about 150 /< in length, 130 m in width, and 20 M in
thickness. The largest colonies are about 165 X 145x25 )i,
and the smallest free-swimming ones about 25x21x4 //.
Colonies of 16 cells are smaller than those of 32 cells, and
are also narrower in proportion to their length, measuring
about 70x43x16 yw.

The colors of Platydorina are quite as striking as those of
related forms. The cells, which are imbedded in the trans-
parent gelatinous matrix of the colony, are a bright chloro-
phyll-green, and each has, as a rule, a red stigma, or eyespot,
of unusual brilliancy.

The substance in which the cells of the colony are imbedded
is similar in appearance to that in Eudorina. It is a trans-
parent colorless substance of considerable consistency, show-

On Platydorina. 423

ing in the living condition, as a rule, no trace of differentia-
tion. The gelatinous nature of the substance is shown by the
great numbers of bacteria which swarm within it in moribund
specimens. Colonies killed in formalin and stained in Dela-
field's hematoxylin exhibit a difference in the intensity of
coloration, indicating the presence of a denser peripheral
layer or sheath 3-4 f* in thickness (PI. XXXVIII., Fig. 1, 4,
p. sh.). This is apparent along the edges of the colony, and
presumably extends over its faces. In several living colonies
a granular differentiation of this outer layer was noted about
the margin. This sheath is similar to that of Eudorina and
Pleodorina, but shows no trace of the concentric layers so
prominent in Pandorina.

One of the most characteristic features of the colony is the
presence, upon the posterior border, of 3 or 5 projections or
tails, which are merely extensions of the sheath. Colonies of
16 cells have but three tails, while those of 32 cells have
uniformly five. These projections are bluntish finger-like
processes without structural differentiation, tapering some-
what to a rounded or pointed end. Occasionally the outer-
most pair, and more rarely the inner one, are slightly diverg-
ent. In the 16-cell colony there are two latero-posterior
tails and one median one (Fig. 2), the former being better
developed, and measuring 15 to 20 /< in length. The median
tail is variable in length, being sometimes a mere rudiment
appearing on a slight elevation on the margin. Its average
length is about one third that of the adjacent pair, though it
occasionally attains two thirds their length. The latero-
posterior tails are upon each side of the colony directly
behind the marginal row of cells, while the median tail is
midway between the central rows. In the 32-cell colony
(Fig. 1) there is, in addition to the three tails above noted,
another pair which may be designated as the lateral pair.
These tails are slightly divergent, arising at the outer pos-
terior angles of the marginal row of cells, between the last
transverse quartet and the last sextet of cells. They are
from 10 to 15 fi in length, and are often of the same size as
the median tail of the colony. The other three tails occupy

424 Illinois State Laboratory of Natural History.

the same position with respect to the posterior quartet of cells
that they do in the 16-cell colony, hut are as a rule much
larger, the postero-lateral pair measuring from 20 to 30 m in
length, while the median one reaches only a length of 15 to
18 M. The five tails do not lie in one plane, but share in the
spiral of the colony, at times, indeed, exceeding it in the
degree of the twisting. These structures are all subject to
considerable variations and irregularities of development
(Fig. 5), such as suppression, inequality of members of pairs,
differences in size and relative development, in attenuation,
and in degree of divergence. These irregularities are often
correlated with the. loss of cells in the colony due to parasites
or other causes. The tails, nevertheless, exhibit such a con-
stancy of position and so much of symmetry and regularity
of development that they cannot for a moment be considered
as ephemeral features of little structural importance. In
their position they recall the protuberances noted by me
('98) at the posterior end of Pleodorina illinoisensis. In
Pleodorina, however, these structures are apparent only in
disintegrating maternal colonies, and it may be that they
also indicate the point at which the embryonic cup closes.
On the other hand, in Platydorina caudata these tails are
present upon the colonies at the time of their escape from the
maternal matrix and persist throughout the life of the adult,
being permanent structures, characteristic of the species.

Within the outer sheath is a homogeneous gelatinous matrix
(Fig. 1, m.) which in Delafield's hematoxylin stains less
readily than the sheath. In the living colony no differentia-
tion of this matrix is to be seen, but, after staining, a delicate
sheath showing deeper color is demonstrated about each of
the cells. In most places a considerable space intervenes
between this secondary sheath (Fig. 4, s. sh.) and the inclosed
cell, so that the sheaths crowd upon each other and appear
to divide the field of the matrix into irregular polygonal areas.
These areas, as a rule, fill the greater part of the plate, leav-
ing unoccupied only a few corners, principally about the
second transverse row. The two poles of this swollen second-
ary envelope are not of equal size, the inner being somewhat

On Platydorina. 425

the smaller, and slightly overlapped by those of the contiguous
cells. This is due to the intercalation of the cells of the two
sides of the plate, and to the fact that the outer ends of the
cells are slightly nearer the surface of the plate than are the
inner ones. The gelatinous substance within the secondary
sheaths does not differ in structure or stainibility from that
of the surrounding matrix. As a result of the form of the
colony, the amount of the matrix substance is much less in
Platydorina than in related forms such as Eudorina.

The cells of the colony are all of one type, alike in structure,
and approximately similar in size. Each is biflagellate and
has a central body of protoplasm with a nucleus, two contrac-
tile vacuoles, one stigma, and one chromatophore with a single
pyrenoid.

The number of cells in the colony is either 16 or 32; at
least no normal colony with cells of any other number has
been detected among the hundreds, if not thousands, of
colonies examined. Colonies are frequently seen which, by
reason of parasites or from other causes, have lost one or more
cells, indeed in some cases all but one or two ; but the form
of these colonies is usually preserved, and the empty second-
ary sheaths frequently remain as evidence of the original
complement of cells. The 16 -cell colonies are not mere
stages in the development of the 3 2 -cell form, for division of
the cells of this type in observed cases leads to the develop-
ment of new colonies and not to the formation of the 32-cell
stage. As in other nearly related genera of the family — for
example, Eudorina, Pandorina, and Pleodorina — the number
of cells in the colony varies, within narrow limits, in the ratio
of geometrical progression. In Platydorina, however, this
pleomorphism is manifested not only by this difference in the
number of cells in the colony, but also by a structural dis-
tinction— the presence of three tails in the 16-cell, and five
tails in the 32-cell, colony. Inasmuch as the two types
always occur together, and since this pleomorphism is in some
respects similar to that of related genera, it does not seem
justifiable to regard the two as distinct species of the genus.
They are, I believe, two forms of one species.

426 Illinois State Laboratory of Natural History.

The arrangement of the cells is characteristic, and is
strikingly different from that of any other genus of the family.
The gelatinous matrix and sheath conform to the horse-shoe-
shaped plate of cells, and even the caudal appendages bear a
fixed relation to the plan of cell arrangement. The 32-cell
colony is composed of a marginal U-shaped row of 12 cells
about three sides of a 20-celled somewhat rectangular plate,
which, in turn, consists of an outer row of 12 cells on three
sides of a row of four pairs of cells. The colony might also
be regarded as made up of three U-shaped rows of 12,12, and
8 cells respectively, nested in such a fashion that the inner
two project one cell beyond the outermost. The cells also
fall into six quite irregular transverse rows of 4, 6, 6, 6, 6,
and 4 cells respectively, and into the same number of corre-
sponding longitudinal ones. As before stated, the lateral
tails are posterior to the marginal row, while the postero-
laterals are behind the first row within the marginal, and the
median one midway between the innermost rows. In the
colony of 16 cells (Fig. 2) the marginal row has but 10 cells
and the central plate but six. The cells fall into four some-
what irregular transverse rows, and there are the same
number of longitudinal ones of 4 cells each. The horse-shoe
shape, however, masks somewhat this simple Gonium-like
arrangement. The plate-like form of the colony and the
arrangement of the cells, especially in the 16-cell form, give
this new genus a superficial resemblance to Gonium. It is,
however, fundamentally different, for in Platydorina the two
faces of the plate are exactly alike, while in Gonium the face
anterior in locomotion bears all the flagella, and the other
face presents only the bases of the cells. This similarity of
the two faces in Platydorina, neither of which is anterior or
posterior, is brought about by the fact that every other cell
upon either face presents to that face the pole which bears
the stigma and the flagella, while the intervening cells present
the opposite pole, with its pyrenoid. This alternation of stigma
and pyrenoid is constant, and can be followed in any row of
cells except the diagonal ones (c/., Fig. 1). The cells of the
marginal row, in both the 16- and 32-cell colonies, point

On Platydorina. 427

obliquely outward, the direction alternating, however, in
conformity with the arrangement of cells in the central area,
as may be seen in a view of the edge of the colony (Fig. 3).
The alternation of the cells in the colony as a whole is the
same whichever face is presented, the right-hand cell of the
posterior row of four cells always presenting the basal end
uppermost. From this as a starting point the regular alter-
nation of stigma and pyrenoid can be traced from cell to cell
throughout the whole colony. An examination of twenty-five
colonies showed that all conformed to the same plan of alter-
nation, there being no case of reversal. In the arrangement
of the cells in the colony, Platydorina is thus more like
Eudorina than like Gonium, being, not a simple plate like the
latter genus but, in reality, a flattened ellipsoid so much
compressed that the cells of the two faces intercalate
regularly, and thus give to the colony its superficial resem-
blance to Gonium.

The individual cells are all substantially alike in size and
structure. They have the form of an oblate spheroid, slightly
larger in the outer hemisphere.* Some cells, especially the
marginal ones, often exhibit a slight flattening or even a
depression at the outer pole. In the full-grown colony the
cells have an equatorial diameter of 15-20 yu and a polar one
of 15-18yu. The cells of young colonies still within the
maternal matrix do not exceed 4-6 M in diameter. I do not
find that the cells of the 16-cell colonies are appreciably
larger than those of the 32-cell.

The protoplasm is small in amount, consisting of a very
thin pellicle (Fig. 4, p.) on the surface of the cell on the out-
side of the chromatophore, and an axially-placed knob-
shaped mass (pr.) located somewhat nearer the outer pole
than the inner one. Near the center of this mass lies the
spherical nucleus (Fig. 4, n.), containing a single spherical
nucleolus (ncl,). Within this protoplasmic mass lie the two
contractile vacuoles (c. v.) and the stigma (st.), while from
the outer end of the cell arise the two flagella (/.).

* As in the case of Eudorina and Pleodorina, the terms "outer" and -inner" are
used to designate respectively the ends which bear the stigma and the pyrenoid.

428 Illinois State Laboratory of Natural History.

There is but a single, cup-shaped chromatophore (Fig. 4,
chr.), which is inclosed within the pellicle above noted and
itself contains the knob-shaped protoplasmic mass. It is of a
brilliant chlorophyll-green color, and contains numerous
small granules of irregular and somewhat angular outline.
Towards the inner end of the cell, imbedded in the thickest
part of the chromatophore, there is a single spherical pyrenoid,
having a diameter of 4-6 yw.

The stigma, or eye-spot, seen from above is circular in
outline, but in lateral view has the form shown in Fig. 4, s.
The slightly convex outer surface appears to project some-
what beyond the rounded contour of the cell. The color is
usually a bright reddish brown, often brightest in the anterior
and marginal cells and rarely entirely faded in the posterior
ones. The stigma is a homogeneous body, showing no trace
of structure beyond the well-defined contour line, which is
best seen in fading and moribund cells. It is normally
present in all cells of the colony, and may readily be demon-
strated by full illumination. The position of the stigmata in
the cells is somewhat unusual, and is significant of the pro-
nounced polarity of the organism. The customary position
in other genera is adjacent to the bases of the flagella. In
Platydorina, however, the location of the stigma is not con-
stant with respect to the liagella, but seems rather to bear a
definite relation to the form of the colony, since it lies towards
the peripheral and posterior region of the cell (Fig. 1), while
the flagella are centrally located and project outward in the
usual manner. This relation appears not only in the mar-
ginal regions but also in the central. The physiological
significance of this arrangement is not apparent, but it seems
to be correlated with the pronounced polarity of the organism.
Platydorina is positively phototactic. A miscellaneous plank-
ton collection placed in a window with southern exposure in
an aquarium six inches in diameter was, after ten minutes,
quite barren of Platydorina except along the margin towards
the window. On the other hand, this species avoids bright
light. This was very evident in collections fresh from the
field when examined under low power (75 diameters), a very

On Platydorina. 429

slight increase above a moderate illumination causing them
to leave the field of view with considerable rapidity. In one
case, where twenty-eight colonies were in the field when placed
under the microscope, only one of them remained after an
exposure of twenty-five seconds. A very slight decrease in
the amount of light would invariably insure their return to
the field with almost equal rapidity, the number increasing
as the intensity of the illumination was decreased. It may
be that the asymmetrical position and the somewhat unusual
arrangement of the stigmata are connected with the pro-
nounced phototaxis of this organism. At least, the asym-
metrical position has a tendency to place the long axis of the
stigma parallel to the main axis of the colony, with the outer
end directed towards the source of light in negative, and away
from it in positive, phototaxis.

The flagella are uniformly two in number for each cell, are
similar in the same cell and in different parts of the colony,
and are in the adult colony 20-25 ft in length. From the
outer pole of the cell they pass through the matrix, leaving
the appearance of a tube-like structure in the gelatinous
substance (Fig. 4). When not in activity the flagella project
beyond the sheath in a position perpendicular to the surface
of the colony at the place of exit. As in other genera of this
family, the flagella persist after the division of the cell to
form the daughter colony, and even after the divisions are
completed still provide locomotion for the maternal organ-
ism. In some instances the flagella could be seen passing
through the matrix toward that cell of the daughter colony
which bears the largest eye-spot.

The contractile vacuoles (Fig. 4, c. v.) are two in number,
and are located in the peripheral layer of protoplasm, near
the outer end of the cell. They lie in the outer part of the
knob-shaped mass of protoplasm, upon either side of the
place of origin of the flagella, being somewhat widely sep-
arated. At diastole the vacuoles of an adult colony have a
diameter of 1.5-2 /<. The contraction is rhythmical, and the
two vacuoles usually alternate at regular and equal intervals.
At a temperature in the laboratory of 20° C. each vacuole

430 Illinois State Laboratory of Natural History.

contracted at intervals of forty-five to fifty seconds. In rare
instances the contractions of the two vacuoles were separated
by unequal intervals, being almost coincident in one case
observed.

The method of locomotion in Platydorina is similar in
many respects to that of other genera of the family. The
lashing of the flagella produces a forward movement of the
colony and causes its rotation about the major axis, either
from left over to right or from right over to left. The
rounded end of the colony is uniformly directed forward in
locomotion ; at least no instance in which the caudal end
led was noticed. The forward movement is, as a rule,
accompanied by the rotation of the colony, though the amount
of rotation varies somewhat with the individual, the freedom
of movement, and the speed of locomotion. When locomo-
tion is blocked by obstructions the rotation continues, as in
Plcodorina, with frequent reversals in direction. In fact,
obstruction to progress seems frequently, though not uni-
formly, to act as a stimulus to the reversal of the direction
of rotation.

The two directions of rotation are not equally prevalent,
that from right over to left having a marked predominance.
Thus, of twenty-five colonies observed in motion twenty were
rotating from right over to left and but five from left over to
right. In another twenty-five the corresponding numbers
were nineteen and six respectively. Keeping a single colony
under observation for some time, it is found to rotate from
right over to left about four fifths of the period and to turn
in the opposite direction the balance of the time, this pro-
portion representing the totals of the periods of rotation,
while the individual periods vary greatly in length, that from
left over to right lasting at times but a few seconds.

This predominance of one direction in locomotion is doubt-
less correlated with the torsion of the colony, whose shape is
such that the rotation would necessarily be from right over
to left in forward locomotion, as a result of the resistance of
the water, unless, of course, there should be some disturbing
factor. The immediate and most potent cause of the direc-

On Platydorina. 431

tion of rotation is doubtless the coordinated action of the
flagella, since reversal of direction does not seem to be
accompanied by any change in the direction of the torsion of
the colony. The evidence upon this point is not conclusive,
but repeated efforts have failed to detect any change in the
form of the plate when the direction of rotation is reversed
in the living and moving colony ; and, again, colonies when
killed suddenly have always the usual form of spiral, though
some of them were moving in the reverse direction. When
the usual direction of rotation is reversed, the forward motion
still continues in spite of the fact that then the form of the
plate favors a backward movement ; the form of the colony,
therefore, does not control the direction of rotation though it
is correlated with the direction which predominates. The
fact that the rotation from right over to left predominates
also in Pleodorina illinoisensis and Eudorina elegans, where
there are no structural features favoring such a predominance,
suggests the possibility that the form of the colony in
Platydorina is the result and not the cause of this predom-
inance, and that the function of turning from right over to
left predominantly preceded the structure which favors it.
The organization of Platydorina suggests a descent from a
Eudorina-like form, in which event the systematic series and
the phylogenetic series alike afford evidence of a function
arising in an organism before the structure with which it is
correlated appears.

In another connection ('98) the subject of locomotion and
polarity in the different genera of the Volvocince was reviewed
and discussed. It will suffice, therefore, for the present to
give a brief resume of the facts. In the lower genera of the
family, Stephanosphcera and Goniiim, as also in Pandorina,
the rotation seems to be indifferently to the right or left, while
in Eudorina and especially in Pleodorina illinoisensis it is
oftenest to the left, rotations to the right in observed cases of
the latter species being to those to the left as 100 to 117-138.
With respect to Volvox there are no data at hand. In Pkity-
dorina, we find by far the most pronounced predominance of
one direction of rotation, the ratio in observed cases being

432 Illinois State Laboratory of Natural History.

100 rotations from left over to right to 355 from right over to
left. In this respect, then, so far as there is evidence,
Platydorina is the most highly differentiated genus of the
family.

The polarity of the lower genera, Stephanosphcera and
Gonium, is likewise of the simplest form, being merely physio-
logical, the same pole or face of the colony always leading in
locomotion. In Pandorina, Eudorina, and Volvox, however,
there is the added feature of the greater brightness of the
anterior stigmata, and in Pleodorina the two poles are differ-
entiated by the two types of cells as well as by the characters
found in the genera just mentioned ; but Platydorina is the
only genus of the family in which polarity is expressed by the
arrangement of the cells and by structural features of the
envelope. In regard to polarity, also, the new genus is thus
the most highly specialized member of the Volvocince.

The reproduction of Platydorina has been observed by me
repeatedly in the past five years, but only the asexual phase
has thus far been discovered. All of the cells of the organism
are gonidial, each dividing to form a daughter colony. The
sequence of the divisions and the position of the successive
planes are of the type found in Eudorina and Pleodorina,
the resemblance being so close that the figures illustrating the
asexual development of Pleodorina illinoisensis ('98,
PI. XXXVII.) might almost be used for cleavage in Platy-
dorina. There is one difference, however^ for in Platydorina
the curved plate of cells, which becomes first cup-shaped and
then ellipsoidal, subsequently flattens, the cells of the two
faces intercalating during the process. The daughter colony
acquires the adult form, including the tails and the torsion of
the plate, before it escapes from the maternal matrix, the
young colonies moving about for some time in the disinte-
grating matrix before making their escape through the ruptured
outer sheath. The secondary sheath surrounding the gonidial
cell becomes the outer or primary sheath of the new colony.
No stages of sexual reproduction have been seen, though the
collections examined represent a considerable range of season
and locality. It may be that these are to be sought upon

On Platydorina. 433

the bottom rather than in the superjacent strata of water
where plankton collections are usually made. Aquaria about
to dry up were also searched in vain for sexual stages of
Platydorina .

The mode of development of Platydorina is significant of
its systematic position and its relationships. The number
and the original arrangement of the cells, the type of develop-
ment, and the character of the envelope, all indicate that
Platydorina is a more highly specialized form descended from
some Eudorina -like ancestor, and that it is more closely
allied to Eudorina than to any other existing genus.

Throughout this paper the customary term "colony" has
been used to designate the organism herein described and
others related to it. The wide use of the term in the literature
of the subject is doubtless due to the fact that, as a rule, the
organisms are composed of similar cells arranged in symmet-
rical form with no pronounced axial differentiation, without
contact or protoplasmic connection, separated from each
other by a non-living gelatinous matrix, and each capable of
performing all the functions necessary for its own life and the
continuance of the species. Furthermore, the destruction of
individual cells does not impair the life of the other cells of
the organism, for so long as a single cell remains it continues
its customary activity. The use of the term colony is, however,
objectionable. A number of facts militate against this con-
ception of the organism, and the discovery of the new genus
here described adds to the array. (1) The cells are not
always similar, for in all forms with poles physiologically or
otherwise differentiated the anterior stigmata are brighter
than the posterior, and in Pleodorina there are two kinds of
cells, the vegetative and the gonidial, the former distinctly
smaller than the latter. (2) There is in all of the higher
genera a well-defined physiological polarity accompanied by
the difference in the anterior and posterior stigmata, and also,
in Platydorina, by a differentiation of the poles by the
arrangement of the cells and the structure of the envelope,
and by the further differentiation of a transverse axis.
(3) In Pandorina the cells are almost in contact, and in

434 Illinois State Laboratory of Natural History.

Volvox they are actually connected by protoplasmic processes.
(4) The beginnings of histological differentiation are also
evident in the cells composing the so-called colony. In
Eudorina, according to Carter ('58), the cells are differen-
tiated into male and female in definite regions, the male cells
developing from the anterior quartet and the remainder
becoming female ; in Volvox sexual and asexual reproduction
alike are limited to a few of the cells ; and in Pleodorina the
asexual process is confined to the posterior hemisphere. The
cells of the organism are thus histologically and functionally
differentiated in this particular in these higher genera.
Although the degree of differentiation is slight, it is neverthe-
less appreciable. (5) In the matter of locomotion the
activities of the individual cells of the organism are not
independent of each other but are correlated, the flagella
acting together to produce rotation, its reversal, or its cessa-
tion. The predominance of the direction in the higher genera
plainly exhibits the phenomenon of correlated locomotor
activities of the constituent cells.

The facts above cited emphasize the desirability of regard-
ing each of these so-called colonial flagellates of the sub-
family VolvocincB as a unit, with an organization of its own,
and not as a colony, that is. an aggregation of independent
and similar cells associated merely as a result of descent from
a common parental cell, the form being a matter of chance
or circumstance. The group of cells as a whole, and not
each of the constituent cells, is the unit of descent, of form,
and of function, and the word colony can be applied to it
only by the license of usage and as a matter of convenience.

Reference has been made frequently in the preceding pages
to the prevalence of colonies whose symmetry has been dis-
turbed by loss of cells. In most instances only the empty
secondary sheath remains, giving no clue to the cause of the
loss of its contents. In collections made in Phelps Lake,
Havana, 111., in August, 1896, however, colonies were often
found which were parasitized by one of the Sj)orochytriace<z,
which upon examination proves to be Danyrardia mamillata,
described by Schroder ('98) as a parasite of Pandorina

On Platydorina. 435

morum. As these infested colonies frequently showed a loss
of one cell or more and exhibited all stages in the destruction
of the cell, it seems probable that the loss was due to the
parasite. Eudorina elegans and Pandorina morum occurred
in the same collection and were similarly infested. Two
additional genera, Platydorina and Eudorina, are thus to be
added to the list of hosts of Dangeardia.

For the convenience of systematists a brief statement of
the generic and specific characters of the form herein described
is now given, followed by a key to the genera and species of
the Volvocince for the assistance of students of this interest-
ing and not uncommon group of fresh-water organisms.
Species not as yet reported, to my knowledge, from Illinois
are indicated by an asterisk when found elsewhere in this
continent, and by a dagger when not as yet reported from it.
It is not at all improbable that all the species here listed will
yet be found within this State.

Platydorina n. g.

Colony flattened, the two faces compressed so that the cells
of the two sides intercalate ; flagella upon both faces on
alternate cells. Anterior and posterior poles of major axis
differentiated by the arrangement of the cells and by the
structure of the envelope. Long and short transverse axes
differentiated by the flattening of the colony. Cells similar,
biflagellate, each with stigma, chromatophore, and pyrenoid.
Asexual reproduction by repeated divisions of all of the cells,
each forming a daughter colony.

P. caudata n. sp.

Colony flattened, horse-shoe shaped, twisted about one
eighth of a turn from right over to left; cells 16 or 32,
arranged in a marginal row of 10 or 12 and a central area
of 6 or 20 ; posterior end with 3 or 5 prolongations or tails
formed by extension of the common outer sheath.

Known habitat, lakes and streams in central Illinois.
Types in the collections of the Illinois State Laboratory of
Natural History and deposited in the United States National
Museum.

436 Illinois State Laboratory of Natural History.

*

KEYS TO THE GENERA AND SPECIES OF THE SUBFAMILY

VOLVOCIN^.

Cells arranged in ccenobia of definite forms varying with
the species, biflagellate, with stigma and one or more chro-
matophores; surrounded by a gelatinous envelope whose
development separates them to a greater or less degree;
number not uniform, varying in the different species, often,
but not always, definite. Asexual reproduction by repeated
divisions of gonidial cells, which constitute the whole or only
a part of the parental organism, to form daughter organisms ;
sexual reproduction in some species (in others unknown) by
the conjugation of male and female gametes, resulting in the
formation of a resting stage which later develops into a new
organism.

Genera.

Cells arranged in form of plate with flagella upon
one face only. 2,

Cells arranged in spherical, ellipsoidal, or flattened

colonies, flagella not confined to one face. 3.

Cells in a squarish plate, envelope closely adherent.

Gonium.

Cells in a rounded plate, envelope swollen, oval, or
spherical. Stephanosphcera.

Colony ellipsoidal or spherical, cells crowded to-
gether, conical, reaching towards center, outer
membrane of concentric layers. Pandorina.

Cells not crowded together, nor reaching towards
center of colony. 4.

Colonies ellipsoidal or flattened, cells uniform in
size. 5.

Colonies spherical or spheroidal, or, if ellipsoidal,

with small vegetative and large gonidial cells. f>.

Colony ellipsoidal or spherical, poles not differen-
tiated by arrangement or size of cells, or by struc-
ture of envelope. Eudorina.

Colony flattened, horse-shoe-shaped, with poles dif-
ferentiated by arrangement of cells, posterior end
with tails. Platydorina.

5 \

On Platydorina. 437

Cells not connected by protoplasmic processes, of
two sizes, smaller vegetative at anterior pole and
6 <[ larger gonidial at posterior. Pleodorina.

Cells connected by protoplasmic processes, not mark-
edly different in size. Volvox.

Species.

Gonium.

f Cells, 4. sociale (Duj.).t

\ Cells, 16. pectorale Mull.

Stephanosphsera.

Kepresented by a single species, characterized as follows :
Cells 4 or 8, ovoid or spindle-shaped, with numerous pro-
cesses, pluvialis Colin.*

Pandorina.

Eepresented by a single species, characterized as follows :
Cells 16 or 32, crowded, each with a single chromatophore
and pyrenoid. morum Bory.

Eudorina.

Eepresented by a single species, characterized as follows :
Cells 32, 16, or 64, similar, not crowded together, common
outer membrane without marked concentric structure.

elegans Ehrb.
Platydorina.

Kepresented by a single species, characterized as follows :
Cells 16 or 32, arranged in a horse-shoe-shaped plate,
those of the two faces intercalated. Posterior end with 3
or 5 tails. caudata Kofoid.

Pleodorina.

Cells 64 or 128 ; gonidial cells about 2-3 times the diam-
eter of vegetative cells, which constitute about one half
the total number and lie in anterior hemisphere.

calif orn ica Shaw.

Cells 32, rarely 16 or 64; gonidial cells not more than
twice the diameter of the vegetative cells, which con-
stitute the anterior quartet. illinoisensis Kofoid.

438 Illinois State Laboratory of Natural History.

Volvox.

Cells about 10,000 (minimum 1,500, maximum 22,000),
angular, with stout connecting protoplasmic processes
into which the chromatophore may enter. Diameter of
colony about 700 /< (minimum 400, maximum 1,200) ;
diameter of cell body 3-5 a*. globator L.

Cells 500-1,000 (minimum 200, maximum 4,400),
rounded, with slender connecting protoplasmic processes
into which the chromatophore does not enter. Diameter
of colony 170-850 /<; diameter of cell body 5-8 /*.

aureus Ehrb.

Urbana, 111., Dec. 5, 1899.

On Platydorina. 439

LITERATURE CITED.

Carter, H. J.

'58. On Fecundation in Eudorina elegans and Cryptoglena. Ann.
Mag. Nat. Hist., Ser. 3, Vol. II., pp. 237-253, PI. VIII.

'71. Note on a Fresh-water Species of Ceratium from the Lake of
Nynee (Naini) Tal in Kumaon. Ann. Mag. Nat. Hist., Ser. 4, Vol.
VII., pp. 229,230.

Garman, H.

'90. A preliminary Report on the Animals of the Mississippi
Bottoms near Quincy, Illinois, in August, 1888, Part I. Bull. 111.
State Lab. Nat. Hist., Vol III., pp. 123-184.

Kofoid, C. A.

'98. Plankton Studies, II. On Pleodorina illinoisensis. a new Spe-
cies from the Plankton of the Illinois River. Bull. 111. State Lab.
Nat. Hist., Vol. V., pp. 273-293, PI. XXXVI., XXXVII.

Schroder, B.

'98. Dangeardia.ein neues Chytridineen genus auf Pandorina rnorum
Bory. Ber. d. deutsch. Bot. Gesellsch., Jahrg. 1898, Bd. XVI.,
pp. 314-321, Taf. XX.

440 Illinois State Laboratory of Natural History.
EXPLANATION OF PLATE.

ABBREVIATIONS.

A., anterior pole. p. sh., outer or primary sheath

c v., contractile vacuole. P. posterior pole.

chr.. chromatophore. p., outer pellicle of protoplasm.

/., flagellum. pr., knob-shaped mass of protoplasm

m., matrix. pyr., pyrenoid.

«., nucleus. s. sh., secondary sheath.

ncl., nucleolus. st., stigma.

Plate XXXVIII. *

Fig. 1. Platydorina caudata, face view of 32-cell colony. X 5o0.
Fig. 2. Face view of 16-cell colony, y 628.
Fig. 3. Edge view of 32-cell colony. X 350.
Fig. 4. Lateral view of one of the marginal cells. X 1400.
Fig. 5, a — e. Outline of the posterior ends of several deformed colonies.
X 280.

* Figures drawn by C. A. Kofoid and inked by Miss L. M. Hart.

Plate XXXVIII.

BULLETIN

OF THE

Jllinois Qtate I aboratory

OF

NATURAL HISTORY

Urbana, Illinois.

VOLUME V.

ARTICLE X. NOTES ON SPECIES OF NORTH AMERICAN
OLIGOCHMTA. III. LIST OF SPECIES FOUND IN
ILLINOIS, AND DESCRIPTIONS OF ILLINOIS TUBIFIC-
ID^E.

By FRANK SMITH, A. M.

Illinois State Laboratory of Natural History.

URBANA, ILLINOIS.

March 21, 1900.

Article X. — Notes on Species of North American Oligochaeta.
III. List of Species found in Illinois, and Descriptions
of Illinois Tubificida; By Frank Smith.

The study of Illinois Oligochtzta has been mostly confined
to collections of the Illinois State Laboratory of Natural
History, made near the Biological Station at Havana, 111.,
and in the vicinity of the University of Illinois, at Urbana ;
it is probable, therefore, that several species occur in the
State which are not included in the following list, Thus far
no attention has been given to the Discodrilida and but
little to the Enchytr<eidte of the State.

A list of the earthworms found in North America was pub-
lished in 1888 by Garman in Vol. III. of this Bulletin, in
which those mentioned as occurring in Illinois are three
species of Lumbricidce, one of Acanthodrilidce, and one of
Periclueta which had become established in the University
greenhouses. To these must now be added seven other
species, most of which have been described since Garman's
paper appeared.

The species recorded have all been identified by the writer,
but a considerable part of the detailed study of sections of
the two new species of Tubificidce here described has been
made by a student of the University of Illinois, Miss Ella V.
Engstrom, whose careful work has been of material assistance
in the preparation of this paper. The drawings for the
figures were made by Miss Lydia M. Hart, Artist of the
Illinois State Laboratory of Natural History.

LIST OF SPECIES.1

Lumbricidce.

Lumbricus liercideus Savigny. Urbana ; infrequent.
Allolobophora fcetida Savigny. Urbana; abundant.
Allolobophora rosea Savigny.2 Urbana; frequent.
Allolobophora profuga Rosa. Urbana; abundant.

1 The classification of families is that adopted by Beddard in his Monograph.
'-' A. 7nvcosa Eisen. 441

442 Illinois State Laboratory of Natural History.

Allolobophora caliginosa trapezoides Duges.1 Urbana and
Havana ; abundant.

Allolobophora sp." Urbana and Havana ; frequent.

Geoscolicidd'.

Sparganophilus eiseni Smith. Urbana and Havana;
abundant.

Acanthodrilidce .

Diplocardia communis Garman. Urbana; abundant.
Diplocardia riparia Smith. Havana; abundant.
Diplocardia singularis Ucle. Urbana and Havana ; fre-
quent.

Diplocardia sp.3 Havana; frequent.

Lumbriculidce.

Thinodrilus inconstans Smith. Havana; abundant.
Mesoporodrilus asymmetricus Smith. Havana; infrequent.

Phreoryctidce.

Phreoryctes emissarius Forbes. Urbana, infrequent;
Havana, abundant.

Enchytrceidce.
Fridericia agilis Smith. Havana; abundant.

Tubificida.

Tubifex rivulorum Lamarck. Urbana and Havana ;
abundant.

Limnodrilus claparedianus Eatzel. Urbana and Havana;
abundant.

1 A- tunjida Garman, non Eisen.

- A species closely allied to A. giesleri Ode, Knit its exact relationship has not yet
been determined.

3A species closely allied to D. verrucosa Ude. Exact relationship not yet
determined.

Illinois Oligochceta. 443

Rhizodrilus lacteus n. g. et n. sp. Havana; abundant
locally.

Embolocephahts multisctosus n. sp. Havana; abundant
locally.

Naidomorpha.1

Nais lacustris Linnaeus. Urbana and Havana ; abundant.
Nais elinguis 0. F.Miiller. Urbana and Havana ; abundant.
Nais lurid a Timm. Havana; frequent.
Nais serpentina 0. F. Miiller. Havana; frequent.
Dero limosa Leydig. Havana ; abundant.
Dero obtusa D'Udekem. Havana ; abundant.
Dero vaga Leydig. Havana ; abundant.
Dero /areata Oken. Havana; frequent.
Pristina leidyi Smith. Havana ; abundant.
Pristina flagellum Leydig- Havana ; one specimen.
Chcetog aster limncei v. Baer. Havana ; abundant.
Chcetogaster diaphanus Gruithuisen. Urbana and Havana ;
abundant.

Chcetogaster diastrophus Gruithuisen. Havana; abundant.

JEolosomatidee.

sEolosoma hemprichii Ehrenberg. Urbana and Havana;
frequent.

JEolosoma tenebrarum Vejdovsky. Havana; abundant.
Mblosoma sp.2 Havana; abundant.

DESCRIPTIONS OF TUBIFICID.E.

#

As the first two species of Tubificidce in our list are well-
known European forms which have been described at length
by previous writers, a brief recapitulation of some of their
more important characters will suffice in this connection.

1 But little attention has been given to the Naidomorpha of Urbana.

2 A species with colorless integumental globules, not yet described.

444 Illinois State Laboratory of Natural History.

Tubifex rivulorum Lamarck.

Length 25-50 mm.; number of somites 50-60. Dorsal
bundles with three kinds of setae : capilliform setae, four or five
per bundle anterior to clitellum, decreasing in number pos-
teriorly and absent from the last few somites ; pectinate setae,
in somites anterior to the clitellum ; and uncinate setae in
other regions. Ventral bundles with four or five uncinate
setae in anterior part and fewer posteriorly. In Illinois
specimens the ventral bundles sometimes contain pectinate
setae. No ventral setae on XL Clitellum on XI and most of
XII. Alimentary tract spiral-like in appearance, but with
dorsal vessel on the upper side throughout its course. One
pair of "hearts" in VIII. First nephridium in VII. Penis
with a very short delicate chitinous sheath near tip.

Limnodrilus claparedianus Ratzel.

Length 40-70 mm. ; number of somites 145-160. Setae
all uncinate ; five to seven per bundle in anterior part, fewer
posteriorly. Clitellum on XI and XII. " Hearts " in VIII.
Penis with chitinous sheath .5-1 mm. in length, which is
twenty to thirty times its diameter.

Rhizodrilus lacteus n. g. et n. sp.

The species bearing this name is fairly abundant in Flag
Lake, one of the larger bodies of water occurring in the bot-
tom-lands of the Illinois River near Havana, 111. Nothing-
is known of its distribution in other regions. Specimens have
been found in considerable numbers among the roots of sub-
merged or partially submerged Sagitta/ria variabilis, but thus
far in no other situation. They are sexually mature in July.

The worm is rather sluggish in habit, and the body is
usually contorted and in an almost inextricable tangle. It
varies from 70 to 100 mm. in length in sexually mature
individuals ; is quite slender, varying from .4 to .6 mm. in
diameter; and is largest in the region of the reproductive
organs. The body is nearly white, owing to the great number

Illinois Oligochcsta. 445

of coelomic corpuscles Avith which the ccelomic fluid is crowded,
and which are readily visible through the delicate walls. In
nine specimens, apparently complete, the number of somites
varies from 215 to 365, the average number being 281.

The setoe, except the genital ones, are all of the ordinary
uncinate, or cleft, type, and have the usual arrangement of
four bundles to each somite. Anterior to the clitellum the
number of setae in each bundle is usually five or six, but
posterior to it, throughout the greater part of the length, the
number is commonly four, while near the posterior end it is
more frequently one to three. The ordinary uncinate seta?
are slightly enlarged at a point about one third of their length
from the outer extremity. They are usually .09 to .1 mm.
in length and about .005 mm. in diameter at the middle.
The genital setae are of two kinds. On the ventral side of IX,
in place of each bundle of ordinary setae, there is a specially
modified seta (PI. XXXIX., Fig. 4, b, and PI. XL., Fig. 6—
viewed in different planes) .12 mm. in length and about .01
mm. in diameter at its largest part, which is near the proxi-
mal end. These seta? are in close relation to the openings of
a pair of glands to be described later. In one specimen ven-
tral setae of the same sort were present in X. The ventral
bundles of XI each consist of four to six peculiarly shaped
setae entirely different from the ventral setae of IX, the outer-
end of each being spatulate and rather abruptly hent (Fig.
4, c). These setae are from .14 to .16 mm. in length, and the
diameter is about .009 mm. at the inner end and .006 mm.
near the expanded outer end, while the outer end itself is
about .01 mm. in width.

The clitellum is of the same general character as the clitel-
lum present in other Tubificida, and extends from about the
middle of X to the posterior part of XII, in some individuals
encroaching on XIII. It is incomplete ventrally. The pros-
tomium is relatively large and subcorneal.

The brain has a. slightly convex anterior margin, without
any such median anterior extension as is present in some
Tubificidce. There are two posterior lobes extending back-
wards, one from each side of the middle of the ventral margin.

446 Illinois State Laboratory of Natural History.

The pharynx extends through somites II and III, and its
dorsal and ventral walls are of about equal thickness. The
oesophagus extends backwards into VI, where the epithelium
gradually assumes the character of that of the intestine. In
VII the alimentary tract increases in diameter, and the intes-
tine may be regarded as commencing in that somite. Septal
glands are present in IV and V, those of the latter somite
being the smaller. Ccelomic corpuscles are very numerous
in the ccelomic spaces not otherwise filled. They are spherical
and mostly without granular contents, although some contain
a few rather large spherical granular bodies.

The circulatory system cannot be studied in the living
worm because of the opacity due to the numerous corpuscles,
and our knowledge of it is chiefly derived from a study of
transverse and longitudinal sections. The dorsal and ventral
vessels do not divide in the anterior region of the body to
form supra- and sub-intestinal trunks. In the posterior part
of each of somites VII-X a pair of large lateral vessels, or
"hearts," is present, connecting the dorsal and ventral ves-
sels directly, without giving off branches to the body wall as
is the case in Ilyodrilus. These vessels are approximately
equal in the somites mentioned. The diameter of the lateral
vessels of VI is only about one fifth as great as that of the
corresponding vessels of VII.

The nephridia have been studied with reference to charac-
ter and arrangement in but three individuals, and in these
only in the anterior twenty somites. These organs first
appear in VIII, but in VIII, IX, and somites posterior to XI
only one nephridium is present in each somite, and that is in
the left side of the body in all cases observed. In sexually
mature individuals nephridia are absent in X and XI. The
ventral vessel lies in the left side of the body, and is closely
invested by the expanded glandular part of each nephridium,
the relation between them being much like that described by
Goodrich as existing in Vermiculus pilosus ('95, p. 258).
The nephridium enlarges almost immediately behind the
anterior septum, forming a mass of considerable size, through
which the duct passes in a tortuous course, finally leaving the

Illinois Oligochceta. 447

main mass at a point a little anterior to the middle and
extending to the body wall in a latero -ventral and posterior
direction, opening a little anterior to the inner margin of the
ventral bundle. Absence of nephridia from one side of the body
in several successive somites has been frequently observed
in Naidomorpha (Benham,'93, p. 385, and Smith, '96,"p. 398)
and occasionally in the Tiibijieidce (Stole, '88, p. 23). In
nearly all the species of Tiibifie'uhc studied by this latter
observer he found rare cases in which one of the nephridia of
some somites was entirely degenerate, and others in which a
whole row of nephridia on one side, especially in the last
somites, was less developed than the row of the other side. In
Rhizodrilus lacteus this degeneration has gone still further,
so that a row of nephridia on one side is entirely wanting.

The testes are in the anterior part of X, in the usual posi-
tion, and the spermiducal funnels are in the posterior part
of this somite, the sperm- ducts leading from them into XI
and opening on its ventral side. Following the sperm- duct
backwards from the point of entrance into XI, it is at first of
small diameter, with relatively thin walls, and extends pos-
teriorly and somewhat ventrally for a distance equal to one
sixth the length of the somite. Bending then abruptly toward
the dorsal side of the somite it passes directly upward to the
dorsal wall, and then extends in a posterior direction to a
point slightly beyond the middle of the somite, where it bends
toward the ventral side, opening on the antero-lateral wall of
a spermiducal chamber into which opens also the sperm-
duct of the other side. (PL XXXIX., Fig. 5.) From the
point at which the sperm- duct bends towards the dorsal wall
throughout the rest of its course the lumen remains of small
diameter. From this same point on, for nearly its whole
length, the walls are greatly thickened, so that the diameter
of the duct is nearly one third that of the entire somite. A
short distance from the spermiducal pore the walls become
thin again. There is no enlargement of the lumen to form
an atrium, nor any modification of the wall in any special
region to form a prostate gland, nor is there a penis. The
great diameter of the duct throughout most of its length is

448 Illinois State Laboratory of Natural History.

due to the glandular peritoneal layer which is formed of
much-elongated cells.

