QL 444 C73M36 1910 INVERT. SPECIES C. DWIGHT a : pee a [Usswed April, 1910.] A REVISION OF THE NORTH AMERICAN SPECIES OFVCVCLORS: C. DWIGHT MARSH. As collections are made more and more widely from all parts of the world and as these collections are studied more thoroughly, it becomes increasingly evident not only that the genus of Cyclops is distributed over the whole world, but that individual species have an exceedingly wide distribution. Many of the species which have been described as peculiar to America have been clearly shown either to be identical with species in Europe or merely varieties of those species. Little by little it has been necessary to reduce to synonyms the names which have been proposed for American species. It can not yet be said that all American species are identical with those in Europe, but it is very evident that most of them are. Most of the species of Cyclops have wide limits of variation, and it is these variations which, at a time when the knowledge of the entomostraca was imperfect, lead to the intro- duction of many new names for species which we now know are only varieties. This leads to a great deal of confusion when students of anatomy or plankton, who may have no particular interest in a systematic knowledge of, Entomostraca, attempt to name the species which they are studying. So great is this con- fusion that many students of plankton do not attempt to use specific names, but simply describe the distribution of “Cyclops.” This is extremely unfortunate, for the species of Cyclops have very different habits and a discussion of plank- 1068 Wisconsin Academy of Sciences, Arts, and Letters. ton with all the species of this genus grouped together has very little value so far as Entomostraca are concerned. It may be a matter of doubt whether the general student of Zoology is ever likely to determine the species of Copepoda easily, as special training is almost necessary for such work. But, even if one had patience and a willingness to do the necessary work, authoritative publications have not been available. Probably the majority of students of North American Entomostraca refer to Herrick and Turner’s work because it is more comprehensive than any other work published. This is now, however, pretty thoroughly out of date, and it is very aggravating to a student to feel that his book of reference is unreliable. A much more accurate paper is that of E. B. Forbes (Forbes °97) and it seems to me that the real value of this paper has never been recognized. It is now ten years since Forbes’s paper was published and additions have been made to our knowledge of the genus, and facts which lead to a reconsidera- tion of some of his statements. It has seemed to the author that the time has come when a paper which would accurately present our knowledge of the genus today, would be of real assistance to those students who have anything to do with Entomostraca. There is really very little to add that is new from the standpoint of the species maker, only one new species is suggested, but it is worth while to know what it is best to call the old species which have been recognized under different names. In preparing this paper we have accepted the work of Schmeil as authoritative for European species. Sometime it is to be hoped that equally thorough work can be done for our American species, but it does not seem wise to undertake it at present. Our knowledge of the distribution of species in America has been very much enriched in the past few years, but nothing like thorough work has been done. The present paper is based on collections made from the northern Canadian provinces to Mexico and the West Indies, and from the At- iantic to the Pacific, but vastly the most complete collections have been made in the Mississippi Valley. Marsh—North American Species of Cyclops. 1069 It will be noticed, doubtless, that the sub-generic names that have been adopted by some authors have not been recognized. The species of Cyclops certainly fall into certain groups, but it is the feeling of the author that our knowledge of the relation- ships of the species in these groups is not yet sufficiently wide to warrant the formality of fixed sub-generic names. I must con- fess to a dislike of multiplying names in systematic work, and do not enjoy sub-generic names under any circumstances, pre- ferring to avoid them when practicable. The number of species in the genus Cyclops is not very large, and the addition of sub- divisions in our present state of knowledge is distasteful to me. A considerable number of figures has been used to illustrate the paper, enough, it is hoped, to make clear the diagnoses. The synopsis is not published as a final production. No one appreciates better than the author how much work re- mains to be done on these forms. On the other hand the paper is the result of accumulations of material covering many years. A large number of slides have been made from these collections, and while the work is confessedly incomplete, it is perhaps due to others who are interested in these animals to make some of the results available for use. The systematic study of entomostraca is, at best, a very laborious process, and it is hoped that this brief paper may help in lightening the labors of others who may wish to use specific names for the Cyclopidae. The key is based on the characteristics of mature females and includes only those species which are recognized members of the American fauna. 6—S. & A.—3 1070 Wisconsin Academy of Sciences, Arts, and Letters. KEY TO SPECIES OF CYCLOPS FOUND IN NORTH AMERICA. Antennae composed of 17 segments Fifth foot composed of one segment, armed with one spine and two long setae,—a large species of dark color, ater Fifth foot composed of two segments, Second segment of fifth foot armed with seta and short spine viridis Second segment of fifth foot armed with two _ setae, The second segment of the fifth foot is elongate, its length as much as twice its width, the seta of the inner distal angle spine-like, less than one half the length of the outer seta, bicuspidatus The second segment of the fifth foot is shorter, length less than twice its width, armed with two nearly equal setae, The seventeenth antennal segment is armed with a serrate hyaline plate, Leuckarte The seventeenth antennal segment is not armed with a hyaline plate, tenuis The second segment of the fifth foot is armed with three setae The twelfth antennal segment has a sensory club, the ege-sacs stand out from the abdomen, the hyaline plate of the seventeenth antennal segment is ser- rate, or smooth, albidue The twelfth antennal segment has a sensory hair, the ege-sacs lie close to the abdomen, the hyaline plate of the seventeenth antennal segment is deeply notched, Suscus Antennae composed of sixteen segments, fifth foot of three seg- ments, modestus Antennae composed of twelve segments, fifth foot of one segment. Fifth foot armed with three setae, rami of swimming feet of three segments. Furca of variable length, armed externally with arow of spines, found almost everywhere. serrulatus Furca short, without spinous armature, a small limnetic species, : prasinus Fifth foot armed with one seta, rami of swimming feet of two segments, varicans Antennae composed of eleven segments, Rami of swimming feet composed of three segments, phaleratus Rami of swimming feet composed of two segments, bicolor Antennae composed of eight segments, fimbriatus Antennae composed of six segments, aequoreus Marsh—North American Species of Cyclops. 1071 CYCLOPS ATER HERRIcK. Plate, LXXII. figs. 1 to 6 and 9. 1882. Cyclops ater Herrick, p. 228, pl. III, figs. 9-12. 1884. i p- 145, pl. Q, figs. 9-12. 1887. oS SF ae jos | 14 1895. = “Herrick and Turner, p. 89, pl. VI, figs. 11-12. 1895. i ** Marsh, p. 13, pl. VI, figs. 1-4 and 6-12. 1897. ‘ ** Forbes, p. 49, pl. XIV, pl. XV, figs 1-3. 