BULLETIN

Illinois ^tate Laboratory

NATURAL HISTORY.

Urbana, Illinois.

VOLUME V.

ARTICLE II.— A COXTKIBUTION TO A KNOWLEDGE OF

XOA' TLI AMEKICAX FRESH- \VA TER CYCLOPID. K.

By ERNEST 1^. EORBES, B. S.

Illinois State Laboratory of Natural History,

LK15AXA, ILLINOIS,

1897.



State Laboratory of Natural History.

LABORATORY STAFF.

Professor Stkimikx Ai.kukd Fokbes, Ph. D.,

Director of State Laboratory and Statf Entomokxjist.

Chaklks Arthur Hart,

Stistematic Entomoloijist and Curator of Collections.

Frank Smith. A. M.,

Assistant Zoologist.

Ciiari.es Atwuod KokoU), Ph. D.,

Zoologist, and Superintendent of Biological Station.

Charles Christopher Ai)a:ms, B. S.,

Entomological Assistant.

Ralph Waldo Braicher, B. S.

Entomological Assistant.

Mary Jane Snyder,

Secretary.

Henry Clinton Forbes,

noisiness Agent and Librarian.

Lydia Moore Hart,

Artist.



ERRATA.

Page 136, line 2, and jiage 182, line 17 from bottom, f(jr 'g^a read 'gj.

Page 226, line 2, page 263, line 17 from bottom, and page 267, lines

2 and 15, for 'g8, read 'g6.

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. IV.

Page 457, line 5, for Genera read Genus.

{



Article IL—.4 Contribution to <t Knoirlcdtjc of Xortli Aiiicri-

can Fresh-water Ciiclopiihe* By Ernest B. Forbes.

INTRODUCTION.

During the past tAventy years the fresh-water Copcpodi of

North America have received considerahle attention from a

small number of pioneer investigators, l)ut as yet no one

has made a careful comparative study of authentic repre-

sentatives of the species described l)y them. It is my pur-

pose in this paper to make a first contril)ution 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 lu'ought into careful comparison. I have

embodied in this paper, not a complete revision of the Ameri-

can species of CjiclopH, but only such results of my study on

that group as have now been l)rought to a satisfactory con-

clusion.

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 possilde

for me to l)egin a revision of the American species along the

same general lines.

The receptaciih(ni sc minis, 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 Ulinois. and was accepted by the Faculty of the University June 7, 1897. as a

thesis for the degree of Bachelor of Science in Zoology.
+ Dentschlands freilebende Siisswasser-Copepoden, I. Teil: Cyclopidae.



28 Illinois State Laboratory of Natural History.

been used for the separation of species by onr most eminent

workers.

I have made a vigorous effort to ol)tain authentic examples

of all the species considered ; and while I have been in

general successful, I have been forced in the case of Herrick'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 Herrick'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 U. 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. Eoss, of Drake University, Iowa,

and kindly loaned me by these gentlemen ; and all of the col-

lections made at the Illinois 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,
W^ashington, 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 Eocky and

Sierra Nevada Mountains. In these collections are (hjclops

from small temporary ponds 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 Fresh-zvatcr Cyclopidce. 29

treated, and a more careful iiis'pec-tion 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: C'l/rlojm an'ilis, hcltioliiiuHriiii, j>iilr]iclltl.s, aij/itdtils,

and strciniKs. During the present year Dr. Schmeil has

sent specimens of (_'i/cl(>j)>; Jnsciis, r<tric(iihs, h'iicl,<irti, alhidiis,

atroiHiiH, NcrnildtiiH, riri(Ii>i, and jiltalcyatHs, while Prof. Sars

has sent to Dr. Forbes examples of the species of the follow-

ing list : Cyclops viridi.s, ikdiiis, robustiis, }tf/(iliiiiis, oitlt.oiioidcs,

(tUi'uJiiH, t^scus, vcDutliH, })i((cnii-i(ii, (/if/dii, IcKckarti, 'nisifpiia,

liisctosiiH, jiiithridtus, })ici(>i])i<J((fns, (ijfiiiis, cnis.sicdiidi.s, phdl-

enitxa, hlcolor, scutifev, acrnildtiis, r((rir<tiis, (h/Jio/rsI,}}, la-

custris, and strenuiis. These authoritatively named European
specimens have given me the opportunity for comparative

studies of American and European Cyclopid;!'—the first, so

far as I am aware, which have been made in America.

The mere study of American specimens of species first

descril)ed 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 Claus ('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, ()rf]iori/cloj>s and Hoinoci/rloj)^,

for the two American species C. iiiodcstiis and C. ((fci-. 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. soTuhttits. 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. phalcratus for instance, the propor-

tions of the stylets are quite constant, but in C. virtdts, scrrii-

latus, and hicuspidatus, 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 C.

viridis var. hrevlspinosus (PI. XI., Fig. 1).

The armature of the swimming feet is of considerable value in

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 betAveen spines and setfe, and it would be

impossible from this character to say which of the two names

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 setfe, 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 recej^taculwm scminis. Unfortunately, it

is often very difficult to see this organ distinctly, especially if



North American FrcsJi-ivater Cyclopidce. 31

the specimens have been killed in alcohol ; but this difficulty

is readily avoided by the use of formalin as a preservative.

A l*'o solution is amply strong, and the osmosis of fluids is

not rapid enough to rupture the reeeptaculum, as is the case

when strong alcohol is used. Some slight differences in the

appearance of the reeeptaculum are due to stage of sexual

activity of the animal. In the case of t\ rhidis var. insectus

such a difference is noticeable. In Fig. 3, PL XI., the solid

line represents the outline of the empty reeeptaculum ; 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. E. W. Sharpe and F.

\V. 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 Glaus. (PI. YIIL, Fig. 1-3.)

Cyclops leilckarti, Claus, '57. p. 35, PI. I., Fig. 4; PJ. II.. Fig. 13, U.
Cyclops leuckarti, Schmeil. *92, pp. 57-64, PI. III., Fig. 1-8.

Cyclops leuckarti, Herrick and Turner, '95, pp. 96-98, PI, XVI.;

XVIII., Fig. 1, A-J : XXIV., Fig. 2-6.

This species is of medium size, but is rather more slender

than usual (PI. YIIL, 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 In'oad

space between their points of attachment. The outer apical

seta is delicate and as long as the stylet. Of the remaining

three, all of Avhicli are "well developed, the middle one is the

longest and the innermost the shoiiest.

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. YIII., Fig. 2). The margin of the one

borne by the sixteenth segment is entire, Init 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 setse 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 sette ; inner ramus, one seta, one spine, four setcie.

Second and third pairs : outer ramus, three spines, three

setfe ; inner ramus, one seta, one spine, four set?e. Fourth
pair : outer ramus, three spines, four set* ; inner ramus,

one seta, two spines, two setae.

The rudimentary foot (PI. A7II., 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 receptaculiim seminis is large and elliptical, and the

anterior part, from which proceed the canals, is laterally

expanded.



Xorth American I-'rcs/i-icatcr Cyclopidcc. 33

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

abdomen.

In length the female varies, in American specimens, from

.95 to l.o mm.
The color is always inconspicuous and may l)e light Itlue

or gray.

This is in general a very rare species in America. I liave_

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 Paver, Illinois. It is found in

just such situations as is L' . ctht-r, but usually in very much
smaller numbers. I have seen this species in collections

from Lake Harriet, Minnesota ; Delavan Lake, AVisconsin

;

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 Fokbes. (PI. IX., Fig. 1-3.)

Cyclops edax. Forbes, '90a, p. 709, PI. III.. Fio;. 15; IV.. Fig. lG-19.

Cyclops annulatus, Wierzejski, "92, pp. 237. 238, PI. Yf., Fig. 14-lS.

Cyclops leuckarti. Marsh, "93, pp. 209-211, PI. IV.. Fig. 17: V.,

Fig. 2-(;.

SYNONYMY .VND COMPARISON.

This form has been confounded with C. Iciichdiii 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

antennal segment, or of the hyaline plates of the sixteenth

and seventeenth segments. As in C. Icnchnvt'i (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 C. leuckarti. In ('. cddr the

edge of the plate is cut by a series of deep oblicpie 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 both

directions. Tlie segment itself is deeply excavated within and
the plate merely completes its usual outline, while in (',

Iriicl,(trti the segment is but slightly excavated and the broad

plate projects far beyond the outline of the segment.

In C. eda.f the last tAVO segments are equal, while in

C. leiK'liart'i 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. leurkarti, may
sometimes be present in C. 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. letirkdrti, are usually

absent in C. c(htx and when present are quite inconspicuous.

They begin, as in C. Iciickayti, at the proximal end of the seg-

ment, but soon fade away.

The abdominal stylets in C. cdax are more divergent than

in C. leuchiirt'i, and are inserted farther apart.

The fifth feet (PL IX., Fig. 3) are markedly different. In

C. (')h(x the two sette 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 C. lenclcarti the surface of

attachment of the loAver 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 C. exlax.

There are differences in general proportions and appear-

ances which make it veiy 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 receptacnltim seiulnis

is identical in the two species, so far as I can tell ; but

though the species are undeniably closely related, I think

that on account of the al)Ove-mentioned differences they

should be kept distinct.