The spermiducal chamber, already mentioned, is formed
by an invagination of the mid- ventral wall 'of XI posterior to
the middle of the somite. Its lateral walls are connected
with the body wall by muscular strands which control their
movements. When the form of this chamber is normal the
innermost part is transversely elongated, and the outer part
has its greatest length parallel with the long axis of the body ;
but at times the lateral walls may be pulled far apart, the
chamber thus becoming mereiy a ventral depression. It
seems probable, therefore, that the structures are chiefly
functional during copulation. The wall of the chamber
includes a cuticula, continuous with that of the body wall,
a layer of hypodermis but slightly modified, and a layer
beneath the hypodermis which is quite thick and includes
many large cells, perhaps of a glandular nature, the contents
of which are usually nearly transparent, though sometimes
of a granular character. The peculiar genital setse already
referred to as constituting the ventral bundles of XI are
borne on the posterior wall of the spermiducal chamber, into
which they project.

But one sperm-sac is present. It extends from its opening
in the dorsal part of septum X/XI into XY or XVI. In the
somites posterior to XI it is included in the ovisac. The
anterior septum of X is sometimes pushed far forward into
IX, but there is no anterior sperm-sac.

Ovaries are present in the usual situation, in the anterior
part of XL The ovidueal funnels and oviducts are small but
fully developed, and situated between XI and XII. The
single ovisac extends backwards from its opening in the
dorsal part of septum Xl/XII into XVII or XVIII. The ova
develop in the same manner as in the majority of the Tubi-
ficidce, and not as in Ilyodrilus and Naidomorpha.

Two spermatheese are present in the anterior part of X.
Each of them has a sac, nearly spherical in outline, which
communicates with the exterior through a short duct (PI.
XL., Fig. 7) opening on the anterior margin of X at a point

Illinois Oligochteta. 449

dorsad of a line connecting the ventral bundles of one side.
The interval between the two spermathecal pores is about
one fourth of the circumference of the body. The sperma-
tozoa in the sperm athecae are present in loose masses. No
signs of spermatophores have as yet been found.

A pair of elongate tubular glands is present in IX, their
openings being in close relation to the peculiar genital setae
of that somite (PI. XL., Fig. 6). In the specimen previously
referred to as having genital setae on X similar to those on
IX, a pair of such glands is also present in X, having similar
relations to the setae of the somite. These glands are about
equal in length to the somite, and their diameter, which is
nearly uniform throughout their length, is about one eighth
the diameter of the somite. The diameter of the lumen is
about .01 mm. and the walls are .03 mm. in thickness. The
wall consists of two layers of cells, the outermost being very
thin and composed of flattened epithelial cells, while the
inner layer is formed of relatively large glandular cells,
largest at their distal ends, in which the nucleus is com-
monly situated. The openings of these glands and the asso-
ciated setae are on prominent rounded elevations of the ventral
wall of the somite (PI. XL., Fig. 6) and in line with the ventral
setae of adjacent somites. On the summit of these elevations
the hypodermis is modified as it is in the genital papilla' of
some earthworms ; for example, Diplocardia and Allolobophora.

For the sake of greater convenience in the comparison of
11. lacteus with other forms Igive the following summary of
its more important characters :

The number of somites is 215-365.

All the setae are uncinate except the genital ones, which are
of two kinds, one form in IX and the other in XI.

The clitellum extends from the middle of X to the posterior
part of XII.

Coelomic corpuscles are very numerous.

Supra- and sub-intestinal vessels are wanting, and the
lateral vessels or "hearts," which connect the dorsal and ven-
tral vessels in VII-X, are enlarged, nearly uniform in size,
and do not give off branches to the body Avail.

450 Illinois State Laboratory of Natural History.

The nephridia closely invest the ventral vessel, and, so far
as observed, but one nephridium is contained in a somite.

The sperm-ducts have no prostate gland, atrium, or penis,
and open into a median spermiducal chamber on the ventral
side of XI.

A pair of sperniathecre is present in the anterior part of X,
and the spermathecal pores are a considerable distance from
each other.

A pair of elongated tubular glands is present in IX, opening
in close relation with the genital setae of that somite.

No attempt has been made to distinguish between generic
and specific characters, since only one species of the genus
is known. From the foregoing it is apparent that Rhizodrilus
lactejis is somewhat closely related to Lumbriculus spiralis of
Leidy ('52a, p. 285) in respect to length, number of somites,
form and character of seta?, color, and habits ; but as Leidy's
description is entirely inadequate for the purpose of identifi-
cation, and as he left no type specimens of his species, the
relationship between the two forms cannot be determined. It
is unfortunate that the description of a new species of Tubi-
ticidic so frequently involves the description of a new genus, but
according to present ideas of the classification of this family
the character of the species under discussion will not permit
its inclusion in any existing genus. The presence of two
distinct kinds of highly modified genital seta? and the pres-
ence of such seta? in the ninth somite distinguish this worm
from all other described forms of Tubificida. In the absence
of distinct prostate glands and in the presence of a common
spermiducal chamber it differs from most Tubificidee but
resembles Vermiculus. There is a farther resemblance to the
latter genus in the simplicity of the longitudinal blood-vessels
and in the absence of both supra- and sub-intestinal vessels,
but the relation of the lateral vessels of the anterior somites
to other parts is very different in the two genera. In Vermic-
ulus pilosus, in II-X there is no direct communication
between the dorsal and ventral vessels, the single pair of
branches of the dorsal vessel in each of those somites break-
ing up into a capillary network in the body wall, from which

Illinois Oligochceta. 451

the blood is conducted to the ventral vessel through two pairs
of vessels in each somite, of which the posterior pair is the
larger. In V. limosus, recently described from Japan by
Hatai('98, p. 110), the same general relation exists between
these lateral vessels and the body wall, except that there is
but one pair of lateral branches of the ventral vessel in each
of the somites referred to, and that there is a slight differ-
ence in the number of somites in which such vessels occur.
Goodrich ('95, p. 262) regarded this condition of the circu-
latory system as distinguishing' Vermiculus from all other
Tubificidte. The circulatory system of Ilyodrilus coccineus,
as described and figured by Stole ('88, p. 15, Tab. II., Fig. 9),
seems to constitute a very interesting mtermediate type
between that of Vermiculus and such forms as Bhizodrilus.
As Stoic's paper is unfortunately written in Czech, it has
been inaccessible to most students of the Oligochceta.
Through Mr. L. F. Miskovsky, of Oberlin College, I have
been so fortunate as to obtain a very careful translation of
this admirable paper, and quote here that part which treats
of the vascular arches of Ilyodrilus.

"In the following segments, i. e., in the fourth to the ninth
inclusive, the dorsal artery is united with the ventral always
through one pair only of lateral arteries, which issue before
the posterior septum of each somite from the dorsal artery
and gradually swell behind until in the last three of the
named segments they assume the largest proportions, resem-
bling thus the swelled lateral arteries (so-called hearts) which
are found in the remaining genera of the Tubificida. The
lateral arteries here described do not, however, open simply
into the ventral artery. Each one of the lateral arteries
approaches closely to the lateral diameter of the body and
sends several branches into the integument. The branches
running through the integument form in each segment an
elegant vascular network which is connected through numer-
ous anastomoses with the plexuses of the other segments.
The sanguineous fluid after coursing through this integument-
ary network returns into the ventral vein through two special
veins, which, issuing out of the integument from the lateral

452 Illinois State Laboratory of Natural History.

diameter of the body, after a short course, empty into the
ventral vein."

Figure 9 of Plate II in Stoic's paper is a diagrammatic
representation of the circulatory system in the anterior part
of I. coccineus. Through some typographical error that part
of the description of plates dealing with this figure is headed
Bothrioneuron vejdovskyanum, and is thus somewhat confus-
ing. A comparison of this figure with that of the correspond-
ing organs of Vermiculus jiilosus (Goodrich '95, PI. XXVI.,
Fig. 5) and Hhizodrilus lacteus (PI. XL., Fig. 8) will readily
suggest a common derivation for the different types. For
convenience in making such comparison Figures 9 and 10 of
Plate XL. have been prepared from the figures by Goodrich
and Stole.

Embolocephalus mtdtisetosus n. sp.

AVorms of a species of Tubificidce not hitherto described
are found in great abundance in the vegetable debris at the
bottom of Flag Lake, and are occasionally met with in the
vegetation along the banks of the Illinois River and the bot-
tom-land lakes in the vicinity of Havana.

Well-extended individuals are 19 to 35 mm. in length. At
the time of sexual activity a few somites at the anterior end,
including the reproductive organs, are much enlarged, the
diameter of the worm in this region being then two and a half
or three times that of the remainder of the worm. In a rather
large specimen the diameter in the region of the tenth somite
is .8 mm., that of the middle of the worm is .3 mm., and at a
distance from the posterior end equal to one fourth the length
of the body the diameter is .2 mm. The number of somites
varies from 49 to 106 in specimens examined, but 75 to 80
is more common. The main part of the body is of a dark
grayish color, but the posterior end-is lighter and less opaque.
A sheath formed in part of foreign particles cemented together
envelops the anterior part of the body, making it quite opaque.
It adheres very closely to the surface of the worm and is
removed with great difficulty. It is wanting in the posterior
part of the body, which is extended into the open water and

Illinois Oligochaeta. 453

is, as in many Tubificida, the principal respiratory region.
Non-retractile sense papillae similar to those described for
Embolocephalus, Spirosperma, and a few other Tubificidtz, are
present in this species. They are arranged in two rows on
each somite, one row coinciding with that of the seta; bundles
of the somite, and the other one being usually in the plane
of the septum (PL XXXIX., Fig. 1). A few papilla repre-
senting a third, very incomplete, row are often present.

When a specimen is examined with a lens, one is strongly
reminded of some of the marine annelids by the dense clusters
of elongated sets in the dorsal bundles. The dorsal setae are
of two kinds ; long capilliform set*, often .5 mm. in length,
and' palmate or comb-like setae .16 to .18 mm. in length
(PI. XXXIX., Fig. 2, c, d.). In the anterior bundles capilli-
form setae vary in number from three to fourteen per bundle.
Throughout most of the remainder of the body the number
is but one to three per bundle, while the last ten to twenty
somites usually have no dorsal seta? whatever. The palmate
setae are regularly found in only a few anterior somites,
where the number varies from one to five per bundle. In the
dorsal bundles of the greater part of the body back of the
first ten or twelve somites, palmate setae are usually lacking,
though occasionally one such may be found in one or more
bundles posterior to the middle of the worm. The relative
number of capilliform setae and palmate setae per bundle is
extremely variable. Some individuals have setae of the two
kinds in equal numbers, while others having a relatively large
number of capilliform setae have only one to three palmate
setae per bundle. Ventral setae, usually two in each bundle,
are present in all the somites except the first, eleventh, and
last. They are sigmoid, uncinate, and slightly enlarged at a
distance from the distal end about equal to one third the
length of the setae. The ventral seta? of the anterior region
are longer and less strongly curved than those of the posterior
part of the body (PI. XXXIX., Fig. 2, a, b).

There is no well-developed clitellum on any of the speci-
mens in our collection, none of which seem to lie at the
height of sexual activity, but in a few individuals the

454 Illinois State Laboratory of Natural History.

hypodermis of XI is slightly modified. The prostomium and
anterior somite are very sensitive and thin-walled, and at the
slightest irritation are so retracted that the first setigerous
somite seems to form the end of the worm.

The brain is concave posteriorly, and its anterior part is
prolonged into a process on each side of the median line.
The alimentary tract has no special features distinguishing it
from other Tubijicidce. The pharynx occupies somite II and
part of III ; the wall of the dorsal side is somewhat thicker
than that of the ventral side ; the transition from the oesoph-
agus to the intestine is gradual ; and chlorogogue cells
appear rather abruptly in the anterior part of VI. The inner
epithelium becomes like that of the intestine in the posterior
part of VI, while the diameter of the alimentary tract becomes
considerably enlarged in VII. Posterior to this somite there
is no great change in the diameter of the intestine or in the
character'of its walls. The coelomic corpuscles are very few
in number and of irregular form.

The circulatory system cannot be studied in the living
specimens, and it has proved an especially difficult task to
work out its anatomy from sections. One pair of " hearts "
is present in VIII, and in one specimen examined there were
additional lateral vessels nearly as large in IX. The "hearts"
communicate with the dorsal vessel, and no traces of a
supra- or sub-intestinal vessel have been found. Anterior
and posterior to the region of the reproductive organs the
alimentary tract is invested by an extensive system of blood
sinuses connected by a median ventral sinus or vessel, which,
however, seems to have no direct connection with the ventral
vessel nor to have the relations of a sub-intestinal vessel.

Paired nephridia are present in VII-IX, wanting in X-XIII,
and begin again in XIV. The nephridiopores are in line with
the ventral setae and a short distance in front of them.

The reproductive organs are similar in structure and
arrangement to those of many other Tubijicidce. The testes,
spermathecaj, and spermiducal funnels arc in X, and the
ovaries, sperm-ducts, and spermiducal glands in XI, on
which somite are the spermiducal pores. The sperm-duct

Illinois OligocJueta. 455

is somewhat elongated and occasionally protrudes backward
into the . sperm-sac as far as the posterior part of XII. The
diameter of that part of the duct nearest the funnel is very
small (.01mm.), and that of its lumen not over .003 mm.
The diameters of duct and lumen both gradually increase
as the spermiducal gland is approached, and the course of
the duct becomes more tortuous. That part of the duct to
which the spermiducal gland is attached is expanded into an
elongated chamber or "atrium" (PI. XXXIX., Fig. 3), of
which the diameter is about .05 mm., that of its lumen being
.025 mm. Between the spermiducal gland and the pore the
sperm-duct is about .03 mm. in diameter where smallest.
The duct terminates in a protrusible penis, which is destitute
of a chitinous sheath. The spermiducal pores are in line
with the ventral setae of adjacent somites, and also with that
row of papillae which is associated with the setae. As before
stated, there are no ventral setae on XI. There are two median
sperm-sacs, lying dorsad of the alimentary tract ; an anterior
one in IX, and a posterior one in XI-XIV. In some cases
the latter extends into XV.

One pair of spermathecae is present in X, and in one of the
sectioned specimens there is an additional spermatheca
in the right side of IX, which is similar in every way to those
of X except that it is slightly smaller. In the specimens
examined none of the spermathecae contained any traces of
spermatophores. The spermathecal duct is nearly uniform
in diameter, and its length is one and a half to two times as
great as the diameter of the sac. In each case observed the
sac appeared like a hollow sphere with a broad invagination
of one side, but whether or not this collapsed appearance is
the normal one lias not been determined. There seems to be
no difference in the character of the wall in the different parts
of the sac, and no glands have been found in connection with
the spermathecal duct. The male organs are well developed
in all the sectioned -specimens studied, but the ovaries have
not contained large ova, nor have there been any traces of
ovisacs or oviducts. These specimens were collected in
October, and the height of sexual activity is probably attained
at some other time of the year.

456 Illinois State Laboratory of Natural History.

The relation of the species under consideration to other
Tubificidce cannot be finally determined in the light of our
present knowledge of the anatomy of this species and of
nearly related forms. In the presence of prominent non-re-
tractile papillae it resembles Peloscolex, Spirosperma, Hemi-
titb'ifex, and Embolocephalus. It probably is closely allied to
Leidy's Peloscolex variegatus ('52, p. 124), but the meager
description of that form and the lack of type specimens make
it impossible to determine this point. The absence of a chiti-
nous sheath about the penis distinguishes it from Spirosperma
and Hemitubifex, but there are no characters given in the
description of Embolocephalus Randolph ('93, p. 472), which
exclude it from that genus. The description includes, however,
no account of the circulatory system in the anterior part of
the worm nor any statement as to the presence or absence of a
chitinous penis sheath. Sections of E. plicatus kindly sent
me by Dr. Randolph furnish no evidence of the presence of
this sheath in that species, but as they include none of the first
eight somites it is impossible to compare the anatomy of the
circulatory systems of the two species in that region. In
view of the above facts I have included the Illinois species in
the genus Embolocephalus, giving it the species name multi-
setosus. It differs from E. velutinus in having two kinds of
dorsal seta?; and from E. plicatus in having palmate seta?
in the dorsal bundles, and in other particulars as follows :
(1) In plicatus the dorsal bundles are said to contain usually
but six capilliform seta? and three uncinate ones, and no state-
ment is made to indicate that there is any considerable vari-
ability in the number in different regions of the body. In
multisetosus, however, the dorsal bundles of the anterior region
each contain from eight to sixteen setaj, while in the middle of
the body the number is much smaller, and the posterior somites
usually have no dorsal seta? whatever. (2) The papilla? of
plicatus are in two rows, equally distant from the septa, while in
multisetosus one row is in the plane of the setaj and the other in
the plane of the septa. The papilla? of multisetosus are also
much larger and more conspicuous than those of plicatus.
(3) The diameter of the lumen of the sperm-duct of plicatus is
nearly uniform throughout, while that of multisetosus is several
times greater in the region of the atrium than elsewhere.
Urbana, 111., Jan. 25, 1900.

Illinois Oligochceta. 457

LITEEATUEE CITED.

Beddard, F. E.
'95. A Monograph of the Order of Oligocha-ta. 769 pp , 5 pis.

Benham, W. B.

'93. Note on a New Species of the Genera Nais. Quart. Journ. Micr.
Sci., Vol. XXXIV., pp. 383-386, PI. XXXIII.

#

Garman, H.

'88. On the Anatomy and Histology of a New Earthworm (Diplocar-
dia communis, gen. et sp. nov.). Bull. 111. State Lab. Nat. Hist., Vol.
III., Art. IV, pp. 45-77, PI. I.-V.

Goodrich, E. S.

'95. On the Structure of Vermiculus pilosus. Quart. Journ. Micr.
Sci., Vol. XXX VII., Pt. 3, pp. 253-267, PL XXVI.-XXVIII.

Hatai, S.

'98. On Vermiculus limosus, a New Species of Aquatic 01igoch*ta.
Annot. Zool. Japon., Vol. II., P. IV., pp. 103-111. 5 fig.

Leidy, J.

'52. Description of two New Genera of Vermes. Proc. Acad. Nat.
Sci. Phila., Vol. V., pp. 124 120.

'52a. Corrections and Additions to former Papers on Helminthology.
Proc. Acad. Nat. Sci. Phila , Vol. V., pp. 284-290.

Randolph, H.

'93. Beitrag zur Kenntnis der Tubificiden. Jena. Zeitschr. f. Natur-
wiss., Bd. XXVI., pp. 463-476, Taf. XVII.-XIX.

Smith, F.

'96. Notes on Species of North American Oligoclueta. II. Bull. 111.,
State Lab. Nat. Hist., Vol. IV., Art. XIV., pp. 396-413, PL XXXV.-
XXXVIII.

Stole, A.

'88. Monografie Ceskych Tubificidu. Morfologicka a Systematicka
Studie. Abh. Bohm. Ges. (2) VII., pp. 1-45, Tab. I. IV.

458 Illinois State Laboratory of Natural History.
EXPLANATION OF PLATES.

ABBREVIATIONS.
at., atrium. «. c, nerve cord.

clit., clitelluin. pr. spermiducal gland.

coel., coelom. p. v. L v., posterior ventral lateral

vessel.
'/. I. v., dorsal lateral vessel. Sep., septum.

(I. v., dorsal vessel. */>. ch., spermiducal chamber.

(7- p., genital papilla. sp. <L, sperm-duct.

g. 8., genital seta. *}>. th.., spermatheca.

0- -s- (it > gland of genital seta. sp. 8., sperm-sac.

I. v., lateral vessel. v. n., integumental vascular

network.

m., muscles. ». v., ventral vessel.

m. v. J. v., median ventral lateral vessel. po., spermiducal pore.

Plate XXXIX.
Embolocephalus multisetosus.

Fig. 1. Anterior part. X.18.
Fig. 2. Sets, x 250.

a and b, from ventral buudles.

c, palmate seta from dorsal bundle.

d, distal end of same.

Fig. 3. Sections of sperm-duct. X 180.

Rh izo clri lus lacteus .
Fig. 4. Seta-. X 250.

a, ordinary uncinate seta.

b, genital seta from IX.

c, genital setse from XL

Fig. 5. Transverse section through spermiducal chamber, x 70.

Plate XL.

Rhizodrilus lacteus.

Fig. 6. Sagittal section through genital papilla, seta, and gland of IX.,

combined from several sections. X 180.
Fig. 7. Transverse section through spermathecae. x 70.
Fig. 8. Diagram of blood-vessels in VII-IX.

Ilyodrilus coccineus.

Fig. 9. Diagram of blood-vessels in V VIII., adapted from a figure by
Stole.

Vermiculus pilosus.

Fig. 10. Diagram of blood-vessels in IV VI, from a figure by Goodrich.
Those of VII-X are similar.

Plate XXXIX.

. -i ■}

.

■'■:•-■■ ,-

ess ■-:

sag*

:"»C5" ,.7' " ''•«?* '" ".**=

ap.^^^i^'

... ,.^rt-:-":":-:--v
/ /V'eoe/./

; / .- S

■ / / % \

V*

uu

% - / %a0

Plate XL.

\ 9f-9-L-v£-f*-S.

IX

X

-

9P-

''■'■ ■'-"*&"*"

l/.M.

VII

m.

' 1 I I x rrTT '

: 1 YHI

- s5._-. ...J j&? y

■•V ■ Nl Jfe, JF

vm-- i-d.v.

ill ix

.. ■-.-■ «gk.- " ■' Tjg --•■

»m Wmzd -mi**.

.V /.v.

u.-n.

10

BULLETIN

OF THE

Illinois Qtate | aboratory

OF

NATURAL HISTORY

Urbana, Illinois.

VOLUME V.

ARTICLE XI. NOTES ON SPECIES OE NORTH AMERICAN
OLIG 0 CHM TA. IV. ON A NE W L UMBRICULID GENUS
FROM FLORIDA, WITH ADDITIONAL NOTES ON THE
NEPHRIDIAL AND CIRCULA TORY SYSTEMS OF ME SO-
P OR ODRIL US ASYMME TRICUS SMI TH

By FRANK SMITH, A. M.

Assistant Professor of Zoology, University of Illinois.

Illinois State Laboratory of Natural History.

URBANA, ILLINOIS.

June 9, 1900.

Akticle XI. — Notes on Species of North American Oligoehceta.
IV. On a New Lumbriculid Genus from Florida, with
Additional Notes on the Nephridial and Circulatory Sys-
tems of Mesoporodrilus asymmetricus Smith. By Frank
Smith.

Premnodrilus palustris n. g. et n. sp.

The worms here described were found by Mr. Adolph
Hempel in a decayed stump in a marsh in Polk county,
Florida, in March, 1897. The collection consists of eight
sexually mature individuals and a few others that are
imperfect or immature. The worms were killed in corrosive
sublimate and preserved in alcohol, and are in excellent
condition for study. x\ll of the facts pertaining to this
species which are presented in this paper have necessarily
been obtained from an examination of this preserved material.

Sexually mature specimens, well extended, average about
50 mm. in length and 1 mm. in diameter at the tenth somite,
where the diameter is greatest. The body gradually decreases
in diameter toward the posterior end, where the somites are
relatively smaller and less distinct. The anterior end termi-
nates in a proboscis about .15 mm. in length, its diameter
being .07 mm. at the base and .035 mm. at the middle. In
these preserved specimens it is bent upwards. In five appar-
ently complete individuals the number of somites varies from
155 to 177, the average number being 167.

The clitellum extends from the anterior part of VIII to the
middle of XII, and is developed on the ventral surface. The
spermiducal pores are on the ventral side of IX (PI. XLL,
Fig. 1) ; the oviducal pores are in the groove between somites
X and XI and in line with the ventral setas ; and the sperm-
athecal pores are on the ventral side of VIII, a short dis-
tance posterior to the ventral setae of that somite. It will be
noted that the external openings of the reproductive organs
are further forward by one somite than is usual in the Lum-
briculidce. The three sectioned specimens which form the

459

460 Illinois State Laboratory of Natural History.

basis of this description show uniformity throughout in the
position of the various reproductive organs.

There are four pairs of setae in each of the setigerous
somites, the interval between the dorsal and ventral bundles
of one side of a somite being five sevenths as great as that
between the two ventral bundles and one half as great as that
between the two dorsal bundles of the same somite. The
seta? are of the ordinary sigmoid form, without a cleft at the
outer extremity, and are somewhat variable in length, but
average about .2 mm. There are no genital setae.

The brain consists of two lateral masses, each with its
longest axis dorso-ventral, the two being connected by a stout
fibrous commissure. The surface layer of each mass, except
in the ventral region, consists of a thick layer of nerve cells.
The commissures extending to the ventral cord and the large
nerve trunks leading to the prostomium are given off from
the ventral side of the lateral masses.

No marked peculiarities have been noticed in the alimentary
tract. There is a gradual transition from pharynx to intestine
without any well-marked intermediate oesophagus. The
anterior part of the pharynx is capacious, with a dorso-
ventral diameter considerably greater than the lateral one.
The ventral wall of the pharynx is quite thin, while a thick
glandular wall extends over the dorsal, and somewhat more
than half over the lateral, region. Toward the posterior
part of the pharynx the dorso-ventral diameter decreases, as
does also the extent of the thin ventral wall, and in the
anterior part of IY the walls are uniform in thickness and
circular in outline. The thickened part of the pharyngeal
wall is ciliated. Chloragogue cells first appear in the sixth
somite. • There are no pharyngeal glands, but there are a
few deeply staining cells on some of the muscular strands in
a few anterior somites. On the anterior face of septum
VI/VII and on both faces of septum VII/VIII are borne
rather small masses of cells which do not stain very deeply.
They may correspond to the septal glands of some Oligocha-la.
In that part of the body containing the reproductive organs
the lateral diameter of the intestine is greatly reduced (PI.

Premnodrilus palustris. 461

XLL, Fig. 3), so that the lumen is a mere slit and the lateral
walls are almost in contact.

The study of the circulatory system in this species, neces-
sarily confined to sections of preserved material, has heen
incomplete and somewhat difficult. The dorsal vessel con-
tains an extensive "Herzkorper" of nearly uniform diameter,
and similar structures are present in the lateral vessels of X
and of a few preceding somites. The ventral vessel forks
near the septum III/IV. In each of somites II-IX a single
pair of lateral vessels connects the dorsal vessel with the
ventral vessel or with its anterior branches. These vessels
have a somewhat tortuous course and are without chloragogue
cells. The lateral vessels of VIII follow the spermathecje
into IX and sometimes farther, while those of IX extend
inside the sperm-sacs through a considerable number of the
succeeding somites. In somite X there are two pairs of
lateral vessels, the anterior pair connecting the dorsal vessel
with the ventral part of an extensive plexus of vessels in the
intestinal wall, and each vessel of the posterior pair extend-
ing posteriorly, through several somites, between the corre-
sponding sperm-sac and its inclosing membrane, and con-
necting the dorsal and ventral vessels. In somite XI and in
each succeeding one there are two similar pairs of lateral
vessels, which pass from the dorsal vessel outward and
downward near the body wall, and enter the intestinal
plexus on the ventral side of the intestine. A short blood-
vessel connects the ventral vessel with that part of the
intestinal plexus into which the lateral vessels of the anterior
pair open, and a similar vessel connects the ventral vessel
with the corresponding region of the plexus into which open
the vessels of the posterior pair. The lateral vessels of XI
and of succeeding somites have ccecal diverticula, and those
of somites posterior to XI are invested with a layer of chlora-
gogue cells. In each of a few somites at the posterior end
there is but one pair of lateral vessels.

The nephridia are quite similar in structure to those of
other members of this group, the funnel being situated in
the posterior part of one somite, and the remainder of the

462 Illinois State Laboratory of Natural History.

nephridium in the somite next following, with the nephridio-
pore a little anterior to the ventral seta-. On the duct, a
short distance posterior to the funnel, is a compact glandular
mass through which ramify minute ductules that seem to be
branches of the main duct. A considerable part of the coiled
region of the nephridium is in close relation to the dorsal
part of the ventral vessel.

The arrangement of the nephridia is an unusual one, or, at
least, different from that ordinarily assumed to exist in the
Lumbr'icul'uhe. In one of the sectioned specimens there are
no nephridia anterior to XIY, while in the other two there
are nephridia in VI-VIII but none in the following somites
anterior to XII, the first nephridiopores posterior to the
reproductive organs being in XII. In each of the two indi-
viduals having nephridia anterior to the reproductive organs
there is but one pair so situated, and the funnels of these
nephridia are in Y, the nephridiopores in YI, and the main
masses of the organs extend along the dorsal side of the
ventral vessel into VII and VIII. Posterior to the clitellum
there is ordinarily but one nephridium in each somite, — an
examination of over a hundred somites affording but two
exceptions to this rule, — and the more common arrangement
is one in which there is on each side of the body, alternately,
a single nephridium in each of several successive somites.

In the three specimens studied there is but one pair of
testes in each, and these are borne on the posterior face of
septum VIII/IX ; but since there is a pair of spermiducal
funnels in VIII as well as in IX, it seems probable that there
has also been at some time a pair of testes in VIII.

The spermiducal apparatus is quite complex and somewhat
similar to that of Eclipidrilus and Mesoporotlr'tlit* (Eisen,
'95, pp. 87-89 ; Smith '96, pp. 404, 405). It will perhaps
be advantageous to mention briefly the principal structures
composing it before giving a detailed description. As already
stated, there are two pairs of spermiducal funnels, one on the
posterior septum of VIII and the other similarly situated in
IX (PI. XLL, Fig. 1). The two sperm-ducts of either side
extend backward to the posterior part of X or to the anterior

Premnodrilus palustris. 463

part of XI, where they enter the wall of the anterior end of
a long sperm-reservoir which extends backward through six
to eight somites. After passing through the muscular layer
of this wall the ducts pass between it and the inner epithelium
to the posterior end of the reservoir, where they open into
its cavity. The anterior part of the reservoir is continued
as a much narrowed and often considerably contorted duct,
which is continuous with the inner end of a large muscular
penial apparatus, the spermiducal pores being situated on
the posterior part of the ventral side of IX.

We can now go a little more into detail in describing the
spermiducal structures. As already stated, there are no
testes in VIII, although that somite contains a pair of sperm-
iducal funnels. The presence of an abundance of sperma-
tozoa in the sperm-reservoir and spermathecas and of well-
developed ova bears evidence that the animals had at least
reached a state of sexual activity, and yet the most careful
examination revealed not the slightest trace of testes in
VIII. A similar condition of affairs is described by Beddard
('92, p. 196) as existing in Sutroa alpestris, in which species
he found spermiducal funnels in IX and X but no trace of
testes in the former somite. The smaller and more variable
size of the funnels in VIII and the smaller diameter of their
ducts — which is only a third of that of the posterior ones-
may reasonably be regarded as indicating a degenerate con-
dition, and that the complete disappearance of the testes has
preceded that of the funnels and ducts.

Each of the sperm-ducts leading from the anterior funnels
bends abruptly down, passing through the testis close to its
attachment to the septum. It then turns posteriorly and
passes into the extensive mass of muscular tissue surround-
ing the ventral part of the penial structure. After emerging
from this mass it extends upward for a short distance along-
side the muscular investment of the penis, passing along its
ental surface, and then extends across to the muscular duct
between the penial organ and the sperm-reservoir, which it
follows to the latter organ, and, as before stated, passes
between its muscular layer and inner epithelial lining, along

464 Illinois State Laboratory of Natural History.

the ventral side of its cavity. Each of the sperm- ducts con-
nected with the posterior funnels extends at first directly
downward, and then, bending posteriorly, takes a quite direct
course to the muscular diu-t, which it follows to the sperm-
reservoir. Passing then through the muscular coat of that
organ it extends posteriorly, having the same relation to the
muscle layer and lining epithelium as has the duct from the
anterior funnel, except that it lies on the dorsal instead of
the ventral side of the cavity and opens into the chamber at
a point nearly opposite the opening of the anterior duct.

Each sperm-reservoir lies in the sperm-sac of its own side,
and extends from the posterior part of X or the anterior part
of XI for a distance of six to eight somites. This organ has
powerful muscular walls, which are not constricted by the
septa, and which consist of a thin inner epithelial layer, a
thin layer of circular muscle fibers, and an outer and much
thicker layer of muscle fibers which are nearly longitudinal
but have a somewhat spiral course. Numerous large cells,
apparently glandular in nature, lie outside the reservoir, and
are connected with its wall by elongated narrowed extensions
which presumably function as ducts, but have not been fol-
lowed beyond the superficial portion of the muscular wall.
The cells are altogether similar to those figured and described
by Eisen ('95, p. 88) as being numerous about the anterior
end of the "storage chamber" of Eclipidrilus frigidus. In
Premnodrilus palustris, however, they are more abundant
near the posterior end' of the chamber, and much less frequent
at the anterior end. Besides these large prostate glands,
following Eisen's nomenclature, there is a more or less inter-
rupted layer of smaller cells much like those called by Eisen
small prostate glands. The inner epithelium is everywhere
thin and the cell walls are indistinguishable.

Throughout the greater part of its length the sperm-
reservoir, exclusive of the layer of prostate cells, -has a
diameter of about .25 mm., that of its lumen being about
.08 to .09 mm. The diameter of the reservoir diminishes
more gradually toward the anterior end than toward the
posterior, and the chamber tapers off into a muscular duct

Premnodrilus palustris. 465

about 1 mm. in length, of which the diameter is .015 to
.025 mm., while that of its lumen is .005 to .010 mm. The
walls of this duct include an inner epithelium, layers of
circular and longitudinal muscles, and an outer layer of
small, more or less isolated cells, like that already described
for the sperm-reservoir. This duct is usually contorted in
its course, and passes through the muscular Avail of the
inner end of the penial apparatus and opens into the inner
end of the greatly elongated penis. There is no " prostate"
nor "atrium" as in Eclipidrilus frigidus, and the muscular
duct, which is perhaps comparable to the "bridge" of
E. frigidus, connects the sperm-reservoir directly with the
penis.

The proportions and relations of the penis in Premnodrilus
palustris can best be understood by reference to Fig. 1,
PI. XL I. The penial apparatus includes an elongated sac
lined with epithelium, continuous with the outer epithelial
layer of the penis proper, and, adjacent to this, a thick layer
of longitudinal muscle, outside of which is a delicate epithe-
lium. No layer of circular fibers is developed. In a speci-
men in which the penis is not much protruded the penial sac
extends upward and backward into the anterior part of XII,
the posterior septa of IX, X, and XI being forced back with
it. Strong muscular bands connect the free end of the sac
with the dorsal body wall of XII-XV, the strongest band
being in the posterior part of XIV. The long slender penis
is inclosed by the walls of the muscular sac, but is nowhere
connected with it except at its inner end. Its entire length
is 1.25 mm., of which .4 mm. is protruded from the body in
one of the specimens studied. Its diameter varies from .015
mm., near the tip, to .08 mm., near the point of attachment,
and at the middle is about .04 mm. Its unusual length is
doubtless correlated with the correspondingly long sperma-
thecal duct, to be described late,)-.

The lumen of that portion of the sperm-duct which forms the
penis has a nearly straight course and is of small diameter,
being but .005 mm. at a point midway of its length. The
penis is covered superficially by an epithelial layer continuous

4(>6 Illinois State Laboratory of Natural Histoinj.

with that of the muscular sac inclosing it, while the lumen
of the sperm-duct which passes through it is surrounded by
an epithelial layer continuous at the inner end with that of the
muscular duct, and at the tip with the epithelium covering
the outer surface. Between these two epithelial layers is ;i
tissue composed of elongated cells, slightly inclined to the
long axis, which connect the inner and outer epithelial layers.
The cells are not as closely packed as are those of muscle
layers, and the tissue which they compose probably corre-
sponds to the "fibrous tissue" which is present in the atrium
of E.frigidus.

A pair of large elongated sperm-sacs extends backward
from the posterior septum of IX through twelve to eighteen
somites. A sperm-reservoir and its connecting ducts are
situated in the anterior part of each, and in one specimen the
spermathecaj also were included in the anterior part of the
sperm-sacs (PI. XLL, Fig. 3). The posterior part of each
sperm-sac is constricted by the septa, and in the specimens
studied the cavities were filled with spermatozoa.

One pair of ovaries is present in the anterior part of X. and
a pair of oviducal funnels is borne on the posterior septum of
that somite, opening to the exterior in the groove between X
and XI. Large ova were present in but one specimen and
were contained in X. From the posterior part of that somite
a thin sheath of cells extends backward, enveloping the sperm-
sac, and including in the cavity between them the posterior
pair of lateral vessels of X. The posterior limits of this
sheath have been difficult to determine, and there is certainly
no appreciable space between it and the posterior end of the
sperm-sac, neither have any signs of ova been found within
it. It may be, however, that it represents an ovisac into which
ova might pass at a later stage of development.

There is one pair of spermathecse, opening on the posterior
part of the ventral surface of somite VIII. These organs are
unusually long and much differentiated in their structure.
In two specimens they push the septum VIII/IX backwards
into IX, forming contorted masses, while in the other speci-
men each spermatheca extends posteriorly into the cone-

Premnodrilus palustris, 467

sponding sperm-sac, and lies dorsad of the sperm-reservoir
and parallel with it (Fig. 3), one extending into XII and the
other as far as XVII. In two specimens, in which careful
measurements were made, the entire length of each sperma-
theca was a little over 3 mm., the greatest diameter being
.25 mm. The general form and proportions of these organs
can be readily seen in Fig. 2.

Each spermatheca includes three distinct regions, which
may be designated respectively as duct, storage region, and
glandular region. The duct is about 1 mm. in length, and
has comparatively thick walls, which consist chiefly of longi-
tudinal muscle fibers. The muscular layer is thickest in the
middle of the duct and gradually thins out near the beginning
of the storage region. The diameter of both duct and lumen
is subject to considerable variation as shown by the following
measurements, which are very nearly the same for the two
spermatheca1 most carefully studied. At a distance of
.25 mm. from the pore the diameter of the duct is .1 mm. and
that of the lumen .05 mm., and in this region the lining epithe-
lium is thrown into numerous high transverse folds, which
nearly fill the cavity. The diameter of the duct .4 mm. from
the pore is .1 mm., while that of its lumen is reduced to
.02 mm. From this point to the beginning of the storage
region the diameter of the duct gradually decreases to
.045 mm,, while the lumen at first increases to .045 mm.,
next decreases to .02 mm., and then enlarges into the cavity
of the storage region. The storage region is about .5 mm.
in length and has a diameter of .15 mm. for the first half,
then widens out to .22 mm., and is next constricted to
.14 mm. where the division between the second and the third
region occurs. Its walls are quite thin in the part nearest
the duct, but gradually become. thicker and more glandular
and like those of the third region. This third, or glandular,
region is about 1.85 mm. in length, and its diameter is pretty
nearly uniform, varying only from .2 mm. to .25 mm., while
that of its lumen varies from .12 to .18 mm. The storage
region and the glandular region are not sharply differentiated,
but the former is filled with spermatozoa while the latter con-

468 Illinois State Laboratory of Natural History.

tains but few or none, and the walls of the two regions are
decidedly different in structure except in the parts adjacent.

The spermathecal wall consists of outer and inner epithelial
layers, in addition to. which layers of muscle tissue are
present in the duct. The outer epithelium is everywhere
thin, and composed of flattened cells except near the middle
of the duct, where this layer is considerably thickened and
the cells are columnar in character. The inner epithelial
layer is of moderate thickness in the duct and in the greater
part of the storage region, and its cells stain quite deeply in
hematoxylin. In the remainder of the storage region and in
the glandular part this layer becomes quite thick, and is
composed of columnar cells having their nuclei in the basal
portion and staining only slightly in Ehrlich's hematoxylin.
A layer of circular muscle fibers, which lies next to the inner
epithelial layer and is comparatively thin, is present through-
out the whole length of the duct. Between this layer and the
outer epithelium there is a layer of longitudinal muscle fibers
which is quite thick in the greater part of the duct, but thins
out, and finally disappears in the part nearest the storage
region.

From the foregoing description it is evident that Premno-
drilus palustris belongs to that branch of the Lumbriculidce
which includes the peculiar genera Eclipidrilus and Meso-
porodrilus. For the purpose of studying the relationships of
these different forms, a more extended examination of the
nephridia! and circulatory systems of Mesoporodrilus asym-
metricus has been made, the results of which are next
recorded.

Nephridial and Circulatory Systems of Mesoporodrilus asym-

metricus Smith.

In the original description of this species the only reference
to the nephridia is to the effect that the first pair is in VII,
and that the nephridiopores are in front of the ventral seta'
(Smith '96, p. 404). A re-examination of the material studied,
however, with more careful attention to the nephridia, shows
that the main masses of the pair belonging to VII extend

Mesopodrilus asymmetricus. 469

alongside the ventral vessel into IX ; that there are no other
nephridia until we reach XII ; and that in this somite and in
each of the following ones there is but one nephridium, the
order of occurrence being that common in Premnodrilus
palustris, in which, as before stated, there is on each side of
the body, alternately, a single nephridium in each of several
successive somites. The asymmetry found to exist in these
two species suggests that possibly the views ordinarily held
as to the universality of the paired arrangement of the
nephridia in the Lumbriculidce may be due to the lack of a
careful examination of their distribution. On the other hand,
in Thinodrilus inconstans, in a species of Sutroa from Yellow-
stone Park, and in Eclipidrilus frigidus, — the only other
species of Lumbriculidce which have been accessible to the
author for study, — the nephridia are paired.

Our knowledge of the circulatory system is necessarily
incomplete, since the material for the study of this species is
limited to serial sections of parts of two specimens ; but it
has been possible to ascertain several facts concerning it.

As in many other aquatic Oligochceta, branches of the
vascular system are freely distributed to the wall of the
intestine, taking either the form of extensive plexuses or of
sinuses of considerable extent. The ventral vessel is forked
near the septum Y/YI, and in each of somites II-V its
branches are connected with the dorsal vessel by one pair of
perigastric vessels. 1 In the anterior part of each of somites
YI-IX a pair of lateral vessels invested by gland cells con-
nects the ventral vessel with the dorsal part of the intestinal
plexus, while in the posterior part of each, a pair of slender
lateral vessels without investing gland cells and having a
somewhat tortuous course connects the dorsal and ventral
vessels. The relations of the lateral vessels in X are similar
to those existing in YI-IX, except that the posterior vessels
extend backward through several somites.

Before describing further the course of these vessels, it

1 The lerms perigastric and gastric are appliei us by Eisen, who calls lateral ves-
sels lying in the ccelomic cavity perigastric, and those closely associated with the

wall of the alimentary tract gastric.

470 Illinois State Laboratory of Natural History.

becomes necessary to correct the statement made in the
original description that there is but one sperm-sac (Smith
'96, p. 405), for while it is true concerning the specimen of
which transverse sections were made and in which the repro-
ductive organs were somewhat degenerate, in the other
specimen there are two sperm-sacs, one containing the
sperm-reservoir and the greater part of the spermiducal
apparatus, and the other, a considerably smaller one, belong-
ing to the other side of the worm, containing no trace of a
sperm-duct. Each of the posterior pair of lateral vessels of
X extends backward into the sperm-sac of its own side,
forming long loops in its course. In the specimen of which
transverse sections were made and in which there is but one
sperm-sac the posterior lateral vessel of X which is in the
side containing the sperm-sac extends posteriorly into that
organ for a distance of several somites, while the correspond-
ing vessel of the other side extends posteriorly for a similar
distance, and is closely invested by a layer of tissue which
doubtless represents a degenerate sperm-sac.