1909. ss Hi By rNess pos ple tres: all too! A large species, conspicuous both on account of its size and its brilliant colors. The cephalothorax is oval and very broad. The length and breadth of the first segment are about equal, and this segment comprises more than two-thirds the entire iength of the cephalothorax. The cephalothorax is nearly three times the length of the abdomen, exclusive of the fureal rami. The first abdominal segment is short and stout and very lit- tle enlarged at its anterior end. The succeeding segments are nearly equal in length, each being about one-third the length ef the first segment. The posterior margin of the last seg- ment is armed with small spines. The fureal rami are about twice as long as wide. Herrick has a figure in which the furcal rami are ciliated on the inner margin. I do not find the cilia in my specimens, and Forbes (Forbes 797) states that they are not ciliate. The lateral spine is situated near the end. Of the terminal setae, the outer is slightly shorter than the inner, the second is about twice as long as the outer, and the third about three times as long. The first antennae are 17-segmented and reach nearly the full length of the cephalothorax. The twelfth segment has. a sensory club, and the sixteenth and seventeenth segments have a lateral hyaline Jamella with an entire edge. This jamella, in the seventeenth segment projects as a blunt process beyond the end of the segment. The spinous armature on the terminal segments of the 1072 Wisconsin Academy of Sciences, Arts, and Letters. exopodites of the swimming feet is represented by the formula 3, 4, 4, 3. The fifth foot is composed of one segment and is armed with a stout serrate spine and two long setae. The form of the receptaculum semis is shown in plate LXXII, fig. 5. Average length of the female 1.77 mm. This is the size of my specimens. Herrick gives 2.1 mm. as the average length and Forbes 1.77 mm. to 2.88 mm. The deep blue of the ordinary coloration is very marked. This color is most pronounced in the appendages and caudal setae and in the posterior margins of the segments of the cephalothorax. Sometimes the cephalothorax is of a deep red or brown. Herrick’s description was written from specimens collected in Mud lake, Hennepin Co., Minn. He afterwards stated that it was found from Alabama to Minnesota, and more abund- antly towards the south. MReighard collected it in Lake St. Clair. I have obtained it from Round lake, Twenty-sixth lake, Intermediate lake and Susan lake in Michigan, and from Rush lake, Catfish lake, and Lake Winnebago in Wisconsin. Forbes reports it from the shallow lakes near Havana, Il]. These are the only recorded localities. It appears to be a rather rare form. me CYCLOPS VIRIDIS Jurrne. Plate LXXII, figs.7 and 8. Plate LXXIV, figs. 1 and 2. Plate LXXIX, figs. 6 and 7. 1820. Monoculus quadricornis var. viridis Jurine, p. 46, pl. II, fig. 1. 1851. Cyclops viridis Fischer, p. 412, pl. IX, figs. 1-11. 1857a. a brevicornis Claus, p. 32, pl. III, figs. 12-17. 1857b. = gigas Claus, p. 207, pl. XI, figs. 1-5. 1863. ne brevicornis Claus, p. 99, pl. IV, fig. 11. 1863. 7 gigas Claus, p. 100. 1863. x brevicornis Lubbock, p. 200. 1870. ue os Heller, p. 71. 1870. - Clausti Heller, p. 73, pl. I, figs. 1 and 2. 1872. Hy Clausti Fric, p. 220, fig. 13. 1872. et gigas Fric, p. 220, fig. 14. 1875. i viridis, Uljanin, p. 30, pl. VII, figs. 3-9. 1876a. os brevicornis Hoek, p. 13, pl. I, figs. 5 and 6. Ee ee 1878. 1880. 1880. 1882. 1882. 1882. 1883. 1883. 1884. 1884. 1884. 1884. 1884, 1885. 1886. 1888. 1890. 1990. 1891. 1891. 1891. 1892. 1893. 1893. 1893. 1895. 1895. 1895. 1895. 1895. 1895. 1895. 1895. 1897. 1897. 1897. 1897. 1897. 1898. 1898. 1901. 1901. 1903. 1903. 1903. 1905. 1905. Marsh—North American Species of Cyclops. 1073 esclope gigas Brady, p. 105, pl, XX, figs. 1-16. viridis Rehberg, p. 540. gigas Rehberg, p. 541. ingens Herrick, p. 228, pl. LV, figs. 1-8. parcus Herrick, p. 229, pl. VI, figs. 12-15. insectus Forbes, p. 649, pl. IX, fig 6. viridis Cragin, p. 3, pl. LV, figs. 8-16. uniangulatus Cragin, p. 6, pl. IV, fig. 17. viridis Herrick, p. 145. parcus Herrick, p. 148, pl. R, fig. 22. orevispinosus Herrick, p. 148, pl. S, figs. 7-11. uniangulatus Herrick, p. 149. insectus Herrick, p. 152, pl. U, fig. 9. viridis Daday, p. 214. “ _-Vosseler, p. 196, pl. IV, figs. 11-14. “ - Sostignnie; jo: Gis jol, Ih tie. 7 peeeluinenliwatzs pani: *“ Lande, p. 44, pl. XIX, figs.117-124, pl. XX, fig. 125. “* Schmeil, p. 29. Richard, p. 226, pl. VI, fig. 4. WBirachy, jo. Wes jolla WG tes, O10 * Schmeil, p. 97, pl. VII, figs. 12-14. americanus Marsh, p. 202, pl. LV, figs. 8-10. brevispinosus Marsh, p. 204, pl. LV, figs. 11 and 12. parcus Marsh, p. 208, pl. IV, fig. 16, pl. V, fig. 1. etridis Herrick and Turner, p. 90, pl. XIV. americanus Herrick and Turner, p. 91, pl. XIV. ingens Herrick and Turner, p. 92. parcus Herrick and Turner, p. 93, pl. XX, figs. 12-15, pl. XXI, fig. 22, pl. XXIII, fig. 8, pl. XXXIV, figs. 1-8. brevispinosus Herrick and Turner, p. 95, pl. XXIII, figs. 124) pl. XXDVE figs! 7El2: uniangulatus Herrick and Turner, p. 96. brevispinosus Marsh, p. 14, pl. VII, fig. 12. parcus Marsh, p. 15. viridis Forbes, p. 37, pl. X, figs. 1-3. “var. brevispinosus Forbes, p. 41, pl. XI, figs. 1 and 2. var. insectus Forbes, p. 41, pl. XI, figs. 3-6. Steuer, p. 6. ‘<’ Matile, p. 128, pl. II, figs. 15 and 16. ‘* Scourfield, p. 324 americanus Brewer, p. 182. gigas Lilljeborg, p. 5, pl. I, figs. 1-5. eiridis Lilljeborg, p. 8, pl. I, figs. 6-11. * Graeter, p. 523, pl: 15: fig. 6: Scourfield, p. 534 parcus Byrnes, p. 152. «« Jensen, p. 118. var. imsectus Pearse, p. 150. “e oe 1074 Wisconsin Academy of Sciences, Arts, and Letters. 1909. Cy. wei americanus Byrnes, p. 13, pl. V, figs. 1-3. 1909. parcus Byrnes, p. 14, pl. VI, figs. 1-8, pl, X, figs. 1-3. 1909. fs brevispinosus Byrnes, p. 16, pl. VII, figs. 1-9. 1909. dy ingens Byrnes, p. 22, pl. VIII, figs. 1-4. Cephalothorax oval, its breadth rather more than one- half its length. The cephalothorax is about twice as long as the abdomen exclusive of the fureal rami. Each cephalo- thoracic segment projects beyond the one following it. The anterior part of the first abdominal segment is larger than the posterior, but this difference is not so marked as in some other species. The posterior margins of all the ab- dominal segments except the last are serrate,—the last seg- ment is armed with small spines; this armature of the ab- dominal segments is more marked in the immature forms, The furcal rami are very variable in length. They may be scarcely longer than the last abdominal segment or they may be four times as long. In some varieties the rami are ciliate on the inner margins. The lateral seta of the furca is com- monly well towards the distal end, varying in position from two-thirds to four-fifths the length of the ramus. Of the terminal armature of the furca, the outermost is very variable; it may be a slender plumose seta, or it may be a short, blunt spine. It is never, however, very much elongated. The first antennae are 17-segmented and reach to ora lit tle beyond the posterior margin of the first cephalothoracic segment. The twelfth segment has a club-shaped sense hair. The spinous armament of the terminal segments of the exopodites of the swimming feet may be 2, 3, 3, 3, or 3, 4, 4, 4. The terminal segment of the endopodite of the fourth foot may have exteriorly either a seta or a spine. The fifth foot, Plate LX XTI, figs. 7 and 8 consists of two seg- ments. The first segment is broad, its breadth ordinarily equalling or exceeding its length; on its inner distal segment it bears a long plumose seta. The second segment is of about the same length as the first segment, while its width is one- half or less than that of the first segment; on its distal end near the outer margin is a long plumose seta, at the inner 0 ne Oe ee ee ee ae! Marsh—North American Species of Cyclops. 