Ciidops i'dax may possibly be the same as C. leeuicenJioekii

Hoek, which Schmeil has made synonymous with C. leuckarti.



North American Fresh-water Cyclopidce. 35

If the figures as published by Hoek are correct, C. vdax differs

from ('. leeKweiiJiockii in the following particulars : In cdftr

the labrum has eleven teeth; in leeidrcnhoekii it has but ten.

In <<I<(r the seventeenth antennal segment is longer than the

sixteenth; in leeiiici'nJtockii the sixteenth is longer than the

seventeenth. In edav the first foot, outer ramus, bears on the

distal segment two spines and four setse ; in leeiiircnhockii the

corresponding segment bears three spines and two setse. In

i'ddv the inner margin of the distal segment of the fifth foot

is not incurved as in lecinrciiJiot'kii. In cda.r there are never

less than five prominent teeth in the lamella of the seven-

teenth antennal segment; in IccKiroihoekil but three are fig-

ured. The transverse ridges on the maxilliped of IccuicoiJiockii

are more prominent, smaller, and more numerous than in

4'd(t.r.

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 Eepublic under the name of C. (tinnddtKs.

SPECIFIC DESCRIPTIOX.

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

l)y 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



86 Illinois State Laboratory of Natural History.

localities this proportion only varied by one thirtieth. The
inner margins of the stylets are ciliate. The lateral spine is

a trifle behind the middle ; the outer seta about as long as

the ramus ; the inner five sixths the length of the third from
within ; the latter two thirds as long as the second.

The antennte 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 (PI. IX., Fig, 2), that of the six-

teenth segment being very narroAV, 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 setie. Second and third pairs : outer ramus, three

spines, three sette ; inner ramus, one seta, one spine, four

setae. Fourth pair : outer ramus, three spines, four setae

;

inner ramus, one seta, two spines, two setae.

The feet of the fifth pair (PI. 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 segpient. This seta is

most strongly spinulose on the outer side, while the distal one

is plumose on both sides.

The rercptdciiliiDi semi ii is 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 receptaculum is almost exactly as in C. Iciickarti.

The egg-sacs are elliptical and stand out from the abdomen.
The usual length of the female is 1.2-1.4 mm.



Xorth American Fresh-ivatcr Cyclopidie. 37

Cyclops viridis Jurine. (PI. X., Fig. 1-8.)

Monocu/us quadricornis var. riridis, Jiirine. '"20. p. 4G, PI. III., Fi^. 1.

Cyrlups viridis, Schmeil, '92, pp. 97-101, PI. Vlll., Fi-;. 1'2-14.

SYXONYMICAL DISCUSSION.

Though the subdivision of the riridin 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

wliich may be of service to any one following me in the study

of the American Cydnp'uhe.

C. riridis occurs in America, so far as I now know, only in

the larger forms of that species. C. iiif/ens (Herrick, '82a)

seems to me the only described form corresponding very

nearly to the European riridis, and 1 therefore regard it as

the American representative of that species. It is considered

by Marsh as equivalent to C. (iiitcrirdnns {= C. inscrfiis), and

Herrick himself says that it is distinguished from this form

only by its greater size. From Fig. 3, PL XXV., in Herrick

and Turner '95, I judge that ('. iikjciis is synonymous with

('. riridis, thus representing in x\merica the maximum devel-

opment of the species, as does C. f/if/ns in Europe.

Dr. Forbes has for years recognized such a form as C.

iiif/ciis, 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 C. Irris, but the description was never pub-

lished. This C. iiii/ois or leris differs from specimens of

riridis received from Sars and Schmeil only in its greater

size, and from specimens of ('. f/ii/ds 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 (/if/as and iiKjens

are undoubtedly typical C riridis. It is of interest to note

that in both of these large form.s 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 ('. riritJis it may or

may not be separated from the segment by a suture. C.

iiHjeiis 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

vir'ulis, in which the small spine of the fifth foot is always

separate from the segment, the inner border of the stylet is

never ciliate, though in rare cases the whole inner aspect of

the stylet seems to he set with the shortest of hairs, only

visible on account of their points of attachment.

The first species closely related to rlrldis described in

America was C. insectiis, 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. i^arcus. 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 C.

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.

insectns.

So variable is C. insectiis, 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 (PL XXXIV., Fig. 5), is a draw-

ing of the fifth foot of C. j^arcus. 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 C. insectiis.

Cyclops americanus, described by C. J). Marsh in 1892,

proves on examination of authentic examples to be synony-

mous with C. ins-ectus. Undoubtedly C. americanus of Herrick

and Turner is identical with Marsh's form and is consequently

also a synonym of insectiis.



North Anicricati Frcsh-icatcr Cyclopidie. 39

Cragin in 1883 figured a form as C. riridis and stated that

it was found at Cambridge, Mass. This form is C. insectiis.

Ci/rlops uniangnlahis, described as new in the same article, is

also ('. iiiscctus, the only apparent difference being a very

slight one in the armature of the swimming feet.

Ci/clojiH lurriapiiio.siiii, described in 1884 by Herrick, differs

from ('. i)isccti(s principally in the shape of the outermost

terminal spine of the stylet. In the type of })rerl.'^j)'ni()siis this

spine is very l)road, 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 ('. hi-evi-

sp'iiiosus should be considered as a good variety. The follow-

ing description of ('. riridis 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

al)domen is almost the same. The cephalothorax tapers about

equally in both directions ; each segment projects laterally

far beyond the follo^ving• 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 pai-t. 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 inner border 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 Hisiory.

proportional lengths are not entirely constant. Usually Uie

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 back 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

are 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 reeeptacvlnm 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 receptanihiin

*In a foot-note Sehmeil states that Olaus, Iloek, Richard, and Land6, consider

this spine as a process of the segment, that Ulianin figures it as separated from the

segment by a suture, and that he, Schmeil, had observed it both ways.



North American Frcsli-ivatcr Cyclopidie. 41

Var. brevispinosus Herrick.

(PL XL, Fig. 1 and 2.)

Cyclops lirevispinoisus, Herrick. '84, p. 148, PI. S. Kior. 7-n.

Cyclops brevispinosus, ]\I;ir.sli, '93, pp. 20;i-20(;, PI. IV., Fi^. 11.12.

Cyclops I'Verispinosus. Herrick and Turner. '95. p. 95, PI. XX 1 11..

IMg. 1-4: XXIV., ri-. 7-1-2.

This species of Herrick's, which I reduce to a variety, is dis-

tinguished from typical ('. riridis, 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

inscrtii.s. -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 l)e in the European riridis and always is in the American
form. This spine is also longer than in viridis and is lanceolate

in shape. 3. By the armature of the swimming feet. The
spines of these appendages are extravagantly long and heavy.

^Yhile at first sight these differences might seem sufficient for

the complete separation of the two forms, the distinguishing

characters are in most species of Ciidops so variable that it

seems to me best to consider hrerispliiosns as merely a variety.

The rcccptacnhnn aciitiiiis is as in iiisertiin. .

I find this variety in collections from Lakes Michigan,

Manitoba, Okoboji, (Iowa) ; and from Lake Winnebago, Green

Lake, and Lake Geneva in AYisconsin; from Swan Lake in

Montana, and Lake Pend d'Oreille in Idaho ; from the Detroit,

Calumet, and Illinois Pavers ; and from Sand, Fox, Quiver,

Dogfish, Phelps, and Thompson's lakes—all in Illinois. It

is never especially abundant but seems to be quite generally

distri])uted.

Var. insectus Foruks.

(PL XL, Fig. 3-6.)

Cyclops insectu.'<, Forbes, "823, p. 049, PI. IX., Fig;. (J.

Cyclops parous. Herrick, S2a, p. 229, PI. VI.. Fig. 12-15.

Cyclops inspctus, Herrick. '84, pp. 151, 152, PJ. U, Fig. 9.

Cyclops viridis, Cragin. "83, p. 68, PI. IV.. Fig. 8-16.

Cyclops uniangulalKS, Cragin, "83, p. 71, Pi. I\'., Fig. 17.

Cyclops insectus, Sehmeil. "92, p. 95.



4 '2 Illinois State Laboratory of Natural History.

Cyclops parens, Marsh, "93, pp. 208, 209, PJ. ]V., Fjo-. 10; V.. Fig. 1.

Cyclops americanus, Herrick and Turner, "95, pp. 91, 92, PI. XIV..

Fig. 1-9.

Cyclops parens, Herrick and Turner, '95. pp. 93, 94, PI. XX.. Fig.

12-15: XXI.. Fig. 22; XXIII., Fig. 8; XXX.. Fig. 1-8.

This variety represents in America the smaller members of

the viridis relationship. It is distinguished from viridis in

Europe hy the lack of cilia on the inner side of the stylets,

by some slight differences in the shape of the vcccptucidHm

seminis (PI. XL, Fig. 3), and by the different shape of the fifth

foot. The rcceptdcidum sc minis differs in that the upper part

is larger in proportion to the segment in hiscrtns 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
insectiis, 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 them all together for the simple reason

that there is no one set or combination of characters suffi-

ciently invariable to subdivide the group.