In the individual most carefully studied somites XI-XVII
have no perigastric vessels, but there seem to be two pairs of
gastric vessels in each (PL XLL, Fig. 4). There is an ante-
rior pair of lateral vessels without cceca in each of somites
XVIII-XXIII, which leave the dorsal vessel as perigastric ves-
sels but unite with the intestinal plexus instead of the ventral
vessel. There is considerable variability in the positions at
which these vessels enter the intestinal wall. It may be any-
where from the ventral part of the intestine to a position two
thirds of the way from the ventral to the dorsal region (Fig. 5).
The posterior pair of lateral vessels in each of these somites
are gastric vessels. In each somite the ventral vessel is con-
nected with the ventral part of the intestinal plexus in the
two regions that are most closely related to the two pairs of
lateral vessels. A considerable number of somites posterior
to XXIII have not been sectioned, but of some of the poste-
rior ones sections have been made, the most anterior of which
has two pairs of perigastric vessels with ccecal diverticula :
an anterior pair, connecting the dorsal vessel with the ventral

North American Lumbriculidce . 471

part of the intestinal plexus ; and a posterior pair, connecting
the dorsal and ventral vessels. In several somites nearest to
the posterior end, both pairs of perigastric vessels have coeca
and connect the dorsal vessel with the ventral part of the
intestinal plexus.

Thus far, our knowledge of the Lumbriculidce of North
America has been limited to species collected in very restricted
and widely separated regions. Two species of Sutroa and
one of Eclipidrilus from California have been described by.
Eisen ('81, '88, '92, and '95); one species each of Mesoporo-
drilus and Thinodrilus from Illinois, by the writer ('95 and
'96); and this paper contains the description of a species
from Florida, for which still another genus name is proposed,
namely, Premnodrilus,1 Of these, Thinodrilus is much more
nearly allied to Lumbriculus and certain other European forms
than to its North American associates that have thus far
become known, while Sutroa seems in certain particulars
intermediate between the European genus Rhynchelmis
(Vejdovsky, '76) and the peculiar group of North American
Lumbriculidce which includes Eclipidrilus, Mesoporodrilus,
and Premnodrilus. The species included in these three
genera are much more nearly related to each other, so far as
the structure of their reproductive organs is concerned, than
is any one oj them to species of other genera of the family,
and yet the differences beeween them seem to the writer too
great to be considered as merely specific. Thus, at present,
six species of North American Lumbriculidce are known, and
they have been placed in five different genera.

Such a condition of things, in which we have, in a com-
paratively small group of animals a number of genera nearly
or quite as great as the number of species, may be due to
one or more of several causes, and in this case it may be
owing to the fact that at present our knowledge of the Lum-
briculidce is insufficient to make it possible to determine which

1 Leidy's descriptions of species presumably belonging lo the Lumbriculidce are
inadequate and must be disregarded.

472 Illinois State Laboratory of Natural History.

characters should be regarded as generic and which as of
specific value merely. It is possible that an unusual varia-
bility in the reproductive organs exists in worms of this group,
and that in a similar length of time and under similar differ-
ences of conditions there might be a greater amount of
divergence in the character of these organs than there would
be in worms of other groups, as, for example, the earthworms,
and hence that differences which among the latter would be
generic ought perhaps to be considered as only specific when
found among the Lumbriculida . On the other hand, it may
be that species which now form the only members of the
genera to which they belong, will after a time, by the discov-
ery of other species, become types of genera which will each
contain two or more species more closely related to each
other than are the species now known, and thus the estab-
lishing of so many genera may be justified. In the case of
the three genera last referred to, when we consider that a
distance of a thousand miles intervenes between Florida and
Illinois and two thousand miles between Illinois and Califor-
nia, and that nothing whatever is known of the Lumbriculida
of the intermediate regions, it seems reasonable to suppose
that subsequent collections from the intervening territory
may bring to light other species more nearly related to one
or more of them than they are to each other. Until future
collections and study shall disclose the facts, it seems best
to the writer not to include in one genus species.which differ
so widely as do Eclipidrilus frigidus, Mesoporodrilus asym-
metricus, and Premnodrilus palustris.

A comparison of these three species will be facilitated by
the use of the following table, which includes characters that
are of more or less importance from the systematic stand-
point.

North American Lumbriculidce.

473

E. frigidus. M. asymmetrxcus.

P. palustris.

Seta'.

Not cleft at outer ex-
tremity.

One pair, extending

through several so-

_mites and having

thick muscular

walls.

The same.

The same.

Sperm-reservoirs
("storage cham-
bers").

A single one, etc.

One pair, etc.

Eversible penes.

One pair in X.

A single one in X.

One pair, verv long,
in IX.

Clitelluin.

Posterior part of IX
to the middle of
XIV.

Middle of IX to the
middle of XIII.

Anterior part of VIII
to middle of XII.

Prostomium.

Without proboscis.

One pair in each of
somites IV-VIII.

With proboscis.

With 'proboscis.

Anterior nephndia.

One pair in VII, ex-
tending into VIII
and IX; pores in
VII.

Absent, or one pair
in VI, extending
into VII and VIII:
pores in VI.

Posterior nephridia.

Paired, beginning in
XIII.

Single, beginning in
XII.

Single, beginning in
XII or XIV.

Testes.

Two pairs — in IX and
X.

One pair — in X.

One pair — in IX.

Sperrniducal fun-
nels.

Two pairs— in IX and
X.

A single one — in X

Two pairs— in VIII
and IX.

Prostate and atrium.

Differentiated parts
of sperm-duct con-
nected with sperm-
reservoir by nar-
rowed part of
sperm-duct
(''bridge") having
muscular walls.

The same.

Absent.

Sperrniducal pores.

A pair: posterior
part of X.

One: on median line
in posterior partof
X.

A pair: posterior part
of IX.

Sperm-sacs.

One pair, extending
back from IX thro'
several somites:
not inclosing
sperm -reservoirs.

One pair, extending
back from X thro'
several somites;
small one with
no corresponding
sperm-duct, and
larger one in-
closing sperm-
reservoir.

One pair, extending
back from IX thro'
several somites;
inclosing sperm -
reservoirs.

Ovaries.

One pair— in XI. One pair— in XI.

One pair — in X.

Oviducal pores.

Anterior partof XII. XI /XII.

X/XI.

Spermathecffi.

One pair: in IX.

.Two ; in IX, on same
side of somite, one
pnsterior to the
other.

One pair; in VIII; of
uuusual length

Sperinathecal pores.

Posterior to ventral
sets of IX.

On mid-ventral line
of IX, on'e behind
the other.

Posterior to ventral
setae of VIII.

474 Illinois State Laboratory of Natural History.

The principal features of the circulatory system of M. asym-
metricus and of that of P. palustris having already been
described at length in this paper, it has seemed unnecessary
to tabulate the characters of this system for all three genera,
and, instead, a summary from Eisen's description of E.
frlgidus ('81, p. 3) is subjoined.

There is in E. frigidus but one pair of lateral vessels in
each of somites I-IX, and they are perigastric, connecting the
dorsal and ventral vessels, those of IX and X extending
posteriorly through several somites in connection with the
spermiducal organs. A considerable number of somites
following X contain only gastric vessels, of which there is
but one pair in each somite. Each of about thirty posterior
somites contains two pairs of perigastric vessels, which are
connected with the dorsal vessel and end blindly in the
eoelomic cavity, all being short, and all more or less imper-
fectly forked or branched. There are no gastric vessels in
these somites.

An examination of the foregoing table shows that sperm-
reservoirs ("storage chambers") are present in all three
genera. These are specially modified regions of the sperm-
ducts, which are found in no other members of the family.
Other characters common to the three genera, but not so
distinctive, are the simple setae, the eversible penes, and the
great extent of the sperm-sacs. These four characters taken
together may be regarded as distinguishing the subfamily
Eclipidrilin<g from other LumbricuLda . As the three included
genera contain but one species each, the definition of genera
and species is not attempted.

E. frigidus is distinguished from the other two members
of the subfamily by the absence of a prostomium and by the
presence of (1) several pairs of nephridia anterior to the
reproductive organs, (2) paired nephridia posterior to XII,
(3) but one pair of lateral vessels in each somite — excepting
thirty or more posterior ones in which are two pairs of
perigastrics ending blindly in the ccelomic cavity, (4) two
pairs of testes, (5) paired spermiducal pores on X, (6) paired
spermatheca' and spermathecal pores in IX, and (7) paired

North American Lumbriculidce. 475

oviducal pores in the anterior part of XII. These differences
seem sufficient to warrant the recognition of the species as
generically distinct from the other two.

M. asymmetricus and P. palustris are more closely related
to each other than is either of them to E. frigidus. They,
alike, have (l)a prostomium, (2) but one pair of nephridia
anterior to the reproductive organs, (3) unpaired nephridia
posterior to XII, (4) one pair of testes, (5) two pairs of
lateral vessels in each of the somites posterior to X, and (6)
no perigastrics ending blindly in the ccelom. They differ
from each other in several important respects, as follows :
(I) in the position of the anterior nephridia, (2) in the
position of all the reproductive organs, (3) in the number of
sperm-ducts and spermiducal funnels, (4) in that the pros-
tate and atrium of M. asymmetricus seem to be replaced in
P. palustris by a greatly developed penial apparatus, (5) in
the position of the spermiducal pores', (6) in the symmetry
or asymmetry of the sperm-sacs, (7) in the structure and
proportions of the spermatheea", (8) in the position of the
spermathecal pores, and (9), in a marked manner, in the
relations of the lateral vessels. As already intimated, only
future collections and study can make it possible to determine
whether these differences ought to be regarded as generic or
as merely specific ; but, all things considered, it seems the
wiser plan at present to regard the two species as generically
distinct.

The writer takes this opportunity to acknowledge his obli-
gations to Mr. Hempel for his kindness in obtaining the
specimens of the new species described ; to Dr. Gustav Eisen
for several specimens of Eclipidrilus; and to Prof. S. A.Forbes
for the opportunity to study a species of Sutroa collected by
him in Yellowstone Park. The drawings for the figures were
made by Miss Lydia M. Hart, Artist of the Illinois State
Laboratory of Natural History.

University of Illinois, May 19, 1900.

471) Illinois State Laboratory of Natural History,

LITEEATUEE CITED.

Beddard, F. E.

'92. A Contribution to the Anatomy of Sutroa. Trans. Koy. Sue.
Edinb., Vol. XXXVII., Pt. 1, No. 13, pp. 195 202. 1 pi.

Eisen, G.

'81. Eclipidrilidge and their Anatomy. A New Family of the Limi-
colide Oligochaeta. Nova Act. Keg. Soc. Upsala, III., pp. 1-10. 2 pis.

'88. On the Anatomy of Sutroa rostrata, a New Annelid of the
Family Lumbriculina. Mem. Calif. Acad. Sci., Vol. II., No. 1, pp.
1-8. 2 pis.

'92. Anatomical Notes on Sutroa alpestris, a New Lumbriculide
Oligochaete from Sierra Nevada, California. Zoe, Vol. II., pp.
321-334, PI. XIV.-XVI.

'95. Pacific Coast Oligocha-ta, I. Mem. Calif. Acad. Sci., Vol. II.,
No. 4, pp. 63-90. PI. XXX.-XLV.

Smith, F.

'95. Notes on Species of North American Oligochseta. Bull. Ill State
Lab. Nat. Hist., Vol. IV., Art. VIII., pp. 285-297.

'96. Notes on Species of North American Oligochseta. II. Bull. Ill-
State Lab Nat. Hist., Vol. IV., Art. XIV., pp. 39(3-413, PI. XXXV.
XXXVIII.

Vejdovsky, F.

'76. Anatomische Studien an Khynchelmis Limosella Horrm. (Euaxes
filimstris Grube). Zeit. f. wiss. zool., Bd. XXVII., 3 Heft, pp. 332
361, Taf. XXI -XXIV.

Plate XLI.

North American LwmbricuUdte.

477

EXPLANATION OF PLATES.

ABBREVIATIONS.

con. </., duct connecting reservoir
and terminal portion of
penial apparatus.
clit., clitellum.
dor. ves., dorsal vessel.

gl., glandular region of sperm-
atbeca.
y. ves., gastric vessel.
int.. intestine.
m. /.. muscular fibers.
in. I., muscular layer of sperm-

athecal duct.
n. c, nerve cord,
or., ovary.
ov. (I. /., oviducal funnel.

p., penis.
plex., intestinal plexus.
p. g. ves., perigastric vessel.
res., sperm-reservoir.
sep.VUI., septum of VIII.
sp. d.. sperm-duct.
sp. d. /., spermiducal funnel.
sp.d.po., spermiducal pore.

sp. s., sperm-sac.
•sp. th. d,, spermathecal duct.
sp.th.po.. spermathecal pore

st., storage region of sperm -

atheca.
t., testis.
v. ves., ventral vessel.

Plate XLI.
Premnodrilus palustris.

Fig. 1. A diagrammatic representation of a part of the reproductive
organs. X 35.

Fig. 2. A diagrammatic longitudinal section of a spermatheca, recon-
structed from a series of sections. X 50.

Fig. 3. A transverse section of XI, from a specimen in which the pos-
terior parts of the spermathec* were included within the
sperm-sacs. X 45.

478 Illinois State Laboratory of Natural History.

Mesoporodrilus asymmetricus.

Fk;. 4. From a longitudinal section through XIII, showing a part of
the circulatory system. X 85.

Fio. 5. A part of the circulator}- system in XXI, composed from several
transverse sections. X 75.

BULLETIN

OK J HI.

Illinois Qtate I aboratory

OK

NATURAL HISTORY

Urbana, Illinois.

VOLUME V.

ARTICLE XII. THE HIRUDINEA OF ILLINOIS.

By J. PERCY MOORE.

Illinois State Laboratory of Natural History

CRBANA, ILLINOIS.

February, J 901.

Article XII. — The Hirudinea of Illinois. By J. Percy
Moore.

This paper is a partial descriptive catalogue of the leech
fauna of Illinois. It is founded on collections gathered from
time to time during the past twenty-five years by the Illinois
State Laboratory under the direction of Prof. S. A. Forbes, of
which material by far the most important part, as regards
both number of species and individuals and state of preser-
vation, is that taken by Prof. Frank Smith and other mem-
bers of the staff of the Illinois Biological Station. For the
opportunity of studying this material I am indebted to the
interest and courtesy of Professors Forbes and Smith. No
doubt other species occur in this region ; indeed several
others have already been recorded from the State.

No general morphological questions are discussed herein,
though the specific descriptions include some evidence point-
ing to several generalizations of fact and theory which will
be evident to the reader. The nomenclature of somites and
annuli used, is that suggested in two recent papers (Moore
'98 and 1900). Some differences (in the enumeration of
somites of certain species) between this paper and the earlier
one just mentioned are due to the recognition of an additional
somite in the preocular lobe, as pointed out by Apathy ('88)
and Whitman ('92), and the adoption of the neuromeric
standard for the determination of somite limits as maintained
by Castle (1900) and Moore (1900). A sharp distinction has
not always been made between the different kinds of cutaneous
sense organs, unless such distinctions are readily discernible
in surface views. Eyes are described as single if they appear
so in surface views, even though sections show them to be
compound. In the figures the pigment cups alone of the eyes
are exhibited, so that in some cases they are indicated in
somites different from those which furnish their sensory
cells. In fact, with very few exceptions, the descriptions
have purposely been restricted to such features as are

479

480 Illinois State Laboratory of Natural History.

visible under a good dissecting lens, though nearly all of the
species have been sectioned and the distribution of sensillse,
etc., verified in that way. It has also been thought best to
omit full synonymical tables (partly because of the doubt
which attaches to some descriptions) and to include just
sufficient names to connect the species under consideration
with the previous descriptive literature. Blanchard's opinion
has been followed with regard to the names of European
forms. The order in which the species are considered does
not express the writer's view of their relationships. The
brief notes on habits are the results of observations made
chiefly in the neighborhood of Philadelphia, where most of the
species occur.

GLOSSIPHONID^.

PLACOBDELLA BLANCHAKD.

Placobdella parasitica (Say).

Hirudo 'parasitica Say ('24).

Diagnosis. — Somites I and II are included in the preocular
lobe, which may or may not exhibit a furrow separating
them ; one pair of small pigmented eyes on the large anterior
annulus of III; the furrow ~Val/a2 is much less distinct
than Va2/a3; cutaneous warts and papillae are numerous
but low and often inconspicuous, and the median series is
feebly developed ; the epididymes and ducti ejaculatorii form
a close coil chiefly confined to somite XI.

General Description. — This tortoise leech reaches a large
size, occasionally attaining a length in extension of more
than four inches. Such huge individuals are, however, rare,
and the ordinary examples are seldom more than one half
that size. In the resting state the outline is rather broadly
oval, the anterior ends being only slightly less broadly
rounded than the posterior. The body is depressed, with
sharp margins and gently convex dorsum. When fully ex-
tended— and the capacity for extension is very great — the

The Hirudinea of Illinois. 481

body is widest near the posterior end and very slender
anteriorly. Under such circumstances the head may be
much wider than the constricted region immediately follow-
ing it and has a somewhat cordate form.

The dorsal surface is provided with numerous sensory
papilbe or cutaneous warts (PI. XLIL, Fig. 4). Except
toward the margins, where they are arranged somewhat in
two rows, they form a single series across each annulus. On
many specimens none of the papillae are at all conspicuously
elevated, and the surface may appear quite smooth ; in others
each annulus bears from ten to twenty quite large warts
which in general correspond in position with the larger warts
of P. rugosa, but have very different proportions. The median
series, so prominent in the latter, is in this species almost
obsolete. The largest and most constant are those which
overlook the dorso-lateral sensillpe. In all cases they are
low, smooth, and rounded, and seldom bear more than a
single sense organ ; never a rough rosette-like aggregation at
the summit.

The shape of the head differs much according to conditions
of contraction and extension. Generally in the larger indi-
viduals it partakes of the even outline of the body and is
broadly rounded anteriorly. In the younger specimens,
especially in extension, it is somewhat expanded beyond a
neck-like constriction, and the preocular lobe is somewhat
sharply pointed. In such, also, the annuli are very clearly
differentiated, and in a few cases the preocular lobe, which
is generally simple, is distinctly subdivided into two rings
(PL XLIL, Fig. 1).

A single pair of eyes — they are really compound— (Pl#
XLIL, Fig. 1), frequently united in a common pigment spot,
is situated on the posterior part of the second (occasionally
the third) distinct annulus. Then follow a short annulus, a
very large one, again a distinct short one, which forms the
posterior rim of the sucker below, and then two imperfectly
separated annuli V (a l-\-a 2) which completely unite ventrally
to constitute the postoral ring. On the ventral surface of
the sucker and lip most of these furrows may be readily

482 Illinois State Laboratory of Natural History.

recognized, and under some conditions are very deep. The
mouth is relatively small, and placed far forward on a median
thickening of the rim of the sucker beneath the preocular
lobe.

There is no distinct clitellum, and the gonopores have the
usual glossiphonid position of XI/XII for the male and
XII a 2/« 3 for the female. The nephridial openings, of
which there are 16 pairs, are situated on low papilla? a little
anterior to the middle of the annulus a 2 on somites VIII to
XXIII.

Compared with P. rugosa the posterior sucker is relatively
large, its anterior margin reaching to XXII and the posterior
largely free. It is circular, flat, and smooth. The anus is
large and at XXVII/XXYIII.

Annuli and Somites (PL XLIL, Fig. 1). — The annulation of
this species is especially interesting and suggestive, inasmuch
as it presents the strongest kind of confirmation of the com-
parison recently made (Moore, 1900) between the biannulate
somite of Mierobdella and the triannulate of the glossiphon-
ids. Even in the largest specimens, and more or less
obviously in all parts of the body, the annuli a 1 and a 2 are
evidently more closely associated than are a 2 and a 3. In
young examples and toward the extremities of the body, the
neuromeric limits of the somites and the more primitive
relations of their component annuli become extremely clear.
The gradations between the biannulate and the triannulate
types are so gentle that the exact number of complete somites
cannot be definitely stated; it is impossible to decide just
where the biannulate type ends and the triannulate begins.
Of course this is more or less true of many leeches, but one
can usually rest satisfied with a decision that a particular
furrow is to be described as incipient or as complete. Not so,
however, with this species. The different values of these fur-
rows have, however, not been brought out in the plate.

I and II are preocular and are rarely separated by a recog-
nizable furrow. In some cases the furrow II/III is very
faint. At least one pair of metameric sensillas are constantly

The Hlrudinea of Illinois. 483

discernible ; the others are obscure and must be sought for
in sections.

III is biannulate. The first annulus is large and generally
divided by an incipient cross-furrow, posterior to which are
the eyes and a full set of metameric sensillae. The second
annulus (a 3) is smaller, and loses its individuality at the
margins.

IV is also biannulate, the annulus (a 1 + a 2) being very
large, but sometimes scarcely more visibly divided than its
preceding homologue. All of the four pairs of sensillre except
the dorso-median are very distinct. This somite forms most
of the lateral margins of the sucker, and its posterior ring
contracts suddenly and sweeps caudad and mesiad as the
narrow posterior ventral rim of the latter.

V. When the head is expanded as described above, this
somite forms its posterior limit. The furrow a \\a 2 is more
evident than in somite IV, but a 1 and a 2 together may still
be regarded as a single large and incompletely divided
annulus. In no case does this furrow extend beyond the
margins of the body, so that the ventral surface of the
annulus is entirely undivided. The dorsal metameric sensillae
occupy the posterior constituent (a 2). The small annulus
a 3 is a trifle more than half the length of the large one, and
the furrow a 2/a 3 is very much deeper and more distinct
than a l/« 2, though somewhat less so than V/VI ; it is also
fully developed ventrally.

VI may be provisionally and arbitrarily regarded as com-
plete, but even in this somite the furrow a 1/a 2 is dorsally
much less obvious than a 2/a 3 and becomes on the ventral
side very faint, and in small specimens especially obsolete.
These two potential annuli are also smaller and more inti-
mately associated on the ventral than the dorsal surface.
Viewed from either above or below the marginal curvatures
of a 1 and a 2 are more homogeneous and the emarginations
much less deep and abrupt than between al and a 3, thus
further indicating the closer growth relations of the former
two.

Much the same conditions prevail in succeeding somites,

484 Illinois State Laboratory of Natural History.

but become gradually less and less obvious as a 1 becomes
relatively larger and more completely dissociated from a 2.
At the same time all of the furrows and the emarginations
become more uniform ; but in some specimens of large size
and in a great many of the smaller ones the intersomitic
furrows remain more distinct and a l/«2 less distinct for the
entire length of the body, and especially is this so on the
ventral surface. The external limits of the somites are often
quite as distinctly indicated as in Microbdella,

On the fully developed somites of the middle region a 3 is
always the largest annulus (PI. XLIL, Fig. 4), but, except in
the posterior somites of large individuals, there is no indica-
tion of further subdivision into b 5 and b 6. Anteriorly, and
especially in young individuals, a 2 is longer than a 1, but in
the middle region it is only equal to or slightly less than this.
Unlike P. rugosa this relative size of the annuli is the same
ventrally and dorsally, and the ventral furrows are either
exactly continuous with the dorsal or all are slightly and
equally in advance of them at the margins.

At the posterior end, somite XXIII is triannulate above ;
but below the furrow a lja 2 becomes more or less reduced.
Dorsally the marginal curvatures and emarginations present
the features described for the anterior end, and a 3 is slightly
shorter than a 1 .

XXIV. Although the annulus a 3 unites with a 2 mesially
and a 1 remains distinct for its entire width, contrary to the
relative disposition of these annuli anteriorly, the marginal
curvatures and emarginations still associate a 2 more closely
with its predecessor than with its successor. Marginally, at
least, a 1 is the largest component. On the ventral side all
three annuli unite more or less completely into one.

XXV is very incomplete ; a 1 and a 2 are inseparable
and a 3 is distinct only marginally. XXVI is still more
faintly biannulate at the margins or even entirely unian-
nulate. XXVII is uniannulate.

Reproductive Organs. — The six pairs of testes lie in the
posterior parts of somites XIII to XVIII, extending some-
what into the succeeding somite in each case. The vasa

The Hirudinea of Illinois. 485

deferentia are ventrad and laterad of the testes. A slightly
enlarged coiled region of the ducts in somite XI corresponds
to the epididymes and ducti ejaculatorii, which latter become
constricted before opening into the somewhat enlarged prostate
cornua. The latter are quite distinct from one another
except where they join beneath the nerve cord at the small
bursa. There is no true muscular atrium.

Alimentary Canal. — The protrusible pharynx is very slender
and when at rest reaches into somite X, where at its base it
receives the pair of common ducts of the pharyngeal glands.
There are two of these much lobulated glands on each side.
The larger one extends by the side of the pharynx from a
point opposite to the female pore in XII to the middle of IX.
The main duct arises in this lobe at the junction of its
anterior and middle thirds. The second gland is smaller.
Beginning in a short duct which joins the middle of the
principal one, it extends forward, dipping beneath the
pharynx, as far as the anterior end of the main gland, where
it emerges from beneath the pharynx and continues forward
a short distance. Very frequently, but apparently not invari-
ably, a median annectant lobe joins the lateral halves across
the ventral face of the pharynx.

The lateral creca are exceedingly well developed and their
numerous lateral divisions reach almost to the margins of the
body. Six pairs correspond very nearly to as many somites
(XIII to XVIII). Except the first, they are arranged as a series
of overlapping chevrons with the angles directed posteriorly.
A seventh much larger pair of creca arises in XIX and con-
tinues backward parallel with the intestine to about XXIII.
The intestine bears' four pairs of long simple c»ca which are
directed laterad dorsal to the last described.

Color. — Placobdella parasitica is very richly colored. On
the dorsal surface the ground color of brown, greenish brown,
or olive green is variously spotted, striped, and blotched with
bright yellow, which replaces the ground color more or less
extensively. Two specimens entirely alike can scarcely be
found, so that a description applicable to all' cannot easily
be framed in a few words. The following, however, probably

486 Illinois State Laboratory of Natural History.

includes the most essential features : The preocular region
is very light colored, with a bright orange spot, sometimes
including the eyes. The light yellow areas are chiefly con-
fined to a median longitudinal stripe, to marginal spots, and
to a pair of series of spots or blotches between these two.
Sometimes the median band is continuous for the whole
length, sometimes its middle part disappears, and sometimes
small remnants of it remain at the ends only. It is of very
irregular width, alternately expanding widely at intervals of
about three somites and contracting between. The marginal
spots are generally very regular, of somewhat triangular
shape, and extend over the two annuli which lie between the
successive neural annuli, the latter being dark colored at the
margins. It is only at the ends of the body that they suffer
modification. The intermediate series are the most variable.
They may be formed of small spots including the dorso-
lateral sensillfle, and occurring on the neural annuli of every
somite or only on every second or third somite ; they may
extend over a 3 as well as a 2 or they may become large
irregular blotches reduced in number and extending over
several somites ; they may coalesce more or less into irregular
longitudinal stripes which are likely to be constricted on
a 1 ; and they may unite in various ways with the mar-
ginal spots or with the median band. The ground color
may greatly predominate or almost disappear.

Habits. — This very common leech is found most frequently
adhering to the plastron or naked parts of the skin of
various species of turtles, to which it clings very tenaciously.
In the early spring, before and during the period of produc-
tion of spermatophores and oviposition, they feed eagerly
and gorge themselves with blood. Like other species of
similar habit they not infrequently kill their host by thus
draining its blood. At other seasons they may be kept for
months without food. Not infrequently this species is also
found on floating wood in ponds and ditches or under stones
in streams, where it feeds on small oligocha?tes, etc.

The Hirudinea of Illinois. 487

Placobdella rugosa (Vekrill).

Clepsine ornata var. rugosa Verrill CIA).

Diagnosis. — Somites I and II distinctly and completely sep-
arated, usually strictly uniannulate ; the single pair of eyes
very close together on the posterior part of the large annulus
of III ; the furrow V alja 2 quite as distinct on the dorsal side
as V a2/a3 ; cutaneous papillae numerous, mostly very large
and rough and the median series very conspicuous ; repro-
ductive organs essentially as in P. parasitica.

General Description. — Although reaching a large size the
largest individuals probably do not equal the largest of
P. parasitica. Generally the length is from one to two
inches. When resting this is the broadest and flattest of
our leeches, the whole body being excessively depressed and
foliaceous. A living individual in this state measures twenty-
two millimeters long by fourteen broad. Incapable of the
great degree of extension possible to P. parasitica it never
becomes very slender.

The integuments have a peculiar translucent appearance,
quite different from the opacity of P. parasitica. The whole
dorsal surface of the body is exceedingly rough, in large living
examples being clothed with a veritable forest of papilla? from
which the eye readily picks out three longitudinal series of
more prominent ones, conspicuous not only because of their
large size but because of the regularity and constancy of their
occurrence. One of these is median, the others about half-
way to the margin. Toward the anterior end they become
smaller and fewer ; at the posterior, the median series ceases
and several very prominent papillae appear in a short series
on each side of the median line. Further details are given
below under the description of a typical somite.

Under all conditions of contraction or extension the anterior
sucker partakes of the regular curvature of the body and never
appears as an appreciably expanded disc. In preserved spec-
imens it is deeply concave, with a high but thin posterior
margin formed by IV, and thicker lateral margins. Anteriorly
the preocular lobe is rather narrow and more or less inrolled

488 Illinois State Laboratory of Natural History.

ventrally, where it is continuous with a thick rounded ridge
which extends to about the middle of the sucker and ends at
a deep curved furrow continuous laterally with III/IV. The
mouth is a minute pore placed near the anterior end of the
ridge beneath the overhanging preocular lobe. Metameric
sensillffi on the preocular region have not been detected in
surface view, though they can be demonstrated readily enough
in sections. The eyes are essentially as in P. parasitica.

No clitellum has been found. The male sex pore is at XI/XII
and the female at XII a2/a 3, but a 3 is enlarged mesially and
pushes forward into an emargination in a 2, so that the female
pore generally lies rather more within the latter. The male
orifice is the larger and is surrounded by more or less promi-
nent rugosities. The most anterior nephridial openings which
have been detected are on VIII, the last on XXIII.

Although of smaller size than in P. parasitica the posterior
sucker is rather large and has a longitudinal diameter slightly
exceeding the transverse. It extends anteriorly to XXIII.
The entire free dorsal surface bears papillse which are nu-
merous and rough on the posterior exposed part, where four
to six radiating rows are larger than the others. Anus
XXYII/XXYIII.

Annuli and Somites (PI. XLIL, Fig 2). — I and II consti-
tute the preocular lobe.

III is biannulate, with the large anterior ring very faintly
divided by an incipient cross-furrow, posterior to which are
the closely approximated eyes, two pairs of metameric sen-
sillffi, and one pair of warts which apparently belong to the
dorso-lateral series. The second annulus bears a full set of
the characteristic papillae or warts, but they are of very small
size.

IV differs from III dorsally in that a 1 is more distinctly
differentiated from a 2 by a furrow which is always distinct
marginally but may disappear mesially. The anterior annu-
lus (a 1) thus indicated is smaller than a 2, and bears no
papillae except in the case of two exceptionally rough indi-
viduals from Tinicum Island, near Philadelphia. The a 2
constituent bears all of the dorsal sensillfe except the dorso-

The Hirudinea of Illinois. 489

median and the supra-marginal, and the more characteristic
papillae belonging to this ring. .4 3 is about half the
length of the larger double annulus, bears its characteristic
papillae, and forms the margin of the posterior rim of the
sucker.

V is triannulate dorsally, a 2 is slightly wider than a 3, and
the latter than a 1, but all furrows are equally well developed,
until at the margin a l/# 2 suddenly disappears, leaving two
ventral annuli of approximately equal size.

Eighteen somites (VI to XXIII) are completely triannulate.
A curious feature of these (PL XLII., Fig. 3) is that the
relative lengths of the annuli differ dorsally and ventrally ;
above, a 2 is the largest, a 3 slightly less, and a 1 obviously
the smallest; below, a 2 is the shortest, and a 3 just appreci-
ably shorter than a 1. This is readily explained by compari-
son of the relative positions of the furrows. Along the margins
of the body is an exceedingly thin expansion, crenulated in
correspondence to the annuli. Set in the emarginations be-
tween successive lobes are narrow wedge-shaped pieces which
in the contracted leech assume the position of more or less
vertical folds uniting the dorsal and ventral furrows. When
the leech is extended these pieces of course become horizon-
tal, and the dorsal and ventral furrows assume the following
relative positions ; a S/a 1 is ventrally in advance of its dorsal
part, a l/a2 is ventrally slightly behind, and # 2/« 3 again
ventrally in advance. This lack of alignment characterizes
all furrows from about VI/YII to XXIV/XXV.

On the dorsal surface some very faint transverse wrinkles
pass between the principal papillae and are about equally
apparent on all of the annuli. Ventrally a 1 and a 2 may be
more or less divided, the portions toward the ends of the
somites being the smaller ; a 2 very rarely shows faint traces
of such a division. In this feature and in the rough cutaneous
papillae the species resembles Hcementeria officinalis.

The disposition of the papillae on a typical complete somite
is shown in the figure (PI. XLII., Fig. 3), and is as follows:
On the dorsal surface of each annulus are two rows of small
smooth sense papillae separated by the transverse wrinkles

490 Illinois State Laboratory of Natural History.

above mentioned and differing somewhat in size and distance
apart. They are generally single but here and there are
grouped in twos, threes, or fours. The number in a transverse
row counted singly or as groups is from thirty to fifty on the
middle region of the body. A few others may be scattered
between the rows or even form a third broken row between the
larger papilla?, particularly on a 3. Along the margins large
numbers may be aggregated. The large rough papilla? are
prominent wart-like elevations of the integuments, some of
which measure more than a millimeter in height in living
examples. They appear not to contract under ordinary stim-
uli, but are sometimes very much less elevated in preserved
material. They are generally conical in shape, their summits
bearing a ring of from four to twenty smaller sense papilla?
arranged around a central larger one. When the number is
greater than eight or nine they are likely to form a less regular
ring and to extend further down the sides of the wart, while the
central one becomes replaced by two or three. A relation
between the size of the wart and the number of papilla? in its
crown seems to exist. Of the median series (nip) that on a 2
is the largest and often bears twice as many sense organs as
that on a 1, which is the smallest. The next series counting
laterad (mdp) is always represented by a very large wart on
a 3, by a much smaller, frequently absent, one on a 1, and
on a 2 is replaced by a rathsr prominent but smooth papilla
which supports the dorso-median sensilla (md). This cannot
be confounded with the rough papilla?. The next important
series (dip) is made up of a large one on a 2, a smaller one
on a 3, and a very much smaller one or none on a 1. Just
external to the large one on a 2 is the dorso-lateral sensilla
(dl), which is somewhat elongated transversely and is litttle
elevated above the surface. At the margin are two rows
so imperfectly developed that they are probably better
described as a single irregular row (dmp) sometimes repre-
sented by two warts on a single annulus. Warts of smaller
size are generally present, but are more irregularly distrib-
uted than the fairly constant ones just described. They are
most frequent on a\, where one such is likely to be present

The Hirudinea of Illinois. 491

between the median and dorso-median rows, two between
the latter and the dorso-lateral, and two between this and
the marginal. A 2 sometimes bears one internal and one
external to the dorso-median sensilla. The marginal sensillaB
are small.

At the posterior end somite XXIII, though triannulate,
shows some peculiarities. The median papilla on a 2 is
much reduced in size or absent, and on each side of the
middle line appears a very large rough wart not represented
on" any of the anterior somites. In surface views no trace of
the dorso-lateral sensillse can be found, but it is suspected
that they have been raised to the top of the large warts just
described, where a truncated clear area is sometimes visible.
Annulus a 3 is somewhat shortened, but in all other respects
this somite is typical.

On XXIV the same features appear somewhat exaggerated ;
the papilla are as described for XXIII, and annulus a 3 is
distinctly smaller and mesially joined to a 2.

XXV, XXVI, and XXVII show successive steps toward a
simpler condition. The first is generally divided into two
annuli nearly or quite to the middle ; the second, for a greater
or less distance from the margin ; and the third, just at the
margin or not at all. In all of these cases the anterior
annulus is the larger and bears a rather large median wart ;
the peculiar pair of warts of XXIII and XXIV is wanting ;
and the reduction in size of all other warts leads to the
relatively greater prominence of the dorso-lateral series.

Reproductive Organs. — The genital organs differ in no im-
portant respect from those of P. parasitica. The only differ-
ence apparent in a number of dissections is that the prostate
cornua of this species are rather longer.

Alimentary Canal. — Only two minor characters in which
the digestive tract of this species differs from P. parasitica
need be mentioned : the pharyngeal glands have no median
annectant lobe; and the cseca are less finely and numerously
divided.

Color. — The colors of living examples of this species gener-
ally impress one as a pepper-and-salt mixture of various

492 Illinois State Laboratory of Natural History.

light and dark browns, yellows, and greens, which, owing to
the translucency of the integuments, are seldom sharply
defined. They appear to be more definite on preserved
specimens, and certain metameric features and resemblances
to the plan of coloration of P. parasitica are recognizable.
The light marginal spots are present with the same regularity
as in that species. The light median stripe may usually be
distinguished at the anterior, and less frequently at the
posterior, end. It is constricted or quite interrupted by the
dark color of the neural annuli, which encroaches on it,
while in the intervals between them the light color extends in
narrow bands more or less laterad. In the middle region of
the body short longitudinal median brown or brownish green
lines alternate with light spots. The former correspond to
the constrictions, the latter to the expansions, of the median
stripe of P. parasitica. Sometimes there is a very distinct
continuous narrow median dark brown line. The rest of the
dorsal surface is generally variegated browns, with the
papillte light yellow or green and the position of the dorso-
lateral sensillae indicated by rather large and conspicuous
light spots.

Habits. — A species of sluggish habit; abundant in running
waters, where it is found clinging to the under sides of stones.
It also attaches itself to the under side of floating wood in
ponds and ditches. Particles of mud cling to the mucous
secretion on the body and render it inconspicuous, and the
leeches frequently bury themselves partially beneath the
sediment at the bottom. They seldom swim, but creep along
the surface to which they are attached. If thrown into the
water they roll up and sink to the bottom. They carry
the eggs or young in early spring, a habit which is common
to most members of the family.

The Hirudinca of Illinois. 493

Glossiphonia Johnson.
Glossiphonia complanata (Linnaeus) Johnson.

Hirudo complanata Linnaeus (1758).
Clepsine elegans Verrill ('74).

Diagnosis. — Somites I to IV each uniannulate, II and III
often imperfectly separated and IV sometimes faintly subdi-
vided ; three separate pairs of pigmented eyes in somites II,
III, and IV, the first pair commonly crossed by the furrow
I-I/III ; V is biannulate ; male pore at XI/XII, female pore at
XII a 2/ a 3 ; dorsal cutaneous papilla? low and inconspicuous,
principally in four series, no median series; epididymis
folded into a long loop which reaches into somite XVIII or
XIX; nine pairs of testes (XIV to XXI).

This is a species well known in Europe, of which figures
may be found in Moquin-Tandon ('46, Plate XII.), and dia-
grams of the annulation and a description in Blanchard ('96),
while Verrill describes the colors of American specimens.
It abounds in certain localities under stones in running water,
is very active but rolls itself into a ball when disturbed, and
feeds chiefly on small snails and annelids.

Glossiphonia lineata (Verrill).

Clepsine papillifera, var. lineata Verrill ('74).
? Glossiphonia triseriaUs E. Blanchard ('49).
? Helobdella triseriaUs R. Blanchard ('96).

This species is almost certainly G. triseriaUs, and I hesitate
to give it that name only because E. Blanchard ('96) has
stated that the male pore of his specimens is situated at
23/24 (XI/XII) instead of one annulus further caudad as in
the form here described.

Diagnosis. — Somites I and II uniannulate, III and IV bian-
nulate, and V triannulate ; the single pair of very large eyes
situated in IV; male pore at XII al/a2, female pore at XII
a%/a 3 ; dorsal cutaneous papilla? conspicuous (owing to black
color), generally in three (sometimes in five) longitudinal

494 Illinois State Laboratory of Natural History.

series, of which the median is the best developed ; epididymis
forming a loop which reaches into somite XV.

General Description. — A small species seldom over half
an inch in length, but capable of moderate extension. In
the resting state broad and slightly convex above but not
foliaceous, the body being rather thick ; when extended,
strongly convex.

The anterior sucker is of moderate size and has a rather
thick margin into which the annulations extend. It is deeply
concave and presents no central elevation. The mouth is
large and situated just behind the anterior rim of the sucker,
apparently in somite II. Occasionally it is succeeded by a
transverse fold. The eyes, of which there is a single pair,
are of remarkable size, their diameter being nearly equal
to the length of annulus IV {a 1+a 2) in which they lie. They
are simple and correspond to the second pair of G. complanata.
The genital pores are separated by but a single annulus, the
neural annulus of -somite XII ; they consequently both lie
within the limits of that somite.

The posterior sucker is large but relatively little exposed,
elliptical in form, and with a thick margin. It reaches for-
ward to XXIII a 2.

Annuli and Somites (PL XLIL, Fig. 6). — I and II are
uniannulate and constitute the undivided anterior lobe.

III is biannulate, the anterior ring being somewhat the
larger. No sensillre are visible in surface views, but sections
show that the eyes are derived from this somite.

IV is biannulate, but the anterior annulus is relatively larger
and is faintly subdivided; it bears the very conspicuous pair
of eyes. At the margin this somite becomes uniannulate
and forms the posterior rim of the sucker.

V is triannulate above. y!2 is much longer than a 1,
especially mesially, where it appears to be almost subdivided.
The furrow a 2/a 3 is the deepest in this neighborhood and
defines the posterior limits of the head very sharply. Ven-
trally a 1 and a 2 unite while a 3, as usual, remains distinct.

VI is the first of the fully triannulate somites, and all three
annuli are distinct ventrally as well as dorsally. In all of the

The Hirudinea of Illinois. 495

complete somites a 2 is somewhat wider than its fellows,
dorsally at least, and is rendered further conspicuous owing
to the papillae which it alone bears, its slightly protuberant
margins, and the white spots which characterize it.

The arrangement of the cutaneous papillae, though variable
in detail, is very characteristic of the species among local
forms. But three constant and conspicuous series exist
(PI. XLIL, Fig. 6) ; a median (mp) and a pair of dorso-
laterals (dip) situated nearly half-way to the margins. The
median series begins sometimes as far forward as somite
VI or VII, but seldom becomes prominent before IX or X,
from which it continues to XXVI. This is really not a strictly
median series, as the papillae comparatively seldom lie exactly
in the median line but usually a little to the right or the left.
Very frequently the single conical papilla is replaced by two
which are placed more or less close together, in contact or even
united into a bilobed or a transversely elongated one. The
whole appearance of the series must lead one to recognize its
dual character. All of these papillae are prominent, sharp-
pointed, simple cones, whose black color amid white or pale
surroundings renders them doubly conspicuous. They are
largest in the middle of the series and diminish toward the
ends, that on XXVI being very small and some of the
anterior ones minute.