1075 angle on the distal end is a small, lanceolate spine; in some varieties this spine is separated from the segment by a joint, while in others, this joint does not appear. The form of the receptaculum seminis is shown in the figure, Plate LX XIV, fig. 2. It varies greatly in size. The common American varieties are 1.25 to 1.5 in length. It may reach, however, as much as 3° mm. Cyclops viridis seems to be universally distributed in the northern hemisphere. Cyclops viridis var. ingens, Herrick. This variety, which is also mentioned by E. B. Forbes, is distinguished by three features, first its greater size, sec- ond by the fact that the spine of the second segment of the fifth foot is not separated from the segment by a joint, and third by the ciliated internal margins of the furca. It cor- responds, doubtless to the gigas of Claus. Inasmuch, how- ever, as so good an authority as Schmeil considers that gigas differs from typical viridis only in size, it seems to me wise to retain Herrick’s name for the American variety. Ingens occurs in pools. Cyclops viridis var. brevispinosus Herrick. Brevispinosus is rather elongate in form, the fureal rami are long and slender, and the terminal appendage at the outer angles of the furcal rami is a short thick spine, Plate LX XIX, fig. 7, shaped much like the blade of a knife. The formula for the spines of the terminal segments of the exopodites of the swimming feet is 3, 4, 4, 4. The terminal segment of the endopodite of the fourth foot has a spine on its outer margin. Brevispinosus is most common in larger bodies of water where it frequently has a limnetic habitat. It is by no means confined to large bodies of water, however, as it is found in many of the smaller lakes of Wisconsin and Michi- gan. ) 1076 Wisconsin Academy of Sciences, Arts, and Letters. Cyclops viridis var. parcus Herrick. Parcus has the second segment of the fifth foot with the spine separated by a joint. The formula for the spines of the terminal segments of the exopodites of the swimming feet is 2, 3, 3, 8, the terminal segment of the endopodite of the fourth foot is armed with a seta. The outer terminal appendage of the furea is a short seta. Parcus is most common in shallow bodies of water. It does not appear to have a very wide distribution. Cyclops viridis var. americanus Marsh. Americanus has the fureal rami of varying length, the outer terminal appendage a short seta. (Plate LX XIX, fig. 6.) The spine of the second segment of the fifth foot is sep- arated by a joint. The terminal segments of the exopodites of the swimming feet have as the formula of the spines. . 3, 4, 4, 4. The terminal segment of the endopodite of the fourth foot has externally a seta. Americanus is the most abundant variety of viridis in American waters, being found almost universally especially in the smaller bodies of water. This is the form which E. B. Forbes calls imsectus, reviving the name proposed by 8, A. Forbes, but never so described as to make it possible to identify the form. It is evident that in this case americanus has the rights of priority, as it was possible to recognize m- sectus only after the publication by E. B. Forbes in 1897, and he recognizes the identity of the two forms. Discussion of viridis. The first to recognize clearly the identity of the forms which are here grouped under the common specific name of viridis was E. B. Forbes, and the synonomy which I have adopted does not differ materially from that proposed by him. I agree with him that all the varieties distinguished above merge the one into the other with no clear cut dividing line. This is my impression from the study of my somewhat ex- tensive collections from nearly all sections of North America. Marsh—North American Species of Cyclops. 1077 The work of Miss Lehmann (Lehmann ’03) proved this in regard to the distinctions between brevispinosus and amert- canus. And yet I am inclined to put much more stress than does Forbes on the varietal distinctions. While we can find connecting forms, if we look for them, yet it is true that col- lections from any locality are apt to contain only one variety in abundance. It is true that one can find the blunt furcal spine of brevispinosus merging by insensible stages into a seta, but it is also true that we can make collections in which practically all the individuals have the blunt spine. These same individuals will have, correlated with the blunt spine, elongated fureal rami, a formula for the spines of the terminal segments of the exopodites of the swimming feet represented by 3, 4, 4, 4, and a spine on the external margin of the terminal segment of the endopodite of the fourth swimming feet. One may find brevispinosus forms with a seta on the ex- ternal margin of the terminal segment of the endopodite of the fourth swimming foot, but this is by no means common, So when one finds parcus forms he is not likely to find other forms mingled with it. So with the americanus. There are grades connecting this with the other varieties, but in any given col- lection where americanus is found, nearly all will be typical americanus. It is true that the armature of the swimming feet may vary, but variation is not so common, in my experience, as would be inferred from the statements of Forbes. I have even found a form in which the right and left fourth feet in the same individual had a different spinous armature, but this is so unusual, that it may be considered, in all probability, as the result of some mutilation. I have sometimes thought that we might well consider these varieties as distinct species, and that the intermediate forms were the result of hybridizing. Whether this is true or not could only be determined by a course of breeding, and it is likely to be a long time before we shall know the pedigrees of the species of Cyclops. Meantime students who must discuss these forms as elements in the plankton, and who, perhaps, have no interest in the taxonomic side of the question, must \ 1078 Wisconsin Academy of Sciences, Arts, and Letters. have some means of designating the forms, and it makes little difference to them whether they are called species or varieties. This is my excuse for proposing the use of these varietal names. The European type of viridis does not have the spine of the second segment of the fifth foot separated by a joint, has for the spine formula of the terminal segment of the exopodite of the swimming feet 2, 3, 3, 3, and has the internal margin of the fureal rami ciliate. There are, among the European forms, however, all the variations noted in the American forms. The typical form is vastly the more common in Europe, while in America americanus is the most widely dis- tributed variety, ingens and parcus being comparatively rare. CYCLOPS BICUSPIDATUS Cuaus. Plate LXXIII, figs. 1-11; Plate LX XIX, fig. 11. 1857a. Cyclops bicuspidatus Claus, p. 209, pl. XI, figs. 6 and 7. 1863. oe 4 name ery) ope) C0) 1863. pulchellus Sars, p. 246. 1870. ae bicuspidatus Heller, p. 71. 1872. 4 aR Fric, p. 221, fig. 16. 1875. Be odessanus Schmankewitsch. 13 //G ane bicuspidatus Hoek, p. 17, pl. I, figs. ‘7-11. 1880. te pulchellus Rehberg, p. 548. Ikstel OH 92k helgolandicus Rehberg, p. 64, pl. IV, fig. 5. 1882. re pulchellus Vejdowsky, p. 638, pl. VII, figs. 11 and 12. 1882. Thomasi Forbes, p. 649, pl. LX, figs. 10, 11 and 16. 1882. ai navus Herrick, p. 229, pl. V, figs. 6-13, 15-17. 1883. gigas G. M. Thompson, p. 96, pl. TX, figs. 8-10. 1883. oe pectinatus Herrick, p. 499. pl. VII, figs. 25 and 28. 1883. rf Thomasi Cragin, p. 3, pl. IL, figs. 1-13. 1884. is Pe Herrick, p. 151, pl. U, figs. 4, 5, '7 and 8. 1884. oe navus Herrick, p. 152. 1885. Vi pulchellus Daday, p. 220. 1885. gi Fntzti Daday, p. 221, pl. I, figs. 1-6. 1886. a pulchellus Vosseler, p. 194, pl. V, figs. 19-29. 1888. ;: ue Sostaric, p. 66, pl. I, figs. 8 and 9. 1890. 1 i Lande, p. 50, pl. XXI, figs. 146-155. 1890. s ee Thallwitz, p. 79. 1891. 3 Thomast Forbes, p. 707, pl. I, fig. 8. 1891. sty ‘* Brady, p: 14, pl. VI, figs, 1-4. 1891. ‘i bicuspidatus Schmeil, p. 27. 1891. 4 x Richard, p. 229, pl. VI, fig. 6. 1892. me af Schmeil, p. 75, pl. II, figs. 1-3. Cf | L\f . aa /. ¢ ~~ _) (S426 wecw Meant Le toe: PANY (prgw. [S— ’ Marsh—North American Species of Cyclops. 1079 1892. Cyclops pulchellus Lande, p. 161. 1898. a Marsh, p. 207, pl. IV, figs. 18 and 19. * 1893. i minnilus Forbes, p. 247. 1893. 2 serratus Forbes, p. 247. 1895. rig pulchellus Herrick and Turner, p. 101, pl. XXVII, figs. 4 and 5, pl. XXVIII, figs. 5-8. 1895. 0 pulchellus var. navus Herrick and Turner, p. 102. 1895. a minnilus Herrick and Turner, p. 103. 1895. fae Forbest Herrick and Turner, p. 104. 1895. oa pulchellus Marsh, p. 15, pl. VU, fig. 14. 1897. a bicuspidatus Forbes E. B., p. 44, pl. XII, figs. 1-4. 1897. SE bicuspidatus Steuer, p. 5, pl. III, fig. 1. 1898. i pulchellus Brewer, p. 133. 1898. ‘93 navus Brewer, p. 132. 1901. Ls bicuspidatus Lilljeborg, p. 11, pl. I, figs. 12-17, pl. Il, fig. 1. 1903. a Be Graeter, p. 528, p]. XV, figs. 23 and 32. 