The antennge 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 FrcsJi-ivatcr Cyclopidic. 43

Pond, Normal, 111.. . . . . 03:9
Creek. Wyoming, . . . . 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, but it may be

entirely absent or only present in a slight degree of develop-

ment. Whatever the function of this peculiar indentation, it

does not seem to be 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 Eiver, this seg-

ment is very fehort, 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 receptaenhun semhiis (PI. XI., 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 rectp-

tacidiiDi sciiiitiis of C. rtridis (PI. X., Fig. 2), the anterior

portion of the receptaculum is comparatively larger in in sectus

and its outline as a whole is somewhat different.

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



l-l Illinois State Laboratory of Natural History.

dependence can be placed upon it for purposes of distinction.

Tiiis 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 C't/rlojis 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 Glaus. (PI. XII., Fig. 1-4.)

Cyclops bicuspidatus, Clans, '57, p. 20'J.

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

Cyclops navies. Herrick, •S2a. p. 229, PI. V.. Fig. G-13, 15-17.

Cyclops thomasi. Forbes. "823, p. 649.

Cyclops bicuspidatus, Schmeil, '92, pp. 7.0-87, P]. II.. Fig. 1-3.

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

Cyclops sprratus, Forbes, '93, pp. 247,248.

Cyclops forbesi, 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 wliicli a few years ago were considered as specific

must be cast aside and the W'hole 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

Cyclops thomasi 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 Glaus. 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



XortJi American Frcsli-ivater Cyclopidte. 45

pond at Wood's Holl, Mass. The most conspicuous difference

between this form and C tJioiiuo^t is a slight one in the shape

of the fifth foot.

In the Illinois River are specimens which l)ridge over com-

pletely the gap between C. l/ieKsjiidatiis and Herrick's C.

itanis, and I see no reason for considering ikivks as a good

variety.

Ci/rlops miuiiihi.s Forbes is distinguished from C. tliomas'i

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.
Ci/dojis s('rr((tiis Forbes is found in the same situations as

C. )i) ill II this, 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 serratiis being already in use, Herrick

renamed the species fm-lx'st. 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) w'ith

seventeen-segmented antennae, oval cephalothorax, slender

abdomen, very long and slender caudal stylets, and but two

developed setie to each stylet. The longer of these setae 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 w'estern 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 American 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. Tlie inner of the two longer

sette is as long as the entire abdomen, and the outer of the

two but half that length. The extreme outermost of the

terminal setie 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 (PL 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 antennae, 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 setfe ; inner ramus, one seta,

one spine, four sets. Second pair : outer ramus, three spines,

four setfe ; inner ramus, one seta, one spine, four setae.

Third pair, exactly like second. Fourth pair : outer ramus,

three spines, four setae ; inner ramus, one seta, two spines,

two setae.

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 setae, 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 Frcsh-icatcr Cyclopidic. 47

The irceptactdiuii sciiiiiih (I'l. 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 varial)le,

but I note no variation in the shape of the rccepiacnliiiii houI-

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—prol)ably on account of the frequent

transfers of individuals from one of these situations to another.

Subgenus Macrocyclops Claus.

Cyclops albidus JuraxK. (PI. XIII.)

Monoculus quadricornis v;ir. albidus. 3avlnQ.' 10, p. 44. P). 1 1.; Fi>i^. 10. 1 1

.

Cijclops gijrinus, Forbes, "OUa, pp. 707-709, PI. II.. Fig. 9; I J I.. V'lg. 14.

Cyclops sujnatus viir.tenuicornis,llevT'ick and Tnrner,'9o. pp. 106, 107,

PI. XV.. Fiir. 5-7: XX.. Fig. 1-7; XXXIII.. Fig. 1, 2.

Cyclops albidus, Schmeil, "92, pp. 128-132, PJ. I., Fig. S-14b; PJ. IV.,

Fig. n.



48 Illinois State Laboratory of Natural History.

SYNONYMY.

Since the description of C. (jijrinus by Dr. Forbes in 1890,
more careful descriptions of C. alhidus in Europe and fur-

ther studies in America have established the identity of the

two forms. The original description of C. (/i/riniis 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. rirldls. 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 antennae 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 set?e ; inner ramus, one seta.



NortJi American Fresh-water Cyclopidee. 49

one spine, four setfe. Second and third pairs : outer ramus,

four spines, five setie ; inner ramus, one seta, one spine, four

setae. Fourth pair : outer ramus, three spines, five setae

;

inner ramus, one seta, two spines (inner naked and movable),

two seta; (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 rccej>t(tci(Ii(iii scniiiiis is kidney-

shaped and the posterior is two-lobed. The lateral canals

are attached to the low'er 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. Antennae seventeen-segmented.

Rami of swimming feet three-segmented. Fifth feet one-

segmented, bearing one spine and two setae.

Cyclops ater Herrick. (PI. XIY., and PI. XY., Fig. 1-3.)

Cyclops ater, Herrick, "823, p. -228. P], III.. Fig. 9-12.

Cyclops atf>r, Marsh, '95. pp. 13, 1-1, PI. VI., Fig. 1-4, 6, 12.

Cyclops ater, Herrick and Turner, '95. pp. 89, 90, PI. VII.. Fig.

11, 12: XII., Fig. 9-12; XXI., Fig. 13-15, 17, 18.

The cephalothorax is peculiarly short and broad. Its first



50 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 ahdomen 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 opporj;unity 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 fu'st antennse 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 setae of the swimming feet are short and stout. The

armature is as follows :—First pair : outer ramus, three

spines, five setae ; inner ramus, one seta, one spine, four

setae. Second and third pairs : outer ramus, four spines, five

setae ; inner ramus, one seta, one spine, four setae. Fourth

pair : outer ramus, three spines, five setae ; inner ramus,

one seta, two spines, two setae.

The fifth feet (PI. XY., Fig. 2) are one-segmented and bear

one strong spine and two setae each. The spine is about one

third the length of the setae. The inner seta, that is the one

next the spine, is borne on a conical projection from the



North Auicrican FrcsJi-watcr Cyclopidw. 51

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

The irceptdcidiim seiiiinifi (PL XY., 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 poms
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 Paish, Eound,

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.

Sul)genus Orthocyclops n. subgen.

Antenna; sixteen-segmented. Eami of swimming feet, three-

segmented. Fifth feet three-segmented, distal segment bear-

ing two apical setae.

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

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

Cyclops modestus, Herrick and Turner, "Oj, pp. lOS, 109, Pi. XXI.,
Vhr. 1-5.

Cyclops modestxis, IHarPli, '93, pp. 213, 214, Pi. V., Fi^. 10-13.

Cyclops capilli/erus, Forbe.s, '93. pp. 248, 249, Pi. XL., Fig. 14-17:

XLI., Fi^. IS.

SYNONYMY AND DISTRIBUTION.

By a study of the type specimens of Ci/eJojis (itpiUifcriiii 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, hut 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 species.

I have noted its occurrence in collections from Quiver, Dog-

fish, and Thompson's lakes, and from the Illinois Eiver,

near Havana, 111. ; from the Sangamon Eiver, in Champaign
county, Illinois ; and from Grebe Lake in Yellowstone Park.

Marsh reports it from Eush 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, but 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 setae are well developed. Of

these three the middle one is considerably the longest and
the inner one slightly shorter than the outer.



North American Fresh-ivater Cyc'opidce. 53

The antennae are regularly sixteen-segmented, though

Herrick mentions having notes on a similar form in which

the antennie are seventeen-segmented. They reach to the

middle of the second cephalothoracic segment. On the third,

tenth, and thirteenth segments are remarkably long, heavy

setcT. The antenna (PL XYL, Fig. 1) is given a characteristic

appearance by the conspicuous seta on the third segment
and a sharp change in direction betw-een the third and fourth

segments. The last segment is much shorter than the one

preceding.

The settle 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 setae

;

inner ramus, six setae. Second pair : outer ramus, four spines,

five setae ; inner ramus, six setae. Third pair : outer ramus,

three spines, five setae ; inner ramus, six seta3. Fourth pair

:

outer ramus, three spines, five setae ; inner ramus, one seta,

two spines, two setae.

The fifth foot (PL XYI., 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

setae—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 n'ccj)taci(liiin scmliiis (PL XYL, Fig. 3) is very much
as in Cijcloi)s bicuspidatiis Glaus. 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 Evicyclops Claus.

Cyclops serrulatus Fischer. (PI. XYII., and PI. XVIII.,

Fig. 1-3.)

Cyclops serrulatus and (J. serriilatus VAy. mo7Uanus, Brad}', "78. Vol.

I., pp. 109-111, PI. XXII.. Fi<r. 1-14.

Cyclops serrulatus and C. serrulatus var. f^fijuns, Ileriiek, '81, PJ. Q.
Ficr. 17-19; PI. Q3, Fig. 10.

Cyclops serrulatus, Schmeil. '92, pp. 141-1-lG, PI. V., Fio. G-14.

SYNONYMY, VARIATION, AND DISTRIBUTION.