In every important feature the dorso-lateral series is
similar to the median. The papillae begin further back and
are seldom conspicuous anterior to XIII, from which point
they continue to XXVI or XXVII, the last two or three being
small. They are somewhat smaller than the median ones
and are more likely to be absent from a somite. Though
forming a nearly perfect series anteriorly, they present an
even greater tendency toward irregularity and doubling
posteriorly.

Occasionally one or two isolated papillae are found between
the median and dorso-lateral series, and remnants of a very
imperfect supra-marginal series occur more frequently on
several of the posterior somites. Very few and faint papillae
occur on the sucker. The dorsal surface of the body

496 Illinois State Laboratory of Natural History.

is everywhere roughened by projecting cutaneous sense
organs.

The anterior metameric sensillfe (PI. XLIL, Fig. 6) are very
difficult to make out in surface views, but about X or XI they
become very conspicuous and continue so to the posterior end.
Here they appear as eight dorsal series of clear white spots.
The dorso-medians (md) are placed on each side of the median
papillae, separated by a distance about two thirds of that which
intervenes between them and the dorso-laterals. The latter
(dl) are just about half-way between the mesion and the
margins, or a trifle nearer to the latter, and consequently are
external to the dorso-lateral papillae. The dorso-marginals
{dm) are well back from the margins, being about as far from
the dorso-laterals as are the dorso-medians, except on the
incomplete somites, where the former distance is less. The
supra-marginals (sm) are very minute and on the exact
margins as viewed from above, except on the incomplete
posterior somites, on which they are somewhat removed from
the margins. The ventral sensillse have not been studied.

Reproductive Organs. — In most respects resembling the
species of Placobdella the reproductive organs differ from
theirs and resemble those of G. complanata in one important
feature : the enlarged portion of the sperm-duct (epididymis
and ductus ejaculatorius), instead of simply coiling up, extends
caudad in a long straight loop which lies ventrad to the gas-
tric caeca and reaches at least as far as ganglion XV.

Alimentary Canal. — The proboscis is of relatively much
greater diameter than in the two species of Placobdella
described, and the gastric caeca are of small size and scarcely
lobed. There are but six pairs of these caeca, which increase
in size caudally, and the first of which (in XIV) is rudi-
mentary or sometimes absent. In all of these respects this
species is intermediate between G. complanata and G.
stagnalis.

Color. — The colors are here described from preserved
material. They are very simple and effective. Below, a
plain ash-color; above, the same color marked by eleven or
twelve longitudinal stripes of brown which are further com-

The Hirudinea of Illinois. 497

pounded of narrow brown lines, the number of which varies
according to the width of the stripe. The longitudinal stripes
correspond with the arrangement of the musculature as
described for other species by Graf ('99). On many speci-
mens these stripes are more or less interrupted on «2 of each
somite by transverse whitish spots which occur almost con-
stantly in two, four, or six longitudinal series, of which the
most constant lie just external to the dorso-lateral papilla?,
the next on the flanks of the median papilla?, and the third
near the margins. The extreme of this arrangement results
in a handsome metameric pattern in which a 2 becomes con-
spicuously marked by a row of white spots which on the
posterior somites unite to form a band. In such specimens
the ground color becomes a pale brown marked by numerous
narrow dark brown or almost black lines, of which a pair
near the middle line are very conspicuous. The white spots
are least developed anteriorly, but become more extensive
and closer together posteriorly. Individuals differ greatly as
to the exact manner and extent of the complementary develop-
ment of light and dark elements in the pattern. The entire
preocular region is beautifully white, while brown rays on a
white ground mark the sucker.

Habits. — In habits G. lineata resembles G. complanata, with
which it is frequently found. Probably this species inhabits
colder brooks than any other of our glossiphonids.

Glossiphonia stagnalis (Linn^us).

Hirudo stagnalis Linnaeus (1758).
Hirudo bioculata Bergmann (1757).
Clepsine modesta Verrill ('74).

Diagnosis. — Somites I to III included in preocular region ;
single pair of eyes on anterior annulus of IV, which is
obscurely biannulate ; V biannulate ; VI to XXIV triannu-
late ; XXV and XXVI biannulate, the latter somewhat united
to XXVII ; genital orifices as in G. lineata ; a dorsal chitinoid
glandular bursa situated at VIII a 1/a 2 ; gastric cseca small,
simple, variable, never more than six pairs, of which any or
all of the first three may be absent ; size small and form con-

498 Illinois State Laboratory of Natural History.

vex, capable of great extension ; no papilla? nor conspicuous
markings.

This widely distributed species is figured by Moquin-Tandon
('46, PL XIIL, Fig. 16-26), and the annulation of the
anterior end by Blanchard ('96).* The species is exceedingly
abundant everywhere in the shallow waters of rivers, lakes,
and ponds, in small streams, pools, and ditches, in fact
everywhere where comparatively warm shallow fresh waters
are found. It is found clinging to the under sides of stones,
and between the ensheathing leaf stalks of aquatic plants,
fallen leaves, etc. When disturbed it creeps actively to a
place of concealment. The favorite food is small annelids
and gastropods, but blood is also taken from injured fish,
frogs, etc. The breeding season lasts all through the spring
and early summer.

HEMICLEPSIS \tEJDOVSKY.

Hemiclepsis carinata (Yerrill).

Clepsine papillifera, var. carinata Yerrill ('74).

Diagnosis, — Somites I and II rather distinctly biannulate ;
the single pair of eyes on III ; the widely expanded head
pedicellate on a wide pedicle formed by VI ; annulus a 3 of
complete somites much larger than a 1 or a 2 and unequally
subdivided at the margins ; the dorsum bears three prominent
papillated keels; the epididymis and ductus ejaculatorius
form a few simple coils in XI and XII.

General Description. — A medium-sized glossiphonid of
striking appearance. It seldom reaches a length of more
than one and one half inches when partially extended in the
act of creeping. The shape of this species is entirely char-
acteristic among known Illinois leeches. In the large size,
distinctness, free margin, and pedicellate attachment the head
resembles that of the Ichthyobdellida. The body is more slen-

* By far the best description of this species extant has recently been published by
Castle, in Bull. Mus. Conip. Zool., XXXVI. (1900), pp. 21-33.

The Hirudinea of Illinois. 499

cler and less flattened and foliaceous than in other glossiphon-
ids of equal size. It is never very wide and depressed, but on
the contrary rather strongly convex dorsally. Capable of
great extension and contraction the body may become very
slender, especially anteriorly, or short, thick, and elliptical,
and very convex above. In both states the head stands out
clearly and sharply as a distinct region. This is an excellent
character for distinction from the other leeches described
in this paper.

Viewed from above the head is very broadly cordate, the
bluntly rounded apex being anterior. Below, the very free
posterior margin is entire and slightly convex or straight.
This margin appears to be formed by the very strong down-
ward and backward development of V, which becomes much
enlarged below and whose ventral sensillre are visible on the
lateral parts of the posterior margin of the sucker. Dorsally
the surface of the head or sucker is strongly annulated. At
the margins the annuli are supplemented by a narrow but
distinct undivided rim. The ventral surface is smooth, with
sometimes two or three faint transverse furrows. -Just inside
of the anterior border is the small mouth, apparently in II.
The labial sense organs are exceptionally well developed
around the entire margin of the sucker.

The posterior limit of the head is clearly defined both above
and below by the furrow V/VI. This is followed by two small
annuli (which are regarded as a divided VI al) which form
a short neck embraced anteriorly and concealed below by
V a 3. Ventrally they become still smaller and perhaps
united. Posterior to this point the body increases rapidly in
width and the posterior part of VI is equal to IV, the widest
part of the sucker.

The most striking characteristic of the species, however,
is the presence of three prominent carinse which extend from
just behind the head to the posterior sucker. These are
formed chiefly of high and closely appressed papillae, the tips
of which produce a sharp erect serrate crest.

There is no true clitellum, and the genital pores have the
usual situations at XI/XII and XII a Z/a 3. Sixteen pairs of

500 Illinois State Laboratory of Natural History.

nephridiopores have been determined on somites VIII to
XXIII inclusive.

The posterior sucker is exactly circular, with a finely but
distinctly denticulated margin. It is, though not of large
size, widely exposed behind, and reaches anteriorly to XXIII
a\. Its pedicle of attachment is unusually small, permitting
great freedom of movement.

Annuli and Somites (PL XLIL, Fig. 5). — I forms the apex
of the head and is divided dorsally into two small rings by a
cross- wrinkle.

II is quite distinctly biannulate and bears evident dorso-
median and dor so-lateral sensillre.

III consists of two large annuli, of which the anterior is
slightly divided by a faint cross-furrow which is confined to
the median region. It bears the eyes, which are separated
by a space about equal to their own diameter, and three pairs
of sensillae, one of which is remarkable by reason of its
position directly above the eyes. Sections of this species
have not been studied.

IV closely approaches the triannulate condition, a 1 having
very nearly the typical relations. Three or sometimes four
pairs of sensilla? are easily discernible.

V. This somite presents several interesting features. It
consists of two annuli of about equal size, both enlarged at
the margins, where the anterior one is somewhat divided into
a 1 and a 2. Three pairs of sensillse are present on a 2, but the
dorso-medians are wanting, while on a 3, almost directly
behind the dorso-laterals, appear what seem to be an extra
pair of these sense organs.

VI is also peculiar in that al is completely divided on the
dorsal side into two small annuli which appear as one
ventrally.

VII is fully triannulate and the annuli present the typical
proportions. ^41 is the smallest, a 2 intermediate, and a 3
the largest. A 1 and a 3 exhibit shallow ventral furrows across
their entire width, and the furrow of a 3 continues on to the
dorsal side, from the margin almost to the dorso-lateral
carinas It cuts the annulus posterior to the sensillre. XXII,

The Hirudinea of Illinois. 501

the last triannulate somite, lacks this subdivision, but it exists
on all other complete somites.

XXIII, in addition to the differences of papulation already
mentioned, shows peculiarities in annulus ad, which is the
smallest of all and is differentiated from a 2 at the margins
only.

On XXIV the complete individuality of all three annuli is
suppressed, their boundaries being evident only at the
margins. On XXV only the marginal notches a 2/a 3 are
indicated.

XXVI and XXVII are uniannulate and contracted to form
the supporting pedicle of the sucker.

The arrangement of the papilla: is as follows : The median
series (mp) begins in small isolated papillae of about equal
size, usually on VI a 2 and a 3. By about IX they are well
established on all three annuli, a 3 bearing the largest, a 2
the next in size, and a 1 a very small one, and this relative
size is maintained throughout the series. A few somites
caudad they are higher, more prominent, crowded, and
elevated on a ridge. Nearing the posterior end the ridge
increases in height and the papilla on a 2 and a 3 increase in
size, but the crowding becomes relieved and the papillae on a 1
smaller or more frequently absent. Both the ridge and its
papilla: cease completely and abruptly on XXII a 3.

The paired carina? (dip) are slightly nearer to the margins
than to the middle line. In essentials they are precisely
similar to the median one, but present the following special
features : the carina? as a whole are slightly less prominent ;
they require a greater distance in which to become fully
established, i. e., the papillae are not supported on a con-
tinuous ridge, nor present on every annulus until about
XII or XIII ; scattered papilla? of small size are found on a 1
and a 2 as far forward as VI, but they are very small ; in the
region of full development the papilla on a 2 is by far the
largest of this series and generally larger than any of the
middle series, and the papilla on a 1 is very small and
frequently absent, especially in the posterior region. The

502 Illinois State Laboratory of Natural History.

last papilla of the series is on XXII a 3 and is displaced
slightly mesiad.

On somites XXIII to XXVI the carina? are absent and are
replaced by four pairs of large papilla?. These form two
short series which if continued forward would pass midway
between the median and lateral carina?. The first pair,
situated on the larger annulus of XXIII, is the largest, the
next somewhat smaller, while the others diminish rapidly
and converge posteriorly. Very minute papilla? may occur
on the preanal somite.

All of the papilla? enumerated are of prominent conical
form, sharp-pointed, and high. Their summits bear a con-
tractile apex, which in some cases is almost filiform in exten-
sion, in others short truncate in contraction. Around the
base of this appendage a few smaller points may be clustered.

In addition to those more prominent papilla? which have
been described, a more or less complete irregular series of
small papilla? forms a dorso-marginal line, external to which
a few are scattered along the margin and a still smaller
number on the internal side. None of these are ever elevated
on a ridge.

The metameric sensilla? have the following positions (PI.
XLIL, Fig. 5 ). The dorso-medians (md) are just a little way to
the mesial side of the middle of the area between the median
and the dorso-lateral carina?, and are quite easily traced as
far forward as II. A curious* circumstance which requires
investigation is that a pair appears to lie on the integument
directly above the eyes. In the middle body region the
papilla? of this series are slightly elevated and they are every-
where the most conspicuous. The dorso-lateral sensilla1 (dl)
are almost as evident on the head as the dorso-median, but
much less so on most of the body somites. They are just
external to the large papilla? of the dorso-lateral series, but
after the suppression of their guardian .papilla^, on XXIII,
they stand out much more prominently in their isolation.
The dorso-marginals (dm) become visible on III and continue

♦Inasmuch as the eyes seem to be the representatives of the dorso-median sensitise
of somite III and to have undergone no shifting.

The Hirudinea of Illinois. 503

distinct to XXV, on which latter they approach very close to
the dorso-laterals. By the fusion of the sensillre of these two
series on XXVI and XXVII but three pairs remain. Very
minute supra-marginals (sra) are also present on most of the
annuli. Near the margin of the sucker one or two very
regular circles of eight sensillse are ranged.

Reproductive Organs. — The six pairs of testes are in the
anterior ends of somites XIV to XIX, extending somewhat
into the preceding somites. The enlarged region of the
sperm-duct (epididymis and ductus ejaculatorius) forms a
coil or two, and its full length when extended laterally
scarcely reaches to the margin of the body at the male pore.
The prostate cornua are short and wide. The anterior and
dorsal lobe of the ovary, which represents the closed end of
the sac, is large and prominently projecting.

Alimentary Canal. — Pharynx slender and very extensible,
its glands small. The same number and general arrangement
of the gastric caeca as in P. parasitica are found in this species,
but they are much less subdivided and branched.

Color. — The colors of this species are generally dull and
uniform. Very commonly the entire body is a light or darker
green or brownish green with a few flecks or lines of deep
green and an obscure pale yellow border. Sometimes the
pattern is more definite, as in the following case : The entire
central region of the dorsum is of a brownish green color
which on the neural annuli extends to the margins in the
form of narrow sharp-pointed projections, by which a series
of large yellow marginal spots are separated from one another
and thus barely escape forming a continuous yellow border.
Six or seven elongated light yellow spots form a median series
and alternate with short dark greenish brown longitudinal
lines. Smaller, more or less confluent light yellow spots mark
the lateral carina?. The head is marked by an irregular green-
edged dark brown "spread eagle" figure, which leaves a large
anterior and a pair of posterior lateral light spots.

Habits. — This species to a great degree lacks the social
instincts of most glossiphonids. A far larger number of
specimens are found singly than in company. In the neigh-

504 Illinois State Laboratory of Natural History.

borbood of Philadelphia they are most frequently found in
meadow brooks, adhering to stones, or attached to frogs and,
during the spring, to toads. They frequently enter the shells
of living mussels, which they probably attack. During the
spring at least they are voracious blood-suckers, and along
the Delaware Eiver congregate at points where fish are
cleaned and the waste thrown into the water.

ICHTHYOBDELLID^.

The collection contains several specimens of a small
species of Piscicola and another probably of Piscicolaria,
both parasitic on several species of small fishes. The
material is not sufficiently well preserved to permit of
determination or description. This family is further repre-
sented only by

ACTINOBDELLA gen. nov.

Generic Characters. — The head small, not explanate ; the
posterior sucker large, hemispherical, with a marginal circle
of slender processes ; the complete somites with six secondary
annuli of unequal size.

Actinobdella inequiannulata sp. nov.

Diagnosis. — A median series of papillae on annuli b 3 and
b 5 ; annulus b 5 the longest, b 4 the shortest, in complete
somites; male orifice at XI/XII, the female at XII b4;
acetabular papillae about thirty, provided with adhesive
glands.

General Description. — The single specimen representing
this species is of small size ; the total length is 9.7 mm., the
greatest width 1 mm., and the diameter of the posterior
sucker about 1.8 mm. The sexual organs are very incon-
spicuously developed, and it is possible that the species may
reach a somewhat larger size.

The form is slender (PI. XLIII., Fig. 8), with the margins
of the body parallel for almost its entire length, but suddenly
contracted posteriorly to constitute the narrow pedicle of

The Hirudinea of Illinois. 505

the conspicuous sucker, and gently tapering anteriorly to the
broadly rounded upper lip. Depressed throughout, with the
dorsum convex and venter flat ; the margins somewhat sharp.

There is no expanded anterior sucker (PI. XLIII., Fig. 8)
or head as in typical ichthyobdellids, but this end of the body
is formed like a glossiphonid or, excepting the character of
the mouth, more like a nephelid. The lip is broad and
rounded and in this example is turned in ventralward. On
the dorsal side it is divided into annuli as described under
the caption Annuli and Somites. The ventral surface pre-
sents a very deep cavity from out of which rises a prominent
rounded elevation, near the summit of which the pore-like
mouth is situated. The posterior boundary of the sucker is
formed by somite V. No pigmented eyes can be detected, but
an opaque spot on the third and fourth rings may possibly be
eyes, though appearing more like a gland.

No clitellum is developed. The male genital orifice (PI.
XLIII., Fig. 8, cf) is a minute pore situated in a transversely
extended elliptical disc at XI/XII ; but on the ventral side
the annuli XII 6 1 and b 2 are obsolete and the male
disc therefore somewhat overspreads annulus b 3. The female
pore (?) is in the form of a small transverse slit in annulus
XII 1)4 and, owing to the great reduction of b 1 and 6 2,
appears to be separated from the male opening by only one
and one half annuli.

Most remarkable of all of the external features of this
leech is the posterior sucker (PI. XLIII., Fig. 8-10). It is
much wider than any part of the body, of hemispherical
form, largely free on all sides, and supported by a narrow
central pedicle. The ventral surface (PL XLIII., Fig. 10) is
very deeply cupped, and in the specimen described the rim is
somewhat contracted, making the diameter of the opening
somewhat less than that of the internal cavity. From the
inner face of the sucker, a short distance back from the sharp
margin, spring about thirty (exactly thirty in this example)
slender finger-like processes, which project more or less
freely into the cavity. Owing to their contractile nature
they may vary in length and diameter, but when extended

506 Illinois State Laboratory of Natural History.

are about .4 to .5 mm. in length and perhaps .1 in diameter.
Each one (PI. XLIII., Fig. 11) contains a central gland duct
or perhaps a group of ducts surrounded by a sheath of
muscle fibers springing from muscular ridges which pass like
radii down the inner face of the sucker. The gland ducts
arise from a circle of glands which appear as a ring of whitish
spots arranged around the sucker about half-way between
the margin and the pedicle, and which raise the outer face
into a slightly marked encircling ridge. The anus is incon-
spicuous and appears to be situated in the usual position
posterior to somite XXVII.

Annuli and Somites. — It is obviously unsafe to assign to a
species all of the details of annulation exhibited by a single
specimen. The arrangement of the annuli in certain regions
is so obscure and appears so differently under different con-
ditions of fixation and preservation, and, moreover, is so sub-
ject to individual variation, that the typical conditions in
many species can be determined only by the careful study of
many individuals. What follows, therefore, must be con-
sidered as applying in entirety only to the type specimen.
The characters of the complete somites and the composition
of most of the incomplete somites will in all probability be
confirmed by the study of further material.

As the type specimen is interpreted the somites are consti-
tuted as follows (Fl. XLIII., Fig. 8, 9) :—

I to IV are uniannulate and the furrows which separate
the first three annuli are faint. No sensillre are recognizable.

V, VI, and VII are biannulate, with three pairs of
distinct sensillre on the first annulus of each. In each case
the second annulus is somewhat the larger.

VIII is triannulate, and a 3 is somewhat larger than its
fellows and subdivided by a faint furrow. The sensillse are
on « 2.

On IX we find a 1 subdivided equally into b 1 and 6 2 by a
shallow furrow, a 2 more distinctly split into a larger anterior
and a smaller posterior ring, of which the former bears the
three pairs of sensillre, and a 3 subdivided equally.

X is similar to IX except that 6 5 is considerably larger

The Hirudinea of Illinois. 507

than b 6 and the secondary furrows are more nearly equal
to the primary.

XI is a typically complete somite and presents characters
which are found with some slight individual variations as far
back as XXIV inclusive. In all of these the annuli are very
clearly indicated both on the dorsal and ventral surfaces.
A 1 is divided equally into b 1 and b 2, which are quite short
rings unmarked by any papilla ; a 2 is very distinctly divided
into a long 63, which bears a large median cutaneous papilla
and the three pairs of metameric sensillse, and a 6 4, of half
the size or less, which is the smallest anuulus of the somite
and bears no papilla? ; a 3 is cut into b5 and 6 6, of which
the former is the largest annulus of the somite, both in length
and breadth, and which bears a large papilla similar to that
on b 3, while b 6 is a simple unadorned ring equal to b 1 or
b 2. Thus each complete somite is divided into six annuli of
unequal size, and, leaving out of sight the limits of the
somites, this region of the body exhibits a regular alternation
of groups of three equal small rings with groups composed
of two large rings separated by a very small one. Each
of the large rings is marked by three cross ridges which
appear to be due to transverse muscle bands, while the
narrow rings present only two such ridges, b 4 sometimes
only one ridge.

The cutaneous papillae (PI. XL 1 1 1., Fig. 8) are rather con-
spicuous conical elevations with the long axes of their ellip-
tical bases directed longitudinally. In the middle region they
are strictly confined to the annuli indicated, but posteriorly
somewhat overlap the succeeding secondary annuli. On
other specimens they will probably be found to begin further
forward than on the type, as opaque thickenings of the integu-
ments appear in the proper regions of somites X and IX,
though there are no elevations.

Of the dorsal sensilke (PI. XLIIL, Fig. 8) the supra -
marginals cannot be distinguished, but the dorso-marginals
(dm), dorso-laterals (dl), and dorso-medians (md) are obvious,
and are very regularly arranged on all somites from V to
XXVI. Peripherad of these points they have not been traced.

508 Illinois State Laboratory of Natural History.

The distances separating the two dorso-medians and the dorso-
laterals from the dorso-marginals are about equal and some-
what less than that between the dorso-medians and dorso-
laterals.

XXV exhibits very much less distinct secondary furrows,
the annuli all of about equal size, and the somite prac-
tically triannulate. This is also the last somite to bear
distinct papillae.

XXVI is strictly triannulate, with the sensillae on a 2,
but lacking any distinct papillae and secondary furrows. In
the figure, XXVII is represented as divided into three narrow
rings, but owing to a distortion of this region it is quite im-
possible to make a satisfactory determination. In some
lights and positions there appear to be three rings here, in
others two, and two drawings made at different times and
independently illustrate the two interpretations.

The color has faded to a uniform gray. Nothing of the
internal organization could be learned by studying the speci-
men, either stained or unstained, in various clearing media,
and consequently this description leaves much to be desired.
The position of the ganglia and lateral nerves was deter-
mined by a partial dissection of the mid-ventral region of
two somites.

HIRUDINTD.ffi.
Macrobdella Yeerill.

Macrobdella decora (Say) Verrill.

Hirudo decora Say ('24).
Hirudo decora Leidy ('68).

Diagnosis. — Copulatory glands opening by four pores
arranged in a quadrate figure on XI I lb 6 and XIV b 1 and /; 2 ;
male pore at XI/XII or XII b 1, female, at XI I/XI 1 1 or XIII 6
1 ; somite XXVI has annuli (a 1 -j- a 2) + a3 ; annuli VII a 3
and VIII a 1 relatively large and partly subdivided dorsally ;
atrium short and spherical ; alimentary canal with exten-
sively developed caeca; denticles small, about 65 on each jaw,
and monostichodont ; color pattern metameric.

The Hirudinea of Illinois. 509

General DescrijJtion. — This fine leech is so well known and
has been so fully described by Say ('24), Leidy ('68), Verrill
('74), and Brooks ('82), that only a few notes on certain
features need to be added.

The anterior sucker is provided with a rather wide unseg-
mented and very mobile border which materially increases
its capacity for expansion. Anteriorly a distinct median
emargination corresponds with a deep ventral sulcus, which
divides the upper lip and is flanked by a pair of scarcely less
deep sulci. When strongly contracted the upper lip is folded
and turned into the buccal chamber, where it is almost
entirely concealed by the lateral lobes formed by the margins
of somite IY.

A well-marked clitellum is seldom present. In one example
it is firm and thick and extends over eighteen annuli, from
the posterior half of X b 5 to XIV b 2. In the fully retracted
state the male pore appears as a rather large opening on the
furrow XI/XII, into which the surrounding rugosites are
converged and inflected, forming a small sinus perhaps com-
parable with the pit of Philobdella. These inflected parts
may be everted, in which event they form a prominent conical
organ having deeply fluted sides and the small male aperture
at the apex. As protrusion of the parts takes place annulus
XII b\ becomes relatively longer at the middle and comes
to support almost the entire base of the papilla, so that the
male pore now lies well within the boundaries of this annulus.
I have never seen any other penial organ protruded.

When fully developed each of the four copulatory gland pores
lies in the center of a prominent rugous area, the four being
arranged in the form of a square. The anterior pair extends
half over annulus XIII b6 and equally over XIV bl, and
the posterior pair holds a similar relation to XIV b 1 and £2.
The pores consequently open on the line of the furrows
separating these annuli.

Annulation. — The external annulation differs but slightly
from the closely allied species M. sestertia, figured by Whitman
('86). The principal differences (characters stated as they
occur in M. decora) are as follows : 1. The annulus IV (a 1 -+-

510 Illinois State Laboratory of Natural History.

a 2) — that bearing the third pair of eyes — is distinctly longer
than IV a 3, and in some examples the furrow al/al is
more or less distinctly discernible. 2. The annuli VII a 3
and VIII a 1 are relatively very much longer, and on the
dorsal side the secondary annuli and furrows are distinctly
developed. 3. XXVI a 1 is always marginally and some-
times completely separated on the dorsal side from a 2.
4. The relative lengths of the annuli of complete somites
differ in the two species. In M. sestertia the neural annulus
(a 2) is figured as of equal or greater size than the secondary
annuli, while in M. decora it is typically shorter than any of
these in the same somite.

Reproductive Organs.— Testes (PI. XLIV., Fig. 23, t)— ten
pairs, situated at XIII/XIY to XXII/XXIII inclusive. The
vasa deferentia (vd) are glandular, and follow sinuous courses.
In somite XI they become narrow and lose their glandular
coating. Opposite to ganglion XI they turn abruptly into
the compact, massive, much convoluted epididymes (ep).
From the posterior end of each of the latter a wide somewhat
folded and coiled ductus ejaculatorius (de) leads to the term-
inal organ. Just before plunging into the outer glandular
and muscular wall of the latter the ducti become constricted,
and then form a pair of slightly enlarged sacs which proceed
upward side by side to open together into the end of the male
invagination (PI. XLIV., Fig. 22). This terminal male organ
(PI. XLIV., Fig. 23), which is evidently intermediate in its
structure and character between the atrium of H<emopis and
the genital pit of Philobdella, is, when entire, spherical in
shape ; but when its external coat of muscle fibres and pros-
tate glands (pg) is stripped off, the lining sac is found to be
somewhat pyriform (ati).

The ovaries (PI. XLIV., Fig. 23, ov) are large and globular,
situated just behind ganglion XII, and ventral to the nerve
cord. Short paired oviducts (od) unite in a common oviduct
(ode) without any evident gland at the point of junction.
The vagina (va) is short, of irregular diameter, and bent on
itself.

The copulatory glands (PI. XLIV., Fig. 23, egl), the external

The Hirudinea of Illinois. 511

openings of which have been described, form a conspicuous
mass occupying the posterior half of XIII and the entire region
of the floor of XIV included between the vasa .deferentia.

Alimentary Canal. — The jaws differ greatly from those of
Philobdella and resemble those of Hirudo ; they are more than
twice as long as high and each bears about sixty-five fine
monostichodont teeth. The remainder of the canal is very
like that of Diplobddla. Each somite from X to XVIII
inclusive is provided with two pairs of caeca which are very
spacious from XIII caudad. The large posterior pair, which
arise from the stomach in XIX, reach backward clear into
XXIV or XXV.

Habits. — Macrobdella is probably strictly aquatic and is a
true blood-sucker. It attacks man, cattle, turtles, frogs,
fishes, etc., which enter its domain, and is frequently found
gorged with blood. However, this is not its exclusive food.
In the spring great numbers of frogs' eggs are devoured. In
the neighborhood of Philadelphia these are sucked from the
masses of jelly after the gelatinous envelopes have been cut
by the leech's teeth. Large numbers of tubificid worms
have also been found in the caeca. Whitman ('86) gives an
account of the sensory reactions of this species.

Philobdella Yerrill.
Philobdella gracile sp. nov.

Philobdella floridana Moore ('98), not Verrill ('74).

Diagnosis. — Copulatory gland pores in two nearly counter-
part groups related respectively to the male and female
genital orifices ; male pore at XII b 2 fa 2, in mature examples
opening into a conspicuous deep pit, female pore at XIII b 1 ;
alimentary canal of Hmnopis type, the denticles about 35,
partly distichodont ; annulation essentially as in Hamopis
marmoratis; color partly non-metameric blotches.

512 Illinois State Laboratory of Natural History.

General Description. — The largest extended specimen has

the following measurements : —

mm.
Total length, . . . . . . . .84.

Length to male pore, . . . . . . 19.

Greatest width (about XX), . . . . .7.8

Width at male pore, . . . . . . 7 .

Width at anus, . . . . . . 3 .

Depth at XX, . . . . . . . 2.5

Depth at male pore, . . . . . .2.8

Depth at anus, . . . . . . . 1.5

Diameter of posterior sucker, . . . . .4.3

This is a very pretty leech of moderate size and slender
graceful form. The preserved specimens are depressed
throughout, except just posterior to the mouth, the ventral
surface is flat, the dorsal gently convex, with an evident
tendency to rise to a rounded median ridge. In some exam-
ples the middle two thirds, or so, of the body remains of
nearly uniform width; in others the outline tapers gently and
regularly from the place of greatest width forward to the
mouth.

Probably the body of the living leech has a texture about
like Htsmopis lateralis, as the muscles and botryoidal tissue
display a similar relative degree of development. Except for
a few wrinkles and the very slightly elevated sensitise the
surface is quite smooth.

All of the annuli are clearly marked by smooth even fur-
rows, but owing to the absence of any well-marked transverse
ridges they are not angulated and the margins of the body do
not appear denticulate. Most of the annuli, however, do
show a faint incipient transverse furrow, dividing them into
approximately equal halves, the posterior one of which may
be marked by a very faint raised line.

As in Hirudo, but unlike Hcemopis, there is a distinct very
narrow unsegmented margin or border to the anterior sucker
(PI. XLIV., Fig. 13), which is separated on the ventral side
by a shallow trench from the actual mouth rim. The mouth
and sucker are small. A median sulcus divides the ventral

The Hirudinca of Illinois. 513

surface of the upper lip deeply into two halves, hut fades out
posteriorly ; at least one fainter sulcus appears on each side.
Somites I-IV constitute the lip and sucker, and the united
annuli of V form the postoral annulus.

The five pairs of eyes (PL XLIV., Fig. 12, 19) present
the arrangement usual in the family, except that the second
and third pairs are closely approximated, owing to the posi-
tion of the latter very close to the anterior border of somite
IV. The fourth pair also is somewhat in advance of the line
of sensillge.

No specimens have been seen in 'which the clitellum is
sufficiently developed to permit of the determination of its
form and extent.

As Verrill ('74) long ago pointed out, the external genital
region (PI. XLIV., Fig. 16) is very remarkable; in some
respects, indeed, unique among known leeches. This is true
not only of the elaborate adhesive arrangements, which are
probably important aids to successful copulation, but also of
the location of the genital apertures. The features of this
region have been described by Moore ('98) from examples
collected in Louisiana, but are now figured for the first time.
The figure is a composite of the three specimens which this
collection contains and which differ from one another in cer-
tain particulars.

Comparison of the previous account with this figure will
bring to notice some disparity in minor details, due to the
fact that almost every specimen presents some individual
peculiarities. It is very probable that this results not more
from individual variability than from the temporary, seasonal,
and developmental character of the structures concerned.

In specimens sexually inactive the male pore appears
near the anterior margin of XII a 2 ; the female pore, on XIII
b 1. They are surrounded by a more or less wrinkled area in
which appear a variable number of copulatory gland pores
more or less conspicuously developed. Omitting consider-
ation of intermediate states the active condition is represented
in PI. XLIV., Fig. 16. The surface immediately surround-
ing and succeeding the male pore is inflected as a deep pit

£14 Illinois State Laboratory of Natural History.

(d), on the anterior face of which the male pore is carried
and concealed by the slightly overhanging* margin. Thus is
formed, probably through the contraction of the dorso-ventral
muscles, a sort of genital sinus inclining dorsad and cephalad
deeply into the body and opening by a wide mouth on to the
surface of annuli XII « 2 and bo.

The neighborhood of the female pore is reciprocally elevated
as a sugar-loaf shaped papilla, inclining caudad and ventrad
and consequently well adapted to occupy the male pit, in
which event the female pore ( 9 ), situated at its apex,
would come into contiguity with the male pore near the
bottom of the pit.

The copulatory gland pores {cgp) are much more conspic-
uous than in the individuals first described, but are subject
to much variation. Typically they are arranged as follows :
In the male system {dcgp) a pair (concealed in the figure) is
placed symmetrically beside the male pore ; a second pair,
and sometimes an additional median one, is situated just in
front of the anterior border of the pit ; on the furrow
XII a 1\b 5, just external to the pit, is a third pair; a
fourth pair is found just abreast of the last but on the lateral
walls of the pit within its month ; and, finally, a median pore
appears on the sloping posterior face of the pit cephalad of
the third and fourth pairs.

An almost exact reversed counterpart of the male system
is found in the female system of adhesive organs ( 9 cgp). It
is described in the order in which the pores are supposed to
correspond with those of the male system as respectively
enumerated. The first pair occupies the sides of the female
papilla close to the genital orifice ; the second is found on
annulus XIII b2, caudad and laterad of the papilla and
sometimes accompanied by a median one ; the third and
fourth pairs of the male system are represented by a
single pair in the female system, which is just caudad of the
male pit on annulus XII b 6. A median pore situated just pos-
terior to these completes the parallelism.

*The ventral surface being turned uppermost.

The Hirudinea of Illinois. 515

Besides those mentioned, two or three additional pairs are
located far from the middle line on annuli XIII bl, a 2,
and b5.

Each of these pores is the crescentic or slit-like external
orifice of a little subcutaneous bursa, usually filled with a
more or less hardened substance which may raise the integu-
ments into a small papilla and is probably the secretion of a
mass of glands (eg I) occupying the whole of the middle region
of somites XII and XIII and covering the walls of the male
pit internally.

Seventeen pairs of nephridiopores (PI. XLIV., Fig. 13, 14)
are situated on small papillae near the posterior margins of
annuli VII ((1 to XXIV b'2 inclusive. The posterior are
entad, the anterior ectad, of the ventro-lateral sensillse.

Annuli and Somites (PI. XLIV, Fig. 12-15, 18, 19).— Ex-
cept in a few minor respects the incomplete somites possess
the same number of rings as in Macrobdella and Hcemopis
marmoratis.

Fifteen somites (IX to XXIII inclusive) are complete and
quinqueannulate, b l-\-b 2+a % + b 5 + /? 6. In each of these,
except IX, a '2 is just perceptibly shorter than the others and
is less likely than they to show the depressed transverse
line, though the raised line just behind the sensillre is quite
as distinct.

The sensillae are very regular in arrangement but very
small. They appear as white circular spots, and, in the best
preserved examples, are distinctly but very slightly elevated,
above the surface. They encircle the exact middle of the
annulus. The dorso-medians (md) are very close together,
scarcely an annulus length apart. About twice this distance
separates these from the dorso-laterals (dl) ; from the
dorso-laterals to the dorso-marginals (dm) and also from the
latter to the supra-marginals (sni) the distances are slightly
greater than that first mentioned. Owing to the flatness of
the ventral surface the relative positions of the sensillre as
shown in Figures 13 and 14 represent accurately the
distances which separate them.

There are eight incomplete somites at the anterior end.

516 Illinois State Laboratory of Natural History.

I is incompletely separated from II and bears but one pair of
metameric sensillse. II is a narrow imperfectly differentiated
annulus bearing the first pair of eyes and, externally to these,
three pairs of sensilla?. Ill is also uniannulate, and the
second pair of eyes which it bears represents the dorso-lateral
sensillre, the other three pairs being unmodified.

IV is biannulate (al + a2)+a3. The first ring is wider
than the second, and its composition is indicated by an inter-
rupted furrow which passes across the third pair of eyes but
anterior to the other sensillse. V differs from IV only in its
somewhat greater length and its relation to the mouth.

VI and VII are each triannulate ; the latter is considerably
the larger, but in each the annulus a 3 is dorsally about two
fifths of the entire length of its somite and in VII shows a
slight furrow all around. The furrow VI a 1 /a 2 disappears
ventrally.

VIII is quadriannulate ; a 1 is longer than a 2 and faintly
subdivided all around, but is not equal to VII a 3 ; b 5 and
b 6 are fully developed and about equal to a 2.

In IX the relative size of the annuli isM=£2 <a1 <b5=b6 ;
in X, £l=£2=a2 <bo=b6 ; and in XI and succeeding somites
bl=b%=b5=b6> a'2. The posterior annuli of XII and the
anterior of XIII are somewhat contracted in length.

in XXIII. b5 and b6 are relatively slightly shorter, while
in XXIV they are no longer distinct, the separating furrow
being very shallow, so that this is counted as a quadri-
annulate somite. Bl and b 2 are longer than a 2.

XXV is a contracted quadriannulate somite in which the
following relative proportion exists in the lengths of the
annuli of the specimens examined : £l=a3>a2 — #2.

XXVI presents the following variations : In the specimen
drawn it is a single large annulus, particularly long at the
sides, where a faint emargination and slight dorsal depres-
sion indicate an incipient division at about the middle.
The sensilla? are fully developed and lie well toward the pos-
terior margin of the ring. Another example from the same
lot has this somite very distinctly and completely divided on
the dorsal side into two annuli, of which the anterior is almost

The Hirudinea of Illinois. 517

twice the length of the posterior, except at the margins, where
they are more nearly equal. The sensilhe are very distinct and
are all placed very close to the anterior margin of the second
annulus which, therefore, in spite of its smaller size, is re-
garded as (a2+ad).

XXVII is irregular and more or less divided into two rings,
especially at the margins. The anus cuts into the posterior
margin of the somite, which at that point is irregularly lobed.
The sensillae are close to the furrows by the side of the anus
and the dorso-medians are widely separated. XXVIII is
somewhat distinct from the sucker and bounds the anus
posteriorly.

Reproductive Organs. — Two examples were dissected, and
the small size of the organs renders it probable that they
were taken at a time when these were not in full activity.
The internal organs of generation (PI. XLIV., Fig. 17) are
very simple.

But seven pairs of small testes (t) were found at the anterior
ends of somites XIV to XX. The very slender vasa deferentia
(vd) reach to ganglion XI, where they bend back on them-
selves and become almost immediately much enlarged and
thrown into several folds (ep, de). This region appears to
correspond to both the epididymes and ducti ejaculatorii of
Hremopis. The two ducts immediately open together into a
small thin- walled bursa, and the bursa communicates with
the pit as above described. There is no muscular atrium
and no penis. Numerous muscular fibers pass between the
ventral integuments in the neighborhood of the pit and the
dorsal integuments. Ganglion XII is crowded caudad from
its normal position to the posterior end of its somite.

The female organs (PI. XLIV., Fig. 17, 21) are of the
Hirudo type. In the specimens examined they are sym-
metrically related to the body axis. The ovaries (ov) are
sausage-shaped and each is folded on itself. Separate slender
oviducts (ov) lead to an unpaired organ, into the large end of
which they open. There is no evident external distinction
between glandula albuginea, oviductus communis, and vagina,
but the. three together are combined in a slender claviform

518 Illinois State Laboratory of Natural History.

organ, which is doubled on itself forward and opens by a duct
on the external papilla.

Alimentary Canal. — Except for the jaws the alimentary
canal is most like that of Hcemopis. It is straight and simple,
with one pair of large posterior caeca and numerous small
pockets, usually two pairs per somite along the middle region.
The jaws, however, are of a very different form, resembling
those of Diplobdella. They are very high and prominent, the
height being greater than the length. The denticles are
small, sharp, and in part at least ranged in paired series
(PI. XLIV., Fig. 20). It is quite possible to draw them
apart with needles and to display the groove which divides
the two rows.

Color. — The colors are described from alcoholic specimens
which are evidently somewhat faded and otherwise altered.
Light brownish drab above, yellowish below. A distinct con-
tinuous narrow yellow line marks the dorsimesion, becoming
very faint anteriorly while posteriorly it is more or less broken
by intrusion of the ground color. A pair of rather broader but
less distinct yellow lines mark the margins. Between the dorso-
marginal and dorso-lateral sensillre on each side is a row
of small irregular deep brown spots, generally well separated
but at intervals becoming aggregated and more or less con-
fluent. A very few faint and suffused brown spots are scat-
tered over the dorsal surface. Ventrally the only markings
are some rather larger reddish brown spots which are chiefly
aggregated along the margins and become in places confluent.

Habits. — That this leech feeds in part at least on weaker
creatures is shown by the presence of remains of earthworms
(Allolobophora) in the canal. One of Yerrill's specimens of
P . jioridana was captured in the act of swallowing a small
lumbricoid worm. The structure of the alimentary canal
would also indicate a diet of this character varied by an
occasional meal of blood.

The Hirudinea of Illinois. 519

i

HiEMOPIS Savigny.
Hsemopis marmoratis (Say).

Hirudo marmorata Say ("24).
Aulastomum lacustre Leidy ('68).

Diagnosis. — Amrali VII b5 and b 6 and VIII b\ and £2
indicated on the enlarged primary annuli but not fully devel-
oped; d pore on 32 (XI b 6) or 31/32 (XI b5/b6), ? pore
on 37 (XII £6) or 36/37 (XII bojb6); atrium and vagina
reaching into somite XVII; ovaries just behind ganglion
XIV.

General Description. — This species reaches a greater size
than is attained by any of the Illinois examples, the largest
of which measures : —

mm.

Total length, 104.

Length to cT pore, . . . . . . .22.

Greatest width, (XVII), 15.5

Width at d pore, 12.