1909. = bicuspidatus Byrnes, p. 25, pl. X, figs. 4-7. The cephalothorax is elongate oval, its length being con- siderably more: than twice its breadth. Seen from above the lateral angles of the segments back of the first are somewhat extended backward. The cephalothorax is rather more than twice as long as the abdomen exclusive of the furcal rami. The first abdominal segment is only slightly narrower than the last cephalothoracic segment, and its anterior part is con- siderably wider than the posterior. The first abdominal seg- ment about equals in length the three following. The posterior margins of the abdominal segments are more or less clearly marked with serrations, with the exception of the last seg- ment which is armed with small spines. The fureal rami (Pl. LX XIII, figs. 3, 7 and 8, pl. LX XIX, fig. 11) vary greatly in their length. The length may exceed little more than twice the breadth, or it may reach to six or eight times the breadth. The inner margins of the rami are ordi- narily ciliate, although this is not an invariable characteristic. At about one-quarter of the distance from the proximal end is a row of small spines on the lateral margin. These spines are almost invariably present on the forms with elongated fureal rami but are not found on those with the very short rami. The lateral seta, which is surrounded with minute spines, is placed at about two-thirds of the length of the ramus. Of the terminal setae, only the inner ones are elongated. 1080 Wisconsin Academy of Sciences, Arts, and Letters. The antennae consist of 17 segments. Richard (Richard 1891) and Steuer (Steuer ’*97) have shown that the number of antennal segments varies in the European forms, but I have not found. this to be true in my American collections. The anten- nae vary somewhat in length, reaching about to the end of the first cephalothoracic segment, but they may fall short of this. length or exceed it. The twelfth segment bears a sensory club. The setae arming the segments are rather short. The spinous armature of the terminal segments of the swim- ming feet is 2, 3, 3, 3. The fifth foot (Pl. LX XIII, figs. 10 and 11) consists of two segments. The breadth and length of the first segment are about equal; it bears on its outer distal angle an elongate plu- mose seta. The second segment is commonly twice as long as broad, but it may be still more slender; on its outer distal angle it bears an elongate and plumose seta, on its inner distal angle it bears a spine like seta which is less than half the length of the outer seta. This inner seta may be serrate as in the European forms, but neither the serration of this seta nor the plumose character of the other setae is very commonly seen in our American forms. The outer seta is borne upon a process of the segment, the outer margin of the segment being longer than the inner. The size is somewhat variable, the American forms, ap- parently, being smaller than those found in Europe. The fe- male is commonly about 1.1 mm. in length but may be not more than .95 mm. C. bicuspidatus is found in all our northern states north of the Ohio river, and has been collected as far north as the Saskatchewan. Generally speaking those found as limnetic forms have an elongated form, while those in shallow bodies of water and pools are shorter. Herrick’s navus (Pl. LX XIX, fig. 11) is an example of this short form. There is no doubt that navus is simply a variety of bicuspidatus for I can verify the state- ment of Forbes that all intermediate forms can be found. Bicuspidatus is the common limnetic form of the Great Lakes, and in its elongated form is common in other deep lakes, Marsh—North American Species of Cyclops. 1081 although it is not confined to them. I have already discussed (Marsh 1903) its occurrence in Wisconsin lakes. It seems to prefer cold water, and my work in Wisconsin seemed to show, that it might be considered as preeminently a winter form. Miss Pratt (Pratt 1898) finds it a winter form in Lake Bassenthwaite in England. JI have found it in small bodies of water in Indiana in the winter, while in the cold lakes of the Rocky Mountains it is a summer form. Birge and Juday, in a recent paper (Birge and Juday 1908) have noted an interesting fact in the life history of C. bicuspidatus. In certain of the Wisconsin Lakes, in the sum- mer season it is found in large numbers in a resting stage enclosed in a cocoon, hatching out in the fall. The authors find themselves unable to correlate this cocoon stage with either changes of temperature or oxygen content of the water. It would seem to us from our knowledge of the habits of the species, that it is probable that temperature will be found to be the controlling cause of this encystation. CYCLOPS LEUCKARTI Cuavs. Plate LXXIV, figs. 4-11; Plate LXXV, figs. 1-3. 1857. Cyclops Leuckarti Claus, p. 35, pl. I, fig. 4, pl. IL, figs. 18 and 14. 1868. i Sars, p. 239. 1863. nt we Claus, p. 101. 1874. a simplex Poggenpol, p. 70, pl. XV, figs. 1-8. 1875. a tenuicornis Uljanin, p. 30, pl. IX, figs. 12 and 13. 1876a. me Leeuwenhoektt Hoek, p. 19, pl. ILI, figs. 1-12. 1876b. he Leeuwenhoekti Hoek, p. 132, pl. VII, figs. 1-12. 1880. ‘ simplex Rehberg, p. 542. 1884. a “* Herrick, p. 150. 1884. ie oithonoides Herrick, p. 150, pl. S, figs. 2-6. 1884. ee Léuckarti Herrick, p. 146. 1885. cK ¥ Daday, p. 218. 1885. et simplex Daday, p. 236. 1885. sf pectinatus Daday, p. 223, pl. I, figs. 7-13. 1886. ea simplex Vosseler, p. 193, pl. IV, figs. 15-17. 1887. es ‘“* Herrick, p. 17, pl. VII, fig. 1, a-j. 1890. e “* Thallwitz, p. 79. 1890. os ‘« Lande, p. 55, pl. XVI, figs. 42-45, pl. XVII, figs. 46-50, 1082 Wisconsin Academy of Sciences, Arts, and Letters. 1891. Cyclops Leuckarti Schmeil, p. 25. bolts DOM o Richard, p. 230, pl. VI, fig. 20. 1891. cr edax Forbes, p. 709, pl. III, fig. 15, pl. IV. figs. 1-20. 1891. = Scourfeldi Brady, p. 10, pl. IV, figs. 1-8. 1892. ie Leuckarti Schmeil, p. 57, pl. III, figs. 1-8. 1892. sh simplex Lande, p. 161. 1893. oe Leuckarti Marsh, p. 209, pl. IV, fig. 17, pl. V. figs. 2-6. 1895. i Leuckarti Herrick and Turner, p. 96, pl. XVI, figs. 1-11, pl.. XVI, fig. 1, a=j, pl. XUXTV, fies 226; 1895. ae Leuckarti Marsh, p. 15, pl. VII, fig. 15. 1897. 2 Leuckarti Forbes, p. 31, pl. VIII, figs. 1-3. 1897. He edax Forbes, p. 33, pl. IX, fig. 1-3. 1897, ee Leuckarti Scott, p. 322, pl. IX, figs. 23-25. 1897. ai “Steuer, p. 32. 1898. a “Brewer, p. 131. 1900. ue “* Burckhardt, p. 640. 1901. if ‘* Lilljeborg, p. 35, pl. II, figs. 28-29. 1903. ty ‘‘ Graeter, p. 509, pl. 15, figs. 26 and 30. 1905. at ‘* Van Douwe, p. 681. 1909. ay pulchellus Byrnes, p. 24, pl. X, figs. 1-3. A conspicuously slender species. The length of the cephalo- thorax compares with that of the abdomen as 7 to 4. The breadth of the cephalothorax is about one-half its length. The elongated oval form of the cephalothorax is a characteristic pe- culiarity of this species. The segments of the cephalothorax. do not project markedly on the sides. The abdomen (Pl. LX_XTV, fig. 3) is slender. ‘The first seg-- ment is equal in length to the remaining segments, and its an-~ terior end is only slightly larger than the posterior. The suc- ceeding segments are all of about the same length. The last segment 1s armed posteriorly with a row of spines. The fureal rami equal in length the two preceding segments.. Generally the inner margins are ciliated, although this is not always the case. The lateral seta is so situated as to divide the furea in the ratio of three to two. The terminal] setae vary in their length; of the four, the inner is more than twice as long as the outer, the outer is commonly not far from the length of the furca. The first antennae are 1%-segmented and reach to the fourth cephalothoracic segment. The twelfth segment bears a sensory club. Upon the sixteenth and seventeenth segments is a ee Marsh—North American Species of Cyclops. 