This is one of the most common and widely distributed of

'American Ci/clops. It occurs almost everywhere between

Maine and California and from Florida to Manitoba.

Herrick's variety degans 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. BeloAv 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 Frcsh-ivatcr Cyclopidte. 55

Local ity



56 Illinois State Laboratory of Natural History.

crease rapidly in length at the posterior end and fade 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 are 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 barbules

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 antennae. 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, five setae ; inner

ramus, one seta, one spine, four setae. Second and third

pairs : outer ramus, four spines, five setae ; inner ramus,

two spines, four setae. Fourth pair : outer ramus, three

spines, five setae ; inner ramus, one seta, two spines, two

setae.

The fifth foot (PL XA^III., 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 tl^e outer side is a

delicate little seta projecting outward at a considerable angle.

The recejjtacKlnm seminis (PI. 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 receptaculum 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 FrcsJi-watcr Cyclopidie. 57

Ordinarily the egg-sac tapers to a sharp point at the lower

end, and stands out from the ahdomen 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. (PL XIX., Fig. 1 and 2, and
PI. XX., Fig. 1 and 2.)

Chjclops prasinus^ Fischer. '(iO. pp. G52-654. PJ. XX., Fig. 10-26a.

Cyclops fluriatilis, Herriek. '82 a, p. 231, PI. VII.. Fig. 1-9.

Cyclops mafjnoctavus, Cragin, *83, pp. 70,71, PI. III.. Fig. 14-23.

Cyclops prasinns, Sohmeil, "92, pp. 150-156. PI. V., Fig. 1-5.

Cyclops fluviatilis, Herriek and Turner. '95, pp. 114, 115, PI. XXVI.,
Fig. 1-S; XXX., Fig. 1.

SYNONYMY AND DISTRIBUTION.

On account of the great difticulty in determining the struc-

ture of the reccytaciiliint seminis of C. jjrashiiis, this organ

has escaped study in the American representatives of this

species, and although Marsh had noted a general resemblance

of Herrick's C. jiKr'uittlis to Yosseler's C. pcittagonus {C.

prasinus Fischer), he did not consider these as identical. By
a careful study of a large number of specimens of C. jiuvhit-

tlis from Illinois, Florida, and Wisconsin, I find a complete

agreement in the characters of the receptaculKm seminis of C.

prasinus and C. jiuviatilis and in all other specific characters

as well.

I have noted the occurrence of C. 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. Herriek 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 West. 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 tlu'ee 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 setae ; 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 setae ; inner ramus,

-

one seta, one spine, three setae.

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



NortJi American FresJi-^i'iitcr Cyclopidce. 59

three bristles. The inner one is a ciliate spine while the other

two are plumose setfe. 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 recejitactdiim scminis (PL 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. (PL XX., Fig. 3.)

Cijclops phaleratus, Koch, '35-'41, Heft 21, pp. 8, 9. PI. IX.

Cyclops perarmatus, Cragin, '83, pp. 72, 73, PI. I., Fio^. 9-lS.

Cyclnps phaleratus, Schmeil, '!)2, pp. 170-178, PI. VIII., Fig. 1-11.

Cyclops phaleratus, Herrick and Turner. '95, pp. 120, 121, PI. XYII.,

Fig. 1-7; XVIII., Fig. 2-2(1; XIX., Fig. 1; XXI., Fig. 6-10.

Cijchips phalcratvs, Marsh, '95, pp. 19, 20.

DISTKIBUTION.

In America this species is rare, though evidently widely

distributed. I have noted its occurrence in collections from

the Illinois Pviver 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 Eiver, and Intermediate

Lake, Michigan. Cragin describes this species as Cij<i(>j)s

])€}•(( nil <it IIS 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. phaleratus 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 irt figure.



North American Frcsh-7^'atcr Cyclop idie. 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 antenuit of the female may be either ten- or eleven-

segmented and reach only a little beyond the middle of the

first eephalothoracic 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 antenna; 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 yows of long spinules. The
armature of the distal segments is as follows :—First pair

:

outer ramus, three spines, live set;!:' ; inner ramus, one spine,

four sette. Second pair : outer ramus, four spines, four seta3

;

inner ramus, one spine, four set;e. Third pair : outer ramus,

four spines, live seta3 ; inner ramus, one spine, four setie.

Fourth pair : outer ramus, three spines, live seta; ; inner

ramus, one seta, two spines, two seta^.

The rudimentary feet are lateral rather than ventral and

consist of mere Hauge-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 reccptdculiiiit scmtiiis 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 C. pluderatas 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-

cainptus.

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 hrevispinosus of virldis are char-

acteristic of America, while the remaining fifteen species and

one variety are common to both Europe and America.

Probably hicuspidatus, seiridatus, vlridis, alhidus, 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

hicuspidatus 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 : hicuspidatus, viridis var.

insectiLS, serrulatus, and alhidus, though virldis var. hrevis-

pinosus, hicolor, dyhowskii, modestus, and edax have been

found in such situations. In collections from Crater Lake,

Oregon, I found a very few specimens of alhidus and ser-



North American FrcsJi-ivatcr Cyclopidce. 63

rnhifiis. This lake is in the Cascade Mountains and is the

highest hike of its size in the worhl.

As very few ohservations have heen made on the Cyelopidai

of rivers, I examined a continuous series of collections made
in the Illinois River at the Illinois Biological Station, ex-

tending from May to Septemher, 1896, In the first of these

collections bici(S2>id(iti(s was the predominating form, hut it

soon disappeared entirely, its place heing taken by viridis

var. insectiis. From this time throughout the summer /nsccfjts

was hy far the most abundant form. Eda.v, rlrtdis var.

brerisphiosKS, Icucharti, prasinns, serrulatus, aw^varlcans yfere .

common in the collections, \\\\\\e fimhr'uitns xav.poppel, viridis,

modestiis, hicolor, cdhidiis, and pludcnttiis were of rare occur-

rence.

LIST OF NOETH AMERICAN SPECIES.

Below is a list of the fresh-water CyclopidaB reported from

America. I have myself seen all of the species of this list

except those herein credited to lierrick.

Genus CYCLOPS.

I. Subgenus Cyclops s. str. Glaus.

1. Cjidops h'lickarti Glaus.

This is a rare species throughout the north central States.

2. Cyclops insignis Glaus, /z^/c Herrick.

Herrick has found at Long Island a form Avhich 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 oitJionoidcs ^Sivs, Jide Herrick.

I regard the occurrence of this species in America as very

doubtful.

5. Cyclops dyhoicskii 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 NatJiral History.

6. C!/cI<)j>s vir'idis 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. hrevlspinosiis Herrick.

h. var, insectns Forbes.

7. Cyclops hicuspidatus Claus.

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 Macrocyclops Claus.

9. Cyclops fusciis Jurine.

Occurs sparingly in the ponds and lakes of Wisconsin,

Michigan, Illinois, and Massachusetts.

10. Cyclops albidus Jurine.

Eather 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 modestus Herrick.

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

V. Subgenus Microcyclops Claus.

13. Cyclops hicolor Sars.

Eare 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 FresJi-i^'atcr Cyclopidie. 05

YI. Subgenus Eiiciirli)p>i Claus.

15. Cyclops serridatKS Fischer.

Very common everywhere.

16. Ci/clops jirasDiKS Fischer.

Abundant in all sorts of Avaters in the Mississippi Valley,

Massachusetts, and Florida.

VII. Subgenus Panicjiclojis Claus.

17. Ci/dojis pJialeratus Koch.

A rare species in Manitoba, Massachusetts, Alabama, and

the north central States.

18. Cyclops Jimhriatits var. poppcl Kehberg.

A rare species in Manito])a, Alabama, and the north central

States.

19. Cyclops ajfiiiis Sars,7?V/<' 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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NortJi American FrcsJi-tvater Cyclopidce. G7

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Canu, E.

'92. Les Copepodes du Boulonuais, Morpholoo^ie, Embryoloo^ie,

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des ( 'rustaceen-Systems. Ein Beitragzur Desceudenzlehre. 114 pp.,

19 Pis. Wien.

'91. Uber das Verhalten des nervcJsen Endapparates an den Sinnes-

haaren der Crustaceeu. Zool. Anz.,XIV. Jahrg.,Xo. 375, pp. 363-368.

'93. Uber die Bildung der Greifantenne der Cyclopiden und ihre

Zuriickfiihrung auf die weiblichen Antennen und auf die der Calanl-

den. Zool. Anz., XVI. Jahrg.. Xos. 423 u. 424, pp. 261-269, 277-285.

'93a. Uber die Antennen der Cyclopiden und die Auflosung der

Gattung Cyclops in Gattungen und Untergattungen. Anz. der

K. Akad. d. Wissensch. Wien., Xr. IX., pp. 79-83.

'93b. Uber die sogenannten Bauchwirbel am integumentalen Skelet

der Copepoden und die medianen Zwischenplatten der Ruderfuss-

paare. Arb. Zool. Inst. Univ. Wien., T. X.. 3 Heft. pp. 217-232,

Taf. XXIII.-XXV.