" " anus, 7.7

Depth at XVII, 6.5

" " c? pore, 3.8

" " anus, . . . . . . .2.5

Diameter of posterior sucker, . . . . 6.5

Owing to the great development of botryoidal tissue the
body is exceedingly soft and consequently varies greatly in
shape, when alive, according to the various states of rest and
activity, in preserved specimens, as a result of the different
methods adopted for fixation and preservation; When
actively swimming, and especially when the stomach is
empty, the body is elongated and flattened but never very
slender. (This is yearly the condition of the example meas-
ured.) The width is generally greatest at about the middle
of the body, but differs very little between the clitellum and
the last complete somite. In preserved specimens the clitel-
lum is frequently the widest part of the body. Anterior to
the clitellum the body tapers rapidly to the broadly rounded

520 Illinois State Laboratory of Natural History.

prostomium and is less flattened. When exploring, but not
swimming, the form is much less depressed and more terete,
and may become much more extended and slender. The
resting attitudes are varied and interesting. The body may
be contracted to an ovoidal form, the upper lip is usually
inflected, and the anterior end of the body variously inrolled
or folded on the ventral surface.

Living specimens held in the fingers are so soft and hang
so limp that they appear more like pieces of dead tissue than
living animals. This peculiarity also enables them to squeeze
into the most narrow clefts and thus often to escape from con-
finement. None of the cutaneous sense organs are- elevated
upon papillae, so that the surface appears perfectly smooth.

Both living and well-preserved specimens are strongly
annulated (PI. XLV., Fig. 24), and in the latter each ammlus
is raised into a transverse ridge situated about one third of
the length of the annulus from its posterior border. As a
result the margins of the body usually appear rather decidedly
serrate. In some specimens such elevated ridges extend
around the entire circumference of the body.

The anterior sucker (PI. XLVI., Fig. 34) is mobile and
comparatively large, but without any definitely expanded
disc. The mouth is large. The upper lip is broad and
bluntly rounded, crenulate on the margin, but almost per-
fectly smooth and undivided ventrally. Several rows of labial
sense organs are situated around its margin and on the pre-
ocular and oral annuli. Dorsally the furrows which divide
it into annuli may be very faint, but are usually discernible
for a portion of its width (PI. XLVI., Fig. 33).

Of the five pairs of eyes (PL XLVI., Fig. 33) the first three
pairs are conspicuous and arranged in a regular arc on the 2d,
3d, and 4th annuli; while the fourth and fifth pairs are more
widely separated on the 6th and 9th annuli respectively, and
are increasingly smaller and deeper and, as a consequence,
more obscure. Their optical axes are variously directed ; the
first pair forward and slightly outward, the second decidedly
outwards and forwards, the third directly outwards, the fourth
outwards and backwards, and the fifth backwards and some-

The Hirudinea of Illinois. 521

what outwards ; thus, together, they cover an arc of perhaps
160°.

Annulus 6 — V (a 1+a 2) — unites with 7 (V a 3) ventrally to
form the broad postoral ring; but the immediate oral ring or
lower lip is a rim, more or less narrow and more or less dis-
tinct from 6, which is contributed by 5 (IV a 3). At the
sides the mouth is bounded by the 4th and 5th annuli, which
coalesce laterally (PI. XLVL, Fig. 33).

In mature examples the clitellum (PI. XLV., Fig. 24) is
very distinct and equally well developed dorsally and ven-
trally. It is smooth, thick, and firm, and at its posterior
end as wide or wider than the succeeding annuli. Posteriorly
it is straight, anteriorly concave ; and it extends over fifteen
annuli (X£5-XIII « 2 inclusive).

The Illinois specimens exhibit no variation in the position
of the genital pores, which are, invariably, the male in XI b 6
and the female in XII b6. The male orifice is situated close
to the anterior border of its annulus, which enlarges
mesially and encroaches slightly on the preceding annulus-
Occasionally the region immediately surrounding the orifice
is elevated as a low broad papilla. The size of the actual
opening, as well as its form, differs according to the state of
retraction or protrusion of the penis and related parts. The
female pore is rounded or slit-like, is smaller than the male,
and, like that, is usually close to the anterior border of its
annulus though more liable "to shift as far as half its width
caudad. The annulus' is enlarged and its anterior furrow
becomes obsolete in its middle part.

The relatively small posterior sucker is circular, broadly
attached, thick posteriorly, and projects by about one third
of its diameter beyond the body, its anterior margin reaching
to XXV a 2. Just anterior to it is the large anus with its
much wrinkled margin cutting into XXVII. Prolapsus of
the rectum frequently occurs in individuals which contract
excessively as a result of irritation.

There are 17 pairs of nephridiopores situated just anterior
to the posterior margins of the b'2 region of somites VIII to
XXIV inclusive (PI. XLVL, Fig. 34). Each is in a faint

522 Illinois State Laboratory of Natural History.

depression bounded anteriorly by a slight forward displace-
ment of the transverse ridge. The anterior pores are exactly
in line with or very slightly mesiad of the ventro-lateral
sensillse, while the posterior lie well inside of this line.

Annuli and Somites (PI. XLVI., Fig. 33, 34).— Somite I
can seldom be distinguished as a distinct ring, but in well-
preserved preparations a pair of dorso-median sensilla' may
always be found anterior to and a little mesiad of the first
pair of eyes. Sometimes the furrow may be discerned at and
near the middle line, but it is always very faint and incom-
plete. This region bears numerous labial sense organs,
which are arranged in about eight transverse rows ; but,
except in one case in which two were found, only the one
pair of segmental sensilhe can be distinguished.

Somite II consists of a single narrow annulus imperfectly
distinguished from the preceding and succeeding annuli.
The posterior furrow sometimes extends quite-to the lateral;
margins of the lips, but is usually very faint and imperfect.
This somite bears the first pair of eyes, together with dorso-(
median, dorso-lateral, and dorso-marginal sensilla?, the latter
being very difficult to distinguish from the labial sense
organs.

III is also uniannulate but is more distinct, though here
again the furrows are frequently incomplete. The dorso-
median sensilla3 are small but distinct, while the lateral and
marginal pairs are quite evident. A few goblet -shaped sense
organs form a broken transverse series.

IV is biannulate, the two annuli uniting at the margins to
form the lateral boundaries of the mouth. The anterior
annulus is somewhat the wider and bears the eyes and the
full set of sensilla? toward its posterior part. It is conse-
quently regarded as potentially constituted of the two primary
annuli a 1 and al. Each annulus bears one row of goblet-
shaped organs.

Y is a more fully elaborated biannulate somite. The
anterior annulus is decidedly the larger, and exhibits on the
dorsal side two transverse series of goblet-shaped organs
which are ventrally united into one. A full set of metameric

The Hirudinea of Illinois. 523

sensillfe is present on the posterior portion of the dorsal
surface, but the ventral ones have escaped notice, if present.
The second, smaller annulus (aS) has one series of goblet-
shaped organs.

On VI a partial furrow indicates the line of division between
the constituents a 1 and a 2 of the much enlarged an-
terior annulus. The extent of this furrow is variable. It
extends from the dorsal mid-line, where it is deepest, laterad
sometimes as far as the dorso-marginal or even to the supra-
marginal sensillse, but may reach as far as the eyes
only. All of the sensillre, both ventral and dorsal, are
well developed and, including the 5th pair of eyes, are on the
a 2 constituent. Annulus a 3 is the last on which a complete
row of goblet-organs is distinguishable.

VII is triannulate, a 1 being slightly shorter than a 2 and
a 3 much longer, the latter constituting about two fifths of the
total length of the somite. Occasionally in large specimens
a very evident furrow divides this annulus into two equal
halves on the dorsal surface, and at least a shallow furrow is
always present. The sensilhe are normal and on a 2.

VIII is quadriannulate. Al is slightly wider than VII a 3,
and like the latter shows a partial division into the secondary
annuli. A% bears the sensilhe and a 3 is completely divided
into b 5 and b 6, each of which equals a 2 in size.

The series of complete quinqueannulate somites begins
with IX and ends with XXIII, making 15 in all. The five
annuli of each of these are of equal length. The sensilla; are
small but very conspicuous on properly prepared material ;
but the exact size of the sensory areas is difficult to figure, as
they appear as circular white spots in small unpigmented
areas the limits of which are rather vaguely defined. All of
the sensillse are much subject to variation, even the dorso-
medians and dorso-laterals being frequently subdivided,
changed in position, or entirely wanting. But the two
marginal series are especially prone to subdivision ; and they
are very commonly represented by a chain of contiguous
smaller sensory areas, not infrequently made up of four or
five members.

524 Illinois State Laboratory of Natural History.

Somite XXIV is quadriannulate, bat it is the posterior
end (a 3) which is least developed, instead of the anterior
end (al) as in the quadriannulate somite VIII. In some
examples the large posterior annulus (a 3) is marked by a
slight furrow, which is more frequent on the ventral surface.

XXV. Because of its variations this normally triannulate
somite is one of the most interesting. ^41 is always longer
than XXIV a 3. In four specimens it exhibits no trace of a
subdivision dorsally or ventrally ; in six there is more or less
evidence of a ventral furrow ; four examples, while lacking
any trace of a furrow, show two distinct integumental ridges
at the margins of this annulus ; two others have both the
marginal ridges and the furrow ; and in one individual of
large size the furrow extends even half way around the dorsal
side. The remaining annuli a 2 and a 3 are of equal size
and present no noteworthy features.

XXVI is uniannulate above, and the sensillre, with the
exception of the dorso-median, which are at about the middle
of its length, are situated close to the posterior border. On
the ventral side a partial annulus is developed in many cases
posterior to the line of sensilla\

XXVII. For the reason just stated the short preanal
annulus is regarded as XXVII al, while a 2 and a 3 are
united in a single sensilliferous annulus which is cut into
by the anus. The furrow a 1/a 2 is sometimes incomplete
mesially.

The dorsal surface of the sucker is marked by a variable
number of concentric furrows crossed and connected by
irregular wrinkles. The sensillre are difficult to distinguish,
but generally about three belonging to each of the dorsal
series are present.

Reproductive Organs. — The dissection represented in the
figure (PL XLV., Fig. 26) was made upon a well-extended
mature specimen of medium size. In this the nerve cord
passes to the right side of both the genital orifices, and the
unpaired portions of the genital ducts lie to its left. The
dissection of a number of specimens of this species from
several localities shows that while this relation between the

The Hirudinea of Illinois. 525

nerve cord and the genital apparatus usually obtains, it is
not constant and diagnostic of the species. Cases have been
found in which the nerve cord passes to the left of the genital
exits or to the right of one and the left of the other, or in
which the atrium or vagina crosses the nerve cord dorsally
and lies partly on each side of it.

Ten pairs of testes (tl, tS), belonging to somites XIV to
XXIII inclusive, appear to be constant. Each occupies
the first two annuli of its somite and the posterior
annulus, or even two annuli, of the preceding somite. They
are largest in the middle of the series, and become smaller
toward both ends. The twenty short vasa efferentia are simi-
lar in structure and appearance to the paired vasa deferentia
into which they empty. Each of the latter (vd) is a rather
conspicuous glandular tube of yellowish color which takes a
more or less sinuous course just entad of the line of nephridial
vesicles. When about opposite to the male pore it turns
sharply caudad, having become narrower and of firmer, less
glandular, texture, and soon passes into a much convoluted
region, the epididymis (ep). The latter is neither compact
nor massive, and in the posterior part of XIII opens into the
sperm sac (ss), a fusiform enlargement with which the ductus
ejaculatorius (de) begins. Throughout its greater part the
latter is a delicate tube which extends forward to a point
opposite to the male pore and then again bends on itself
sharply caudad to open into the fundus of the atrium or
penial sheath (at) at the anterior limit of somite XV.
Throughout its entire length the ductus ejaculatorius has
firm glistening muscular walls. Generally the right ductus
passes beneath the nerve cord at its anterior turning point
behind ganglion XI, but •occasionally it is the left which
makes this crossing.

The atrium or penis sheath (at) is very long and slender.
Beginning at the anterior end of somite XV it reaches caudad
to ganglion XVII, bends sharply on itself, and passes directly
cephalad to the male orifice. In the specimen figured, which
measures 92 mm. in total length, the atrium has a length of
40 mm., the ratio between the short and long limbs being as

5 26 Illinois State Laboratory of Natural History.

1 to 2.3. The organ is of firm consistency and very mus-
cular. In shape it is terete with the closed end slightly
enlarged and provided with an ensheathing layer of prostate
glands {(ip). The protruded penis is a long filiform organ
reaching a length of at least 30 mm., though this condition
is not exhibited by any of the Illinois examples.

The female organs are equally and correspondingly special-
ized. A pair of ovaries (or) lie on the 2d pair of testee
dorsal to the nerve cord and in the posterior end of XIV.
Very short oviducts pass from them to a common meeting
place, where they are enveloped by the large glandula albu-
ginea (go), from which the common oviduct emerges. This
narrow firm-walled tube {ode) leads to a large pyriform
ovisac (os), which it joins a short distance from the extremity
of the narrow end. The vagina (ra) begins near the large
end of the ovisac at the posterior end of somite XVI. It is
long, slender, and terete, about 2-3 times the diameter of the
common oviduct, of an appearance similar to the latter, and
with muscular walls. The coil and whorls into which it is
thrown are sufficient to give it, when straightened out, a total
length equal to the penis sheath.

Alimentary < 'anal. — The lip is separated by a slight circular
sulcus and fold from the three jaws. Each of the latter is
the anterior termination of a pharyngeal fold which here
becomes slightly more prominent and curves peripherally into
a little pocket into which the jaw may be retracted, so that
the whole tooth-bearing ridge may be concealed. The jaws
are low and rounded, not at all compressed on the free edge
and very little prominent. They bear a double file of
large coarse teeth (PI. XLII., Fig. 7) arranged in from
12 to 16 pairs. The individual denticles have bilobed
l>ases and sharp, slightly hooked, apices, those of each
pair meeting in a common ridge above the groove which
separates their bases. From each side of the pharyngeal folds,
which continue the jaws caudad, somewhat lower folds arise,
and in the intervals between these three triad systems addi-
tional single or double folds may arise. Thus the pharynx
is thrown into from nine to twelve, or even more, longitudinal

The Hirudinea of Illinois. 527

ridges extending throughout its entire length. The pharynx
reaches into somite X.

A long narrow straight stomach reaches to XIX, where a
pair of large lateral caeca arise and pass caudad to XXII or
XXIII. Along the course of the stomach are numerous
small lateral caeca, as many as two or three pairs per somite ;
and just posterior to the origin of the large posterior pair are
two or three pairs of quite large, short, globular caeca which
extend laterad dorsal to the principal caeca.

Color, — Many color varieties of this species occur, some of
which have been indicated by Verrill ('74) ; but only the
blotched kinds are represented in the Illinois collection-
During life the ground color in such is generally some shade
of olive-green or greenish brown, blotched with irregular
intermixed spots of lighter grays and darker browns and
black. The former kind are likely to predominate on the
ventral side, from which the darker pigments may be alto-
gether absent. The darker markings may be scattered and
distant or so close as to become confluent and give to the
animal an almost black color. Most of the Illinois examples
are only moderately blotched. Preservation always causes
the loss of the green pigments. No metameric features have
been detected in the pigmentation of this species, nor is there
any evident close relation between the disposition of the pig-
ment and the arrangement of the muscles.

Habits.— In the neighborhood of Philadelphia this so-
called horse-leech lives in the mud by the sides of pools,
ditches, and streams. At times it leaves the water in search
of earthworms, which constitute part of its food. Various
kinds of aquatic insects and their larva?, aquatic oligochaetes,
gastropods, and lamellibranchs are eagerly eaten, and large
quantities of mud containing organic matter are swallowed.
When the opportunity arises this leech will take blood,
attaching itself to drinking cattle or to the legs of boys
wading in its haunts. .

528 Illinois State Laboratory of Natural History.
Hsemopis lateralis (Say).

Hirudo lateralis Say ('24).
Macrobdella valdiviana Philippi ('72).
Semiscolex terreslris Forbes ('90).

Diagnosis.— VII 65 and b 6 and VIII b 1 and b 2 are fully
developed, so that VII is quadriannulate and VIII quinque-
annulate. The male pore is on annulus 34 (XI b 6), the
female on 39 (XII b 6) ; the vagina and atrium extend to the
anterior part of XIV ; the ovaries lie between the female
pore and ganglion XII.

General Description. — Many of the characters of this large
leech have been described by Forbes ('90). It reaches a size
much larger than H. marmoratis, some examples of the
terrestrial variety from Illinois measuring as contracted
alcoholic specimens nearly 8 in. in length and f- in. wide.
The smallest specimen in the collection measures 38 mm.,
the largest 190 mm., in length. A medium-sized individual
from which the drawings were made, measures : —

Total length, .......

Length to c? pore, .....

Width at d pore, ......

Greatest width (just anterior to 17th nephridiopore).
Width at anus, •. . . . . about

Diameter of posterior sucker,

Depth at d pore, ..... about

Depth at last nephridiopore, . .

Depth at anus, ......

Living aquatic examples which I have watched assume the
attitudes and shapes described for H. marmoratis, but
H. lateralis is much more slender and capable of much
greater elongation. The greatest width is further back
(about XXIII), from which point the body tapers gently
forward. Compared with //. marmoratis the ventral surface
seems flatter, the dorsal more abruptly, but still gently,
arched, and the anterior region more terete. As in that
species the surface of the body is perfectly smooth, without

mm.

103.

21.

10.

5

13.

5

5 .

6.

4.

5.

5

2.

5

The Hirudinea of Illinois. 529

any papilla, but unlike that species the metameric sensillse
are exceedingly difficult to detect, and I am not *yet satisfied
that they have been correctly identified in surface views. A
better developed muscular system gives the body of this
species a somewhat firmer consistency.

The annuli (PL XLVI., Fig. 28-32) are remarkably
distinct, which results chiefly from the presence on each of a
strong welt or ridge which encircles it and causes the margins
to stand out like so many seme. Just anterior to the ridge
a faint furrow appears on many of the secondary annuli.

The upper lip (PL XLVI., Fig. 29, 32) is rather slender
and pointed and its ventral surface divided by a slight
median and several lateral longitudinal grooves. The mouth
and sucker are relatively smaller than in the horse-leech. A
slight constriction is usually evident between the fourth and
fifth pairs of eyes. The eyes (Fig. 28) are arranged as in
H. marmoratis.

Very few examples exhibit a well developed clitellum, but
when present it has a form and extent similar to that of
H. marmoratis. Although the male and female pores are
situated on the annuli homologous to those bearing them in
J[. marmoratis, two more annuli intervene between them and
the anterior end than in that species. This results from the
presence of an additional annulus in each of somites VII and
VIII. The orifices are also situated further caudad on their
respective annuli (though seldom beyond the middle) than in
that species.

The usual seventeen pairs of nephridiopores (PL XLVI.,
Fig. 29) are situated on the annulus £2 of somites VIII to
XXIV inclusive. As in H. marmoratis they open just pos-
terior to the transverse ridges, which at each pore are pushed
forward as short spout-like projections which may serve to
direct the flow of the excreted fluid. The distance separating
the two pores of a pair is almost exactly half the width of the
body at that point.

Annuli and Somites. — Owing to its distinctness the annula-
tion (PL XLVI., Fig. 28-32) is very easy to work out, but
on account of the difficulty or impossibility of detecting the

6 30 Illinois State Laboratory of Natural History.

metameric sensillse in surface views the metamerism is less
readily determined. Comparison with //. marmoratis hrings
to light some interesting points of distinction between the
two species. No differences of any consequence are notice-
able in the first five somites.

In VI, a 3 is relatively much longer, and occasionally a
faint subdivision appears on its dorsal surface.

VII presents a similar condition in a 1, while a 3 is repre-
sented by the fully developed secondary annuli b5 and b6,
which are completely separated both dorsally and ventrally,
making this somite quadriannulate, with the formula
al+a 2+£5+£ 6, or [b l+£2)+a*2+£5+£6.

VIII is quinqueannulate, owing to the complete separa-
tion of b 1 and b 2. This species presents, therefore, one
more complete somite — having the formula b l-\-b 2+#2-r
b 5-\-b 6 — than does H. marmoratis.

In most of the complete somites, usually from about X to
XXI, a characteristic relative size of the component annuli
is maintained. .42 is always the shortest, b\ and £2 are
equal and slightly longer, and b 5 and b 6 are equal and still
longer. The faint depressed line which is mentioned above
as crossing most of the annuli is rarely discernible on a 2,
while on the secondary annuli it is usually quite evident.

In XXIV, which is the last complete somite, the relative
size of the annuli anterior and posterior to the neural annulus
(a2) is reversed, bl and b 2 being larger than b5 and b6.

XXV is triannulate, a 3 being distinctly smaller than a 1
or a 2, especially on the ventral side, where it becomes some-
what approximated to a 2 and the dividing furrow less deep.

XXVI is biannulate, the first annulus being dorsally as long
as the second at the margins, or even longer, but relatively
smaller mesially. By displacing the sucker the second ring is
seen to include on each side a remnant of a very narrow
posterior ring, which in one specimen is well developed both
dorsally and ventrally. As the supposed sensilla? are found
on the anterior part of the second ring this is regarded as
representing a 2 and ad.

XXVII is biannulate and includes the anus.

The Hirudinea of Illinois. 531

Fortunately, in the posterior region of some aquatic indi-
viduals from Ohio the sensillre are comparatively distinct, so
that the determination of the values of the annuli and of the
limits of the somites is accomplished with greater ease and
confidence than would otherwise be possible.

Reproductive Organs. — The reproductive organs also have
been described by Forbes, to whose account a few notes may
be added. The nerve cord may pass to the right of the
genital exits, as described by Forbes, or to the left, as here
figured. In two out of three dissections the latter condition
prevailed ; but the number is of course insufficient to
determine which is the more usual.

The figure (PI. XLY., Fig. 27) will serve to show the
marked contrast in several respects between these organs in
H. lateralis and H. marmoratis, in most of which the former
approaches nearer to the H. sanguisuga of Europe. The
sperm-sacs (ss) and epididymes (ep) of H. lateralis are con-
fined to the distance between ganglia XI and XII, and the
latter are massive and compact and closely molded around
the sperm-sacs. The atrium (at) of this species is much
shorter, its posterior turn being at ganglion XIV ; the relative
lengths of the short to the long limb is as 1 to 1.7. The
penis is not protruded in any of the Illinois specimens, but
in the aquatic variety from Ohio is essentially similar to
that of H. marmoratis.

Unlike the latter species the ovaries (ov) of this are situated
far in advance of the second pair of testes. Sometimes, at
least, they lie beneath the nerve cord and between the female
exit and ganglion XII. Similarly to the atrium, the vagina
is relatively short and never extends posterior to ganglion XIV •

Alimentary Canal. — Counting the rudimentary denticles
which complete the series posteriorly the number on each
jaw is from 20 to 25 pairs (PI. XLY., Fig. 25), arranged,
as in H. marmoratis, in two contiguous series. They
are of more irregular shape than in that species and of
smaller size, but their greater number causes them to occupy
an approximately equal distance on the jaws.

Color. — Forbes ('90) has described the colors from living

532 Illinois State Laboratory of Natural History.

specimens of the terrestrial variety. On living aquatic ex-
amples from Ohio the dorsal black stripe may be conspicu-
ous, but is. more frequently faint and obscure, broken into
small spots, or totally wanting.

Habits. — The habits of this species have been briefly
described by Say ('24) and Forbes ('90).

HERPOBDEKLIDJE.
"Erpobdella Blainville.
Erpobdella punctata (Leidy).

Nephelis punctata Leidy ('70).
Nephelis lateralis Bristol (in part) ('98).

It has been found impossible to certainly identify this with
any of Yerrill's species. There is little doubt that Nephelis
lateralis Yerrill and Nephelis quadristriata Verrill are founded
on two distinct species which are common in New Eng-
land and both of which are quite distinct from Leidy's
species ; but N. quadristriata, Verrill (not Grube) may be in
part synonymous with E. punctata.

Diagnosis. — Complete somites quinqueannulate, b 6 some-
times slightly larger than the other annuli but not typically
divided in the middle by a cross-furrow ; pigmented eyes three
pairs, the first situated on II, the second and third on IV ;
genital orifices, male at XII 6 2/a2, female at XII b 5/b 6;
atrium deeply cleft, the prostate cornua prominent, and the
anterior loops of the vasa deferentia reaching to ganglion XL

General Description. — Bristol ('98) has given an excellent
description of the external characters, the annulation, and the
neural metamerism of this species, most of which need not be
repeated, especially as the external features distinguishing
species of this family are mostly slight and obscure. The
number and arrangement of the external annuli may be

*Blainville's original spelling is here followed. Blanchard has changed this to
Herpobdella, and separated the family from the Hirudinidce.

The Hirudinea of Illinois. 533

almost exactly the same in several species, which are never-
theless readily distinguished by other and very obvious char-
acters, and especially by the terminal portion of the male
genital ducts.

Erpobdella punctata reaches a large size and has a more
robust form than any other of our common nephelids. In
preserved specimens the dorsal surface is rougher and the
posterior lateral margins thinner than in most other species.
The body is very muscular and has a firm feel.

For the purpose of comparison with the species of Dina
which are described below some features of the complete
somites may be mentioned. Of these there are seventeen,
YIII to XXIV inclusive. All of the five annuli are of
nearly equal size, but b 6 is frequently slightly enlarged.
This is, however, never very obvious, and the annulus is
never marked by a transverse furrow except in strongly con-
tracted specimens in which all of the annuli are equally
affected. .12 is noteworthy as being rougher than the
secondary annuli, and its papillae are frequently larger and
more numerous, extend further marginally, and are more
subject to concrescence into a transverse ridge. When fully
extended all of the annuli are free from cross-furrows or
wrinkles, but when contracted irregular and interrupted
transverse furrows may appear on all of the annuli. These
may occur anterior to the papillae only, or both anterior and
posterior, in which latter case the annulus is more or less
completely divided into three parts, of which the middle bears
the principal papillae. Such transient subdivisions must not
be mistaken for the true tertiary annuli which appear in
Dina, etc.

Reproductive Organs. — The external male organ when fully
extruded has the form of a low circular disc occupying nearly
the entire median width of two annuli. It consists of a
marginal rim fitting closely around a transverse • elliptical
central cushion of about twice the height of the rim. The
terminal openings of the sperm-ducts appear well separated
on the sides of the cushion.

The testes extend through six and one half somites

534 Illinois State Laboratory of Natural History.

(posterior part of XYIII to the anterior part of XXIV). In
one specimen in which they were counted the number varied
from fifty to sixty on each side of each somite. They are
small pyriform or globoid bodies grouped about the vas
deferens, into which they empty, in most cases by separate
ducts. The vas deferens (PL XLVIL, Fig. 35, rd) is an
extremely line, straight tube reaching to ganglion XYIII.
At this point the duct suddenly enlarges into a very conspic-
uous epididymis or sperm-sac (ss). This much convoluted
tube continues through several somites but gradually dimin-
ishes in diameter. By somite XV it has become only one
half or one third of its greatest size, and in XIY the convo-
lutions become more open and soon the duct is merely wavy.
This region is the ductus ejaculatorius (de), which passes
forward in a long loop to ganglion XI, at which point it
turns sharply mesiad and caudad and returns to the terminal
organ. Eegarding all of the latter as the atrium, it consists
of two more or less elongated curved conical horns (j>)
directed longitudinally. At their bases they rest on a pair of
swollen pedestals covered with a layer of prostate glands,
which also extend somewhat on to the bases of the cornua
themselves. This basal region, the two halves of which
embrace the nerve cord between them, may be separated
quite to the basal integuments, where each half communicates
by a separate orilice with a small bursa. The median part
of the atrium appears to be represented by these two basal
halves of the cornua.

The ovaries (PI. XLVIL, Fig. 35, or) are a pair of long
slender sacs, each doubled on itself, with both ends in somite
XII, and the loop reaching far back along the median line,
ventral to the alimentary canal, to the neighborhood of
ganglion XVII. From somite XIY to somite XYII the two
ovarian sacs lie side by side; just anterior to ganglion XIY
they diverge, the closed end of each arching upwards around
the pharynx ; and they end close together, near the median
line. The external ends of each, on the other hand, retain
their ventral position and join beneath the nerve cord at the
common external opening (• 9 ).

The Hirudinea of Illinois. 535

Habits. — The favorite food of this species is small aquatic
oligochgetes. Bristol ('98) and Leidy ('70) have given some
account of its habits.

DiNA R. Blanchard.
Dina fervida (Verrill).

Nephelis fervida Verrill ('74).

Nephelis fervida is supposed to have been described from
individuals of this species having eight eyes, a variation
which frequently occurs. The species here described is
abundant in the Lake region from which Verrill's types were
taken, and has the size, form, and color of that species.

Diagnosis. — Complet esomites quinqueannulate, b 6 being
distinctly enlarged and divided by a cross-furrow into two
equal halves ; pigmented eyes normally three pairs, the first
situated on III ; genital orifices at XII b 2/a 2 and XII b 5/b 6 ;
median chamber of atrium of medium size and not deeply
cleft, the prostate cornua prominent, and the vasa deferentia
not reaching anterior to their ends in somite XII.

General Description. — A single small specimen represents
this species in the Illinois collections, and the following notes
are derived from numerous examples in my own collection
received from Ohio and Michigan and from the well-preserved
series taken by Professor Reighard during his recent explo-
ration of Lake Erie.

None of the large number of specimens examined reaches
a length of much more than two inches. The body is
depressed posteriorly ; the mouth is relatively large and the
lip blunt. The posterior sucker is relatively larger ihan in
most small nephelids, with its anterior margin more broadly
free and reaching as far forward as XXV a 2. The body is
not of particularly firm consistency. The clitellum extends
over fifteen annuli, X b 5 to XIII a 2.

The annulation and metamerism are essentially as in
E. punctata, except that the first pair of eyes is placed on
the third instead of the second annulus, and that in the com-

536 Illinois State Laboratory of Natural History.

plete somites b 6 is subdivided. In addition to these there
are some incipient differences, but they are too minute to be
used in this connection. The larger size and subdivision of
the annulus b 6 is a very obvious and constant character. It
is true that many of the other annuli at times show faint
cross-furrows, but these lack the constancy, depth, and com-
pleteness of the diagnostic one.

Reproductive Organs. — The testes are larger and fewer than
in E. punctata. In one specimen they average thirty-two to
each side of each somite. As in that species, they extend
from the posterior part of XVIII to XXIY. The vasa defer-
entia (vd), sperm-sacs (ss), and the greater part of the ducti
ejaculatorii (de, PI. XL VII., Fig. 36) exhibit no important
differences ; but the anterior ends of the latter stop short at
the anterior limit of somite XII, where they join the apical
ends of the prostate cornua. When the copulatory organ is
fully retracted the ducti form no loops whatever anterior to
these cornua; but when it is protruded the latter are drawn
somewhat caudad, leaving a short sweep of the ductus
anterior to it on each side. The prostate cornua (/>), though
prominent, are shorter than in E. punctata and diverge more
widely laterally. A third important difference is found in
the presence of a well-developed median atrial chamber (at).
This is quite undivided in the median line, where the nerve
cord, instead of sinking between two separated lobes, is raised
some distance above the body floor. The prostate glands
cover the dorsal portion of this chamber as well as the bases
Of the prostate cornua.

The protruded male copulatory organ differs in some
details from that of E. punctata. It is relatively larger and
especially higher. It is supported on a broad pedicle which
projects freely through the male pore. Around the entire
edge of the disc is a groove which divides it into a proximal
and distal circular ridge. The latter bears a delicate ring-
like flange which probably corresponds to the muscular
border here present in E. punctata. The central cushion is
subcircular, and instead of two widely separated openings has

The Hirudinea of Illinois. 537

a single large crescentic one, into the deep ends of which the
prostate cornua open.

The female organs present no important differential char-
acters, although the ovaries (ov) of all of the specimens dis-
sected reached to ganglion XYIII.

Color. — Living specimens, according to Verrill's description
and a water-color sketch sent me by Professor Eeighard, are
pale red with some darker cloudings.

Preserved specimens may be separated into two groups
according to the amount of pigment present. One group,
which includes the smaller and a portion of the larger ones,
lacks pigment entirely ; the other, which includes most of the
larger examples, has the dorsal surface marked with more or
less numerous minute black flecks which differ greatly in
number and somewhat in arrangement. Many specimens
have so little pigment as to appear light-colored, with a faint
dark band on either side of a median clear band ; in others
the dark bands are very broad ; and still others appear quite
dark, the pigment specks being very numerous and close and
extending continuously over the median region. In all cases
the margins, including the region of the lateral vessels, are
unpigmented ; and in no case does the pigment assume any
other form than that of minute flecks more or less closely
placed.

Dina microstoma sp. nov.

Diagnosis. — Complete ' somites quinqueannulate, b 6 en-
larged and subdivided ; first pair of eyes in III ; male orifice
at XII b 2/ a 2, female orifice at XII/XIII ; median chamber of
atrium relatively large and without median groove ; prostate
cornua inconspicuous, shorter than diameter of median
chamber ; vasa deferentia lacking anterior loop and ending
abruptly at the atrium.

General Description. — This is a generally slender species.
Well-preserved specimens are nearly terete and in extension
linear. An average specimen measures : —

538 Illinois State Laboratory of Natural History.

mm.
Total length, . . . " . . . 42.

Length to male pore, . . . . . .10.

Width at male pore, 3.4

Greatest width (middle), 4.2

Width at anus, '• 3.5

Depth at male pore, .... about 1 . 5

Depth at middle, about 2 .

Depth at anus, . . . • • .1.2

Diameter of posterior sucker, . . . . 2.5

The width is greatest at about the middle of the body but
varies little in the entire postclitellal region. The margins of
the body are rounded except just about the anal region,
where lateral flanges begin at about XXIII and become
more and more prominent until they terminate in a pair
of thin expansions which embrace the base of the sucker. A
curious feature which appears in a great many specimens
is a short contracted region just behind the clitellum, where
the body becomes perfectly terete and bellies ventralward.
From the genital region forward the body tapers quite rapidly
to a point just posterior to the mouth and then rapidly con-
tracts into the narrow lip. As in nephelids generally, the
entire body is covered with small sensory papillae arranged
in zones on every annulus.

The mouth is small, even in specimens which have been
killed in a much relaxed condition. In most specimens the
upper lip is extended, slender, and prominent, and is often
most sharply distinguished from the succeeding annuli by a
deep furrow which passes behind the postoral ring. Dorsally
it is smooth, divided into distinct but very narrow rings, and
provided around the margins very richly and above sparingly
with labial sense organs.

There are three pairs of eyes, of which the first are the
largest and are situated on somite III, instead of on II as in
most nephelids. Sometimes one or each of these is repre-
sented by two. The second and third pairs are on IV, the
dorsalmost slightly in advance.

The Hirudinea of Illinois. 539

The male gonopore is situated as usual at XII £2/# 2, the
female at XII/XIII, three annuli consequently intervening.
The former is a large and conspicuous opening usually sur-
rounded by a thin integumental disc which spreads over
about one half of the contiguous annuli. The female pore is
small and usually concealed. A strongly developed clitellum
is generally present. It is thick both dorsally and ventrally,
sharply defined, and extends over fifteen annuli, from X b 5
to XIII bl. The nephridiopores are as usual.

Even for a nephelid the posterior sucker is weak and small.
It is very broadly attached, with scarcely any free margin
anteriorly, where it reaches only as far forward as XXVI.
Eight low radiating ridges or lines of papillae disposed in
pairs mark its upper surface. Anus large, with a much
wrinkled margin, XXYI/XXYII.

Annuli and Somites. — The external features of metamerism
in this species differ but little from those of E. punctata,
but as Bristol has adopted another standard of enumera-
tion in his description of that species it seems best to give a
brief account of the present species.

I is the wide anterior region of the lip.

II is a narrow preocular annulus bearing one row of sen-
sory papilla?.

III is a single wide annulus faintly subdivided and bearing
a complete row of sense organs posteriorly and an incomplete
row anteriorly. The large pair of eyes are on its extreme
anterior part and are separated by a distance of about three
times their width.

IV is biannulate, the first ring being distinctly subdivided
and separated from the second dorsally but united to it ven-
trally. In many cases its posterior furrow is very deep and
limits the head region as noted above. The second group of
eyes is borne by this somite, the ventral pair being on the
furrow a 2Ja 3, the dorsal just in advance of it.

V is also biannulate, the first annulus bearing two rows of
sense organs and being somewhat wider than the second.

VI is triannulate. A 1 and a 3 are each slightly wider than

540 Illinois State Laboratory of Natural History.

a 2, bear two rows of sense organs, and are faintly divided
marginally.

VII is quadriannulate, the fourth ammlus being double ;
but as none of the other annuli show any indication of further
division the formula is regarded as b 1+6 24-a 2-f(6 5+6 6).

VIII to XXIII inclusive are complete somites. In these
the relative 'widths of the annuli and the subdivision of 6 6
are not such constant and obvious features as in Dina fervida,
but careful measurements of a large number of cases show
the approximate equality of the first four annuli, while b 6
proves to be about twenty per cent, larger. In many of the
best-preserved specimens this relative proportion appears
with great constancy and regularity, but in others is more or
less obscured. In well-extended specimens a dividing furrow
cuts b 6 approximately into two equal sub-rings, but in con-
tracted examples this is also obscured by the development of
transient wrinkles as described for E. punctata. Of the more
distinct sensory papilla? there are on each ring from fourteen
to eighteen above and about an equal number of smaller
ones below. These are arranged in an irregular transverse
row along which smaller sense organs are scattered.
Frequently a median longitudinal dorsal tract is entirely free
from them, and they always become more evident marginally.
On a 2 the papilla? are usually more prominent, especially so,
as Bristol has observed, on some of the posterior somites.
On b 6 two rows of papilla? appear. These are especially
distinct at the margins of large individuals.

XXIV is sometimes complete, and is always quinque-
annulate so far as observed. In most cases it differs from
the complete somites only in the relatively smaller size of 6 6
and the tendency, sometimes quite evident, for b 5 and b 6 to
unite on the ventral side.

XXV is usually quadriannulate, sometimes only tri-
annulate, but it has been found impossible to find any in-
herent clue to the exact values of the annuli. Analogy with
other species would point to the first form as being composed
of b 1+6 2+a 2 -fa 3 ; the second, of a 1+a 2+a 3.

XXVI is biannulate, the wide anterior annulus showing

The Hirudinea of Illinois. 541

two rows of papillae. The anus cuts the second, which bears
but very few papilla;. XXVII is postanal and biannulate.

Reproductive Organs, — The numerous small testes are found
in somites XVIII to XXIII, but their number was not deter-
mined. The vasa deferentia, sperm-sacs, and ducti ejacula-
torii are sufficiently indicated in the figure (PI. XLVIL,
Fig. 37). The latter end abruptly, without any preatrial
loop whatever, at the prostate horns, into the ends of which
they empty.

The atrium is a very characteristic one and differs from
that of any other species of American nephelid which I have
examined. It may be remarked in passing that the efferent
male apparatus of this species and Dinafervida have many
characters in common which distinguish them from D.mexi-
cana Duges, which Blanchard regards as being co-specific
with the type of the genus. The median chamber (at) is a
thick-walled sac of relatively large size. It stands up promi-
nently from the body floor, raising the nerve cord with it and
barely marked by a median groove. Its transverse diameter
is much greater than the antero -posterior and about equal to
its height, but in immature specimens the organ is spherical.

The prostate cornua (p) are small, —when straightened,
less than the shortest diameter of the median chamber, — and
their attachments are far apart on the dorsal surface of this
chamber, with which they remain in close contact as they
curve strongly ventrad on each side. At their lowest point
at the sides they become continuous with the ducti ejacu-
latorii as above described.

The ovaries (ov) present no peculiar features, and their form
and relations are sufficiently indicated in the figure.

Color. — Not one of many examples of both young and old
shows any pigment. This would indicate that during life
they are red, the color of the blood showing through the
integuments.

Small tubificid worms have been found in the stomachs of
those examined.

542 Illinois State Laboratory of Natural History.

Note on Discodrilidce. — The collection sent me includes
three bottles of Discodrilidce comprising altogether about
sixty specimens of Bdellodrilus philadelphicus (Leidy) Moore.
This species was originally described by Leidy under the
name of Astacobdella philadelphica in the Proceedings of the
Philadelphia Academy of Sciences for 1851, page 209.
Some additional notes on it may be found in two papers by
Moore in the "Journal of Morphology," Vol. X., page 498,
and Vol. XIII., page 327 et seq. The Illinois specimens were
taken from the exterior of Cambarus diogenes and C. Han-
ding ii.

University of Pennsylvania, August, 1900.

The Hirudinea of Illinois. 543

BIBLIOGRAPHY.

Apathy, Stefan.
'88. Analyse der ausseren Korperform der Hirudineen. Mittheil.
Zool. Station Neapel, Bd. VIII., pp. 153-232.

Blanchard, Emile.
'49. Gay's Historia fisica y politica de Chile. Zoologia, Tomo III.,
pp. 43-50. Paris.

Blanchard, Raphael.
'92. Description de la Glossiphonia sexoculata (Bergmann). Bull,
Soe. Zool. de France, Vol. XVII., pp. 178-182.

'96. Hirudinees de la Prusse Orientale. Bull. Soc. Zool. de France.
Vol. XXL, pp. 118-120.

'96a. Viaggio del dott. A. Borelli nella Kepublica Argentina e nel
Paraguay, Hirudinees. Boll. Mus. Zool. An at. comp. R. Univ. di
Torino, Vol. XL, X. 263, pp. 1-24.

Bristol, C. L.
'98. The Metamerism of Nephelis. Journ. Morph., Vol. XV., pp.
17-72.

Brooks, W. K.
'82. Handbook of Invertebrate Zoology, pp. 160-167. Boston.

Castle, W. E.

1900. The Metamerism of the Hirudinea. Proc. Amer. Acad. Arts
and Sciences, Vol. XXXV., pp. 285-303.

Forbes, S. A.
'90. An American Terrestrial Leech. Bull. 111. State Lab. Nat.
Hist., Vol. III., pp. 119-122.

Graf, Arnold.
'99. Hirudineenstudien. Abh. der Kaiserl. Leop.-Carol. Deutschen
Akad. der Naturf., Bd. LXXIL, pp. 213-404.

Leidy, Joseph.
'68. Notice of some American Leeches. Proc. Acad. Nat. Sci.
Phila., 1868, pp. 229, 230.

'70. Description of Nephelis punctata. Proc. Acad. Nat. Sci. Phila.,
1870, p. 89.

Moore, J. Percy.
'98. The Leeches of the U. S. National Museum. Proc. U. S. Nat.
Mus., Vol. XXL, pp. 543-563.

544 Illinois State Laboratory of Natural History.

1900. A Description of Microbdellabiannulata with especial regard
to the Constitution of the Leech Somite. Proc. Acad. Nat. Sci.
Phila., 1900. pp. 50-73.

Moquin-Tandon, A.
'46. Monographic de la famille des Hirudinoes. Paris, 2d ed., 1846.

Philippi, R. A.
'72. Macrobdella, ein neues Geschlecht der Hirudineen. Zeitsch. fur
die gesammt. Naturwiss. (2), Bd. VI., pp. 439-442.

Say, Thomas.
'24. Narrative of Expedition to the Source of the St. Peter's River,
etc., Vol. II., Appendix, pp. 266-268. Philadelphia.

Verrill, A. E.
'74. Synopsis of the North American Fresh-water Leeches. Rep.
U. S. Comm. of Fish and Fisheries for 1872-73, pp. 666-689.

Whitman, C. O.
'86. The Leeches of Japan. Quar. Journ. Micr. Sci., Vol. XXVI.,
pp. 317-416.