1083 lateral hyaline lamella. The lamella on the seventeenth seg- ment is serrate on its margin, and has besides either a single deep depression near its distal end, or four or five such de- pressions. The figure (Pl. LX XIV, fig. 10) shows a common form. I do not find, in our American forms the spines spoken of by Schmeil on the antennal segments. The segments of the second antenna (Pl. LX XV, fig. 3) are elongated. The lower margin of the second segment of the outer maxillipede always has a number of shallow depressions, giving it a more or less crenulated appearance. This appear- ance is described by the German authors under the term ge- perlite. While, in some of our forms, this term could be prop- erly applied, more frequently crenulated would describe the ap- pearance more accurately. The figures (Pl. LX XIV, figs. 4, 5, 6) show the extreme forms as they occur in America. In one (Pl. LX XIV, fig. 4) this appearance is confined to only a small part of the margin, but is there very distinct, while in the other (Pl. LXXIV, fig. 6) it is not so marked but extends through the greater part of the length of the margin. Pl. LX XIV, fig. 5 shows another form intermediate between the others. The second segment of the inner maxillipede has on its anterior margin a number of scattered and rather long setae (Pl LXXIV, fig. 11). This seems to be a constant character- istic of this species; I think it was first mentioned by Brady (Brady 1891) in his description of Scourfeldi. It is not men- tioned by Schmeil but it 1s shown in his figure of the inner max- illipede. The spinous armature of the terminal segments of the ex- opodites of the swimming feet is represented by the formula, Z, 3, 3, 3. The membrane connecting the feet of the fourth pair is armed on the posterior border with two blunt spines. (Pl. LXXYV, fig. 1.) Each segment of the rami is armed on - the distal border with a row of spines. The fifth feet (Pl. LX XIV, figs. 8, 9) are two-segmented. The first segment is short and broad and bears upon its distal outer angle a plumose seta; this seta is ordinarily long as in Pl. LXXIV, fig. 9, but sometimes it is quite short, as in Pl. LXXTV, fig. 8. The second segment bears a long plumose seta 1084 Wisconsin Academy of Sciences, Arts, and Letters. on its distal end, and an almost equally long one on its inner side. This appendage of the inner side is spoken of by Schmeil as a spine, but in most of our specimens it would more properly be called a seta. There is a good deal of variability in the form and proportions of the fifth feet as shown in the figures of the plate. The egg sacs are carried at a marked angle from the abdo- men. The form of the receptaculum semims is shown in PI. LXXIV, fig. 7. Average length of females is about 1.14 mm. This is a truly cosmopolitan species, being found in nearly all parts of the world. In India it is reported as found not only in fresh water but in brackish ponds. (Annandale 1907.) The synonomy of this species prior to 1891 has been dis- cussed by Schmeil and there is no reason to dissent from his ‘conclusions. As pointed out by me in an earlier publication (Marsh 792) it appeared from Forbes’s original description of edax, that the only reason for separating it from Leuckarti was the ab- sence of hyaline membranes on the 16th and 17th antennal segments. E. B. Forbes (Forbes ’97) redescribes the species. He states that the hyaline membranes are present on the 16th and 17th segments. He makes the following points of difference between edax and Leuckarti: 1st. The hyaline membrane of edaw has several deep inden- tations, Leuckarti but one. 2nd. In edax the 16th and 17th antennal segments are equal, in Leuckarti the 16th is a fourth longer. 3rd. The crenulations of the second segment of the outer maxillipedes are less marked. 4th. The abdominal stylets are more divergent in edaz. 5th. In edax the surfaces of attachment of the setae of the terminal segment are parallel, in Leuckarti the surface of at- tachment of the proximal seta is at an angle of about forty- five degrees with the long axis of the segment, instead of at right angles. In edax the distal segment is broader. 6th. Other differences which can only be recognized by a Marsh—North American Species of Cyclops. 1085 long series of measurements, but such “that one well acquainted with these species can distinguish them at a glance.” In regard to these points of difference, I can only say that none of them seem to me of more than varietal value. In regard to the indentations in the hyaline membrane of the last antennal segment, I find both forms in the same collection with every reason to think that they grade the one into the other. I have found, in my collections, the form with a single indentation the more abundant. Burckhardt (Burckhardt 1900, p. 640) recognizing this possibility of variation, states that in his specimens, the outer three-fourths of the membrane was uniformly indented. I have already discussed the variations in the crenulations of the second segment of the outer maxillipede. There is great variation in this characteristic. The other points of difference are minor things, differences which one would expect within species limits. The sixth point of difference, of course, can hardly be taken seriously, for © differences which can not be accurately defined should not be used in the diagnosis of a species. Without doubt, if we are to recognize the differences on which E. B. Forbes distin- guishes edaz we should have to use the name of Leeuwenhoekw Hoek, which has prior standing. | The figures in Brady’s plate (Brady 791) make it evident that Scourfeldi is the same as Leuckarte. Tt seems probable that pulchellus of Miss Byrnes (Byrnes 1909) is Leuckarti. Cyctors TENUIS sp. nov. Plate LX XV, figs. 4-9; Plate LX XIX, fig. 5. A long slender species. The cephalothorax is oval,. its length being more than twice its breadth; it is twice as long as the abdomen exclusive of the furcal rami. The segments of the cephalothorax do not project at their posterior angles. The anterior end of the first abdominal segment (Pl. LX XV, fig. 5) is somewhat larger than the posterior end; this segment is less in length than the three following. 7—S. & A.—3 1086 Wisconsin Academy of Sciences, Arts, and Letters. The fureal rami are rather slender, nearly equalling in length the last two abdominal segments. The lateral seta is at about one-half the length of the ramus. Of the terminal setae, the outer is short, while the inner one is rather un- usually long. The first antennae (Pl. LX XV, fig. 7) are long, exceeding the second cephalothorax segment. The antenna is composed of seventeen segments, the twelfth bearing a sensory club. The terminal segments of the antenna have no special armature. The spinous armature of the terminal segments cf the exo- podites of the swimming feet is 2, 3, 3, 3. The fifth foot consists of two segments. The length of the first segment is rather less than twice its breadth; it bears on the outer distal angle a long seta. The second segment is twice as long as broad; on its outer distal angle it bears a seta; on its inner distal angle, but set back a little from the end, it bears a slender serrate spine or seta; this inner spine nearly equals in length the outer seta. The form of the receptaculum seminis is shown in the figure (PL LX XV, neo). The females are about 1.1 mm. in length. This was found in Calabasas, in southern Arizona. C. tenuis resembles, in its form, C. Leuckarti, but differs in the form of the fifth feet, in the lack of armature on the an- tennal segments, and of crenulatons on the outer maxillipede, and in the form of the receptaculum seminis. It seems to be most nearly related to the European oitho- noides. JI at first thought it should be a variety of that species, The difference in the form of the fifth foot, however, with the lack of antennal armature and the somewhat different re- ceptaculum seminis have led me to consider it a new species. a Marsh—North American Species of Cyclops. 1087 CYCLOPS ALBIDUS |JuRINE. / Plate LX XVI, figs. 1-9. 1820. Monoculus quadricornis albidus Jurine, pp. 44 and 47, pl. I, figs. 10 and 11, pl. II], fig. 24. 1841. UGE annulicornis Koch, H. 21, pl. VI. 1850. quadricornis var. b Baird, p. 202, pl. XXIV, fig. 4. 1857. i tenuicornis Claus, p. 31, pl. III, ee JUL, 1857. ‘* pennatus Claus, p. 35, pl. III, figs. 12-17. 1863. << tenuicornis Claus, p. 99, pl. I, fig. 3, pl Il, fig. 17, pl. IV, figs) od; 1863. “ tenwicornis Sars, p. 242. 1863. “ annulicornis Sars, p. 248. 1863. ‘* tenuicornis Lubbock, p. 202. 1870. os tenuicornis Heller, p. 71. 1872. i tenuicornis Fric, p. 219, fig. 12. 1874. “ Clausti Poggenpol, p. 70, pl. XV, figs. 4-14. 1875. ‘* signatus Uljanin, p. 29, pl. IX, figs. 6-11, pl. XI, fig. 8. 1876a. ** tenwicornis Hoek, p. 12. 1876b. ‘« tenuicornis Hoek, p. 130. 1878. me tenwicornis Brady, p. 102, pl. XVIII, figs. 1-10. 1882. “ tenwicornis Herrick, p. 227, pl. VI, figs. 1-11 and 20, pl. V, fig. 14. 1883. as tenuicornis Cragin, p. 3, pl. II, figs. 1-14. 1883. “< signatus var. fasciacornis Cragin, p. 2, pl. II, fig. 15. 1884. ue tenuicornis var. a Herrick, p. 153, pl. Q*, figs. 1-7. 1885. ‘* tenuicornis Daday, p. 211. 1886. es tenuicornis Vosseler, p. 189, pl. IV, figs. 6-10. 1887. os tenwicornis Claus, var. distinctus Richard, p. 162. 1888. oa tenuicornis Claus, var. annulicornis, Richard, p. 61. 1888. a albidus Sostaric, pl. I, figs. 3, 4 and 12. 1890. “* tenwicornis Thallwitz, p. 79. 1890. ‘* tenuicornis Lande, p. 36, pl. XVI, figs. 22-32. 1891. ‘* gyrinus Forbes, p. 707, pl. Il, fig. 9, pl. III, fig. 14. 