'93c. Xeue Beobachtnngen iiber die Organisation und Entwicklung

von Cyclops. Ein Beitrag zur Systematik der Cyclopiden. Arb.

Zool. Inst. Univ. Wien. T. X., 3 Heft. pp. 283-356, Taf. XXXI.-
XXXVII.



68 Illinois State Laboratory of Natural History.

'93d. Weitere Mittheilnnwen iiber die Antennen-gliederung und
iiber die Gattuno^en der Cyclopiden. Anz. der K. Akad. d. Wis-

seusch. Wien., Nr. XIII., pp. 116-120.

'95. iiber die Wiederbelebuno^ irn Schlarame einojetrockneter Cope-

poden und Copepoden-Eier. Arb. Zool. last. Univ. Wien, T. XL,
1 Heft, pp. 1-11. Taf. 1., II.

'95a. Uber die ^laxillarfiisse der Copepoden. Arb. Zool. Inst. Univ.

Wien, T. XI., 1 Heft, pp. 49-63, Taf. VIII.

Cragin, F. "W.

'83. A Contribution to the History of the Fresh-water Copepoda.

Trans. Kansas Acad. Sci., Vol. VIII.. pp. 66-80. Pis. I.-IV.

Daday, E. v.

'84. Catalo<^us Crustaceorum fauufe Transylvania^. Orv.-Term6=zet-

tud. ifrtesitr), Vol. IX., pp. 161-187.

'85. Neue Thierarten aus der Siisswasserfauna von Budapest. Term.

fiiz.. Bd. IX.. No. 2, pp. 208-215, Taf. IX.

'85a. MonographiaEucopepodorum liberorum in Hungaria hucusque

repertorum. Math, es Term6szettud. Kozlem, Vol. XIX., pp.

117-311, Pis. I.-IV.

'91. Adatok Magyarorszag edesvizi niikroskopos faunajanak is-

meretehez. Term, fiiz., Vol. XIV., pp. 16-31. PI. I.

'91a. Beitriige zur mikroskopischen Siisswasserfauna Ungarns.

Term, fiiz , Bd. XIV., pp. 107-123, PI. I.

Dana, J. D.

'48. Conspectus Crustaceorum qufe in Orbis terrarum circumnaviga-

tione, Caroli Wilkes e Classe Reipublicae Foederatas duce, col-

lectornm. Proc. Am. Acad. Arts and Sci., Vol. I., pp. 149-155.

Eusebio, J. B.

'88. Reeherches sur la faune des eaux du Plateau Central. Le
Faune Pelagique des Lacs d'Auvergne. Trav. Labor. Zool. Girod,

T. I., pp. 1-29, PI. L

Fischer, S.

'60. Beitriige zur Kenntniss der Entomostraceen. Abhandl. d. kgl.

bayerisch. Acad. d. Wissensch., Bd. VIII., 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 Comm,, 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.



North American Frcsh-xvatcr Cyclopidie. 69

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

'90. Preliminary Keport upon the Invertebrate Animals inhabiting

Lakes Geneva and ^lendota, Wisconsin, with an Aoi'onnt of the

Fish Epidemic in Lake Mendota in 18S4. Bull. V . S. Fish Conim.,

Vol. VIIL, pp. 473-487.

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

'93. A Preliminarj' Report on the Aquatic Invertebrate Fauna of

the Yellowstone National Park. AV^yomino;, and of the Flathead

Region of Montana. Bull. U. S. Fish Comm., 1891, pp. 207-258,

PJs. XXXVll.-XLIL

Fric (Fritsch), A.

'72. Die Krustenthiere Brilmiens. Archiv der naturw. Landes-

durchf. Br)hmen, Band II., Abth. IV., pp. 203-269.

'95. Uber Schmuokfarben einiger Siisswasser-Crustaceen. Bull,

luternatl Acad, des Sci. de TEmpereur Francois Joseph I., Classe

des Sci. Math, et Xat. II. 7 pp., 2 colored plates.

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

'92. A'orliiufiger Bericht iiber die Fauna des Unter-Pocernitzer- und
Gatterschlager Teiches. Zool. Anz., XV, Jahrg., Xo. 382, pp. 26-30.

'94. Untersuchungen iiber die Fauna der Gewiisser Biihmens. IV.

Die Tierwelt des Unteipocernitzer und Gatterschlager Teiches als

Resultat der Arbeiten an der iibertragbaren zoologischen Station.

Arch. d. naturw. Landesdurchf. v. Bcihmen. Bd. IX., Nr. II. 123 pp.

Fric, J. A.

'82. Xote preliminaire sur Tontogcnie de nos Copfipodes d'eau

douce. Zool. Anz., V. Jahrg., Xo. 121 , pp. 498-503.

Garbini, A-
'94. Primi materiall 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,
Scrie III.. Fase. I., dell' Accademia di Verona. 91 pp.

Giesbrecht, W.
'81. Die freilebenden Copepoden der Kieler Fiihrde. Ber. d. Kom.

z. w. LTnters. d. deutsch. Meere in Kiel, pp. S7-16S, Taf. I.-XII.

Gruber, A.

'78. Die Bildung der Eiersiickchen bei den Copepoden. Zool. Anz.

I. Jahrg.. p. 247,

Guerne, J. de
'87. Xotes sur la faune des A90res. Diagnoses d'un Mollusque, d'un

Rotifere, et de trois Crustac6s nouveaux. Le Xaturaliste, 1887.

7 pp.



70 Illinois State Laboratory of Natural History.

'87a. La faiine des eaux donees des Acores et le transport des ani-

niaux a graiide distauce par I'intermedialre des oiseaux. Compt.

rend, de la Soc. Biol., Seance du 22 Oct., 1887. 4 pp.

'88. Excursions zoologiques dans les ties de Fayal et de San Miguel

(Acores). Campagnes scientifiques du Yacht moncgasque I'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

I'Acad. des Sci., 25 mars, 1889.

'89a. Note sur les Entomostraces d'eau douce recueillis par M. Charles

Rabot dans la ProviTice de Nordland, Norvege septentrionale.

Bull de la Soc. zool. de France. T. XIV., pp. 27-31.

'91. Entomostraces, Rotife res, etProtozoaires provenant desrecoltes

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

Bull, de la Soc. zool. de France, T. XVI., pp. 112-115.

'91a. Sur quelques Entomostraces d'eau douce de Madagascar.

Bull, de la Soc. zool. de France, T. XVI., pp. 223, 224.

'91b. Entomostraces recueillis par M. Charles Rabot en Russie et

en Siberie. Bull, de la Soc. zool. de France, T. XVI., pp. 232-236.

'92. Cladoeeres et Copepodes d'eau douce des environs de Ruflsque.

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

'92a. Voyage de M. Charles Rabot en Islande. Sur la faune des

eaux douces. Bull, de la Soc. zool. de France, T. XVII., pp., 75-80.

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

Assoc, frane, pour I'avanc. des Sci., Congres de Pau, seance du 19

sept. 3 pp.

'93. Sur la faune p61agique des lacs du Jura franeais. Compt. rend,

de I'Acad. des Sci. 3 pp.

Hacker, V.

'95. Uber die Selbstandigkeit der viiterlicheu und miitterlichen

Kernbestandtlieile wiihrend der Embryonalentwicklung von Cy-

clops. Arch. f. mikr. Anat., Bd. 46, pp. 579-61 8, Taf. XXVIII.-XXX.

Hartog, M. M.
'88. The Morphology of Cja-lops and the Relations of the Copepoda.

Trans. Linn. Soc. London, Vol. V,, Part I., pp. 1-46, Pis., I.-IV.

Hartwig, W.
'93. Verzeichniss der lebenden Krebsthiere der Provinz Branden-

burg. Statt handschriftl. Mitteilungen herausgeg. v. Markischeu

Prov.-Mus. der Stadtgemeinde Berlin. Pp. 1-44.



NortJi American Fresh-ivater Cyclcpidie. 71

'94. Die lebenden Krebstiere der Provinz Rrandoiiburt!^, Nachtrag
zii meinein "Verzeichniss" voii 1893. "Brandeiibiir<iia.'' Monats-

blatt der Gesellsch. f. Heimatkuiide der Prov. Brandenburg zu

Berlin, Nr. 7, Okt.. 1894, pp. 1(55-169,

Hay, W. P.

'92. The Crustacea of Indiana. Proc. Ind. Acad. Sci., 1891, pp.

147-151.

Heller, C.

'71. I'ntersuchungen liber die Crustaceen Tirols. Ber. des med.-

naturw. Vereins in Innsbruck, 1 Jahrg., pp. 67-96, Taf. I., II.

Herrick, C. L.

'79. Microscopic Eutomostraca. Seventh Ann. Kep. Geol. and
Nat. Hist. Surv. Minn., pp. 81-123, Pis. I.-XXI.

'82. Habits of Fresh-water Crustacea. Am. Nat., Vol. XYI.. pp.
813-816.

'82a. Papers on the Crustacea of the Fresh Waters of Minnesota.