'92. The Metamerism of Clepsine. Festschr. zur 70 ten Geburtstage
R. Leuckart's, 1892, pp. 385-395.

The Hirudinea of Illinois. 545

EXPLANATION OF PLATES.

The somites and ganglia are indicated by Roman numerals I to
XXVII; and the annuli of individual somites by letters (a, b, etc.)
which indicate the successive generations by which they multiply from
the triannulate type, the indices (1, 2, etc.) being their theoretical num-
ber in an antero-posterior series.

With the exception of a few modifications which are explained in the
text the lettering is uniform for all of the figures.

The metameric sensilla;: md, dorso-median; ill, dorso-lateral; dm,
dorso-marginal; sm, supra-marginal; sbm, sub-marginal; vl, ventro-
lateral; vm, ventro-median.

The cutaneous papilhe: mp, median; mdp, dorso-median; dip, dorso-
lateral; dmp, dorso-marginal; snip, supra-marginal.

General: a, anus; at, median atrium or penis sheath; atf, internal
elevation resulting from male pit (false atrium \ covered by a layer of
copulatory and prostate glands; ati, lumenal coat and sac of atrium; c,
clitellum; cgl, copulatory glands; egp, copulatory gland pores, $ of
male and 9 of female system; de, ductus ejaculatorius (variously modi-
fied and not always strictly homologous as indicated in the several
figures); ep, epididymis (remark under de applies to this also); g,
cutaneous glands; g XI to XVIII, ganglia of the ventral chain, num-
bered to agree with their somites; gp, (or pg), prostate glands and pros-
tate region of penial sheath; ga, glandula albuginea; np 1 to 17,
nephridial openings of pairs indicated by the numerals; od, oviduct;
ode, common oviduct; of, closed end of ovarian sac; os, ovisac (uterus);
ov, ovary or ovarian sac; ov' (in Fig. 27), position of ovary; p, prostate
cornua of atrium; pg (or gp), prostate glands and prostate region of
penial sheath; ss, sperm-sac; t 1, 2, etc., testes, numbered by pairs
from before backwards; va, vagina; vd, vas deferens; tf , male genital
orifice or its position; 9 > female genital orifice or its position.

Unless otherwise stated all of the figures are made from specimens in
the Illinois collection and have been copied to scale as nearly as possible
after the originals, which were drawn upon camera tracings. Diagrams
are indicated.

Plate XLII.

Fig. 1. Placobdella parasitica. Dorsal view showing the metam-
erism and annulation of the twelve anterior somites; the cutaneous
papillae are not indicated. The color pattern is shown, the stippled parts
being the brown or olive background and the plain areas the yellow
spots and band. X 5.

Fig. 2. Placobdella rugosa. Similar representation of the anterior
ten somites (except X a 3). The principal cutaneous papilla? are shown.
From a specimen taken near Philadelphia. X 5.

546 Illiriois State Laboratory of Natural History.

Fig. 3. Placobdella rugosa. Details of papulation, etc., of the right
half of the dorsal surface of somite XIX of a large example. The lines
to the right indicate the relative positions of the ventral furrows. X 5.

Fig. 4. Placobdella parasitica. A similar view of onehalf of somite
XIX, but of a much smaller specimen. X 5.

Fig. 5. Hemiclepsia carinata. The principal features of the external
morphology of the dorsum of somites I to XII. Drawn mostly after a
specimen from Venice, Ohio, and very slightly diagrammatic. X 4. 5.

Fig. 6. Glossiphonia lineata. A slightly diagrammatic figure show-
ing the external morphology of the dorsum of somites I to X. The
annulation is originally derived from young; the sensillae and papillae
added as determined in adults. The young, X 30.

Fig. 7. Hmmopia marmoratis. Surface view of denticles from median
jaw. x 112.

Plate XLIII.
A ctinobdella inequiannulata.

Fig. 8. The dorsal external morphology of the entire leech (somites
XIII to XXI) omitted. Somewhat diagrammatic in that the furrows
are made to appear more regular than in the original. X 35.

Fig. 9. Side view of the posterior end, showing the sucker with some
of its papillfe projecting. X 35.

Fig. 10. Outline of the sucker from below, with the circle of papill*
somewhat diagrammatically shown. X 35.

Fig. 11. A small portion of the sucker rim showing the muscular ribs
and four of the papilla'. The glandular ducts of the latter are stippled.
X 130.

Plate XLIV.

Philobdella gracile.

Fig. 12, 13. Dorsal and ventral views respectively of the anterior nine
somites, showing the chief features of external morphology. X 5.

Fig. 14, 15. Ventral and dorsal views respectively of the posterior
end of the body; the dark spots are outlined. X 5.

Fig. 16. The ventral surface of somites XII and XIII showing the
various features of the region of the genital orifices. A combination
drawing from several specimens. X 5.

Fig. 17. Reproductive organs dissected and partly displayed, x 4.

Fig. 18, 19. Posterior and anterior ends respectively from the left
side. X 5.

Fig. 20. Surface view of a posterior portion of the tooth series of the
median jaw with the outline of the jaw partly shown. X 56.

Fig. 21. Female reproductive organs dissected and viewed from the
right side. From the same dissection as figure 12. X 4.

The Hirudinea of Illinois. 547

Macrobdella decora.

Fig. 22. The male organs dissected and viewed from the right side.
The left sperm-duct has its natural position, the right has been displaced
upwards. The dotted line indicates the form of the atrium before the
removal of a layer of muscles and prostate glands. X 4.

Fig. 23. The greater part of the reproductive organs dissected and
viewed from above. From a specimen from the Fulton Lakes, New
York. X 4.

Plate XLV.

Fig. 24. Hcemopis marmoratis. Diagram of the entire dorsal annula-
tiou, showing also the sensillae, eyes, etc. X 2.

Fig. 25. Hcemopis lateralis. Surface view of denticles of median
jaw. X 112.

Fig. 26. Hcemopis marmoratis. Reproductive organs dissected and
partly displayed in dorsal view. The female organs are shown nearly
in situ; the atrium with the left ductus ejaculatorius and epididymis has
been displaced far to the left and only a portion of the right ductus is
shown; three testes of the left side are included. X 3.5.

Fig. 27. Hcemopis lateralis. Reproductive organs dissected and dis-
played as in figure 26. The ovaries and oviducts are displaced to the
left, but the proper position of the left ovary is indicated in outline (ovr).
The atrium is withdrawn somewhat to the right and the epididymes and
ducti ejaculatorii of both sides are shown, as well as the anterior end of
the right vas deferens and the first testis. X 3.5.

Plate XLYI.

Fig 28, 29, 32. Hcemopis lateralis. Dorsal, ventral, and left lateral
views respectively of the anterior eight (-)-) somites. X 5.

Fig. 30, 31. Hcemopis lateralis. Right lateral and dorsal views
respectively of the posterior end. X 5.

Fig. 33, 34. Hazmopis marmoratis. Respectively left lateral and
ventral views of somites I to VIII and part of IX.

Plate XLV II.

The three figures of this plate represent similar dorsal views of dissec-
tions which were selected because of the equality in size and apparent
equality of sexual activity of the individuals. In each case almost
exactly the same extent of body is. represented, as indicated by the
numbered ganglia, and the somites containing the testes are omitted.
All, X 7.5.

Fig. 35. Erpobdella punctata. The left ovary and the right sperm-
duct have been removed.

Fig. 36. Dina fervida.

Fig. 37. Dina microstoma.

I

Plate XLII.

"T' l ■ o • -o. 9 • O e °

<$—:(•)

tnfy wA il^ ^ dm^T^

i\+W to m'o m&v w& <% &* A'^Y iw sm

-a41

1 ( ■ -e • q

0 0 fa
0^ ©

m-

■ ■ 0_L_^L_^

f° 9 ^^ _

mp mi dtp dl dm

_ TR^ toA dip dl dm. sm.

GlOSSII'HOMD.E Hikudinid.k.

Plate XLIII.

AcTINOBPELLA INEQUIANNULATA.

Plate XLIV

r^J^Z^t-^

«bW

^zJ T ^-i * n

iff

en r

^

°*t—

\ . - • • •

r~ \ ■

z\--'

***Lr~-

_ A *

— — " i

Qk f~~~. ~

!*J

b5/_

b&f^

tyZ

tyCl " \

20 ^ 22

Philoijdella gracilk, Macrobdella decora.

Plate XLVI.

HiEMOPIS MAHMOKATIS, H. LATERALIS.

Plate XLVII.

#'

ov

^ijj- -sc^

0"U

-at

-de

tf

♦

0\J

qXIIK---<^

-K

-/

.55

mvm

ov

?4<

-de

1XVII

yviH

is,

3XVII!

QXVIIh

36

s.V-i-

vSS

Herpobdellid.k.

BULLETIN

♦ ♦

"*

NATURAL HISTORY,

Urbana, Illinois.

VOLUME V.

Contributions to a Knowledge of the Natural
History of Illinois.

1897-1901.

Illinois State Laboratory of Natural History,

Urbana, 111.

1902.

INDEX

abnormipes, Atax, 408.
Acanthodrilidae, 444.

found in Illinois, 442.
Acineta, 342.

food of, 311.

mystacina, 342.
food of, 342.
Acinetidse, 341.
Actinastrum, 421.

Actinobdella, generic characters
of, 504.

inequiannulata, 504-508.

annuli and somites of, 506 508.
color of, 508.
diagnosis of, 504.
general description of, 504-506.
Actinophrys, 321.

sol, 313, 322.
Actinosphaerium, 322.

eichhornii, 313, 322.
Actinurus neptunius, 363.
aculeata, Anursea, 353, 355, 383.

Centropyxis, 320.

Difflugia, 313, 314,320.

valga, Anursea, 383.
acuminata, Difflugia, 313, 319.

Metopidia, 377.

Notholca, 353, 355, 383.

Trachelomonas, 313, 325.
acus, Euglena, 313, 324.
Adinetidae, 357.
jEolosoma, 443.

hemprichii, 443.

tenebrarum, 443.
^olosomatidce found in Illinois,

443-
affinis, Cyclops, 29, 65.

Temora, 225.

Temorella, 225.

agilis, Cyclops, 29.

Fridericia, 442.
Alasmodonta, capacity for infesta-
tion exhibited by, 414.
complanta, 401, 403.

parasites of, 409, 410, 412, 416.
confragosa, 401, 403,412.

parasites of, 409, 410.
marginata, 401, 403.

parasites of, 408, 409, 410, 412,
416, 417.
rugosa, 401, 403, 410, 412.

parasites of, 408, 409, 410.
tappaniana, 401, 403.

parasites of, 409.
undulata, 401, 403.
parasites of, 4oq.
alatus, Lampsilis, 401, 403, 408, 409,
410,412, 413, 414, 416.
Unio, 403.
albidus, Cyclops, 29, 47, 62, 63, 64.
alboflavicans, Megalotrocha, 361.
albuquerquensis, Diaptomus, 98,
101, 113, 115, 146, 176, 183, 184.
Algae eaten by Monostyla cornuta,

375-
filamentous, as food of Euchla-

nis, 374.
alienum, Lecanium hesperidum, as
located on authority of Green,

3Q3-
alveolata, Euglypha, 321.
Allolobophora, 449.

as food of Philobdella gracile,
518.

caliginosa trape/.oides, 442.

foetida, 441.

giesleri, 442.

mucosa, 441.

profuga, 441.

55°

INDEX.

Allolobophora — Continued.

rosea, 441.

sp., 442.

turgida, 442.
alpestris, Sutroa, 463.
ambiguus, Diaptomus, 177.
Amblyophis, 325.

. viridis, 325.
American Naturalist cited, 233, 263,

266, 267.
americanus, Cyclops, 37, 38, 42.
Amoeba, 305, 306, 314, 317, 421.

food of, 311.

proteus, 317.

radiosum, 317.
Amcebidae, 314, 317.
Amphaskandria, 102.
Amphileptinse, 331.
Amphileptus, 331.

anser, 331.
amygdali, Diaspis, 398.
ancylus, Aspidiotus, 398.
angularis bidens, Brachionus, 354,

381.
Brachionus, 353, 354, 380, 421.
Animalcule, bell, 309, 338.

slipper, 332.
Animalcules, sun, 321.

swan, 331. >

Annelida, 356.

Annelids as food of Glossiphonia
complanata, 493.
of Glossiphonia stagnalis,
498.
annulatus, Cyclops, 33, 35.
annulosa, Taphrocampa, 369.
Anodonta, capacity for infestation
exhibited by, 413.
corpulenta, 401, 403.

parasites of, 405, 408, 400, 410,
412, 413, 415, 416.
edentula, 403.
grandis, 401, 403, 406.

parasites of, 409, 416.
imbecilis, 401, 403.

Anodonta imbecilis — Continued.
parasites of, 408, 409, 410, 412,

413-
parasites of, 405.
plana, 403, 406.
suborbiculata, 401, 463.

parasites of, 405, 408, 409. 4'°,
411, 412, 413.
anodonta?, Conchophthirus, 333,

407.
anodontoides, Lampsilis, 401, 403,
406, 408, 409, 410, 412, 413, 416.
Unio, 333, 403.
anser, Amphileptus, 331.

Dileptus, 332.
Anthophysa, 322.

vegetans, 323.
Anuraea, 274, 352, 382.

aculeate, 355- 383-

seasonal distribution of, 353.
valga, 383.
cochlearis, 355, 383.

as food of rotifers, croppie,

and catfish, 351.
eaten by Asplanchna bright-
wellii and A. herrickii, 364,

365-
seasonal distribution of 353.

hypelasma, 382.

serrulata, 383.

tecta, 354, 382.

as food of rotifers, 351.

eaten by Asplanchna bright-
wellii and A. priodonta, 364,

365-
seasonal distribution of, 353.

Anuraeidae, 359, 382.

Apathy, Stefan, Analyse der aus-
seren Korperform der Hirudi-
neen, cited, 479.

Aphrothoraca, 315, 321.

Apiomorpha spp., changes in sy-
nonymy of, 3Q3.

Apstein, C, 6, 7.

INDEX.

551

Apstein, C. — Continued.

Das Plankton des Siisswassers
und seine quantitative Best-
immung, cited, 2, 3, 4, 5, 8.
Das Siisswasserplankton, Me-
thode und Resultate der
quantitativen Untersuchung,
cited, 2, 3, 4, 5.
Ueber die quantitative Bestim-
mung des Plankton im Siiss-
wasser, cited, 3, 4, 5.
aptera, Polyarthra, 367.
arbuscula, Zoothamnium, 339.
Arcella, 305, 306, 312, 318, 421.
dentata, 313, 314,318.
food of, 311.
vulgaris, 313, 314, 318.
angulosa, 313, 314, 318.
discoides, 313, 314, 318.
Arcellidae, 315, 318.
arcuata, Atax, 408.
areolatus, Gomphogaster, 368.
armata, Trachelomonas, 325.
armatus, Diaptomus," 133, 135, 136.
Aromochelys odoratus, Opercularia
irritabilis found on, 340.
Tokophrya quadripartita re-
corded from, 342.
articulata, Opercularia, 340.
Asellus, Carchesium granulatum

found on, 339.
ashlandi, Diaptomus, 98, 100, in,

120, 124, 158, 167, 183, 260, 265.
asperrima, Quadrula, 401, 403, 408,

409, 410, 412, 414.
asperrimus, Unio, 403.
Aspidiogaster, 410, 414.
conchicola infesting Unionidae,

404.
infesting Lampsilis ellipsis, 405.
Lampsilis gracilis and L. ven-

tricosus, 41 1.
Unionidte, 408, 40Q, 411, 412,
413, 415, 416.

Aspidiotus ancylus, resemblance
to Diaspis snowi, 398.
eucalypti as variety of A. per-

niciosus, 396.
hederae, synonymy of, 395.

as type of Evaspidiotus, 395.
ostreaeformis, resemblance of, to

Diaspis piricola, 398.
perniciosus, synonymy of, 396.
Aspirotricha, 307, 316, 332.
Asplanchna, 344, 347, 364, 365, 421.
brightwellii, 354, 355, 364.

food of, 351, 364.
Codonella cratera as food of, 336.
ebbesbornii, 354, 364.

type of trophi of, 345.
girodi, 365.
herrickii, 354, 365.
food of, 351, 365.
parasites of, 305.
priodonta, 354, 364, 365.
food of, 351, 365.
Asplanchnidae, 357, 364.

seasonal distribution of, 352.
Asplanchnopus, 365.

Codonella cratera as food of, 336.
myrmeleo, 365.

food of, 351, 365.
quantity of food taken by, 345.
Astacobdella philadelphica, 542.
Asterionella, Diplosiga frequentis-
sima found on, 328.
rays of, eaten by rotifers, 351,

3"4, 365-
Astrosiga, 328.
radiata, 329.
asymmetricus, M eso po rodrilus,

442, 4"8, 472, 473, 474, 475.
Atax abnormipes infesting Union-
idae, 408.
arcuata infesting Unionidae, 408.
fossulatus infesting I " m' > > 1 1 i < 1 . 1 ■ •

408.
indistinctus infesting Unionidae,
408.

552

tNDEX.

Atax —Continued.

infesting Unionidae, geographical
distribution of, 414, 415.

serratus infesting Unionidae, 408.

spp. infesting Unionidae, 407, 408,
409, 411, 412, 413. 414. 4i6.

stricta infesting Unionidae, 408.

ypsilophorus infesting Unionidae,
408.
ater, Cyclops, 29, 49, 62, 64.
Aulastomum lacustre, 519.
aurelia, Paramecium, 307,313, 332.
aureus, Volvox, 276, 285, 287, 438.
aurita, Eosphora, 324, 370.

Notommata, 369.
australe, Ccelostoma, 390.

B

bacillifer, Diaptomus, 107.
bakeri, Brachionus, 353, 380, 421.

brevispinus, Brachionus, 380
barretti, Stentor, 313, 334.
Barrois, Th., and Daday, E. v., de-
scription of Brachionus caudatus,
cited, 381,
Bdellodrilus philadelphicus, 542.
found on Cambarus blandingii
and on C. diogenes, 542.
Bdelloida, 356, 357, 358, 362.
Beddard, F. E., A Contribution to
the Anatomy of Sutroa,
cited, 463.
A Monograph of the Order

of Oligochaeta, cited, 441.
on spermiducal structures of
Sutroa alpestris, 463.
Bell animalcule, 309, 338.
Benham, \V. B., Note on a New-
Species of the Genus Nais, cited,

447-
Berlese and Leonardi's synonymy

of Aspidiotus hederae, 395.
Bibliotheka Zoologica, cited, 259.
bicolor, Cyclops, 29, 62, 63, 64.
bicornis, Mastigocerca, 371.
bicristata, Mastigocerca, 352, 371.

bicuspidatus, Colurus, 376.

Cyclops, 29, 30, 44, 53, 62, 63, 64.
bidens, Brachionus, 381.
bioculata, Hirudo, 497.
Biological Experiment Station es-
tablished by the University
of Illinois and the Illinois
State Laboratory of Nat-
ural History, 30. (See also
Biological Experiment
Station of the University
of Illinois, and Biological
Station, Illinois,
of the University of Illinois,
Methods and Apparatus in
Use in Plankton Investi-
gation at the, 1—25.
Station, Illinois, 28, 63, 137, 146,
229, 233, 234, 399, 418, 441, 479.
Bi palpus lynceus, 368.
biraphis, Diglena, 371.
Birge, E. A., 173.

birgei, Diaptomus, 99, 108, 117, 172.
bisetosus, Cyclops, 29.
Blainville, H. D. de, 532.
Blanchard, Raphael, 480, 532.

Hirudinees de la Prusse Orien-

tale, cited, 403, 408.
on Dina mexicana, 541.
on situation of male pore in
Glossiphonia triserialis, 493.
blandingii acutus, Cambarus, 340,
342.
Cambarus, 542.

Bogue, E. E., description of Coc-

cidae by, cited, 389.
Borgert, A., Ein einfaches Netz

zum Fischen von Plankton bei

schneller Fahrt, cited, 8.
Bosmina, 274, 421.

as food of Asplanchna herrickii,

365-
Bothrioneuron vejdovskyanum,452.
Brachionidse, 359, 378, 420, 421.

INDEX.

553

Brachionus, 274, 347, 352, 378.
angularis, 354, 380, 421.
bidens, 354, 381.

seasonal distribution of, 353.
bakeri, 380, 421.

brevispinus, 380.

seasonal distribution of, 353.
bidens, 381.
caudatus, 381.
dorcas, 354, 379.

spinosus, 354, 379.

seasonal distribution of, 353.
militaris, 355, 381, 421.

eaten by Asplanchna herrickii,

35L 365-

seasonal distribution of, 353.
mollis, 354, 378.
pala, 354, 355-378-
seasonal distribution of, 353.
varieties of, 378.
punctatus, 354, 379, 421.

seasonal distribution of, 353.
rubens, 379.
urceolaris, 379.

seasonal distribution of, 353.
type of trophi of, 345.
variabilis, 354, 380.
bractea, Metopidia, 377.
Brady, G. S., 98.

Braun, A., Betrachtungen ueber die
Erscheinung der Verjiingung
in der Natur, insbesondere
in der Lebens- und Bildungs-
geschichte der Pflanze, cited,
284.
on rotation of Pandorina, 284.
Ueber einige Volvocineen, cited,
288.
brevicorne, Ceratium, 313, 330.
brevispinosus, Cyclops, 39, 41.
brightwellii, Asplanchna, 351, 354,

355. 364-
Bristol, C. L., 539.

on papillae of Dina micros-
toma, 540,

Bristol, C. L. — Continued.

The Metamerism of Nephelis
cited, 532, 535.
Brooks, W. K., Handbook of In-
vertebrate Zoology, cited, 509.
Bucephalus infesting Unionidae,
402, 404, 408, 409, 411, 416.
geographical distribution of,
414, 415.
polymorphus infesting Union-
idae, 407.
Btitschli, 0., 301.

on locomotion of Gonium. 283.
Protozoa, cited, 274, 283,284,314.
compilation of Synopsis of
higher groups of Protozoa
from, 314.
Buffalo-fish, 351.
bulba, Monostyla, 375.
Bulletin of the Illinois State Lab-
oratory of Natural History
cited, 225, 237, 389, 441.
of the Museum of Comparative

Zoology cited, 498.
Zoological, cited, 406.

C

Calanus, 237.

californica, Pleodorina, 273, 274,

276,277,279, 280, 281, 283, 286,

290, 313, 328, 421, 437.
caliginosa trapezoides, Alloloboph-

ora, 442.
Callidina, 364.

elegans, 364.
Callipappus, species belonging to,

39°-
Cambarus blandingii acutus and C.
diogenes, Opercularia irri-
tabilis found on, 340.
Tokophrya quadripartita re-
corded from, 342.
and C. diogenes, Bdellodrilus
philadelphicus found on, 542.
Cambridge Natural History cited,
344-

bS4

INDEX.

campanula, Vorticella, 338.
Candacidae, 104.
Canthocamptus, 62, 225.
capilliferus, Cyclops, 51.
Carchesium, 338.

granulatum found on Asellus,33g.

lachmanni, 338.

polypinum found on Lemnaceae,

338.
carinata, Hemiclepsis, 4g8.

Mastigocerca, 371.
caroli, Diaptomus, 181.
Carp, 351.

Carter, H. J., Note on a Fresh-wa-
ter Species of Ceratium
from the Lake of Nynee
(Naini) Tal in Kumaon,
cited, 421.
On Fecundation in Eudorina
elegans and Cryptoglena,
cited, 284, 434.
Carteria, 420.

Castle, W. E., description of Glossi-
phonia stagnalis cited, 498.
The Metamerism of the Hi-
rudinea, cited, 471;.
castor, Diaptomus, 98, io5, 130.
catellina, Diglena, 370.
Catfish, Anuraea cochlearis eaten

by, 351.
Cathypna, 374, 375, 421.
leontina, 374.
Luna, 374.
stokesii, 375.
Cathypnidae, 359, 374.

seasonal distribution of, 353.
Cattle attacked by Haemopis mar-
moratis, 527.
by Macrobdella, 511.
caudata, Platydorina, 419, 421, 435,

437-

Traclielomonas, 313, 325.

caudatus, Brachionus, 381.
Centrifuge, Purdy Electric, 20.

Centropages, 235, 244.
grimaldii, 238, 242.
hamatus, 244.
Centropagidae, 98, 103, 244.

collections and literature at com-
mand in preparation of
Schacht's paper on, 228, 229.
first published reference to, 97.
modification of description of

family of, 101.
synopsis of the relationships
of the genera Osphranticum,
Limnocalanus, Diaptomus, and
Epischura, of the family of, 102.
The North American, belonging
to the Genera Osphranticum,
Limnocalanus, and Epischura,
225-269 (Special index, p. 270.)
Centropagina, 103.
Centropyxis aculeata, 320.
Cephalosiphon, 360.

limnias, 360.
Ceratium, 307, 329.
brevicorne, 313, 330.
hirundinella, 330.
kumaonense, 421.
ceratophylli, Limnias, 360.
Ceratophyllum, 234, 302, 349, 354.
Floscularia ornata found on, 360.
Limnias ceratophylli found 011,360.

Me galot roch a alboflavicans

found on, 361.
Qicistes intermedins found 011,361 .

Cercaria infesting Unionidae, 402,
407, 409, 416.
geographical distribution of,
414.
Ceriodaphnia, 421.
Chsetococcus and Kermicus, differ-
ence between, 392.
Chaetogaster diaphanus, 443.
diastrophus, 443.
infesting Unionidae, 40Q.

geographical distribution of,
414.

INDEX.

555

Chaetogaster— Continued.
limnaei, 443.
infesting Unionidae, 407.
Chaetoriotus as food of Protozoa

3i'-
Chalarathoraca, 315, 322.

Chambers, V. T., Two New Species
of Entomostraca, cited, 97, 132.

Charmoy, D. d'Emmerez de, de-
scriptions of Coccidae by, cited,

390.
Chelydra serpentina, Opercularia
irritabilis found on, 340.
Tokophrya quadripartita re-
corded from, 342.
Chionaspis prunicola, validity of,

398.
Chlamydodontidae, 332.
Chloropeltididae, 326.
Clioanoflagellata, 315, 328.
Chrysomonadidae, 326.
Chydorus, 19, 421.

as food of Asplanchnopus myr-
meleo, 351.
of rotifers, 345, 351, 366.
Ciliata, 307,316, 330.

as food of Acineta mystacina,

342.
Cladocera, 12, 19, 62.
claparedi, Strombidium, 335.
claparedianus, Limnodrilus, 442,

444-
Claus, C, 27, 98.

Neue Beobachtung iiber die
Organisation und Entwick-
lung von Cyclops. Ein
Beitrag zur Systematik der
Cyclopiden, cited, 29.

on basal segment of rudimen-
tary foot of Cyclops viridis,
40.

Ueber die Antennen der Cy-
clopiden und die AuflSsung
der Gattung Cyclops in Gat-
tungen und Untergattungen,
cited, 29.

Claus, C. — Continued.

Weitere Mittlieilungen iiber
die Antennengliederung und
iiber die Gattungen der Cy-
clopiden, cited, 29.

clavipes, Diaptomus, 98, 101, 108,
119, 127, 178, 184.

Clepsine elegans, 493.
modesta, 497.
ornata var. rugosa, 487.
papillifera var. carinata, 498.
var. lineata, 493.

Cleve, P. T., Microscopic Marine
Organisms in the Service of Hy-
drography, cited, 12.

Clinton, G. P., Pleodorina in Illi-
nois, cited, 273.

Closterium, 421.

closterocerca, Monostyla, 376.

clupeiformis, Coregonus, 237.

Cocaine-spirit mixture, formula
for, 350.

Coccidae, First Supplement to the
Check-List of the, 389-398.

Coccinae, divisions of, 389.

coccineus, Ilyodrilus, 451, 452.

Coccini, 389.

Coccomytilus as new genus for
certain species of Mytilaspis,

397-
Coccus, 389.

laniger, as synonym oi Walkrer-
iana floriger, 39 1.
cochlearis, Anuraea, 351, 353. 355-

364, 385.
Cockerell, T. I). A., First Supple-
ment to the Check-List of the

Coccidae, 389-398.
Codonella, 274, 336, 421.

as food of rotifers, 312.

cr'atera, 312,313, 335. 336.

as food of rotifers, 336, 351,

364.365-
Codonosiginse, 328.

Coelopus, 372.

556

INDEX.

Ccelopus — Continued.
porcellus, 372.

seasonal distribution of, 352.
tenuior, 372.
Ccelostoma australe, C. immane,
and C. rubiginosum, Fuller's lo-
cation of, 390.
cceruleus, Diaptomus, 99, 101, 107.

Stentor, 313, 334, 348.
Cohn, F., Observations surles Vol-
vocinees, cited, 285.
Ueber eine neue Gattung aus
der Familie der Volvocineen,
cited, 283.
Colepinae, 330.
Coleps, 330, 421.
hirtus, 312, 331.
Collared monads, 328.
Coluridae, 359, 376.
Colurus, 376, 377.
bicuspidatus, 376.
deflexus, 376.
food of, 351.
obtusus, 376.

seasonal distribution of, 353.
communis, Diplocardia, 442.
complanata, Alasmodonta, 401, 403,
409, 410, 412, 416.
Glossiphonia, 493, 494, 496, 497.
Hirudo, 493.
Margaritana, 403.
complanatus, Unio, 401, 403, 40Q,

410, 412, 415, 416.
conchicola, Aspidiogaster, 404, 405.
Conchophthirus, 333.
anodontae, 333.

found on Unionidae, 333, 407.
infesting Unionidae, 408, 409, 414,
416.
geographical distribution of,
414,415.
hirtus infesting Unionidae, 407.
confragosa, Alasmodonta, 401, 403,
409, 410, 412.
Margaritana, 403.

Conochilus, 303, 362.
dossuarius, 354, 362.
leptopus, 362.
resemblance to Megalotrocha

alboflavicans, 361.
seasonal distribution of, 352.
unicornis, 354, 362.
Cooley, R. A., description of Coc-
cidae by, cited, 389.
on Chionaspis, 398.
Copepoda, 27, 98, 420.

mode of collection of, by Dr.
Augustin Kramer, 12.
Coregonus clupeiformis, Limno-

calanus as food of, 237.
Cori, C. J., Ueber die Verwendung
der Centrifuge in der Zoologi-
schen Technik und Beschreibung
einer einfachen Handcentrifuge,
cited, 20.
Cornell College, 418.
cornuta, Monostyla, 375.
cornutus, Unio, 403.
corona, Difflugia, 313, 314, 320.
corpulenta, Anodonta, 401, 403,
405, 408, 409, 410, 412, 413, 415,
416.
Cothurnia, 341.

curva ^found on Urnatella gra-
cilis, 341.
Cotylaspis, geographical distribu-
tion of, 414.
infesting Unionidae, 408, 409, 411,

412, 413, 416.
insignis as parasite of Unionidae,
404.
Cragin, F. W., 39.

A Contribution to the His-
tory of the Fresh-water
Copepoda, cited, 225.
description of Cyclops per-

armatus cited, 60.
on distribution of Cyclops
prasinus, 57.

INDEX.

557

Cragin, F. W. — Continued.

on occurrence ot Hetero-

cope in North America,

225.
Craspedomonadida?, 328.
crassicaudis, Cyclops, 29.
cratera, Codonella, 312, 313, 335,

336, 35 1. 364,365-
Difflugia, 336.
Crayfishes, examination of, fur Pro-
tozoa, 310.
Opercularia irritabilis found on,
340.
Croppie, Anuraea cochlearis eaten

by, 351-
Crustacea, 355.
as food of rotifers, 34$.
examination of, for Protozoa,

310, 312.
rotifers as food of, 351.
Cryptomonadidae, 328.
Cryptomonas, 328.

ovata, 313, 328.
Ctenochiton nuytisiae, Fuller on

validity of, 394.
curva, Cothurnia, 341.
Cyclodininae, 331.

Cyclopidae, A Contribution to a

Knowledge of North American

Fresh-water, 27-82. (Special

Index, p. 83.)

explanation of plates of, 81, 82.

from high lakes and ponds, 62.

list of articles consulted in E. B.

Forbes 's article on, 66-81.
list of North American species

of, 63-65.
most abundant species of, in

Great Lakes, 62.
of the Illinois River at the Illi-
nois Biological Station, 63.
preservative of, 31.
specific characters of, 29-31.
Cyclops, 27, 28, 31, 63, 97, 100, 105,
106, 132, 141, 225, 234, 274, 421.

Cyclops — Continued.
affinis, 29, 31, 65.
agilis,29.
albidus, 29, 47-49, 62, 63, 64.

description of, 48.

distribution of, 48.

synonymy of, 48.
americanus, y], 38, 42.
annulatus, ^, 35.
ater, 29, 49-51, 62,64.
bicolor, 29, 62, 63, 64.
bicuspidatus, 29, 3°. 44-47, 53-
62, 63, 64.

description of, 45.

distribution of, 47.

synonymical discussion of, 44.
bisetosus, 29.
brevispinosus, 39, 41.
capilliferus, 51.
crassicaudis, 29.
Diaptomus, and Osphranticum,

relative hardihood of, loo.
dybowskii, 29, 62, 63.
edax, 33-36, 62, 63.

description of, 35.

distribution of, 35.

synonymy of, and comparison
with other species, 33.
. fimbriatus, 29.

var. poppei, 63, 65.
fluviatilis, 57.
forbesi, 44, 45.
fuscus, 29, 64.
general distribution of, in North

America, 62.
gigas, 29, 37.
gyrinus, 47, 48.
helgolandicus, 29.
hyalinus, 29.
ingens, 37.

insectus, 37, 38, 39, 41.
insignis, 29, 63.
lacustris, 29.
leeuwenhoeckii, 34, 35.
leuckarti, 29, 31-33, 34, 36, 63.

558

INDEX.

Cyclops — Continued.
levis, 37.

longicornis, 130, 132.
macrurus, 29.
magnoctavus, 57.
minnilus, 44, 45.
modestus, 29, 51-53, 62, 63, 64.

description of, 52.

synonymy and distribution of,

5i-

nanus, 29.
navus, 44, 45.
oithonoides, 29, 63.
on movements of, 235.
parens, 38, 41,42.
pentagonus, 57.
perarmatus, 59, 60.
phaleratus, 29, 30, 59-62, 63, 65.

best character for ready recog-
nition of, 62.

description of, 60.

distribution of, 59.
prasinus, 57-59, 63, 65.
pulchellus, 29, 44.
robustus, 29.
scutifer, 29.
serratus, 44, 45.

serrulatus, 29, 30, 54-57, 62, 63,
65.

description of, 55.

synonymy, variation, and dis-
tribution of, 54.

var. elegans, 54.

var. montanus, 54, 55.
signatus, 20.

var. tenuicornis, 47.
strenuus, 29.
thomasi, 44, 45.
Tokophrya cyclopum found on,

341-

uniangulatus, 39, 41.
varicans, 29, 63, 64.
vernalis, 29, 64.

viridis, 29, 30, 37-40, 41, 43, 48,
62, 63, 64.

Cyclops viridis — Continued.
description of, 30.
basal segment of rudimentary
foot, different authors
quoted on, 40.
synonym ical discussion of

37-39-
var. brevispinosus, 30, 41, 62,

63, 64.
var. insectus, 31, 41-44, 62, 63,

64.
Cyclopsina, 97, 105.
cyclopum, Tokophrya, 341.
Cypridopsis, 421.
cyrtopus, Notommata, 369.
Cystonagellata, 305, 315.

D

Dactylopiinae, 389.

Dactylopiini, 389.

Dactylopius, 389.

Uangeardia mamillata as parasite
of Platydorina caudata, Pando-
rina morum, and Eudorina ele-
gans, 434, 435-

Daphnia, 421.

Daphnids as food of Protozoa, 311.

decora, Hirudo, 508.
Macrobdella, 508.

deflexa, Euchlanis, 345, 374.

deflexus, Colurus, 376.

deitersi, Diaptomus, 99.

Dendromonadinae, 322.

dentata, Arcella, 313, 314, 318.

Dero furcata, 443.
limosa, 443.
obtusa, 443.
vaga, 443.

Desmids as food of Protozoa, 31 1.

Desmothoraca, 315.

diaphanus, Chaetogaster, 443.

Diaptomus, 62, 100, 103, 132, 134,
141,225,230,234, 237,250,265,
421.

INDEX.

559

D iaptomus— Co ft tin tied.
albuquerquensis, 98, 101, 113,
115, 146-149, 176, 184.
and I), mississippiensis, means
of distinguishing males of,
149.
distribution of, 183.
ambiguus, 177.
armatus, 133, 135, 136.
ashlandi, 98, m, 120, 124, 158,
167-169, 260, 265.
distribution of, 168, 183.
females of, 100.
bacillifer, 107.
birgei, 99, 108, 117, 172-173.
caroli, 181.
castor, 98, 106, 130.
clavipes, 98, 101, 108, 119, 127,
178-181.
distribution of, 18 r , 184.
similarity to D. piscinae and 1 )•
leptopus, 181.
coeruleus, 99, 101, 107.
color of, 138.

Cyclops, and Osphranticum, rel-
ative hardihood of, 100.
deitersi, 99.
diagnosis and remarks on genus

of, 105-107.
distribution of the American

species of, 182-184.
drieschi, 99.
eggs of, 228.

eiseni, 98, 101, no, 115, 162-164,
166.
distribution of, 183.
first establishment of genus of,

97-
francis£anus, 98, 110, 1 18, 132,
160-162, 166, 182.

distribution of, 183.
fresnanus, 176, 178, 184.
gibber, 99, 101.
giganteus, 138.
glacialis, 101.

Dia ptom us — Continued. .
gracilis, 98, 173, 182.

compared with D. siciloides, 155.
graciloides, 98.
incongruens, 90.
kentuckyensis, 97, 130, 132.
leptopus, 97, 112, 117, 130-132,
135, 181.
distribution of, 182.
fifth pair of legs of male of,
contrasted with those of D.
piscina?, 125, 127.
synonymy of, 132.
lintoni, 113, 118, 127-129,134,160.
contrasted with I), stagnalis,

129.
distribution of, 182.
literature of, 97.
lobatus, 101.
longicornis, 132.
var. leptopus, 130, 132.
var. similis, 132, 162, 182.
minnetonka, 133, 135, 136, 138.
minutus, 98, 106, III, 116, 129,
134, 156-158, 160, 260, 265.
distribution of, 100, 1^7, 158,

183.
normal habitat of, 100.
synonymy of, 158.
minis, 101.

mississippiensis 98, log, 122,
173-176.
and D. albuquerquensis, means
of distinguishing males of,
149.
distribution of, 184.
most favorable seasons for col-
lecting, 99.
North American species of,
()7 207. (Special Index,
p. 208.1

collections examined in

preparation of Schacht's

article on, and localities
represented, 99.

560

INDEX.

Diaptomus, North American spe-
cies ( >f — Continued.
on descriptions in
Schacht's article on, 101.
explanation of plates of,

205-207.
introduction to Schacht's

article on, 07 -101.
key to, based on characters

of female, 1 14-122.
key to, based on characters

of male, 107- 1 14.
keys of, in Schacht's ar-
ticle on, plan and use
of, 100, 101.
literature accessible in
preparation of Schacht's
article on, go.
material at command for
Schacht's article on, qq.
novamexicanus, 99, in, 116,149-
151.
distribution of, 183.
number of recognized North

American species of, 97.
on distinguishing characters of

sex in, 100.
on movements of, 235.
on specific distinctions of males

in, 100.
oregonensis, log, nq, 124, 151-154,
170, 171, 229, 265.
distribution of, 154, 183.
Osphranticum.Limnocalanus, and
Epischura, discussion
of structural similarities
and differences indica-
tive of relationships of
the genera, 226.
general bibliography of
genera of, 185 204; ad-
ditions to, 268.
synopsis of the relation-
ships of the genera, 102-
105.

Diaptomus — Continued.

pallidus, 108, 121, 124, 137, 144-
146, 265. t
distribution of, 183.
females of, 100.
var. sicilis, 122.
piscina?, 98, ioq, 116, 118,125-127,
181.
distribution of, 182.
fifth pair of legs of male of,
contrasted with those of
other species, 125, 127.
reighardi, 98, ioq, 121, 16(5-171.

distribution of, 184.
roubaui, 166.
salinus, 98.

sanguineus, g7, 112, 117,129,133-
138, 160, 166, 234.
and D. stagnalis compared, 136.
color of, 138.
distribution of, 183.
peculiarity in structure of, 134.
synonymy of, 135.
variation in, 136, 137.
serricornis, 162.

shoshone, no, n6, 127, 141 143.
164.
distribution of, 143, 183.
sicilis, 97, 100, in, 121, 122-124,
145, 167, 168, 169, 182,229, 264-
compared with D. siciloides,i 55.
details of structure distinguish-
ing from D. ashlandi and D.
pallidus, 124.
distribution of, 124, 182.
females of, 100.
variation in structure of, 124.
var. imperfectus, 124, 158, 167,
169.
siciloides, g8, ico, 114, 121, 124,
137, 146, 154 156, 157, 165,

l66, l8l, 182, 22Q, 265.
compared with I), caroli, I ).
gracilis, and 1). sicilis, 155,
182.

INDEX.

56l

Diaptomus siciloides — Continued.
distribution of, 183.
eggs of, 155.
females of, 100.
signicauda, 98, 114, 120, 157, 159,
i6o, 164-166.
distribution of, 183.
signicaudatus, 164.
similis, 132, 182.

species of, insufficiently de-
scribed, 181.
stagnalis, 97, 101, 113, 115, 136,
138-141, 142, 164.
contrasted with Diaptomus

lintoni, 129.
distribution of, 183.
theeli, 101.
trybomi, 98, 112, 120, 158-160, 166.

distribution of, 183.
tyrrelli, 99, 108, 119, 160, 176-
178.
distribution of, 184.
wierzejskii, 101, 107.
zachariasi, 99.
Diaspis amygdali, possible syno-
nym of, 398.
piricola, resemblance to Aspidi-

otus ostreaeformis, 398.
snowi, resemblance to Aspidio-
tus ancylus, 398.
diastrophus, Chaetogaster, 443.
Diatoms, 12, 311, 421.

as food of Opercularia irritabilis,
340.
of Protozoa, 311.
of Rotifera, 351, 373.
Didinium, 331.

nasutum, 313, 331.
Difflugia, 274,305,306,312, 318,421.
aculeata, 313, 314, 320.
acuminata, 313, 319.
as food of fishes, 312.
corono, 313, 314, 320.
cratera, 336.
food of, 311.

Difflugia — Continued.

fragosa, 312, 313, 320.
figures of, 321.

globulosa, 312, 313, 314, 318, 320.
as food of rotifers, 351, 364.

lobostoma, 313, 314, 319, 320.

pyriformis, 313, 314, 319.
compressa, 319.
vas, 319.

tuberculosa, 313, 320.

urceolata,3i9.
Diglena, 370.

biraphis, 371.

catellina, 370.

forcipata, type of trophi of, 345.

grandis, 370.
dilatata, Euchlanis, 374.
Dileptus, 331.

anser, 332.
Dina, 533, 535.

fervida, 535~537. 54Q, 541.

annulation and metamerism of

1

compared with those of Er-
pobdella punctata, 535.

color of, 537.

diagnosis and general descrip-
tion of, 535.

reproductive organs of, com-
pared with those of Erpob-
della punctata, 536.
mexicana, 541.
microstoma, 537-541.

annuli and somites of, 539 541.

color and reproductive organs

of, 541.