1891. ‘* albidus Schmeil, p. 23. 1991. ‘ annulicornis and tenuicornis Richard, p. 224-226. 1892. $f albidus Schmeil, p. 128, pl. I, figs. 8-14b, pl. IV, fig. 15. 1892. “ tenuicornis Lande, p. 156. 1892. ‘* gracilicornis Lande, p. 158. 1893. “« signatus Marsh, p. 211, pl. V, figs. 7-9. 1895. ‘ signatus var. tenuicornis Herrick and Turner, p. 106, pl. | XV, figs. 5-7, pl. XX, figs. 1-7, pl. XX XIII, figs. 1 and 2. 1895. “« albidus Marsh, p. 17, pl. VI, figs. 8-10. 1897. “4 oh Forbes, p. 47, pl. XIII. 1897. ue tenuticornis Matile, p. 121, pl. Il, figs. 4 and 5. 1898. ‘* _ stgnatus Brewer, p. 129. 1901. Ue albidus Lilljeborg, p. 49, pl. III, figs. 21, 22. 1901. ue distinctus Lilljeborg, p. 47, pl. III, figs. 16-20. 1903. i Graeter, p. 481, pl. 15, fig. 8. 1088 Wisconsin Academy of Sciences, Arts, and Letters. 1905. Cyclops albidus Pearse, p. 150, pl. XIV, figs. 11 and 13. 1906. distinctus Brady, p. 697. 1909. yy signatus var. annulicornis Byrnes, p. 10, p. LV, figs. 1-6. 1909. ‘“ virido-signatus Byrnes, p. 23, pl. LX, figs. 1-8. A rather large species. The cephalothorax is oval in form, but the tapering at the posterior end is not so pronounced as in some species. The length and breadth compare as about 5 to 3. The cephalothorax is a little more than twice as long as the abdomen exclusive of the furcal rami. The projection of the posterior angles of the segments is not very marked. The dorsal surface of the fifth segment is more or less clearly marked with four rows of small spines. The first abdominal segment (Pl. LX XVI, fig. 5) is not markedly larger at its anterior end; this first segment is some- what longer than the sum of the three following. The last ab- dominal segment has a row of spines on its posterior margin. The furcal rami are about twice as long as wide. The in- ner margins of the fureal rami are not usually armed with cilia; sometimes, however, they are present. I have found this condition in specimens collected in Michigan and in some collected in Colorado. The lateral seta is situated near the end of the furea. Of the four apical setae, the outer is very short, not much exceeding in length the ramus; the inner is about three times the length of the outer. The first antennae are composed of seventeen segments, and reach about the full length of the cephalothorax. The last three segments (Pl. LX XVI, fig. 8) bear a hyaline plate, which in the last segment may be finely serrate on the margin. In oe- casional specimens this hyaline plate may be seen in some of the preceding segments, and in exceptional cases may be traced the whole length of the antenna, being represented in most of the segments by a row of small spines. Occasionally, too, the eighth, ninth, tenth, twelfth, thirteenth and fourteenth segments may have a row of spines on the posterior border as in C. fuscus. The twelfth segment has a long seta and a elub- ‘shaped sensory seta. The first two segments may have ir- ‘regular rows of spines. In exceptional cases, there may be ‘rows of spinules on the fourth, fifth, sixth and seventh segments. Ce er Marsh—North American Species of Cyclops. 1089 In the second antenna, the inner margins of the first two segments are usually setose. The third segment is short, but little exceeding the second in length. (Pl. LX XVI, fig. 7.) The spinous armature of the terminal segments of the ex- opodites of the swimming feet is 4, 4, 4, 3. The distal seta on the inner margin of the endopodite of the fourth foot is rudimentary, being represented by a small spine; very rarely there is a short seta in this place; I have never found a seta of full length. (Pl. LX XVI, figs. 1, 3.) The fifth foot is of two segments (P]. LXXVI, fig. 6). The first segment is longer than wide. It has a patch of spines on the inner margin near the base, and a few spines about midway of its inner margin which may extend over part of the surface of the segment in a curved line. The distal margin is armed with small spines. On its distal outer angle is a long seta. The length of the second segment about equals the breadth of the first. It bears a long median seta and two stout serrate setae, one at each distal angle; the inner of these lateral setae is the longer. The form of the receptaculum seminis is shown in the figure, (PI. LXXVI, fig. 9). The ege sacs of the female stand out from the abdomen al- most at right angles. The females measure upwards of 1.5 mm. Cyclops albidus is universally distributed in North Americs. It belongs to the litoral rather than to the limnetic fauna. Under C. fuscus there is a brief discussion of the distinguish- ing points between these two species. C. annulicornis Sars, C. tenuicornis var. distinctus Richard, and ©. gracillicornis Lande are doubtless identical, and the names have been given to separate a form supposed to be in- termediate between albidus and fuscus. Brady (1906) and Lill- jeborg (1901) make a distinct species using the name distince- tus of Richard. Nothing has appeared in our American co- pepod fauna which seems to need a distinct species name, and I am inclined to agree with Schmeil that there is no good reason for separating this form from albidus. Accordingly I have placed them in the synonomy. 1090 Wisconsin Academy of Sciences, Arts, and Letters. From the description it is impossible to establish the identity of virido-signatus of Miss Byrnes, but it would seem that this is probably a larval form of either albidus or fuscus with the chances in favor of albidus. 1820. 1841. 1850. 1857. 1863. 1863. 1863. 1870. 1872. 1876a. 1876b. 1878. 1882. 1884. 1885. 1886. 1888. 1890. 1890. 1891. 1891. 1891. 1892. 1893. 1895. 1895. 1897. 1901. 1903. 1905. 1906. 1909. CYCLOPS FUSCUS JuRINE. Plate LXXVII, figs. 1-7. Monoculus quadricornis fuscus Jurine, p. 47, pl. II, fig. 2. Cyclops signatus Koch, H. 21, pl. VIIL. 6é quadricornis var. c. Baird, p. 203, pl. XXIV, fig. 5. coronatus Claus, p. 29, pl. I, fig 5, pl. II, figs. 1-11. es oe p.'97%, pl. Il, fig. 16, pl. Xx aig signatus Sars, p. 242. coronatus Lubbock, p. 199. ee Heller, p. 71. 5 Eric. pci Ss miele He Hoek, p. 12. rs Hoek, p. 129. signatus Brady, p. 100, pl. XVII, figs. 4-12. tenuicornis Herrick, p. 227, pl. V, fig. 14, pl. VI, figs. 1-11, and 20. oy Herrick, p. 153, pl. R, fig. 16, pl. Q4, figs. 8-11, and 21. signatus Daday, p. 208. i Vosseler, p. 189, pl. IV, figs. 1-5. fuscus Sostaric, p. 58. signatus Thallwitz, p. 79. iy Lande, p. 33, pl. XV, figs. 1-12. fuscus Schmeil, p. 22. i. Richard, p. 223, pl. VI, fig. 6. signatus Brady, p. 6, pl. II, fig. 5. fuscus Schmeil, p. 123, pl. I, figs. 1-7b, pl. IV, fig. 2. signatus Marsh, fuscws included under this. signatus var. coronatus Herrick and Turner, p. 106, pl. XV, figs. 1-4. fuscus Marsh, p. 16, pl. VI, figs. 5, 7 and 11. coronatus Matile, p. 120, pl. II, figs, 1, 2 and 3. fuscus Lilljeborg p. 44, pl. IL, figs 12-15. ‘“* Graeter p. 473, pl. 15, fig. 37. os Pearse, p. 150, pl. XIV, fig. 12. signatus var. coronatus Byrnes p. 193, pl. VI, figs. 1-6, pl. VIII, figs. 1-3. sf * ‘* Byrnes p. 9, pl. IL, figs. 1-7, pl. III, figs iets The cephalothorax is oval, narrowing decidedly toward the posterior end. Its width is rather more than one-half its ——— a Marsh—N orth American Species of Cyclops. 