Tenth Ann. Rep. Geol. and Xat. Hist. Surv. Minn., pp. 221-255,

Pis. 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. Tj'pes of Animal Life selected for Laboratory LTge 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, Denison Sci, Ass"n, Vol. I., No. I., pp. 1-5G,

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

Xiederlandischen Fauna. Nied. Arch. f. Zool., Bd. III., Heft II.,

pp, 127-140, Taf. VII.-IX,

'78. De vrijlevende Zoetwater-Copepoden der Nederlandsche
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 pelaojische Fauna iind die Tiefseefauna der zwei Savoyer-

seen: Lac du Bourget und Lac d"Aunecy. Zool. Anz., VI. Jahrg.,

No. 155, pp. 65.5-()57.

'84. Weitere Mittlieilano^en iiber die pelagische Fauna der Siiss-

wasserbecken. Zool. Anz.. YIL Jahrg., Xo. 169. pp. :]21-327.

'85. Pelagisclie Tliiei'e aus Slisswasserbecken in Elsass-Lothringen.

Zoo]. Anz.,VIll. Jalirg., No. 211, pp. 720-723.

'85a. Weitere Mittheilung iiber die pelagische and Tiefseefauna der

Siisswasserbecken. Zool. Anz.. VIII. .Tahrg., No. 190, pp. 160-163.

'86. Neue Resultate iiber die pelagische und Tiefseefauna einiger im
Flussgebiet des Po gelegener Slisswasserbecken. Zool. Anz., IX.

Jahrg. Xo. 214, pp. 41-47.

'86a. Vorliiufige Notizen iiber die borizontale and verticale geo-

graphische Verbreitung der pelagischen Fauna der Slisswasser-

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. 612-615.

'87. Uber die raicroscopische Thierwelt hochalpiner Seen. Zool.

Anz., X. Jahrg., Nos. 241 u. 242, pp. 13-17. 33-42.

'87a. Notizen liber die pelagische Fauna der Slisswasserbecken.

Zool. Anz., X. Jahrg., Nos. 204 u. 265, pp. 577-582, 604-606.

'87b. Studien iiber die Fauna hochalpiner Seen insbesondere des

Kantous Graublinden. Jahresber. d. naturf. Gesellsch. Graublin-

clens. N. F., XXX. Jahrg., pp. 45-164.

'88. Die Vertheilung der pelagischen Fauna in den Slisswasser-

becken. Zool. Anz., XI. Jahrg., No. 280, pp. 284-291.

'88a. Beitrag zur Kenntniss der Slisswasserfauna der Vogesen.

Zool. Anz., XL Jahrg., No. 290, pp. 565, 566.

'90. Notizen iiber die pelagische Thierwelt der Seen in Kiirnthen

und in der Krain. Zool. Anz., XIII. Jahrg., Nos. 335, 338, 339. pp.

201-263. 347-349, 372-377.

'90a. Notiz liber pelagische Thiere aus einem Teiche in Galizien.

Zool. Anz., XIIL 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 Samuieln und

Beobachten der den Krainer Tropfstein-Grotten eigenen Arthro-

poden. Berl. Entomol. Zeitschr., Bd. XXVI., Heft 1, pp. 1-50.



XortJi American Frcsh-zvatcr Cyclopidce. 73

Jurine, L.

'20. Ilistoiie ties Jlonocles (lui se trouvent aiix environs ile Geneve,

pp. I-XVI. + 1-258. Pis. I.-XXI I. Geneve et Paris.

Kafka, Josef.

'92. Untersuchuncjen iiber die Fauna der Gewiisser BtUnnens. 11.

Die Fauna der Bfihmischen Teiche. Artiiiv d. Naturwissensch.

Landesdurchf. von Br)iunen, VIII. Bd.. No. II.

Kerville, H. G. de.

'88. I.es Crustaces de la Norniandie: Especes fluviales, staj^nales et

terrestres. Bull, de la See. des Amis des Sei. nat. de Kouen, 1888,

l'*- 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,

lief r. XXI.. XXV. Kegensburg.

Kochs, W.
'92. Versuche liber die kiinstliche Vermehrung kleiner Crustaceen.

Biol. Centralbl., Bd. 12. X'r. 18 u. 19, pp. 599-606; Translation in

Bull. U. S. Fish Conim.. Vol XIV., pp. 306-308.

Ladenburger, B.

'84. Zur Fauna des Mansfelder Sees. Zool. Anz., VII. Jahrg., No.

168, pp. 299-302.

Lande, A
'92. Quelques Remarques sur les Cjclopides. Mem. de la Soc. zool.

de France, T. V., pp. 1.56-173.

Lauterborn, R.
'94. Uber die "Winterfauna einiger Gewiisser der Oberrlieinebene.

Mit Besohreibung'en neuer Protozoen. Biol. Centralbl., Bd. XIV.,

Xr. 11., pp. 390-398.

Lilljeborg, W.
'53. DeCrustaceisexordinibustribus: Cladooera, Ostraeoda.etCope-

poda. in Scania occurrentibus. Pp. I.-XV. -\- 1-122, Pis. I.-XXVI.

Loven, S.

'61. Om nagra i Vettern och Venern funua Crustaceer. Ofv. Kongl.

Vet.-Akad. FGrbaudl., Arg. XVIII., No. 7, pp. 285-314.

Lubbock, J.

'63. Notes on some Xew or Little-known Species of Fresh-water

Entomostraca. Trans. Linn. Soc.. London, Vol. XXIV., pp. 197-210

PI. XXXL



74 Illmois 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 tlie 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. 189-224, Pis.

IIl.-VI.

'93a. Notes on the Copepoda of Wisconsin. Science, Vol. XXIL,
No. 544. pp. 3, 4.

'95. On the Cyclopidaj and CalanidcB 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 Tanatomie,

la physiologic, et la classification de ces animaux. Tome I., II.,

III. 42 Pis. Paris.

Moniez, R.

'87. Liste des Copgpodes, Ostracodes, Cladoceres, et de quelques

autres Crustaces recueillis ti 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

jeuues 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,

V" Ann., pp. 175-179.

'89b. Sur quelques Cladoceres et sur un Ostracode nouveaux du

Lac Titicaca. Kev. Biol, du nord de la France, V^ Ann., p. 421.

Mrazek, A. ^

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

Nauk., pp. 389-393, PI. XII.

'93 Pfispevky k poznnjii Sladkovodnich Copepodu. Vestnik Kr^l.

Ceske Spol. Nauk. Tfida math.-prir., 1893. 74 pp., Pis. VI.-VIII.

'93a. tJber abnorme Vermehrung der Sinneskolben an dera Vorder-

fiihler des Weibchens bei Cyclopiden und die morphologische

Bedeutung derselben. Zool. Anz., XVI. Jahrg., No. 417, pp. 133-138.

'93b. ilber die Systematik der Cyclopiden und die Segmentation

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

425, pp. 293-299.

'93c. Zur Morphologic der Antenna der Cyclopiden. Zool. Anz.,

XVI. Jahrg., No. 430, pp. 376-385.



Xorth Avierican Frcs/i-nurtcr CyclopidcB. 75

'95. Copepodeu. Deutscli-Ost-Afiica Wiss. Forschungsresultate,

etc., Band IV., Die Thierwelt Ost-Afrikas. 11 pp., 3 Pis.

Miiller, 0. F.

1792. Eutomostraca sen Insecta tesiacea quae in aquis Daniae et

Xorvegiae reperit, descripsit et iconibus illustravit. 134 pp., 21

Pis. Havniae.

Nordqvist, O.

'86. Bidrag till Kiinnedomen 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 Kiinnedomen om Bottniska vikens och norra

Ostersjous evertebratfauna. Meddel. af Soc. pro Fauna et Flora

Fenn., 17 Haft., pp. 83-128.

Nusbaum, J.

'92. Zur Kenntnis der Wiirmerfauna und Crustaceenfauna Polens.

Biol. Centralbl., Bd. XII., Xr. 2, pp. 54-58.

Pavesi, P.

'79. Nuova serie dl ricerche della fauna pelagica nei laghi italiani.

Kend. del R. Inst. Lombardo, Ser. II., Vol. XII., faso. XI., XII.

10 pp.

'79a. Ulterior! studj sulla fauna pelagica del laghi 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.

dl 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.

Xaturwissensch., 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 Maus-
felder Sees'' in No. 168 des Zoologischen Anzeigers. Zool. Anz.,

VII. Jahrg., No. 175, pp. 499, 500.

'89. Xotizen zur Fauna "der Siisswasser-Becken des nordwestlichen

Deutschland mit besonderer Beriicksichtigung der Crustaceen.

Abh. d. Xaturw. Ver. zu Bremen, Bd. X., pp. 517-550, Taf. VIII.



76 Illinois State Laboratory of Natural History.

'89a. Berichtigung zn Dr. O. E. Imhot's Aufsatz: "Fauna cler Sliss-

wasserbecken " in No. 275 des Zool. Anz. 1888, p. 166. Zool. Anz,,

XII. Jahrg., Xo. 300, pp. 99, 100.

'91. Beitriio-e zur Fauna der Insel Spiekerooge. Abh. d. Naturw.

Yer. zu Bremen, Bd. XII. 6 pp.

Poppe, S. A., u. Mrazek, A.