' diagnosis of, 537.
general description and metam-
erism of, 537-539-
Dineutes, Megalotrocha scmibul-

lata eaten by, 361.
Dinifera, 329.
Dinobryon, 274, 323, 421.
sertularia, 312, 313, 323.
angulation, 323.
divergens, 323.

562

INDEX.

Dinobryon sertularia — Continued.
Salpingceca minuta found on

loricse of, 329.
undulatum, 323.
Dinobryonina?, 323.
Dinocharidae, 358, 372.
Dinocharis, 372.
food of, 351.
pocillum, 372.
seasonal distribution of, 352.
Dinoflagellata, 307, 315, 32Q.
diogenes, Cambarus, 340, 342, 542.
Diplobdella, 511, 518.
Uiplocardia, 449.
communis, 442.
riparia, 442.
singularis, 442.
sp. 442.
verrucosa, 442.
Diplosiga, 328.

frequentissima, 328.
found on rays of Asterionella,
328.
Discodrilida?, 441.

note on, 542.
Distomidae, encysted and free, in-
festing Unionidae, 405,
406, 407, 408, 409, 416.
geographical distribution
of, 414, 415.
Distyla, 375, 421.
gissensis, 375.
hornemanni, 375.
ohioensis, 375.

cultures of, 348.
stokesii, 375.
diversicornis homoceros, Schizo-
cerca, 382.
Schizocerca, 382.
Dolley, C. S., the Planktonokrit, a
Centrifugal Apparatus for the
Volumetric Estimation of the
Food-Supply of Oysters and
other Aquatic Animals, cited,
20.

donaciformis, Plagiola, 401, 403,
409, 410, 412, 416.

Unio, 403.
dorcas, Brachionus, 353, 354, 379.

spinosus, Brachionus, 354, 379.
dossuarius, Conochilus, 354, 362.
drieschi, Diaptomus, 99.
Dufour & Company, 3.
dybowskii, Cyclops, 29, 62, 63.

Earthworms as food of Haemopis
marmoratis, 527.
of Philobdella gracile, 518.
of North America, list of, by
Garman, cited, 441.
ebbesbornii, Asplanchna, 345, 354,

364.
ebena, Quadrula, 401, 403, 409, 410,

411, 412, 4131 414-
ebenus, Unio, 403.
Eclipidrilinae, distinguishing char-
acters of, 474.
Eclipidrilus, 462, 468, 471, 475.
frigidus, 460, 465, 466.

circulatory system of, 474.
Mesoporodrilus asymmetricus,
and Premnodrilus palustris
compared, 472, 475.
edax, Cyclops, 33, 62, 63.
edentula, Anodonta, 403.
edentulus, Strophitus, 401, 403, 406,

409, 410, 412, 413, 416.
Ehrhorn, E. M., descriptions of

Coccidas by, cited, 390.
Eisen, G., 155, 162, 164, 166, 178,

475-
Anatomical Notes on Sutroa
alpestris, a New Lumbricu-
lide Oligochaste from Sierra
Nevada, California, cited,

471.
Eclipidrilidas and their Anat-
omy, cited, 471, 474.

INDEX.

563

Eisen, G. — Continued.

On the Anatomy of Sutroa ros-
trata, a New Annelid of the
Family Lumbriculina, cited,
471.
on the application of terms
gastric and perigastric, 469.
on the circulatory system of

Eclipidrilus frigidus, 474.
on the prostate glands of

Eclipidrilus frigidus, 464.
Pacific Coast Oligochaeta. I.,
cited, 462, 464, 471.
eiseni, Diaptomus, 98, 101, no, 115,
162, 166, 183.
Sparganophilus, 442.
Eggs of Aspidiogaster conchicola,
404.
of Atax, 407, 414.
of Cotylaspis insignis, 405.
of frogs eaten by Macrobdella

decora, 511.
of Rotifera, 347.
of Sacculus, 366.
ehrenbergii, Gastropus, 368.
eichhornii, Actinosphaerium, 313.
322.
Stephanoceros, 345.
elegans, Callidina, 364.
Clepsine, 493.
Eudorina, 273, 277, 286, 431, 435,

437-
Plagiola, 401, 403, 406, 409, 410,

412, 413, 416.
Raphidiophrys, 322.
Unio, 403.
ellipsis, Lampsilis, 401, 403, 405,
409, 410, 412, 413, 416.
Unio, 403.
elinguis, Nais, 443.
elliptica, Metopidia, 377.
Elodea, 354.

elongata, Mastigocerca, 371.
Embolocephalus, 453, 456.
multisetosus, 443.

Embolocephalus multisetosus
-Continued.
description of, 452-455.
relation of, to other Tubificidce,
456.
plicatus, 456,
velutinus, 456.
emissarius, Phreoryctes, 442.
Enchelidce, 330.
Enchytraeidte, 441.

found in Illinois, 442.
Engstrom, Ella V., 441.
Entomostraca, 19, 97, 225, 228, 351,
421.
species of Rhabdostyla found on,
340.
Eospora, 370.

aurita, 324, 370.
Epischura, 97, 103, 166, 225, 226,
237, 249 251, 267.
distribution of, 251.
doubtful species of, 265.

discussion of published
figures and descriptions
of, 266, 267.
eggs of, 228.
fluviatilis, 226, 250, 265-267.

synonymy of, 266.
key to the species of, 2.51.
lacustris, 228, 229, 249, 250, 251,
252, 260-265.
associate species and distribu-
tion of, 264, 265.
compared with E. nevadensis,
264.
with E. nordenskioldii, 254,
255, 256.
on descriptions and figures of,
263, 264.
Limnocalanus, and Osphranti-
cum, North American Centro-
pagidie belonging to the gen-
era, 225-270.
nevadensis, 98, 168, 229, 249, 250,
251, 256-260, 262.

564

INDEX.

Epischura nevadensis — Continued \
Columbia;, 256, 258, 259.
compared with E. lacustris>
264.
with E. nordenskioldii, 254,

255. 256.
distribution of, 260.
on descriptions and figures of,
259.
nordenskioldii, 98, 249, 250, 251,
252-256.
compared with E. lacustris
and E. nevadensis, 254, 255,
256.
on figures of, 254.
on habitat of, 226.
Osphranticum, Limn 0 calanus,
and Diaptomus, discus-
sion of structural simi-
larities and differences
indicative of the rela-
tionships of the genera,
226-228.
general bibliography of
genera of, 185-204; ad-
ditions to, 268.
synopsis of the relation-
ships of the genera of,
102-105.
Epistylis, 312, 339, 340, 341.
flavicans, 339.
plicatilis, 342.

found on shells of water-snails,

339-
Eriococcini, 389.

Eriococcus, 389.
Erpobdella, 532.

punctata, 532-535, 536, 539, 540.

and Dina fervida, differences

in annulation, metamerism,

and reproductive organs of,

535- 536.

diagnosis and general descrip-
tion of, 532.

food of, 535.

Erpobdella punctata -Contained.
habits of, 535.
reproductive organs of, 533.
eucalypti, Aspidiotus perniciosus,

396.
Euchlanidae, 359, 373.
Euchlanis, 274, 373, 375, 421.
deflexa, 374.

type of trophi of, 345.
dilatata, 374.
food of, 351, 374.
lynceus, 368.
pyriformis, 374.
seasonal distribution of, 352.
triquetra, 374.
Eucyclops, 54, 65.
Eudorina, 274, 275, 276, 277, 278,
280, 284, 286, 287, 288, 420, 422,
423, 425, 427, 431, 432, 433, 434,

435- 436. 437-
disease of, 289.

elegans, 273, 277, 286, 43 '. 435- 437-

parasite of, 435.
polarity and locomotion of, 284,

285, 431, 432.

possible Pleodorina stage of,

286, 287.

Euglena, 274, 301, 306, 313, 323,
325, 420.
acus, 313, 324.
as food of Opercularia, 311.

of Opercularia irritabilis, 340.
of protozoans, 324.
of rotifers, 312, 324.
oxyuris, 313, 324.
spirogyra, 313, 324.
torta, 313, 324.
viridis, 312, 313, 324, 325.
Euglenidce, 323, 325.
Euglenoidina, 323.
Euglypha, 305, 306, 321.

alveolata, 321.
Euglyphidae, 315, 321.
Eurytemora, 225.
herdmani, 226.

INDEX.

565

eustala, Salpina, 352, 373.

Evaspidiutus, type of, 395.

Evermann, B. W., and Meek, S. E.,

259.

F

fervida, Dina, 535, 540, 541.

Nephelis, 535.
fimbriates, Cyclops, 29.

var. poppei, Cyclops, 63, 65.
Fish, 504.

Fishes attacked by Macrobdella,
511.
parasitized by Piscicola, 504.
Protozoa as food of, 312.
Flagellata, 304, 306, 315,322,420.
flagellum, Pristina, 443.
flavicans, Epistylis, 339.
floridana, Philobdella, 51 1, 518.
floriger, Walkeriana, 391.
Floscularia, 360.
ornata, found on Ceratophyllum,
360.
seasonal distribution of, 352.
Floscularidas, 356, 360.
fluviatile, Tintinnopsis, 335.
fluviatilis, Cyclops, 57.
Epischura, 226, 250, 265.
[Epischura] Lamellipodia, 265.
fcetida, Allolobophora, 441.
Forbes, E. B., 98.

A Contribution to a Knowl-
edge of North American
Cyclopidae, 27-82.
Forbes, S. A., 29, 31, 37, 38. 48,98.
124, 127, 185, 263, 301, 303,

418, 475- 479-

An American Terrestrial
Leech, cited, 528, 531, 532.

A Preliminary Report on the
Aquatic Invertebrate
Fauna of the Yellowstone
National Park, Wyoming,
and of the Flathead Region
of Montana, cited, 126, 127,
143,244,259, 263, 267.

Forbes, S. A.— Continued.

adaptation and compilation

from MS. of, 102.
Biennial Report as Director
of the Illinois State Labo-
ratory of Natural History
for 1893-94, cited, 3.
description of Cyclops in-
sectus, cited, 38.
of Diaptomus lintoni, 127-

129.
of Diaptomus piscinae, 125-

126.
of Diaptomus shosho n e,

141-143-

of Epischura nevadensis
columbiae, cited, 259.

of Osphranticum labro-
nectum, 233.
descriptions and figures of

Epischura lacustris cited,

263-264.
List of Illinois Crustacea,

with Descriptions of New

Species, cited, 97, 135, 138.
on color of Diaptomus stag-

nalis, 140.
on distribution of Limnocal-

anus macrurus, 244.
on habitat and movement of

Osphranticum, 226, 234,

235-
on Hasmopis lateralis, 528,

53i. 532.

on parasites of Asplanchna
herrickii, 365.

on segmentation of antennas
of Osphranticum labronec-
tum, and on its color, 234.

On some Entomostraca of
Lake Michigan, cited, 97,
124, 135, 140, 233, 263.

On the Food of Young White-
fish (Coregonus), cited, 233,
244.

566

INDEX.

Forbes, S. A.— Continued.

On the Food Relations of
Fresh-Water F i shes : A
Summary and Discussion,
cited, 237.
Preliminary Report upon
the Invertebrate Animals
inhabiting Lakes Geneva
and Mendota, Wisconsin,
with an Account of the
Fish Epidemic in Lake
Mendota in 1 884, cited, 169,
244. 264.
The First Food of the Com-
mon White-fish (Corego-
nus clupeiformis Mitch.),
cited, 237.
forbesi, Cyclops, 44, 45.
forcipata, Diglena, 345.
forficula, Furcularia, 370.
F o r h a n d ligar i Videnskabs-Sel-

skabet i Christiana, cited, 242.
fossulatus, Atax, 408.
foveolata, Gastroschiza, 368.
Fragillaria, 19, 274, 421.
fragosa, Difflugia, 312, 313, 320.
franciscanus, Diaptomus, 98, no,

118, 132, 160, 166, 182, 183.
frenchii, Lecanium, 394.
frequentissima, Diplosiga, 328.
Fresenius, G., on locomotion of
Gonium, 283.
Ueber die Algengattungen
Pandorina, Gonium, und
Raphidium, cited, 283.
fresnanus, Diaptomus, 176, 178, 184.
Fridericia agilis, 442.
frigidus, Eclipidrilus, 464, 465, 466,

469, 472, 473. 474, 475-
Frogs attacked by Macrobdella, 51 1.
eggs of, eaten by Macrobdella

decora, 511.
Hemiclepsis carinata found at-
tached to, 504.
fucosus, Potomoichetor, 230, 233.

Fuller, Claude, as authority for
changes in synonymy of
Apiomorpha spp., 393.
descriptions of Coccidae by,

cited, 390.
on Lecanium macrozamiae as
a variety of L. frenchii, 394.
on species belonging to Calli-

pappus, 390.
on validity of Ctenochiton (?)

nuytisias, 394.
slides of Aspidiotus pernicio-

sus eucalypti from, 396.
withdrawal of Solenophura
dryandrae by, 392.
furcata, Dero, 443.
Furcularia, 370.
forficula, 370.
longiseta, 370.
type of trophi of, 345.
fuscus, Cyclops, 29, 64.

Garman, H., A Preliminary Report
on the Animals of the Mis-
sissippi Bottoms near
Quincy, Illinois, in August,
1898. Part I., cited, 420.
list of North American earth-
worms cited, 441.
notes on and sketches of Pla-
tydorina cited, 420.
Gastropods as food of Glossipho-
nia stagnalis, 498.
of Haemopis marmoratis, 527.
Gastropus ehrenbergii, 368.
Gastroschiza foveolata, 368.

lynceus, 368.
Geoscolicidge found in Illinois, 442.
gibber, Diaptomus, 99, ioi.
gibbosus, Unio, 401, 403, 409, 410,

412, 413, 415, 416.
Giesbrecht, W., 102.

on a common character of the
Copepoda, 228.

INDEX.

567

Giesbrecht, W. — Continued.

on a distinguishing character

of the Copepoda, 226.
on specific distinctions of males

in Diaptomus, 100.
Systematik und Faunistik der
pelagischen Copepoden des
Golfs von Neapel und der
angrenzenden Meeresab-
schnitte, cited, 98, 101, 226,
228.
Ueber pelagische Copepoden
des Rothen Meeres, gesam-
melt von Marinestabarzt Dr.
Augustin Kramer, cited, 12.
giganteus, Diaptomus, 138.
gigas, Cyclops, 29, 37.
G i s s 1 e r, C. F., Note regarding
Change of Color in Diapto-
mus sanguineus, 138.
Variations in a Co p e p o d
Crustacean, cited, 138.
giesleri, Allolobophora, 442.
gigantea, Vaginicola, 341.
girodi, Asplanchna, 365.
gissensis, Distyla, 375.
glacial'is, Diaptomus, 101.
Glaucea, 97, 105.
globator, Volvox, 276, 285, 287, 312,

313. 327. 365- 438.
globulosa, Difflugia, 312, 313, 314,

318, 320, 351, 364.
Glossiphonia, 493.

complanata, 494, 496, 497.

diagnosis of, 493.

food of, 493.
lineata, 493~497-

alimentary canal, color, and
reproductive organs of, 496.

annuli and somites of, 494-496.

diagnosis of, 493.

general description of, 494.

habits of, 497.
stagnalis, 496, 497.

breeding season of, 498.

Glossiphonia stagnalis— Continued.
diagnosis of, 497.
food of, 498.
triserialis, 493.

situation of male pore in, 493.
Glossiphonidae, 480.
Gomphogaster areolatus, 368.
Gonium, 419, 420, 426, 427, 436, 437.
locomotion and polarity of, 283,

43L 432.

pectorale, 437.

sociale, 437.
Goodrich, E. S., On the Structure

of Vermiculus pilosus, cited, 446,

451, 452.
Goroschankin, J., Genesis im Ty-

pus der palmellenartigen Algen.

Versuch einer vergleichenden

Morphologie der Familie der

Volvocinea, cited, 284, 288.
Gosse, P. H., 372, 373.

On Mastigocerea bicristata,

371. 372.
and Hudson, C. T. See Hud-
son and Gosse.
gracile, Philobdella, 511.
gracilis, Diaptomus, 98, 155, 173,
182.
Lampsilis, 401, 402,403,408,409,
410, 411, 412, 413, 414, 415, 416.
Unio, 403.
Urnatella, 341.
graciloides, Diaptomus, 98.
Graf, Arnold, Hirudineenstudien,

cited, 497.
grandinella, Halteria, 313, 335.
grandis, Anodonta, 401, 403, 406,
409, 416.
Diglena, 370.
granifera, Quadrula, 401, 403, 409.
graniferus, Unio, 403.
granulatum, Carchesium, 339.
Green, E. E., as authority for loca-
cation of Lecanium hesperidum
alienum, 393.

568

INDEX.

Green, E. E. - Continued.

says Coccus laniger isWalk-
eriana floriger, 391.
Gregarina, 306.

grimaldii, Centropages, 238, 242.
Limnocalanus, 226, 229, 239, 242,

243-

Guerne, Jul. de, Description of

Centropages grimaldii,

Copepode nouveau du golfe

de Finlande, cited, 242.

et Richard, J., 99, 160, 176,236.

description and figures
of Epischura lacustris
cited, 263.

diagnosis of Diaptomus
and remarks upon ge-
nus by, — translation,
105, 106, 107.

on Diaptomus minutus,
157.

on Diaptomus tyrrelli,
178.

on differences between
Limnocalanus sinensis
and L. macrurus, 249.

on length of Limnocala-
nus sinensis, 248.

on number of segments
in antennae of Os-
ph rant i c um labro-
nectum, 234.

on second pair of anten-
nae of Limnocalanus
macrurus, 236.

on synonymy of Limno-
calanus macrurus, 242.

Revision des Calanides
d'eau douce, cited, 97,
100, 101, 146, 153, 154,
155, 157, 158, 160, 162,
164, 166, 177, 178, 185,
206, 233, 236, 237, 238,'
242, 243, 254, 256, 259,
263, 264.

Gymnoplea, 102.
Gymnostomata, 306, 316, 330.
gyrinus, Cyclops, 47, 48.

H

Hasmenteria officinalis, 489.

Haemopis,5io, 511,512, 517,518,519.

lateralis, 512, 528-532.

alimentary canal, color, and

reproductive organs of, 531.

annuli and somites of, 529-531.

diagnosis, general description,

and measurements of, 528.
habits of, 532.
m a rmo ra t is, 511,515, 519-527,
528, 529, 530, 531.
alimentary canal of, 526.
annuli and somites of, 522-524.
color and habits of, 527.
diagnosis, general description,
and measurements of, 519-
522.
food of, 527.

reproductive organs of, 524-
526.
sanguisuga, 531.
Halteria, 335.

grandinella, 313, 335.
Halteriidae, 335.
hamatus, Centropages, 244.
Hart, C. A., 303, 418.

mention of collaboration in
preparation of Hempel's
List of the Protozoa and
Rotifera found in the Illi-
nois River and Adjacent
Lakes at Havana, 111., 301.
Hart, Lydia M ., 23, 98, 303, 440, 441,

475-
Hatai, S., On Vermiculus limosus,

a New Species of Aquatic Oligo-

chaeta, cited, 451.
hederae, Aspidiotus, 395.
helgolandicus, Cyclops, 29.
Helizoa, 306, 315, 321.

INDEX.

569

Helobdella triserialis, 493.
Hemiclepsis, 498.
carinata, 498-504.

alimentary canal, color, habits,
and reproductive organs of,

5°3-
annuli and somites (if 500-503.
diagnosis and general descrip-
tion of, 498-500.
found attached to frogs and
toads and in shells of living
mussels, 504.
Hemitubifex, 456.
Hempel, Adolph, 28, 31, 98, 148,'
175, 176, 459, 475.
A List of the Protozoa and
Rotifera found in the Illinois
River and Adjacent Lakes
at Havana, 111., 301 388. (See
Hart, C. A.)
hemprichii, yEolosoma, 443.
Henfrey, A., Notes on some Fresh-
water Confervoid Algae New
to Britain, cited, 274.
on arrangement of cells in
Eudorina, 274.
Hensen, V., 1, 3.

Methodik der Untersuchung
bei der Plankton-Expedi-
tion, cited, 2.
Ueber die Bestimmung des
Planktons oder des im Meere
treibenden M a t e r ia Is an
Pflanzen und Thieren, cited,

2, 13-

herculeus, Lumbricus, 441.

Herdman, W. A., Thompson, I. C,
and Scott, Andrew, On the Plank-
ton collected continuously dur-
ing two Traverses of the North
Atlantic in the Summer of 1897 ;
with Descriptions of New Co-
pepoda ; and an Appendix on
dredging in Puget Sound, cited,
226.

herdmani, Eurytemora, 226.
Herpobdella, 532.
Herpobdellida?, 532.
Herrick, C. L., 28, 38, 30, 45.

A Final Report on the Crus-
tacea of Minnesota, cited
132, 135, 182, 225, 266.

Contribution to the Fauna of
the Gulf of Mexico and
the South. List of Fresh-
water and Marine Crus-
tacea of Alabama, with
Descriptions of the New
Species and Synoptical
Keys for Identification,
cited, 225, 266.

A New Cyclops, cited, 97,
132.

descriptions and figures of
Epischura lacustris, cited,
263.

descriptions and figures of
Epischura fluviatilis cited
and discussed, 266, 267.

description of D i a p t o m us
novamexicanus (compiled
by Schacht), 149-15 1.

description of Potomoiche-
tor fucosus cited, 233.

Habits of Fresh-water Crus-
tacea, cited, 135.

Heterogenesis in the C o -
pepod Crustacea, cited,
267.

Heterogenetic Development
in Diaptomus, cited, 266.

Micro-Crustacea from New
Mexico, cited, 151.

Microscopic Entomostraca,
cited, 132, 146.

on color of Cyclops prasinus.

59-
on color of Diaptomus inin-

netonka and D. sanguin-
eus, 138.

S7°

INDEX.

Herrick, C. L. — Continued.

on Cyclops serrulatus var.

elegans, 54.
on Diaptomus caroli, 182.
on Diaptomus minnetonka,

136.
on Diaptomus siciloides, re-
semblances, 182.
on distribution of Cyclops

ater, 51.
on distribution of Cyclops

prasinus, 57.
on habitat of Osphranticum,

226, 234.
on identity of Scopiphora

vagans and Epischura la-

custris, and on description

of the former, 263.
on inner rami of fifth pair of

feet of male Diaptomus

sicilis, 124.
on occurrence of Temora

affinis (="Temorella af-

finis "), 225.
on segmentation of antennae

of Osphranticum labro-

nectum, 234.
Papers on the Crustacea of

the Fresh Waters of Min-

nesota, cited, 37, 135,

233-
and Turner, C. H., Synopsis

of the Entomostraca of

Minnesota, 37, 38, 54, 124;

132, 136, 138, 149, 151, 154,

158, 181, 254, 266.
herrickii, Asplanchna, 351, 354, 364.
hesperidum alienum, Lecanium,

393-
Heterarthrandia, 102.

Heterochaetina, 104.

Heterocope, 99, 225, 267.

heterodon, Unio, 401, 403, 409.

Heteromonadidas, 322.

Heterotricha, 308, 316, 333.

Hexagenia larvae, Tokophrya
quadripartita recorded from, 342.
higginsii, Lampsilis, 401, 403, 409.

Unio, 403.
hirtus, Conchoplitliirus, 407.

Coleps, 312, 331.
hirundinella, Ceratium, 330.
Hirudinidae, 508.

Hirudinea of Illinois, The, 479-547.
bibliography in Moore's ar-
ticle on, 543.
explanation of plates in
Moore's article on, 545-547.
Hirudinidae, 532.
Hirudo, 511, 512, 517.
bioculata, 497.
complanata, 493.
decora, 508.
lateralis, 528.
marmorata, 510.
parasitica, 480.
stagnalis, 497.
hispida, Trachelomonas, 326.
Hoek, P. P. C, co m pa rison of
figures of Cyclops leeuwen-
hoekii published by, with
C. edax, 35.
on basal segment of rudi-
mentary foot of Cyclops
viridis, 40.
Holophryinae, 330.
Holotricha, 307.
Hoist, N. O., 157.
Homocyclops, 29, 49, 64.
hornemanni, Distyla, 375.
Horse-leech, 527, 529. See Haemo-

pis marmoratis.
Hudson, C. T., Diagram of typi-
cal trophi of rotifers and
a summary of distinguish-
ing features of their types,

344. 345-
on Affinities and Classifica-
tion of the Rotifera, cited,

355-

INDEX.

571

Hudson, C. T. - Continued.

and Gosse, P. H., 301, 367.
on types of trophi of Ro-

tifera, 344.
The Rotifera or Wheel
Animalcules, cited;
also Supplement to
same, 356.
Hunter, S. J., description of Coc-

cida? by, cited, 390.
hyalinus, Cyclops, 29.
Hydatina, 368.
senta, 368.

cultures of, 348.
distribution of, 350.
Hydatinidae, 358, 368.
Hydra, 308.

rrichodina parasitic on, 337.
viridis, Trichodina pediculis fre-
quent on, 337.
hypelasma, Anuria, 382.
Hypotricha, 308, 316, 336.

I

Ichthyobdellidae, 498, 504.

Idiococcinae, 389.

igneus, Stentor, 334.

Ihering, H. von, descriptions of

Coccidae by, cited, 390.
Illinois Biological Station, 28, 63,
137, 146, 229, 233, 234, 399, 418,

44 1. 479-
State Laboratory of Natural His-
tory, 28, 99, 185, 228, 229, 233,
242, 259, 268, 290, 441.
illinoisensis, Pleodorina, 273, 274,
290, 424, 431, 432, 437.
Tintinnopsis, 313, 335.
Illoricata, 357.
llyodrilus, 446, 448.
coccineus, circulatory system of,

451. 452-
imbecilis, Anodonta, 401, 403, 408,

409, 410, 412, 413.

Imhof, O. E., 98.

immane, Ccelostoma, 390.
incongruens, Diaptomus, 99.
inconstans, Thinodrilus, 442, 469.
indistinctus, Atax, 406.
inequiannulata, Actinobdella, 504.
Infusoria, 304, 307, 309, 315, 330.

ciliated, as parasite of Union-
idae, 407.
ingens, Cyclops, 37.
Insect larvae, aquatic, examination

of, for Protozoa, 310.
Insects, aquatic, as food of

Haemopis marmoratis, 527.
insectus, Cyclops, 37, 38, 39, 41.
insignis, Cotylaspis, 404, 405.

Cyclops, 29, 63.
intermedius, CEcistes, 361.
irritabilis, Opercularia, 340, 342.
Isomastigoda, 326.

Jennings, H. S., A List of the Ro-
tatorio of the Great Lakes
and of some of the Inland
Lakes of Michigan, cited,

366, 375-
on Cathypna stokesii, 375.
Journal of Morphology cited, 542.
Juday, Chancey, 229.
Jurine, L., Histoire des Monocles
qui se trouvent aux environs de
Geneve, cited, 97.

K

Kellicott, D. S., 305.
Kelly, H. M., A Statistical Study
of the Parasites of the Unioii-
idae, 399-418.
Kent. W. Saville, 301.

Manual of the Infusoria,
cited, 314.
kentuckyensis, Diaptomus, 07, 130,

132.
Kermicus and Chaetococcus, dif-
ference between, 392.

572

INDEX.

Kermicus — Continued.
dactylopiine character of larva
of, 392.
King, G. B., descriptions of Cocci-
dee by, cited, 390.
Klebs, G., Ueber die Organisation
der Gallerte bei einigen Algen
' und Flagellaten, cited, 276.
Klein, L., Morphologische und bio-
logische Studien iiber die
Gattung Volvox, cited, 276,
285, 287.
Neue Beitriige zur Kenntniss
der Gattung Vol vox.cited, 287.
on polar differentiation and ro-
tation of Volvox, 285.
Vergleichende untersuchungen
iiber Morphologic und Biol-
ogie der Fortpflanzung bei
der Gattung Volvox, cited,
285, 287.
Koch, C. L., Deutschlands Crus-
taceen, Myriapoden, und Arach-
niden, cited, 97.
Kofoid, C. A., 23, 229, 303, 313, 329,
400, 418, 440.
on Cotylaspis insignis as par-
asite of Anodonta corpu-
lenta, 405.
On the Occurrence of Troch-
osphaera solstitialis in the
Illinois River, cited, 362.
on Hempel's Tintinnopsis

illinoisensis, 335.
Plankton Studies. I. Meth-
ods and Apparatus in Use
in Plankton Investigations
at the Biological Experi-
ment Station of the Uni-
versity of Illinois, 1-25.
Plankton Studies. II. ( )n
Pleodorina illinoisensis, a
New Species from the
Plankton of the Illinois
River, 273-293 ; cited, 431.

Kofoid, C. A. — Continued.

Plankton Studies. III. On
Platydorina, a New Genus
of the Family Volvocidae,
from the Plankton of the
Illinois River, 419-440.

kumaonense, Ceratium, 421.

Labidesthes sicculus, L imnoca 1-

anus as food of, 237.
labronectum, Osphranticum, 227,

230.
lachmanni, Carchesium, 33S.
lachrymosa, Quadrula, 401 , 403, 408,

409, 410, 411, 412, 414.
lachrymosus, Unio, 403.
lacinulata, Notommata, 367.
Lacrymaria, 330.

truncata, 330.
lacteus, Rhizodrilus, 443, 444.
lacustre, Aulastomum, 519.
lacustris, Cyclops, 29.

Epischura, 228, 229, 249,250, 251,
252, 254, 255, 256, 260.

Nais, 443.
laevissimus, Lampsilis, 401, 403, 40S.
409.

Unio, 403.
Lamellibranchs as food of Haemo-

pis marmoratis, 527.
Lamellipodia, 267.

[Epischura] fluviatilis, 265.
Lampsilis alatus, 401, 403.

parasites of, 408, 409, 410, 412,
413, 414, 416.

anodontoides, 401, 403.

parasites of, 406, 408, 409, 410,

412, 413, 416.

capacity for infestation exhibited

by, -413-
ellipsis, 401, 403.
parasites 01,405,400,410, 412,

413, 416.
gracilis, 401, 403.

INDEX.

573

Lampsilis gracilis - Continued.

parasites of, 402, 408, 40Q, 410,
411, 412, 413, 414, 415, 416.
higginsii, 401, 403.
parasite of, 409.
laevissimus, 401, 403.

parasites of, 408, 409.
ligamentinus, 401, 403, 410.

parasites of, 407, 409, 410, 412,

413, 414, 416.
luteolus, 401, 403.

parasites of, 409, 410, 412, 413,

414. 4i6.
nasutus, 401, 403.

parasites of, 409.
ochraceus, 401, 403.

parasite of, 409.
parasites of, 405, 408.
parvus, 403.

parasites of, 404, 409, 410, 412,

413-
rectus, 401, 403.

parasites of, 408, 409, 410, 412,
416.
tenuissimus, 401, 403.

parasites of, 409.
ventricosus, 401, 403.

parasites of, 407, 408, 409, 410.
411, 412, 413, 416.
Lande, A., on basal segment of
rudimentary foot of Cyclops vir-
idis,40.
hunger, Coccus, 391.
lata, Mastigocerca, 372.
lateralis, Haemopis, 512, 528.
Hirudo, 523.
Nephelis, 532.
Lecaniodiaspis, 395.
Lecanium frencliii, 394.
hesperidum alienum as located

by Green, 393.
macrozamiae, Fuller on, 394
patelliformis as located by New-
stead, 393.
Leeches, 407, 479-546.

leeuwenhoekii, Cyclops, 34, 35.
Leidy, Joseph, 301, 305, 471.

Corrections and Additions to
former Papers on Helmin-
thology, cited, 450.
description o f Astacobdella

philadelphica cited, 542.
Description of Nephelis punc-
tata, cited, 535.
Description of two New
Genera of Vermes, cited, 456.
Fresh-water Rhizopods of

North America, cited, 314.
Notice of some American
Leeches, cited, 509.
leidyi, Pristina, 443.
Lemna, 234, 310.
Lemnaceae, 349.

Carchesium polypinum found on,

338.
lenticulare, Plcesoma, 368.
Leonardi, G., description of Cocci-
das by, cited, 390.

on dismemberment of Mytilas-

pis, 397-
See also Berlese and Leon-
a rd i .
leontina, Cathypna, 374.
Lepocinclis, 274.
leptopus, Conochilus, 362.

Diaptomus, 97, 112, 117, 125,127,
130, 135, 181, 182.
leuckarti, Cyclops, 29,31,34,36,62,63.
Leuckartiina, 104.
levis, Cyclops, 37.
Lidgett, J., descriptions of Coccidae

by, cited, 390.
ligamentinus, Lampsilis, 401, 403,
407, 400, 410, 412, 113, 414, 416.
Unio, 403.
Lilljeborg, \V., gS, 153, 160, 162, 166,
178, 229, 259.
description of Diaptomus
eiseni and remarks upon,
162-164.

b74

INDEX.

Lilljeborg, W. — Continued.

description of Diaptomus fran-
ciscanus and remarks upon,
160 162.
description of Diaptomus fres-

nanus (=tyrrelli), 176.
description of Diaptomus mi

nutus, 136.
description of Diaptomus ore-

gonensis cited, 154.
description of Diaptomus sicil-

oides, 154.
description of Diaptomus sig-
nicauda and remarks upon,
164-166.
description of Diaptomus try-

bomi, 1 5 1- 1 60.
on length of Epischura nor-
denskioldi, 254.
limnaei, Chastogaster, 407, 443.
Limnias, 360.
ceratophylli, 360.

found on Ceratophyllum and
Potamogeton, 360.
limnias, Cephalosiphon, 360.
Limnocalanus, 104, 225, 226,235-238.
as food of fishes, 237.
eggs of, 228.

Epischura, and Osphranticum,
The North American Centro-
pagida; belonging to the Ge-
nera, 225-270.
establishment of genus of, 236.
grimaldii, 22q, 239, 242, 243.

synonym of, 226.
habits of, 237.
key to the species of, 238.
macronyx, 226.

macrurus, 227, 229, 235, 236, 237,
238-244, 264.
auctus, 239, 244.
difference between, and L.

sinensis, 240.
distribution of, 237, 244.
habitat of, 226.

Limnocalanus macrurus — Contin-
ued.
on illustrations of, 243.
Osphranticum, Epischura, and
Diaptomus, discussion of
st r u c t u ral similarities
and differences indica-
tive of relationships of
genera of, 226-228.
general bibliography of
genera of, 185-204 ; ad-
ditions to, 268.
synopsis of the relation-
ships of the genera, 102-
105.
sinensis, 99, 229, 235, 236, 238, 245-
249.
differences between, and L.

macrurus, 249.
distribution of, 237.
habitat of, 226, 237.
locality from which the species
is recorded, 249.
Limnodrilus claparedianus, 442.

description of, 444.
limosa, Dero, 443.
limosus, Vermiculus, 451.
lineata, Glossiphonia, 493, 497.
lintoni, Diaptomus, 113, 118,127,

134, 160, 182.
lobatus, Diaptomus, 101.
lobostoma, Diniugia,3i3,3i4,3i9,320.
longicauda, Phacus, 313, 326.
longicaudum, Scaridium, 373.
longicornis, Cyclops, 130, 132.
Diaptomus, 132.

var. leptopus, Diaptomus, 130.132.
var. similis, Diaptomus, 132, 162,
182.
longiseta, Furcularia, 370.

Triarthra, 352, 367.
longispina, Notholca, 383.
Loricata, 358.
Lumbricida^, 441.
found in Illinois, 441.

INDEX.

575

lumbricoid worm eaten by Philob-

della floridana, 518.
Lumbriculidae, 459, 462, 468, 469,

472, 474-
found in Illinois, 442.
North American, described spe-
cies of, 471.
variability in reproductive or-
gans of, 472.
Lumbriculus, 471.

spiralis, relationship of Rhizo-
drilus lacteus to, 450.
Lumbricus herculeus, 441.
luna, Cathypna, 374.
lunaris, Monostyla, 375.
lurida, Nais, 443.

luteolus, Lampsilis, 401, 403, 409,
410, 412, 413, 414, 416.
Unio, 403.
lynceus, Bipalpus, 368.
Euchlanis, 368.
Gastroschiza, 368.
Plcesoma, 352, 354, 368.

M

Macrobdella, 508, 515.
decora, 508-511.

alimentary canal and habits of,

511.
annulation of, compared with
that of M. sestertia, 509-510.
diagnosis of, 508.
food of, 511.

general description of, 509.
reproductive organs of, 510.
valdiviviana, 528.
Macrocyclops, 47, 64.
macronyx, Limnocalanus, 226.
macrostyla, Philodina, 363.
macrozamiee, Lecanium, 304.
macrurus auctus, Limnocalanus,
239, 244.
Cyclops, 29.

Limnocalanus, 226, 227, 229, 235,
236, 237, 238, 249, 264.

macrurus — Continued.

Rotifer, 363.
magnoctavus, Cyclops, 57.
Mallomonas, 274, 421.
mamillata, Dangeardia, 434.
Margaritana complanata, 403.
confragosa, 403.
marginata, 403.
rugosa, 403.
undulata, 403.
marginata, Alasmodonta, 401, 403,
408, 409, 410, 412, 416, 417.
Margaritana, 403.
marmorata, Hirudo, 519.
marmoratis, Haemopis, 511, 515, 519,

528, 52Q, 530, 531.
Marsh, C. D., 38, q8, 171.

description and figures of
Diaptomus pallidus cited,
146.
description and figure of
Epischura lacustris cited,
263, 264.
d e s c r i p t ion of Diaptomus
birgei and remarks upon,

I72-173-

on description of Scopiphora

vagans, 267.
on Diaptomus minnetonka,

136.

on Diaptomus reighardi,
length of and localities for,

171.
on distribution of Cyclops
ater, 51.

of Cyclops phaleratus,6o.

of Diaptomus s i c i 1 i s,
124.

0 f Limnocalanus ma -
crurus, 244.

and synonymy of Cy-
clops prasinus, 57.

and synonymy of Di-
a ptom u s in i n utus,
158.

576

INDEX

Marsh, C. D. — Continued.

on identity of Scopiphora
vagans and Epischura la-
custris, 263.
on occurrence of Diaptomus

mississippiensis, 176.
On the Cyclopidae and Ca-
lanida? of Central Wiscon-
sin, cited, 124, 136,153, 154,
169, 244, 264.
On the Cyclopidae and Ca-
lanidie of Lake St. Clair,
Lake Michigan, and cer-
tain of the Inland Lakes
• if Michigan, cited, 160,
244. 264.
on the habits of Limnocala-

nus, 237.
on the Limnetic Crustacea of

Green Lake, cited, 237.
On two New Species of Di-
aptomus, cited, 173, 175.
Preliminary List of Deep-
Water Crustacea, cited, 97.
Mastigocerca, 371.
bicornis, 371.
bicristata, 371.

seasonal distribution of, 352,371.
specific characters of, 371.
carinata, 371.
elongata, 371.
food of, 351,371.
lata, 372.
stylata, 371.
Mastigophora, 306, 315, 322.
Meek, S. E., and Evermann, B. W.,

259.
Megalotrocha, 303, 361.
alboflavicans, 361.

found on Ceratophyllum, 361.
resemblance of, to Conochilus,
361.
semibullata, 361.

eaten by Dineutes, 361.
seasonal distribution of, 352.

megalotrocha, Philodina, 363
Melicerta ringens, type of trophi

of, 345-

Melicertidae, 357, 3^0.
Melosira, 274, 421.
Mesoporodrilus, 462, 468, 471.
asymmetr icus, 442.

Eclipidrilus frigidus, and
Premnodrilus palustris com-
pared, 472-475.
nephridial and circulatory sys-
tems of, 468-471.
metanever, Unio, 403.
metanevra, Quadrula, 401, 403,409,

410, 412.
Metopidia, 377.
food of, 351.
acuminata, 377.
bractea, 377.
elliptica, 377,
oblonga, 377.
oxysternum, 377.
rhomboides, 377.
seasonal distribution of, 353.
solidus, 377.
triptera, 377.
mexicana, Dina, 541.
Microbdella, 482, 484.
Microcodonidae, 357.
Microcyclops, 64.
microstoma, Dina, 537.

Vorticella, 338.
Migula, W., Beitriige zur Kennt-
niss des Gonium pectorale,
cited, 283.
on locomotion of Gonium,

283.

militaris, Brachionus, 351, 353,355.
365, 381, 421.

Milne-Edwards, H., Extrait d'un
M£moire sur la distribution geo-
graphique des Crustaces, cited,

97-

Minnesota Academy of Sciences,

233-

INDEX.

577

minnetonka, Diaptomus, 133, 135,

136, 138-
minnilus, Cyclops, 44, 45.
Minnows, 351,
minuta, Salpingoeca, 329.
minutus, Diaptomus, 98, 100, 106,1 11,

116, 129, 134, 156, 160, 183,260,265.
mirum, Pedalion, 353, 355, 384.
mirus, Diaptomus, 101.
Miskovsky, L. F., 451.
mississippiensis, Diaptomu s,98,

109, 122, 149, 173. l84-
mudesta, Clepsine, 497.
modestus, Cyclops, 29, 51,62, 63,64.
"mollis, Brachionus, 354, 378.

Monostyla, 376.
Mollusks, 351.
Monadina, 322.
Monads, collared, 328.
Monoculus, 97, 105.
quadricornis var. albidus, 47.
var. viridis, 37.
Monostyla, 375, 421.
as food of Asplanchnopus myr-

meleo, 366.
bulba, 375.
closterocerca, 376.
cornuta, 375.

algae eaten by, 375.
food of, 351.
lunaris, 375.
mollis, 376.
quadridentata, 376.
Moore, J. Percy, A Description of
Macrobdella blannulata
with especial regard to the
Constitution of the Leech
Somite, cited, 479, 482.
Notes on Bdellodrilns phila-

delphicus, cited, 542.
The Hirudinea of Illinois,

479-547-
The Leeches of the I . S.
National Museum, cited,

479. 513.

Moquin-Tandon, A., Monographic
de la Famille des Hirudinees,
cited, 493, 498.

m o r u m , Pandorina, 273, 284, 327,

435. 437-

Mottier, D. M., Pleodorina in Indi-
ana, cited, 273.

mucicola, CEcistes, 361.

mucosa, Allolobophora, 441.

Miiller, O. F., Entomostraca seu
Insecta testacea quae in aquis
Daniae et Norvegia reperit, de-
s c r i p s i t et iconibus illustravit,
cited, 97.

multiplicata, Quadrula, 401, 403,
409, 410, 412, 413.

multiplicatus, Unio, 403.

multisetosus, Embolocephalus, 443,
452.

Murray, John, 12.

Museu Paulista, 301.

Musk-turtles, Opercularia irritab-
ilis found on, 340.

Mussels, shells of living, entered
by Hemiclepsis carinata, 504.

my rmeleo, Asplanchnopus, 351,

365.
Notommata, 365.
mystacina, Acineta, 342.
Mytilaspis, new genera separated
from, 397.
philococcus, subgenus Opunti-
aspis proposed for, 397.
mytilus, Stylonichia, 337, 348.