1091 length and the cephalothorax compares in length with the ab- domen as seven to four. The posterior angles of the segments of the cephalothorax are not especially prominent. The first segment is about three-fourths of the length of the whole cephalothorax. The first abdominal segment (Pl. LX XVII, fig. 1) is only slightly enlarged at its proximal end. Its length is rather less than the combined length of the three following segments. The last segment is armed on its posterior border with small spines. The fureal rami are twice as long as wide, and ciliated on their internal margins. The lateral seta is near the distal end. Of the four terminal setae both the outer and the inner are elongated. The inner is seldom more than twice the length of the outer. All the termimal setae are strongly plu- mose. | The first antennae are composed of seventeen segments, and reach to the end of the cephalothorax. The twelfth segment bears a sensory hair. The eighth, ninth, tenth, twelfth, thir- teenth and fourteenth segments have rows of large spines on their posterior borders (Pl. LAXVII, fig. 3). The last three antennal segments bear a lateral hyaline plate (Pl. LX XVII, fig. 4). In the last segment this hyaline plate is deeply notched on the first two-thirds of the segment, having four especially deep notches. The latter third of the plate is finely serrate. As in albidus these hyaline plates in some cases extend back upon the preceding segments. I find, as does Schmeil, contrary to the statement of Vosseler, that the indentations in the mem- brane of the last segment do not disappear in mounted speci- mens, but remain permanently like other cuticular structures. In the second antennae, the inner margins of the first three segments are setose. The second segment is short and the third very long as compared with the corresponding structures in albidus. (Pl. LX XVII, fig. 5.) The spinous armature of the swimming feet is 4, 4, 4, 3. This is as I have found it in all my American specimens. Schmeil gives it 3, 4, 4, 8. Vosseler gives it, however, as I have found it. A structure not mentioned by any of the European authors 1092 Wisconsin Academy of Sciences, Arts, and Letters. is found on the third segment of the endopodite of the fourth foot. The larger of the two terminal spines is armed on its inner margin with long irregular teeth instead of the short spines as is customary. (Pl. LX XVII, fig. 2.) This feature I have found constant in specimens from’ the northern states, but it is absent in most of those that I have examined from the southern states. The structure of the fifth foot is like that of albidus. The form of the receptaculum seminis is shown in the figure, Plate LX XVII, fig. 6 The egg sacs of the female hang close to the abdomen. The female measures 3 to 4 mm. in length, according to Schmeil. American specimens are smaller, being little over half of this length. This species is found widely distributed in the northern continents, although nowhere very abundantly. In the U. S&S. Herrick found it in Minnesota. Later I reported it from Wisconsin and Michigan. E. B. Forbes adds localities in Il- linois and Massachusetts. Pearse reported it from Nebraska. I have found it also in collections from Arkansas and Louisi- ana, and it is probable that it is universally distributed. As will be seen from the literature of the subject, albidus and fuscus have been confused with each other until Schmeil made the clear distinction between the two species. By the difference in size, the darker color of fuscus, and the different habit of the egg-sacs the two are easily distinguished at a glance. In albidus the egg-sacs stand out from the abdomen, while in fuscus they cling close to it. In albidus there is a sensory club on the twelfth antennal segment, while in fuscus that segment bears a sensory hair. In albidus the hyaline plate of the last antennal segment is finely serrate; in fuscus it is deeply notched. In albidus the third segment of the sec- ond antenna is short; in fuscus this segment is long. In albi- dus the distal seta on the inner margin of the third segment of the endopodite of the fourth foot is rudimentary. In fuscus this seta is of the usual size, and commonly the large terminal spine of this segment is armed with long irregular teeth on its outer margin. In albidus the inner margins of the furcal ee Oe Marsh—North American Species of Cyclops. 1093 rami are usually without cilia; in fuscus they are thickly beset with cilia. CYCLOPS MODESTUS HeErricx. Plate LXXVIII, Figs. 1-4. 1883. Cyclops modestus Herrick, p. 500. 1884. a at st (On WS Tolle 1, mes, Wels, 1887. of “5 ig joe Wut 1893. ee ey Marsh, p. 213, pl. V, figs. 10-13. 1893. “ capilliferus Forbes, p. 248, pl. XL, figs. 14-17, pl. XLI, fig. 18. 1895. ‘“ modestus Herrick and Turner, p. 108, pl. X XI, figs. 1-5. 1895. “ capilliferus Herrick and Turner. p. 109, pl. VI, fig. 13, pl. XX VII, figs. 1-4. 1909. ““_ modestus Byrnes, p. 26, pl. XI; figs. 4 and 5. A rather stout species. Cephalothorax broadly oval, its breadth exceeding one-half its length. The cephalothorax is considerably more than twice as long as the adbomen exclusive of the furcal rami. The first segment comprises nearly two- thirds of the length of the cephalothorax. The posterior lateral angles of the segments project very little. The abdomen (Pl. LX XVIII, fig. 4) is very slender and tapers little posteriorly. The first segment equals in length the rest of the abdomen exclusive of the fureal rami; it is wider at the anterior end, and the lateral prominences are each armed with a minute spine. The second and third segments are about equal in length, while the fourth is shorter. The abdominal segments are ciliate on their posterior borders. The furcal rami are rather slender. They are about two and one-half times as long as the last abdominal segment. The inner margins are ciliate. The lateral seta is situated at about one-half the length of the ramus, and the ramus is peculiarly excavated backward from the seta. Of the terminal setae, the outer is short and plumose, and the inner is rather long, being three times the length of the outer. The antennae (Pl. LX XVIII, fig. 2) are sixteen segmented. Herrick states that he has seen individuals “of a similar form” with seventeen segments. They reach, in the female, to the 1094 Wisconsin Academy of Sciences, Arts, and Letters. middle or end of the second cephalothoracic segment. The setae of the antennal appendages are unusually long. The spinous armature of the terminal segments of the exo- podites of the swimming feet is 4, 4, 3, 3. This is an un- unusual armature. The fifth foot (Pl. LXXVIII, fig. 3) is three segmented. The first segment is short and without armature. The second segment is nearly square and bears a seta on its outer distal angle. The third segment is narrower, longer than wide and bears two apical setae. Frequently the outer of these setae is bent over the inner. Length of the females 1.2 to 1.25 mm. This was first described by Herrick from Alabama, and he afterwards reported finding it in Minnesota. I found it in two localities in Wisconsin and Forbes reports it from Wyom- ing, and states that it is an uncommon species in the north central states. JI have received specimens from R. A. Spaeth collected at Haverford, Pennyslvania, and from C. F. Baker collected at Auburn, Alabama. CYPLOPS SERRULATUS FiscHmr. Plate LXXVIIL, Figs. 5-9, Plate LXXIX, Figs. 4 and 8. 1851. Ce sera Fischer, p. 423, pl. X, figs. 22, 23, 26-31. 1853. Lilljeborg, p. 158, pl. XV, fig. 12. 1857. sf ah Claus, p. 36, pl. I, figs. 1-3. 1863. “ s ‘“ p, 101, pl. I, figs. 1 and 2, pl. IV, fig. 12, pl. XD, fies 3: 1863. * 3 Sars, p. 254. 1863. a < Lubbock, p. 197. 1870. ey He Heller, p. 72. 1872. 2 = Fric, p. 222, fig. 18. 1875. 4 ad Uljanin, p. 34, pl. VIII, figs. 1-8. 1876a. “ ee Hoek, p. 22. 1878. ‘ si Brady, p. 109, pl. XXII, figs. 1-6. 1878. Hi ch var. montanus Brady, p. 110, pl. XXII, figs. 7-14. 1880. ‘* agilis Rehberg, p. 545. 1882. fe ‘* Forbes, p. 649. 1882. ‘* serrulatus Herrick, p. 230, pl. V, figs. 1-5, pl. VII, fig. 10. 1883. a G. M. Thompson, p. 96, pl. XI, figs. 19-22. 1883. ‘* pectinifer Cragin, p. 6, pl. IV, figs. 1-7. 1884. “* serrulatus Herrick, p. 157, pl. 0, figs. 17-19. 1884. oF ad var. elegans, Herrick, p. 158. Marsh—North American Species of Cyclops. 1095 1885. Cyclops agilis Daday, p. 240. 1886. ‘* Voseler, p. 190, pl. V, figs. 29-81. 1890. ay ‘* Thallwitz, p. 79. 4890. es ““ Lande, p. 60, pl. XVII, fig. 69, pl. XVIII, figs. 70-80. 4891. “* serrulatus Brady, p. 18, pl. VII, fig. 1. us9gl. “_agilis Forbes, p. 710. 1891. “ serrulatus Richard, p. 234, pl. VI, fig. 19. 1891. ve a Schmeil, p. 29. 1892. s PS DeGuerne & Richard, p. 11. 1892. $s ee Schmeil, p. 141, pl. V, figs. 6-12. 1892. ‘“ agilis Lande, p. 164. 1893. “ serrulatus Marsh, p. 215, pl. VI, figs. 2-5. 1893. or ce Richard, p. 8. 1893. Hig i Scott, p. 73. 1895. eo ae Herrick and Turner, p. 111, pl. XV, figs. 8-11, pl. XIX, figs. 2-5, pl. XX VI, fig. 10, pl. X XIX, figs. 17-19. 4895. ti oe Marsh, p. 19. 1897. ae ae Forbes, p. 54, pl. XVII, pl. XVIII, figs. 1-3. 1897. ki SG Steuer, p. 34. 1897. Re oe Matile, p. 131, pl. I, figs. 18 and 19. 1898. se “4 Brewer, p. 184. 1901. ia ry Lilljeborg, p. 81, pl. V, figs. 1-6. 1901. “ macrurotdes Lilljeborg, p. 85, pl. V, figs. 7-11. 1901. “varius Lilljeborg, p. 87, pl. V, figs. 12-15, pl. VI, figs, 1-9. 1901. oY ““ var. speratus, Lilljeborg, p. 88, pl. V, figs. 12-15. 1901. fe is ‘* proximus, Lilljeborg, p. 89, pl. VI, figs. 1-4. 1991. ye i ‘* brachyurus, Lilljeborg, p. 90, pl. VI, figs. 5-9. 1903. 2p ‘* Graeter, p. 489, pl. XV, figs. 6, 9, 17 and 19. 1903. oe ‘““ var. denticulata Graeter, p. 491. 