'95. Entomostraken des Naturhistorischen Museums in Hamburg.
Jabrb. der Hamburgiscben Wiss. Anstalten, XII., Beiheft. 20 pp.,

4 Pis.

Poppe, S. A., at Richard, J.

'90. Note sur divers Entomostraces du Japon et de la Cbine.

Bull, de la 8oc. zool. de France, T. XV., pp. 73-78.

Rath, O. V.

'91. Zur Kenutniss der Hautsinnesorgane der Crnstaceen. 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. Jabrg., No. 58, pp. 301-303.

'80a. Beitrag zur Kenntniss der freilebenden Siisswasser-Copepoden.

Abh. d. Naturw. Ver. zu Bremen, Bd. VI., pp. 533-554, Taf. VI.

'80b. Weitere Bemerkung liber die freilebenden Siisswasser-Copep-

oden. Abh. d. Naturw. Ver. zu Bremeh, 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. Cladoceres et Copepodes non marins de la Faune fran9aise.

Rev. Sci. du Bourbonnais, mars-avril, 1838, pp. 1-28

'90. Sur les Entomostraces et quelques autres animaux inferieurs

des lacs de I'Auvergne. Eev. des Sci. Nat. Appliquees, No. 10, 20

mai, 1890.

'90a. Sur la glande du test des Copepodes d'eau douce. Note pr6-

liminaire. Bull, de la Soc. zool. de France, T. XV., pp. 113-118.

'90b. Description du Bradya Edwardsi, Copepode,aveug]e nouveau,

vivant au 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 (Morbiban).

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 Sumati-a et de Celebes. Zool.

Ergeb.einerEeiseinNiederland. Ost-Ind., Bd. II., pp. 118-134, PI. X.



Xorth American FrcsJi-icatcr Cyclopidce. 11

'91b. Keeherches sur le SystCnie ^landuhux-e efc siir le Cysteine

uerveux des Copcpodes libi'es d'eaii douce. Ann. Sci. Nat., Zool.,

T. XVI., pp. 113-270, Pis. V.-VIII.

'92. Sur quelques Entoinostraces de Tile d'Elbe et de I'ile de Moiite-

Cristo. Bull, de la Soo. zool. de France, T. XVII., pp. 22G-229.

'93. Copepodes recueillis par M. le Dr. Thcod. Barrois en Ej^ypte,

en Sj'rie, et en Palestine. Rev. Biol, du nord de la France, 5^ ann.,

Xo. 10, juillet, 1893. 36 pp., 51 Fig.

'94*. Sur quelques anirnaux infurieurs des eaux douces du Tonkin
( Protozoaires, Rotiferes, Entomostract-s). Mem. de la Soo. zool. de

France. T. VII., pp. 237-243.

'94a. Entomostraccs recueillis par M. E. Modii;liani dans le Lac

Toba (Sumatra). Ann. del Mus. Civ. di Storia Naturale di Genova,

Serie 2. a, XIV. (XXXIV.), pp. 565-578.

'95. Sur quelques Entomostraccs d'eau douce d'llaiti. Mom. de la

Soc. zool. de France, T. VIII. 11 pp. 11 figs.

'95a. Cladoceres et Copepodes recueillis par M. Kavraisky pre? de

Tirtis et dans le I^ac Goktsha. Bull, de la Soc. zool. de France, T.

XX.. pp. 91, 92.

'95b. Contribution a la Faune des Entomostraccs de la France.

Feuille des jeuiies Xaturalistes, III. Serie, 25e Ann., Xos. 295 et

296. 9 pp.

Riickert, J.

'95. Zur Befruchtung von Cycloj'ts stremius (Fisch.). Anat. Anz., X.

Bd., No. 22, pp. 708-725; Abstract, Zool. Centralbl., II. Jahrg., pp.

555. 556.

'95a. Uber das Selbstiindigbleiben der viiterJiehen und miitter-

licbeu Kernsubstanz wiihrend der ersten Entwicklung des befruch-

teten Cyclops-Eies. Arch. f. Mikr. Anat., Vol. 45, pp. 339-369. Taf.

XXI., XXII.; Abstract, Zool. Centralbl., II. Jahrg., pp. 554, 555.

Sars, G. O.

'62. Oversigt af de indenlandske Ferskvandscopepoder. Forhandl.

Vidensk.-Selsk. i Christiania, 1862, pp. 212-262.

'63. Beretning om en i Sommeren 1862 foretagen zoologisk Reise i

Christianias og Trondhjems Stifter. Nyt Mag. f. Naturvidensk.,

Bd. XII., pp. 193-252.

'64. Beretning om en i Sommei-en 1863 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 Pis. Kristiania.



78 Illijiois State Laboratory of Natural 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 Einflnsses der iiusseren Lebensbedino;ungen

auf die Organisation der Thiere. Zeitschr. f. wiss. Zool., Bd.

XXIX., pp. 429-501.

Schmeil, O.

'91. Beitriige zur Kenntniss der Siisswasser-Copepoden De'utsch-

lands mit besonderer Berlicksichtigung der Cs'clopiden. Zeitschr.

f. Xaturwiss. Halle, Bd. 64, pp. 1-40.

'92. Deutsehlands freilebende Siisswasser-Copepoden. I. Teil, Bib-

liotheca Zoologica, Heft II. 191 pp., 8 Pis.

'94. Zur Hohlenfauna des Karstes. Zeitschr. f. Naturwiss. Halle,

Bd. 66, pp. 339-353.

Scott, T.

'94. On the food of Utricularia vulgaris, an Insectivorous Plant.

Ann. Scot. Nat. Hist., Xo. 10, pp. 105-112.

Scourfield, D. J.

'93. The Entomostraca of Wanstead Park. Journ. Quekett Micr.

Club, Ser. II., Vol. V., No. 32, pp. 161-178.

'94. Entomostraca and the Surface-film of Water. Journ. Linn. Soc.

Vol. XXV., pp. 1-19, Pis. I., II.

'95. A Preliminary Account of the Entomostraca of North Wales,

Journ. Quekett Micr. Club, Vol. VI., Ser. II., No. 37, pp. 127-143.

Seligo, A.

'90. Hydrobiologische Untersuchungen. I. Zur Kenntniss der Lebens-

verhiiltnisse in einigen westpreussischea Seen. Schrift. d. naturf,

Gesellsch. zu Danzig, Bd. VII., N. F,, Heft 3, pp, 43-89.

Sowinsky, W.
'91. Materiaux pour servir a Tetude des Crustaces d'eaux douces

dans la partieoccidentale de la Kussie. Mem. de la Soc. des natural.

de Kiew, T. XL, Part I., pp. 107-161, (French title of Kussiah

article.)

Timm, R.
'94. Beitriige zur Meeresfauna von Helgoland. III. Die Copepoden

und Cladoceren Helgolands. Wiss. Meeresuntersuch. herausg.

V. d. Komm. z. Untersuchung der deutscheu Meere in Kiel und der

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'94a. Beitriige zur Fauna der siidostlichen und ostlichen Nordsee.

IV. Copepoden und Cladoceren. Wiss. Meeresuntersuch. herausg.

V. d. Komm. z. LTntersuchung der deutschen Meere in Kiel und der

Biol,, Anstalt a. Helgoland, N. F., I. Bd., pp. 363-402, Pis. V., VL



Xorth Aincrican Frcsh-i<'atcr Cyclopidce. 79

Turner, C. H.
'92. Notes upon the Cladocera. ( "opepoda, Ostracoda. and Rotifera

of Cincinnati, with Descriptions of Xew Species. Bull. S(;i. Lah.

Denison Univ., Vol. VI., Part 11., pp. 57-74, Pis. 1, 2.

Ulianin, W. N.
'75. Crustaceen von Turkestan. Keise A. P. Fedtschenkos in

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zu Moskau, Bd. XL. Abth. VI., pp. 1-61, Taf. I-XIII. (German

title of Russian article.)

Underwood, L. M.
'86. List of the Described Species of Fresh-AVater Crustacea from

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pp. 323-3S4.

Urbanowicz, F.

'84. Zur Entwicklungsgeschichte der Cyclopiden. Zool. Anz., VII.

Jahrg., Xo. ISl, pp. 615-619.

Vernet, H.
'71. Observations anatomiques et phj'siolooiques sur le genre

Cyclops. 47 pp., 1 PI. Geneve.

Villipoix, R. M. de
'88. Contribution a I'etude de la laune des eaux douces de la vallce

de la Somme. (Copopodes et Cladoceres.) Bull. Soc. linn, du nord

de la France, Xr. 193-195. 23 pp.

Voeltzkow, A.

'91. Vorliiufiger Bericht iiber die Ergebnisse einer Untersuchung

der Siisswasserfauna Madagascars. Zool. Anz., XIV. Jahrg., Xo.
3i;7, pp. 221-230.

Vosseler, J.

'86. Die freilebenden Copepoden Wiirtembergs uud angrenzender

Gegenden. Jahresh. des Ver. fiir vaterl. Xaturkunde in VViirtt.,

1886, pp. 167-202, Taf. IV.-VI.