N

Nageli, C. W. von, on rotation of

Pandorina, 284.
Naidomorpha, 447, 448.

found in Illinois, 443.
Nais elinguis, 443.

lacustris, 443.

lurida, 443.

serpentina, 443.
nanus, Cyclops, 29.

578

IXDFX.

Nassula, 332.
ornata, 332.

Nassulinae, 332.

nasutum, Didinium, 313, 331.

nasutus, Lampsilis, 401,403, 409.
Unio, 403.

navus, Cyclops, 44, 45.

Xelumbo, 302.

Nephelis fervida, 535.
lateralis, 532.
punctata, 532.
quadristriata, 532.

neptunius, Actinurus, 363.
Rotifer, 363.

nevadensis Columbia?, Epischura,
256, 258.
Epischura, 98, 16S, 229, 249, 250,
251, 254,255, 256,262, 264.

Xewell, W., descriptions of Cocci-
die by, cited, 390.

New Mexico Agricultural Experi-
ment Station, 389.

Newstead, R., as authority for lo-
cation of Lecanium patelliformis,

393-

Nicolet, H., Crustaceos, cited, 97.
nordenskioldi, Epischura, 98, 249,

250, 251, 252.
Nordqvist, ()., 98, 236.

die Calaniden Finlands Bidrag
till Kannedom af Finlands
Natur och Folk, cited, 236,
242, 243.
011 second pair of antenna; of
Limnocalanus macrurus, 236.
on synonymy of Limnocalanus
macrurus, 242.
Noteus, 382.
quadricornis, 382.

seasonal distribution of, 353.
Notholca, 352, 383.
acuminata, 355, 383.

seasonal distribution of, 353.
food of, 351.
longispina, 383.

Notommata, 369;

aurita, 309.

cyrtopus, 369.

lacinulata, 369.

myrmeleo, 365.

tripus, 369.
Notommatidye, 358, 360.

seasonal distribution of, 352.
novamexicanus, Diaptomus, 09,1 1 1,

116, 140, 183.
nutans, Opercularia, 340.
nuytisiae, Ctenochiton, 394.
Nymphaea, 302.
Nystrom, C , 157, 254.

°

( >berlin College, 451.
Obliquaria reflexa, 401,403.

parasites of, 408, 409, 410, 412,

413-
oblonga, Metopidia, 377.
obtusa, Dero, 443.
obtusus, Colurus,376.
ochraceus, Lampsilis, 401, 403,
400.
Unio, 403.
odoratus, Aromochelys, 340, 342.
(Ecistes, 360.

intermedins found on Cerato-

phyllum, 361.
mucicola found on R i v u 1 a r i a ,
36l.
officinalis, Haementeria, 489.
ohioensis, Distyla, 348, 375.
oithonoides, Cyclops, 29,63.
Oligochasta, 460.

Notes on Species of North Amer-
ican. III. List of Species found
in Illinois, and Descriptions of
Illinois Tubificida?, 441-458.
explanation of plates in above

article on, 458.
literature cited in above article
"". 457-

INDEX.

579

( Hiogochaeta — Continued.

Notes on Species of North Amer-
ican. IV. On a New Lumbri-
culid Genus from Florida, with
Additional Notes on the Ne-
phridial and Circulatory Sys-
tems of Mesoporodrilus asym-
metricus Smith, 459-478.
explanation of plates in above

article on, 477.
literature cited in above article
on, 476.
Oligochaete parasite of Unionidae,
407.
aquatic, as food of Erpobdella
punctata, 535.
Oligochaetes, aquatic, as food of

Htemopis marmoratis, 527.
Oligotricha, 308, 316, 335.
Opercularia, 311, 312, 340.
articulata, 340.
food of, 31 1.
irritabilis, 342.

occurrence of, on various ani-
mals, 340.
food of, 340.
nutans found on a Planorbis, 340.
rugosa, 340.
Opuntiaspis proposed as new sub-
genus for Mytilaspis philococcus,

397-
oregonensis, Diaptomus, 109, 119,

124, 151, 170, 171, 183, 229, 265.
ornata, Floscularia, 352,360.

Nassula, 332.

var. rugosa, Clepsine, 487.
Orthocyclops, 29, 51,64.
Ortonia preoccupied ; replaced by

Protortonia, 390.
Osborn. H. L., ondistomid parasite

of Anodonta plana (=grandis)

and Strophitus edentulus, 406.
Oscillaria, 19, 419.
Osphranticum,97, 104-225, 226, 220,

237-

Osphranticum — Continued.

Diaptomus, and Cyclops, relative

hardihood of, 100.
Diaptomus, Epischura, and Lim-
nocalanus, discussion of
structural similarities
and differences indica-
tive of the relationships
of the genera, 226-228.
general bibliography of
genera of, 185 ; additions
to, 268.
synopsis of the relation-
ships of the genera, 102
105.
eggs of, 228.
labronectum, 227, 230-235.

distribution, color, and varia-
tions of, 234.
on movements of, 235.
Limnocalanus, and Epischura,
The North American Cen-
tropagidae belonging to the
genera, 225-270.
on localities preferred by, 226,

234-
ostreaeformis, Aspidiotus, 398.
ovata, Cryptomonas, 313, 328.
Overton, E., Beitrag zur Kenntniss
des Gonium pectorale, cited, 287.
oxysternum, Metopidia, 377.
Oxytrichidae, 336.
oxyuris, Euglena, 313, 324.

pala, Brachionus, 353-354. 355. 378-
pallida, Raphidiophrys, 313,322.
pallidus, Diaptomus, 100, 108, 121,
124. 137, 144. 183. 265.

var. sicilis, Diaptomus, 122.
palustris, Fremnodrilus, 450. 468,

469, 472, 473. 474. 475-
Pandorina, 275. 276, 278, 280,284,

286, 287, 327, 419, 420, 423. 425.

433. 436 .437-

580

INDEX.

Pandorina — Continued.

as food of rotifers, 312.

polarity and direction of rotation
of, 284, 431, 432.

disease of, 289.

morum, 273, 327, 435- 437-
direction of rotation of, 284.
parasite of, 434.
papillifera var. carinata, Clepsine,
498.

var. lineata, Clepsine. 493.
Paracyclops, 59, 65.
Paramceciidas, 332.
Paramascium, 332.

aurelia, 307, 313, 332.
Parasite of Eudorina elegans, 435.

of fishes, 504.

of Hydra, 337.

of Pandorina morum, 434.

of Platydorina caudata, 425, 434.
Parasites of Asplanchna herrickii,

365-

of the Unionida?, A Statistical
Study of the, 399-418;
summary of results
reached, 417.

comparison of infestation
by different, 412.

comparison of local in-
festation by, 416.

degree of infestation of in-
dividual hosts by, 410,
411, 415.

geographical distribution
of, 4"4-

relation of local conditions
to number of, and to
character of infestation,

417.
situation of, and manner

of infestation, 404-407.
specific distribution of, 409.
effect of seasonal

changes on, 414.
parasitica, Hirudo, 480.

parasitica — Continued.

Placobdella, 480, 487, 488, 491,

492, 5°3-
parcus, Cyclops, 38, 41, 42.
parvus, Lampsilis, 401, 403, 404, 409,
410, 412, 413.

Unio, 337, 403.
patelliformis, Lecanium, 393.
Patten, Wm.,on dist ribu tionof

Heterocope, 225.
patina, Pterodina, 353, 378.
Peck, J. I., The Sources of Marine

Food, cited, 13. 21.
pectinata,Synchasta,352,354,355,366.
pectorale, Gonium, 437.
Pedalion, 346, 355, 383.

mirum, 355, 384.
seasonal distribution of, 383.
Pedalionidae, 359, 383.
Pedetes, 368.

saltator, 368.
Pediastrum, 421.

as food of rotifers, 351, 365.
pediculis, Trichodina, 337.
Pelomyxa, 317.

villosa, 317.
Peloscolex, 456.

variegatus, 456.
pentagonus, Cyclops, 57.
perarmatus, Cyclops, 59, 60.
Pergande, Theo., descriptions of

Coccida; by, cited, 390.
Perichaeta, 441.
Peridinidae, 329, 421.
Peridinium, 307, 329.

tabulatum, 313, 329, 421.
Peritricha, 308, 309, 316, 337.
perniciosus ? eucalypti, Aspidiotus,

39°.
Pfeffer, W., Loc omo tor is che

Richtungsbewegungen durch
chemische Reize, cited, 283.
on locomotion of Gonium, 283.
Phacus, 274, 326.

longicauda, 313, 326.

INDEX.

58l

Phacus — Continued.

pyrum, 313, 326.

triquetur, 326.
phaleratus, Cyclops, 29, 30, 59, 63,65.
Phaulomytilus as new g enu s for

certain species of M y t i 1 a s p i s,

397-
Phenacaspis as new genus for cer-
tain species of Chionaspis, 398.
Philadelphia Academy of Sciences,

418.
philadelphica, Astacobdella, 542.
philadelphicus, Bdellodrilus, 542.
Phillips, C. E., 98.
Philobdella, 509, 510, 511.
floridana, 51 1.

lumbricoid worm eaten by, 518.
gracile, 511-518.

alimentary canal, color, and

habits of, 518.
annuli and somites of, 515.
diagnosis of, 511.
food of, 518.

general description and meas-
urements of, 512-515.
reproductive organs of, 517.
philococcus, Mytilaspis, 397.
Philodina, 363, 421.
macrostyla, 363.
megalotrocha, 363.
roseola, type of trophi of, 345.
seasonal distribution of, 352.
tuberculata, 363.
Philodinidas, 357, 359, 362.
Phreoryctes emissarius, 442.
Phreoryctidae, 442.

found in Illinois, 442.
Physa, Epistylis plicatilis found on

shells of, 339.
Pickering, C, generic description

of Scopiphora vagans, 263.
Picronitic acid, formula for, 340.
pilosus, Vermiculus, 446, 450, 452.
Pilsbry, H. A., 418.
piricola, Diaspis, 398.

Piscicola parasitic on small fish,

504.
Piscicolaria, 504.
piscina;, Diaptomus, 98, 109, 116,

118, 125, 181, 182.
Placobdella, 480, 496.

parasitica, 480-486, 487, 488, 491,
492, 503.
alimentary canal and color of,

485.
annuli and somites of, 482-484.
compared with P. rugosa,

482.
diagnosis of, 480.
general description of, 400

482.

habits of, 486.

reproductive organs of, 484.
rugosa, 481, 482, 484, 487-492.
alimentary canal, color, and
reproductive organs of, 49 1.
annuli and somites of, 488-491.
diagnosis and general descrip-
tion of, 487.
habits of, 492.
Plagiola, capacity for infestation
exhibited by, 414.
donaciformis, 401, 403.

parasites 0^409,410,412,416.
elegans, 401, 403.

parasites of, 405, 406, 400, 410,
412, 413, 416.
securis, 401, 403.
parasite of, 40^.
Plagiotomida;, 333.
plana, Anodonta,403, 406.
Planarians, 407.

Plankton, centrifugal machine used
in volumetric determination of,
19, 20.
description of apparatus used in
oblique-haul method of
collecting, 3 10.
in pumping method of col-
lecting, 13-16.

582

INDEX.

Plankton — Continued.
enumerative or counting method

of determining, 2 1.
gravimetric method of determin-
ing, 18.
and volumetric method of de-
determining, combined, 18.
oblique-haul method of collect-
ing, difficulties en-
countered in, 11.
operation of, 2, 10.
preservation and examination of,

17-21.
pumping method of collecting,
2, 12-17.
advantages of, 17.
operation of, 16.
quantitative examination of, 18.
settling and centrifugal methods
of volumetric determination of,
ig, 20.
Studies. I. Methods and Ap-
paratus in Use in Plank-
ton Investigations at the
Biological Experiment
Station of the University
of Illinois, 1-25.
bibliography in, 22-23.
explanation of plates in, 23

25-
Studies. II. On Pleodorina illinoi-
sensis, a New Species from
the Plankton of the Illinois
River, 273-293.
bibliography in, 291-292.
explanation of plates in, 293.
Studies. III. On Platydorina, a
New Genus of the Family
Volvocidae, f ro m the
Plankton of the Illinois
River, 419-440.
explanation of plate in, 440.
literature cited in, 437.
variations in, at Havana, 111.,
11.

Plankton — Continued.

vertical-haul method of collect-
ing, 2.
inapplicable in Station
waters at Havana, 111.,

3-

work on the Illinois River and
Adjacent waters, scope of, 1.
Planorbis, Opercularia nutans

found on, 340.
Plate, Ludwig, Beitnige xur Xatur-
geschichte der Rotatorien,
cited, 367.
on Brachionus bidens, 381.
on Triarthra terminalis, 367.
Platydorina, 436, 437.
A new Genus of the Family Vol-
vocidae from the Plankton of
the Illinois River, article on,
419-440.
associates of, 420i42i.
caudata, 419, 437.

arrangement of cells of, 426.
characteristic features of col-
ony of, 423.
description of, 421-435.
parasite of, 425, 434.
size of colony of, 422,425.
specific characters of, 435.
type of cells of, 425, 427.
colors of, 422.

discussion of term colony as ap-
plied to, 433.
explanation of plate in Kofoid's

article on, 440.
generic characters of, 435.
literature cited in Kofoid's arti-
cle on, 439.
locomotion of, 430.
systematic position and relation-
ships of, 433.
reproduction of, 432.
platyptera euryptera, Polyarthra,

367-
Polyarthra, 340, 352,354, 355,367.

INDEX.

583

Pleodorina, 273,277,286,327,419,420,
424, 425, 427, 432, 433, 434, 437-
californica, 273, 274, 276, 279, 280,
281, 313, 328, 421, 437.
locomotion and polarity of, 283.
relationship of, 286.
synoptic characters of, 290.
illinoisensis, 424, 432, 437.

a New Species from the Plank-
tun of the Illinois River.
Plankton Studies. II., 273-

293-
bibliography in Kofoid's ar-
ticle on, 291-292.
description of, 274-281.
disease of, 289.
distribution of, 273.
explanation of plates in Ko-
foid's article on, 293.
hvpothetically considered as
stage in life cycle of Eudori-
na, 286.
locomotion of, 281-285, 43'-
reproduction of, 287-289.
synoptic characters of, 290.
synoptic characters of, 290.
Pleurotrichinae, 336.
plicata, Quadrula, 401,403, 408, 409,
. 410,412,413,316.
plicatilis, Epistylis, 339, 342.
plicatus, Embolocephalus, 456.

Unio, 403
Ploesoma, 357, 368.
lenticulare, 368.
lynceus, 354, 368.
seasonal distribution of, 352.
Ploima, 356, 357, 364, 421.
pluvialis, Stephanosphaera, 437.
pocillum, Dinocharis, 352, 372
Podoplea, 105.

polipinum, Carchesium, 338.
Polyarthra, 274, 346, 366, 421.
aptera, 367.

platyptera, 354, 355, 367-
euryptera, 367.

Polyarthra platyptera — Continued.
Rhabdostyla found on, 340,

367.
seasonal distribution of, 352.
polymorphus, Bucephalus, 407.

Stentor, 313, 334.
Pond snails, examination of, for

Protozoa, 310.
Pontellidae, 102.

Poppe, S. A., 29, 98, 99, 177, 178,
229, 234, 248.
description of Limnocalanus

sinensis cited, 237.
on differences between Lim-
nocalanus sinensis and L.
macrurus, 249.
porcellus, Ccelopus, 372.
Potamogeton, 349.

Limnias ceratophylli found on,
360.
Potamoichetor, 229, 230.
Potomoichetor, 229.
fucosus, 230, 233.
prasinus, Cyclops, 57,63, 65.
Premnodrilus, 471.
palustris, 469.

description of, 459 468.
Eclipidrilus frigidus, and Mes-
oporodrilus as y m metricus
compared, 472-475.
priodonta, Asplanchna, 351, 354,

364, 365.
Pristina flagellum, 443.

leidyi, 443-
Proceedings of the Philadelphia

Academy of Sciences, 542.
profuga, Allolobophora, 441.
proteus, Amceba, 317.
Protortonia superseded by * Mtonia,

390.
Protozoa, 14, 304 342, 348, 351, 421.

and Rotifera found in the Illinois
River and Adjacent Lakes
at Havana', 111.. A List of,
301 388.

5$4

INDEX.

Protozoa and Rotifera — Continued.
collections examined in
preparation of Hempel's
article on, with brief de-
scription of waters col-
lected from, 301-303.
literature consulted in prep-
aration of Hempel's ar-
ticle on, 385, 388.
methods of collection and
preservation. of, 303.
as food of rotifers and fishes,

312.
classification of, 314.
food relations of, 31 1, 324.
geographical distribution of, 311.
local distribution of, 312 314.
methods of capture and study of,

310.
species of, found in open water,

313-
synopsis of the higher groups of,

3*4-

typical forms of, 305-310.

prunicola, Chioriaspis, 308.

Fseudoripersia proposed as new
subgenus and a distinguishing
character given, 392.

Pterodina, 274, 377, 421.
patina, 378-

seasonal distribution of, 353.
valvata, 378.

Pterodinidas, 358, 350, 377.

pulchellus, Cyclops, 29, 44.

Pump, Thresher Tank, used in col-
lection of plankton, 13.

punctata, Erpobdella, 532, 535, 536,

530- 540.
Nephelis, 532.
punctatus, Brachionus, 353, 354,

379. 421.
Purdy Electric Centrifuge, 20.
pustulata, Quadrula, 401, 403, 409,

410, 41 1, 412.
pustulatus, Unio, 403.

pustulosa, Quadrula, 401, 402, 403,

408, 409, 410, 412, 416.
pustulosus, Unio, 403.
pyriformis compressa, Difflugia,

3IQ-
Difflugia, 313,314. 3'Q-
Euchlanis, 374.
vas, Difflugia, 319.
pyrum, Phacus, 313, 326.

quadricornis, Noteus, 353, 382.

var. albidus, Monoculus, 47.

var. viridis, Monoculus, 37.
quadridentata, Monostyla, 376.
quadripartita, Tokophrya, 310, 339,

341-

quadristriata, Xephelis, 532.
Quadrula asperrima, 401, 403.

parasites of, 408, 409, 410, 412,

414-
capacity for infestation exhibited

by, 4'4-
ebena, 401, 403.

parasites of, 409,410,411,412,

413. 414.
granifera, 401, 403.
parasites of, 409.
lachrymosa, 401, 403, 414.

parasites of, 408, 409, 410, 411,
412.
metanevra, 401, 403.

parasites of, 409, 410, 412.
multiplicata, 401, 403.

parasites of, 409, 410, 412,413.
parasites of, 405.
plicata, 401, 403, 409.
parasites of, 408, 410, 412, 413,
416.
pustulata, 401, 403.

parasites of, 410, 411, 412.
pustulosa, 401, 402, 403.
parasites of, 408, 409, 410, 412,
416.

INDEX.

585

Quadrula — Continued.
rubiginosa, 401, 403, 414.

parasites of, 406, 409, 410, 412.
trigona, 401, 403.

parasites of, 409,4 10,4 12,4 1 3,4 1 4.
tuberculata, 401, 303.

parasites of, 408, 409, 410, 412,
413, 415, 416.

R

Rabot, Ch., 158.
radiata, Astrosiga, 329.
Radiolaria, 306, 315.
radiosum, Amceba, 317.
Rafter, G. W., The Microscopical
Examination of Potable Water,
cited, 13, 21.
Randolph, H., 456.

Beit rag zur Kenntnis der
Tubificiden, cited, 456.
Raphidiophrys, 322.
elegans, 322.
pallida, 313, 322.
Rattulidae, 358, 371.
rectus, Lampsilis, 401,403,408, 409,
410, 412, 416.
Unio, 403.
reflexa, Obliquaria, 401, 403, 408,

409, 410, 412, 413-
Keighard, J. E., 8, 535.

A Biological Examination of
Lake St. Clair, cited, 2, 3,

4, 5- 19-
on color of Dina fervida, 537.
reighardi, Diaptomus, 98, 109, 121,

169, 184.
Report of the Biological and Nat-
ural History Survey of
Minnesota, cited, 132, 233.
Massachusetts State Board
of Health, cited, 13.
Khabdostyla, 340.
found on Entomostraca, on Pol-
yarthra platyptera, and on
aquatic worms, 340, 367.

Rhizodrilus, 451.

lacteus, 443.

circulatory system of, com-
pared with that of Ilyodrilus
coccineus and Vermiculus
pilosus, 452.

comparison of, with o ther
Tubificidae, 450-452.

description of, 444-449.

distinguishing characters of,
450.

found on Sagittaria variabilis,

444-
summary of important char-
acters of, 449.
Khizopoda, 304, 305, 313, 314, 31 7-
Rhizota, 356, 358, 360.
rhomboides, Metopidia, 377.
Rhynchelmis, 471.
Riballierdes Isles, 158.
Richard, J., on basal segment of ru-
dimentary f< m it ( if Cyclops viridis,
40. .

See de Guerne and Richard,
ringens, Melicerta, 345.
riparia, Diplocardia, 442.
Rivularia, CLcistes mucicola found

on, 361.
rivulorum, Tubifex, 442, 444-
robustus, Cyclops, 29.
roeselli, Stentor, 334.
rosea, Allolobophora, 441.
roseola, Philodina, 345.
Ross, L. S., 28, 31, 98, 126, 156, 181.
Rotifer, 362.
macrurus, 363.
neptunius, 363.
tardus, 363.
vulgaris, 363.
Rotifera, 12, 14, 19, 3°4. 3i°. 342-
384. 420, 421.
affinities and classification of, 355.
and Protozoa found in the Illi-
nois River and Adjacent Lakes
at Havana, 111., A List of the,
301-388. See under Protozoa
and Rotifera.

586

INDEX.

Rot if era — Continued.

as food of Protozoa, 311.

diagram of types of trophi of, and
a summary of their distinguish-
ing features, 344, 345.

eggs of, 347.

food of, 324.

quantity of, 345.

relations of, 350.
geographical distribution of, 350.
littoral and pelagic forms of,

353-

local distribution of, 353-355.
methods of capture and study of,

348-35°-
modes of locomotion, 356.
seasonal distribution of, 351-353.
synopsis of the families of, 356-

359-
vitality of, 347.

geographical distribution of, 350.
roubaui, Diaptomus, 166.
Rousselet, C. F., 350.

On a Method of preserving

Rotatoria, cited, 304.
Second Note on a Method of
preserving Rotatoria,
cited, 304.
rubens, Brachionus,37g.
rubiginosa, Quadrula, \o\, 403, 406,

409, 410, 412, \\\.
rubiginosum, Coelostoma, 390.
rubiginosus, Unio, 403.
rugosa, Alasmodonta, 401, 403, 408,
400, 410, 412.
Margaritana, 403.
Opercularia, 340.
Placobdella, 481, 482, 484, 487.

Sacculus, 366.

viridis, 366.
Sagittaria, 302.

variabilis, 444.
salinus, Diaptomus, 98

Salpina, 373.
eustala, 373.

seasonal distribution of, 352.
Salpingceca, 329.
minuta,329.
found on loricaa of Dinobryon
sertularia, 329.
Salpingoecinae, 329.
Salpinidae, 358, 373.
saltator, Pedetes, 368.
sanguineus, D i a p to m us, 97, 1 12,

117, 129, 133, 160, 166, 183. 234.
sanguisuga, Haemopis, 531.
Sarcodina, 305, 306, 314, 317.
Sars, G. O., 29, 31, 7,7, 98, 229, 236,
242.
on second pair of antennae
of Limnocalanus macrurus
and of L. grimaldii, 236.
Oversigt af de indenlandske
Ferskvands copepoder,
cited, 236, 242.
Pel'agic Entomostraca of the
Caspian Sea, cited, 242.
Say, Thomas, Narrative of Expe-
dition to the Source of the St.
Peter's River, etc. Appendix of
Vol. II., cited, 509, 532.
Scaridium, 373.

longicaudum, 373.
Scenedesmus, 421.
Schacht, F. W., 31.

The North American Cen-
tropagidae belonging to the
Genera 0 s p h r a n t i cum,
Limnocalanus, and Epi-
schura, 225-269. (Special
index, p. 270.)
The North American Species
of Diaptomus, 97-207.
(Special index, 208.)
Schewiakoff, WL, Qeber die geo-
graphische \*erbreitung der
Slisswasser-Protozoen, cited,
320, 340.

INDEX.

5*7

Schewiakoff, Wl. - Continued.
on Opercularia rugosa, 340.
Schizocerca, 382.
diversicuniis, 382.
homoceros, 382.
seasonal distribution of, 353.
Schmeil, Otto, 29, 31, 37, 38, 44, 45,
98, 185.
description of Cyclops viridis,

39-

D e u t s c h 1 a n d s freilebende

Siisswasser C»|ie p o-

den. I. Teil, cited, 27,

185.

III. Teil, Centropagidse,

cited, 99.
Nachtrag, cited, 259.
on antennas of Cyclops prasi-

nus, 58.
on basal segment of rudimen-
tary foot of Cyclops viridis,
40.
on description of Scopiphora

vagans, 263.
on Epischura fluviatilis, 267.
on Epischura nevadensis, 259,

260.
onHerrick's Temorai >r

Temorella affinis, 226.
on identity of Epischura nev-
adensis and E. nevadensis
columbiae, 259.
on oviducts of Cyclops pliale-

ratus, 61.
on specific distinctions of

males in Diaptomus, 100.
on synonymy of Cyclops
leuckarti, 34.
Schroder, B., Dangeardia, ein neues
Chytridineen genus auf Pando-
rina morum Bory, cited, 434.
Scirpus, 302.
Scirtopoda. 356, 359, 383.
Scopiphora, 249, 263.
vagans, 260, 263.

Scopiphora vagans— Continued.

generic description of, 263.
Scott, Andrew. See Herdman, W.

A., Thompson, I. C, and Scott,

Andrew,
scutifer, Cyclops, 29.
Scyphidia, 337.

sp- 337-

found on Unio parvus, 337.
securis, Plagiola, 401, 403, 409.

Unio, 403.
semibullata, Megalotrodia, 352,361.
Semiscolex terrestris, 528.
senta, Hydatina, 348, 350, 368.
serpentina, Chelydra, 340, 342.

Nais, 443.
serratus, Atax, 408.

Cyclops, 44, 45.
serricornis, Diaptomus, 162.
serrulata, Anuraea, 383.
serrulatus, Cyclops, 29, 30, 54, 62,
63, 65.
var. elegans, Cyclops, 54.
var. montanus, Cyclops, 54, 55.
sertularia angulatum, Dinobryon,
232.
Dinobryon, 312, 313, 323.
divergens, Dinobryon, 323.
undulatum, Dinobryon, 323.
sestertia, Macrobdella, 509.
Sharpe, R. W., 31.
Shaw, W. R., On locomotion of
Pleodorina californica, 283.
on relationships of Pleodori-
na, 286.
Pleodorina, a New Genus of
the Volvocinae, cited, 273,
276, 277, 279, 280, 281, 283,
286.
shoshone, Diaptomus, no, 116, 127,

141, 164, 183.
sicculus, Labidesthes, 237.
sicilis, Diaptomus, 07,100,111, 121,
122, 145.155- l67. i68. l69. 182,22c),
264.

588

INDEX.

sicilis — Continued.

var. imperfectus, Diaptomus, 124,
158, 167, 169.
siciloides, Diaptomus, 98, 100, 114,

121, 124, 137, 146, 154, 157, 165,

166, 181, 182, 183, 265.
signatus, Cyclops, 29.

var. tenuicornis, Cyclops, 47.
signicauda, Diaptomus, 98, 114, 120,

157, 159, 160, 164, 183.
signicaudatus, Diaptomus, 164.
similis, Diaptomus, 132, 182.

Vorticella, 338.
Simpson, C. T., 418.
sinensis, Limnocalanus, 99,229, 235

236, 237, 238, 245.
singularis, Diplocardia, 442.
Slipper animalcule, 332.
Smith, Frank, 1, 98, 228, 229, 303,

348, 479-
List of the Protozoa and Mol-

lusca observed in Lake St.

Clair in the Summer of 1893,

cited, 313.
Notes on Species of North

American O 1 i g o c haeta.

II., cited, 447, 462, 468, 470,

471.
Notes on Species of North
American Oligochaeta. III.
List of Species found in Illi-
nois, and Descriptions of Illi-
nois Tubificidae, 441-458.
Notes on Species of North
American Oligochaeta. IY.
On a New Lumbriculid Ge-
nus from Florida, with addi-
tional Notes on the Nephrid-
ial and Circulatory Systems
of Mesoporodrilus asym-
metricus Smith, 450-478.
on occurrence of Rhizopoda in
surface collections, 313.
Snails as food of Glossiphonia
complanata, 493.

Snapping turtles, Opercularia

i r r i t abi 1 is found on backs of,
340.
snowi, Diaspis, 398.
sociale, Gonium, 437.
sol, Actinophrys, 313, 322.
Solenococcus proposed as new

name for Solenophora, 392.
Solenophora ( ?) dryandrae w i th -
drawn by Fuller, 392.

Solenococcus proposed as new
name for, 392.
solidus, Metopidia, 377.
solstitialis, Trochosphaera, 362.
Sparganophilus eiseni, 442.
Sphaerococcini, 389.
Sphaerococcus, 489.
spiralis, Lumbriculus, 450.
Spirogyra, 354.

as food of Mastigocerca, 371.
spirogyra, Euglena, 313, 324.
Spirosperma, 453, 456.
Spirostomum, 333.

teres, 333.
Spirotricha, 308, 316, 333.
Spondylomorum, 419.
Sporochytriaceae, one of the, as
parasite of Platydorina caudata,

434-
Sporozoa, 305, 306, 315.
stagnalis, Diaptomus, 97,101,113,
115, 129, 136, 138, 142, 164, 183.

Glossiphonia, 496, 497.

Hirudo, 497.
Stentor, 308, 333.

barretti, 313, 334.

cceruleus, 313, 334.
culture of, 348.

igneus < ? ) 334-

polymorphus, 3 1 3, 334.

roeselii, 334.

sp., 334-
Stentorida?, 333.
Stephanoceros eichhornii, type of

trophi of, 345.

INDEX.

589

Stephanosphasra, 419, 436.

locomotion and polarity of, 283,

43'- 432.
pluvialis, 437.
Stukes, A. C, 305.
stokesii, Cathypna, 375.

Distyla, 375.
Stole, A., description and figures
of circulatory system of
Ilyodrilus coccineus cited,

451.452.

on vascular arches of Ilyodri-
lus, 451.

Monografie Ceskych T u b i f i -
cidu. Morfologicka a Sys-
tematicka Studie, cited, 447,

451.
strenuus, Cyclops, 29.
stricta, Atax, 408.
Strombidium, 335.

claparedi, 335.
Strophitus, parasite of, 405.
edentulus, 401, 403.

parasites of, 406, 409, 410, 412,
413, 416.
stylata, Mastigocerca, 371.
Synchaeta, 352, 354, 366.
Stylonichia, 309, 336.
mytilus, 337.
cultures of, 348.
suborbiculata, Anodonta, 401, 403,

405, 408, 409, 410, 411, 412, 413.
Suckers, 351.

Suctoria, 307, 309, 317, 341.
Sun animalcules, 321.
Suirella, 421.
Sutroa, 469, 471, 475.

alpestris, 463.
Swan animalcules, 331.
Synchaeta, 274, 366.
pectinata, 354, 355, 366.

seasonal distribution of, 352.
stylata, 354, 366.

seasonal distribution of, 352.
Synchcetidae, 358, 366, 421.

Synura, 274, 326, 421.
uvella, 327.

tabulatum, Peridinium, 313, 329,

421.
Taphrocampa, 369.

annulosa, 369.
tappaniana, Alasmodonta, 401,403,

409.
tappanianus, Unio, 403.
tardus, Rotifer, 363.
tecta, Anuraea, 351, 353, 354, 364,

365. 382.
Temora, 225.

affinis, 225.

Temorella, 99, 225.

affinis, 225.
Temorina, 103.

tenebrarum, yEolosoma, 443.

tenuior, Ccelopus, 372.

tenuissimus, Lampsilis, 401, 403,

409.

Unio, 403.
teres, Spirostomum, 333.
terminalis, Triarthra, 354, 355,367.
terrestris, Semiscolex, 528.
Testacea, 315.
theeli, Diaptomus, 101.
Thinodrilus, 471.

inconstans, 442, 469.
thomasi, Cyclops, 44, 45.
Thompson, 1. C. See Herdman,

W. A., Thompson , I. C, and

Scott, Andrew.
Tinsley, J. D., descriptions of Coc-

cidae by, cited, 390.
Tintinnida?, 335.
Tintinnopsis, 335.

fluviatile, 335.

illinoisensis, 313, 335.
Toads, Hemiclepsis carinata found

attached to, 504.
Tokophrya, 309, 310, 31 1.

cyclopum found on Cyclops, 341.

590

INDEX

Tokophrya — Continued.

food of, 311.

quadripartita, 339, 341.

found attached to small ani-
mals, 342.
method of preservation of, 310.
torta, Euglena, 313, 324.

Trachelomonas, 326.
Tracheliidcg, 331.
Trachelomonas, 274, 325, 420.

acuminata, 313, 325.

armata, 325.

caudata, 313, 325.

hispida, 326.

torta, 326.

urceolata, 326.
Trematode, 404, 406.
Triarthra, 346, 367, 421.

longiseta, 367.
seasonal distribution of, 352.

terminalis, 354, 355- 367-
Triarthridae, 358, 366.
Trichodina, 337.

pediculis, 337.

frequent on Hydra viridis,

337-

Trichomytilus as new genus for

certain species < >t Mytilaspis, 397.
Trichostomata, 307, 316, 332.
trigona, Quadrula, 401, 403, 409,

410, 412, 413, 414.
trigonus, Unio, 403.
triptera, Metopidia, 377.
tripus, Notommata, 369.
triqueter, Phacus, 326.
triquetra, Euchlanis, 374.
triserialis, Glossiphonia, 493.

Helobdella, 493.
Trochosphaera, 356, 361.

solstitialis, 362.
truncata, Lacrymaria, 330.
Trybom, F., 154, 160.
trybomi, Diaptomus, 98, 112, 120,
• 158, 166, 183.
tuberculata, Philodina, 363.

tuberculata — Con tin tied.

Quadrula, 401, 403, 408, 409, 410,
412, 413, 415, 416.
tuberculatus, Unio, 403.
tuberculosa, Difflugia, 313, 320.
Tubifex rivulorum, 442.
description of, 444.
Tubificidae, 445- 447. 44$, 450, 45 '.
452, 453. 454. 456.
description of, 443-456.
found in Illinois, 442.
1 llinois, Descriptions of, and List
of Species of North American
Oligochseta found in Illinois,

44I-458-
Tubificid worms found in caeca of
Macrobdella decora, 511.
found in stomachs of Dina mi-
crostoma, 541.
turgida, Allolobophora, 442.
Turner C. H., and Herrick, C. L.«
Synopsis of the Entomostraca of
Minnesota, cited, 37, 38.
Turtles attacked by Macrobdella,
511.
examination of, for Protozoa, 310,
312.
Tyrrell, J. B., 177.

tyrrelli, Diaptomus, 99, 108, 119, 160,
176, 184.

U

Underwood, L. M., List of the de-
scribed Species of Fresh-water
Crustacea from America North
of Mexico, cited, 97.
undulata, Alasmodonta, 401, 403,
409.
Margaritana, 403.
uniangulatus, Cyclops, 39, 41.
unicornis, Conochila, 354, 362.
Unio alatus, 403.
anodontoides, 403.
C on ch o ph t h i rus anodontse
found among gills of, 333.

INDEX.

591

Unio— Continued.
asperrimus, 403.
capacity for infestation exhibited

by, 414.
complanatus, 403, 410, 416.

parasites of, 409, 412, 415, 416.
corn nt us, 403.
donaciformis, 403.
ebenus, 403.
elegans, 403.
ellipsis, 403.
gibbosus, 401, 403.

parasites of, 409, 410, 412, 413,
415, 416,
gracilis, 403.
graniferus, 403.
( heterodon, 401, 403.

parasites of, 409.
higginsii, 403.
lachrymosus, 403.
la?vissimus, 403.
ligamentinus, 403.
luteolus, 403.
metanever, 403.
multiplicatus, 403.
nasutus, 403.
ochraceus, 403.
parasite of, 405.
parvus, 403.

Scyphidia sp. found on, 337.
plicatus, 403.
pustulatus, 403.
pustulosus, 403.
rectus, 403.
rubiginosus, 403.
securis, 403.
tappanianus, 403.
tenuissimus, 403.
trigonus, 403.
tuberculatus, 403.
ventricosus, 403.
Unionidas, A Statistical Study of

the Parasites of the, 399-418 ;

summary of results reached,

417-

Unionidae — Continued.

changes in nomenclature of, 402,

403.
comparison of infestation of, by
different parasites, 412.
of local infestation of, 416.
examined in study of parasites,
geographical distribution of,
40 r.
geographical distribution of par-
asites of, 414.
relation of infestation of, to
abundance of given spe-
cies of, 415.
to natural classification,

413.
to local conditions, 417.
relative number of parasites on

males and females of, 403.
sex of individuals examined in

study of parasites of, 402.
specific distribution of parasites

of, 409.
waters in which collections were
made for Kelly's study of par-
asites of, 399, 400.
U. S. Fish Commission, 28, 169,
259.
National Museum, 290, 418.
University of Illinois, 20, 27, 185,
225, 229,268,348, 441.
of Indiana, 229.
of Pennsylvania, 542.
of Upsala, Zoological Museum
of, 164.
Urceolarime, 337.
urceolaris, Brachionus, 345, 353,

379-
urceolata, Ditihigia, 319.

Trachelomonas, 326.

Urnatella gracilis, Cothurnia curva

found 011, 341.
I roglena, 274, 421.
Utricularia, 349.
uvclla, Synura, 327.

5Q2

INDEX.

vaga, Dero, 443.
vagans, Scopiphora, 260, 263
VanDervoort, W. H., machine for
precipitating plankton devised
by, 20.
Vaginicola, 341.
gigantea, 341.
valdiviviana, Macrobdella, 528.
valvata, Pterodina, 378.
variabilis, Brachionus, 354, 380.

Sagittaria, 444.
varicans, Cyclops, 2q, 63, 64.
variegatus, Peloscolex, 456.
vegetans, Anthophysa, 323.
Vejdovsky, F., Anatomische Stu-
dien an Rhynchelmis Limosella
Hoffm. ( E u a x e s f i 1 i r o s t r i s
Grube), cited, 471.
vejdovskyanum, Bothri o neuron,

452.
velutinus, Embolocephalus, 456.
ventricosus, Lampsilis, 401, 403, 407,
408, 40Q, 410, 4 11, 412, 413, 416.
Unio, 403-
Vermes, 356.

Vermiculus, distinguishing char-
acter of, 451.
limosus, 451.
pilosus, 446, 450.

circulatory system of, 452.
resemblance of Rhizodrilus
lacteus to, 450.
vernalis, Cyclops, 29, 64.
Verrill, A. E., 518.

description of colors of
Glossiphonia complanata,
cited, 493.
on color of Dina fervida, 537.
Synopsis of North American
F r e s h - w a t e r Leeches,
cited, 509, 513, 527.
verrucosa, Diplocardia, 442.
villosa, Pelomyxa, 317.
viridis, Amblyophis, 325.

\iridis — Continued.
Cyclops, 2q, 30, 37, 41, 43, 48, 62,

63, 64.
Euglena, 312, 313, 324, 325.
Hydra, 337.
Sacculus, 366.
var. brevispinosus, Cyclops, 30,

41, 62, 63, 64.
var. insectus, Cyclops, 31, 41, 62,
63, 64.
Yivipara, Epistylis plicatilis found

on shells of, 339.
Volvocidae, 327.

New Genus of the family of,
from the Plankton of the Illi-
nois River, 419-440.
Volvocinae, 419, 432, 434.

keys to genera and species of the

subfamily of, 435, 436-438.
locomotion and polarity of, 431,

432.
term colony as applied to the,

434-
Volvocineae, 273, 282, 287.
Volvox, 141, 274, 278, 280, 285, 286,

288, 301, 327, 419, 421, 431, 434,

437-
as food of rotifers, 312, 351.
aureus, 276, 287, 438.
globator, 276, 285, 287, 312, 313,

327, 438.
as food o f Asplanclma prio-
donta and A. herrickii, 365.
locomotion and polarity of, 285,

43'- 432.
Vorticella, 309, 310, 311, 312, 338,

339-

campanula, 338.

V. microstoma, and V. similis
on or among Lemnacea?, 338.
food of, 311.
found 011 roots of Lemna and on

fixed aquatic plants, 310.
microstoma, 338.
similis, 338.

INDEX.

593

Vorticellidas, 311, 337.

Vorticellinae, 337.

vulgaris angulosa, Arcella, 313,314.

Arcella, 313, 314, 318.

discoides, Arcella, 313, 314, 318.

Rotifer. 350, 363.

W

Walkeriana floriger, Coccus hun-
ger a synonym for, 391.
Ward, H. B., A Biological Exam-
ination of Lake Michigan
in the Traverse Bay Re-
gion, cited, 2, 3, tg.
A New Method for the
Quantitative Determina-
tion of Plankton Hauls,
cited, 18.
Water-bloom, 324, 420.
Water-snails, Epistylis plicatilis

found on shells of, 339.
Westwood, J. ()., establishment of

genus Diaptomus, 97.
Whitman, C. O., The Leeches of
Japan, cited, 509, 511.
The Metamerism of Clepsine,
cited, 479.
Wierzejski, A description of C.

annulatus ( = edax) cited, 35.
wierzejskii, Diaptomus, 101, 107.
Wills, A. W., On the Structure and
Life History of Volvox globator,
cited, 276, 285.

Wolcott, Robert H., determination
of Atax collections by, 407.

Worms, aquatic, species of Rhab-
dostyla found on, 340.

ypsilophorus, Atax, 408.

Zacharias, ()., 98.

Beobachtungen am Plankton
des Gr. Ploner See ' s, cited,

313-

Forschungsberichte a us der
Biologischen Station zu
Plon, Theil I.-IV., cited, 2.
F a u 11 i s tische Mittheilungen,

cited, 304.
Leber die Wechselnde Quan-
titat des Planktons im Gros-
sen Ploner See, cited, 18.
zachariasi, Diaptomus, 99.
Zograf, N., Essai d'Explication de
1 ' origine de la Faune des lacs
de la Russie d ' Europe, cited,
226.
Zoological Bulletin cited, 406.
Zoologisches Centralblatt cited,

226.
Zoothamnium, 339.
arbuscula, 330.

ERRATA.

Page 136, line 2, and page 182, line 17 from bottom, for 'gja read 'pj.
Page 226, line 2, page 263, line 17 from bottom, and page 267, lines
2 and 15, for 'g8, read '96.

Page 233, line 15 from bottom, for '82 read "82a.

Page 355, line 2 from bottom, for C. F. Hudson read C. T. Hudson.

Page 389, foot-note, for Vol. V. read Vol. //'.

Page 457, line 5, for Genera read Genus.

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