'89. Die Copepodenfauna der Eifelmaare, [including (p. 123)],''Uber

einen Cyclops mit verkriippelter Furka.'" Arcliiv fiir Xaturgesch.,

LV. Jahrg., Bd. 1, pp. 117-124, Taf. VI.

'91. Die Krebsfauua unserer Gewiisser. In Zacharias's "Die Tier- u.

Prtanzenvvelt des Siisswassers,'' Bd. I., pp. 325-380. Leipzig.

Walter, A.

'88. Transkaspische Binuencrustaceen. Zool. .Jahrbiicher. Abth. f.

Syst., Bd. III., pp. 987-1014, Taf. XXXV.
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'82. Materyaly do fanny jezior tatrzanskich. Copepoda. Sprawozd.

Kora. fiz. Akad. umiej. T. XVI. 25 pp.. 2 Pis.



80 Illinois State Laboratory of Natural History.

'92. Skorupiaki i Wrotki (llotatoria) slotlkowodiie zebrane w
Argeutynie. llozpr. Wjxlz. mat.-prz5'r. Akad. I miej. w Krakowie,

T. XXIV., pp. 229-246, Pis. V.-VII.

'95. Przeglgd fauny skorupiakow galicj'jskicli. Sprawozd.Kom. fiz.

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(German translation), Ubersicht der Crnstaeeen-Fauna Galiziens.

Anz. d. Akad. d. Wiss. Krakau, Juni, 1895, pp. 170-178.

Zacharias, O.

'85. Ergebnisse einer zoologischen Exkursion in das Glatzer-.Tser-,

und Iliesen-gebirge. Zeitschr. f. wiss. ZooL. Bd. 4.3, pp. 252-270.

'87. Zur Kenntnis der pelagischea und littoralen Fauna nord-

deutscher Seen. Zeitschr. f. wiss. Zool., Bd. XLV., pp. 255-281,

Taf. I.

'87a. Zur Kenntnis der Entomostrakenfauna holsteinischer und

mecklenburgisclier Seen. Zool. Anz., X. Jahrg., Xo. 248. pp. 189-193.

'87b. Faunistische Studien in westpreussichen Seen. Schrift. der

naturf. Gesellsch. zu Danzig, X. F., Bd. 6, Heft 4, pp. 43-71, Taf. I.

'88. Zur Kenntnis der Fauna des Siissen und Salzigen Sees bei

Halle a/S. Zeitschr. f. wiss. Zool., Bd. XLVI., pp. 217-232.

'88a. Zur Fauna einiger norddeutscher Seen. Biol. Centralbl., Bd.

VIII., No.l7, pp. 540, 541.

'89. Bericht iiber eine Zoologische Exkursion an die Kraterseen der

Eifel. Biol. Centralbl., Bd. IX., Xos. 2, 3, 4, pp. 56-64, 76-80. 107-113.

'93. Fauna des grossen Pioner Sees. Biol. Centralbl., Bd. XIII., Xr.

11 u. 12 pp. 377-484.

'94. Uber die Verteilung der Planktonorganismen innerhalb eiues

Sees. Biol. Centralbl., Bd. XIV., Xr. 3, pp. 122-128.

'95. Uber die vertikale Verteilung limnetischer Crustaceen, insbe-

sondere iiber diejenige von Cyclops oitlionoides . Biol. Centralbl.,

' Bd. XV., Xr. 18, pp. 680-688.

Zaddach, E. G.

'44. Synopseos Crustaceorum Prussicorum Prodromus. pp. I.-VIII.

-\- 1-33. Kegiomontl (Konigsberg).

Zenker, W.
'54. Uber die Cyclopiden des siissen Wassers. Archiv fiir Xatur-

gesch., XX. Jahrg., Bd. 1, pp. 88-103, Taf. VI., Fig. 8-14.

Zschokke, F.

'90. Faunistische Studien an Gebirgsseen. Verb. d. Xaturf. Gesellsch.

in Basel, Bd. IX. 62 pp.

'90a. Beitrag zur Kenntnis der Fauna der Gebirgsseen. Zool.

Anz . XT II. Jahrg., Xo. 326. pp. 37-10.



North American FrcsJi-watcr CyclopidcB. 81

'91. Weiterer Beitra^ zur Kenntiiis der Fauna von Gebirgsseen.

Zool. Auz., XIV. Jahrg., Xos. 360 u. 361, pp. 119-123 u. 126-129.

'94. Die Tierwelt der Juraseen. Rev. Suisse de Zool., T. II., pp.

349-376, PI. XIV.

'95. Die Fauna hochgelegeuer Gel)ir2,sseen. Verhandlung der

Naturf. Gesellsch. in Basel, Bd. XI., Heft I., pp. 30-133, Taf. I.

EXPLANATION OF PLATES.

Plate YIIL

Fig. 1. Cyclops h'Xirkarti Clans.

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

Fig. 3. Fifth foot of same.

Plate IX.

Fig. 1. Cyclops edax Forbes.

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

Fig. 3. Fifth foot of same.

Plate X.

Fig. 1. Cyclops viridis Jurine.

Fig. 2. Fifth foot of same.

Fig. 3. Receptaculum seminis of same.

Plate XL
Fi(i. 1. Variations in outer terminal spine of stylet of Cyclops viridis

var. hrevispinosus Herrick.

Fi(i. 2. Fifth foot of same.

Fig. 3. Receptaculum seminis of Cyclops viridis var. insectus Forbes.

Fig. 4 and 5. Fifth foot of same.

Fig. 6. Swimming foot of same.

Plate XII.

Fig. 1. Cyclops bicuspidatus Claus.

Fig. 2. Stylet of same.

Fig. 3. Fifth foot of same.

Fig. 4. Receptaculum seminis of same.

Plate XIII.

Cyclops alhidus Jurine.

Cyclops ater Herrick.

Plate XIV.



82 Illinois State Laboratory of Natural History.

Plate XV.

Fig. 1. Last two segments of antenna of CycJnps ater Herrick.

Fig. 2. Fifth foot of same.

Fig. 3. Receptaculum seminis of same.

Fig. 4. Cyclops modestus Herrick.

Plate XVI.

Fig. 1. Antenna of Cyclops modestus Herrick.

Fig. 2. Fifth foot of same.

Fig. 3. Receptaculum seminis of same.

Plate XVIL

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 Yi&ch&T.

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.



ERRATA.

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

Page 34, line 6, for equal read subequal.

Page 44, line 8, for species read variety.

Pase 63, line 16, before America insert North.

Pase 66, 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 7« 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 VUlepaix, R. M. de.

Page SO, under Zacharias, O., for '85 read '86; and in entry for 'd7, for

Taf. r. readTaf. XV.

Page 81. line 5, for '95 read '94.



INDEX.

(Synonyms in Italics.)

Canthocamptus, 62.

Clac'ocera, 62.

Copepoda. 27.

Cyclopidfe. European, 29.

list of Xortli Americau species,

63.

Cyclops. 31.63.

affiuis, 29. 65.

agilis, 29.

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

americanus , 37. 38, 42.

annulatus. 33, 35.

ater, 29, 49. G2, 64.

bicolor. 29, 62. 63, 64.

bicuspidatus. 29, 30, 44, 53, 62,

63, 64.

bisetosus, 29.

brevispinosus. 39, 41.

capilliferus, 51.

cra.«sicaudis, 29.

dybowskii, 29, 62, 63.

edax. 33. 62, 63.

firabriatus, 29.

var. poppei, 63, 65.

fitmatilis, 57.

forbesi, 44, 45.

fuscus. 29, 64.

general distribution of, in

Nortb America. 62.

gigas, 29, 37.

gyrinus, 47, 48.

helgolandieus, 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.

lei-is. 37.

uiacrurus. 29.

Cj'olops

—

Clinthnied.

magnoctavus, hi.

minnihis, 44. 45.

raodestus, 29. 62, 63, 64.

nanus, 29.

navus, 44, 45.

oithonoides. 29. 63.

iiarcw.s, 38, 41,42.

penktgonus, 57.

pr-ramatus, 59. 60.

phaleratus, 29. 30, 59, 63. 65.

prasinus, 57, 63, 65.

pulcliellus, 29, 44.

robustus, 29.

scutifer, 29.

serratus, 44, 45.

serrulatus, 29, 30, 54, 62, 63, 65.

var. elegans, 54.

var. montanus, 54, 55.

signatus, 29.

var. te7niicornis, 47.

strenuu.s, 29.

thoinasi. 44, 45.

unhingulatus, 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. iusectus, 31, 41, 62,

63, 64.

Diaptonius, 62.

Eucyclops, 54, 65.

Homocyclops, 29, 49, 64.

Macrocyclops, 47, 64.

Microcyclops, 64.

Monoculus quadricornis var. alhid.us.,

47.

var. viridis. 37.

Orthocy clops, 29, 51, 64.

Paracyclops, 59. 65.



Plate YIII.

^nj



Plate IX.



Plate X.



Plate XL



Plate XII.



Plate XIII.



Plate XIY



Plate XY



Plate XVI.



Plate XYII.



Plate XVIII.



Plate XIX.



Plate XX.