1905. ui ‘* Jensen, p. 120. 1906. oe “* Brady, p. 698. 1909. “ serrulatus Byrnes, p. 27, pl. XII, figs. 1-5. Cephalothorax (Pl. LX XIX, fig. 8) elliptical rather than oval, its breadth more than half its length. The segments do not noticeably project over the following ones. The cephalo- thorax is more than twice as long as the abdomen exclusive of the furcal segments. The first abdominal segment is enlarged at the anterior end. The second, third and fourth segments are about equal in length. The last segment is bordered posteriorly by a row of spines, and the preceding segments are commonly dentate on their posterior borders. The fureal rami vary greatly in length. At one extreme we have the short stout form, perhaps one and a half times as long as 1096 Wisconsin Academy of Sciences, Arts, and Letters. the last abdominal segment, and at the other extreme the slender form in which the furea may be three times as long as the last abdominal segment. The form shown in the plate, (PL LX XVIII, fig. 7) may be considered typical while the figure in plate LX XVIII, fig. 6 is of the slender form. The outer mar- gin of the furea is bordered by a row of short spines. These are- not present in the male, and while always present in the female, are very variable in size. It was noted by DeGuerne and. Richard (’92) that the specimens collected at Rufisque showed these spines much less clearly than did the European spect- mens. Brady (Brady 1906) also states that the serrulations. in the New Zealand specimens are less marked than in those in Europe. There is much variability even in the same gen- eral region. These short spines are commonly much more prominent at the distal end of the furea. The lateral seta is- at the end of the furca. Of the terminal setae the outer is short, sometimes spine-like, and, in the specimens with a short furea, commonly stands at nearly right angles with the furea. The second and third setae are prolonged; the third is rather less than twice as long as the second and only slightly exceeds. the combined length of the abdomen and furea. The fourth seta is slender and weak, seldom much exceeding the first in length, and sometimes is shorter. The first antennae are twelve-segmented and reach to the third segment, or sometimes nearly to the fourth; their length is quite variable. The last three segments (Pl. LX XVIII, fig. 5) bear an inconspicuous hyaline membrane. Some of the European authors say that these hyaline membranes are some- times finely dentate, though commonly with entire margins.. This dentation has never been noticed in American specimens. The spinous armature of the terminal segment of the exopo- dites of the swimming feet is 3, 4, 4, 3. The fifth foot (Pl. LX XVITI, fig. 8) is composed of a single segment. It is armed on its inner distal angle with a stout: spine with serrate edges, and on its outer distal angle with @ slender seta. Midway between these, on a prominent base is a long slender seta, considerable exceeding in length the outer ‘seta. Marsh—North American Species of Cyclops. 1097 Lhe form of the receptaculum seminis is shown in the figure, {Pl LXXVITI, fig. 9). The egg-sacs are elongate and stand out from the abdomen. ‘The number of eggs is variable. The size is variable, commonly running between .8 and 1.25 mm., but greater extremes are not unusual. The species has been found so widely distributed that it may be considered cosmopolitan. It is convenient to use the varietal names montanus Brady and elegans Herrick in speaking of the extreme forms. Mon- tamus is small, dark colored with short and stout furea, and with few eggs in the egg sacs. Hlegans is larger, slender, with long and slender furcae, and numerous eggs in the egg sacs. As indicated by me in a former publication (Marsh 792) mon- tanus is more common in pools and elegans in lakes. Hlegans may be considered as limnetic and montanus as litoral. ‘There are exceptions to this distribution, however, for elegans may be found in shallow waters, and in collections in the southern states it is not unusual to find both forms in the same col- lection. CYCLOPS PRASINUS FiscHEr. Plate LXXVHE, figs. 1, 2, 3 and 10. 1860. Oe: prasinus Fischer, p. 652, pl. XX, figs. 19-26 ale ville longicornis Vernet, p. 44, fig. 3. 1882. fluviatilis Herrick, p. 231, pl. VIII, figs. 1-9. 1883. “ magnoctavus Cragin, p. 5, pl. II, figs. 14—23. 1884. ‘* fluviatilis Herrick, p. 159, pl. Q’, figs. 1-9. 1886. “ pentagonus Vosseler, p. 191, pl. V, figs. 32-37, pl. VI, figs. 11 and 12. 1887. ““ pentagonus var. vichyensis Richard, p. 162. 1887. ‘* fluviatilis Herrick, p. 15. 1888. “ prasinus Richard, p. 65. 1891. ‘« magnoctavus Brady, p. 19, figs. 1-4. 1891. ‘* pentagonus Schmeil, p. 31. 1891. wi fi Blanchard & Richard, p. 515. 1891. iN Be Richard, p. 233, pl. VI, fig. 8. 1892. ‘* prasinus Schmeil, p. 150, pl. V, figs. 1-5. 1893. <¢ flwiatilis Marsh, p. 214, pl. V, figs. 14 and 15, pl. VI, fig. 1. 1895. ‘< fluviatilis Marsh, p. 18. 1895. ‘* fluviatilis Herrick and Turner, p. 114, pl. XXYVI, figs. 1-8, pl. XXX, figs. 1. 1098 Wisconsin Academy of Sciences, Arts, and Letters. 1897. Cyclops prasinus Forbes, p. 57, pl. XIX, figs.1 and 2, pl. XX, figs. 1 and 2. 1898. ‘* fluviatilis Brewer, p. 135. 1903. ‘* prasinus Graeter, p. 486, pl. 15, figs. 3 and 4. 1909. ‘* fluviatilis Byrnes, p. 28, pl. XV, figs. 1 and 2. A small slender species. Its breadth exceeds one-half its length, and its length is rather more than twice the length of the abdomen exclusive of the furcal rami. The first segment is two-thirds the length of the entire cephalothorax. The last segment has a row of very fine hairs. The first abdominal segment (Pl. LX XIX, fig, 1) is very slightly enlarged at its anterior end and the whole abdomen tapers gradually to the end of the furca. The furea is short, being about one and a half times the length of the last abdominal segment. The lateral seta is situated at about the middle. Of the terminal setae the outer and inner are short and slender, the inner being the longer. The second and third are produced, the third being much the longer. The first antennae (Pl. LX XIX, fig. 2) are composed of twelve segments and reach to the end of the third cephalothor- acic segment. The last three segments bear a very minute hya- line membrane. The antennae are bent in a way that is pe culiar to this species. The spinous armature of the terminal segments of the exopodites of the swimming feet are 3, 4, 3, 3. The fifth foot (Pl. LX XIX, fig. 10) is composed of one seg- ment. It bears at the inner distal angle a slender spine, on the outer distal angle a seta, and between, on a conical base, an elongated seta. The egg-sacs lie close to the abdomen. The females average about .48 mm. in length. This is con- siderably smaller than the sizes given for the European speci- mens. This species is widely distributed in Europe and has been reported from the Azores (Richard 1896), Ceylon (Daday 798) and Caleutta (Gurney 1906 and 1907). It is known to occur in America from the Rocky Mountains to the Atlantic and as far south as Mexico. Its characteristic habitat is lakes rather Marsh—North American Species of Cyclops. 1099 than pools. It is one of the common species in the limnetic regions of the Great Lakes. CYCLOPS PHALERATUS Kocu. Plate LX XIX, fig. 9; plate LXXX, figs 1-6. phaleratus Koch, H 21, pl. IX. canthocarpoides Fischer, p. 426, pl. X, figs. 24, 25, 32-38. ve Lilljeborg, p. 208. o Claus, p. 37, pl. I, figs. 6-10. ue Claus, p. 102, pl. IV, figs. 1-4. ai Lubbock, p. 202. phaleratus Sars, p. 255. canthocarpoides Fric, p. 223, fig. 19. lascious Poggenpol, p. 72, pl. XV, figs. 22-24, pl. XVI, figs. 7 and 8. ; Fischert Poggenpol, p. 78, pl. XV, fig. 28, pl. XVI, figs. 12-15. phaleratus Uljanin, p. 38, pl. IX, figs. 1-5. Ge Brady, p. 116, pl. X XIII, figs. ‘7-13. adolescens Herrick, p. 231, pl. VI, figs. 15-20. perarmatus Cragin, p. 7, pl. I, figs. 9-18. phateratus Herrick, p. 161, pl. R, figs. 6-10. by Daday, p. 252. ies Herrick, p. 14, pl. VII, figs. 2, a-d. a Sostaric, p. 74, pl. Il, figs. 21-22. as Lande, p. 75, pl. XX, figs. 126-136. of Brady, p. 25, pl. IX, fig. 2. iG Richard, p. 238, pl. VI, fig. 12. ok Schmeil, p. 36. ‘\ Lande, p. 171. | uf Schmeil, p. 170, pl. VIII, figs. 1-11. ie Marsh, p. 216, pl. VI, figs. 6 and 7. a Herrick, and Turner, p. 120, pl. XVII, figs. 1-7, pl. XVII, figs. 2-2d, pl. XIX, fig. 1, pl. X XJ, figs. 6-10. ee Marsh, p. 19. oh Forbes, p. 59, pl. XX, fig. 3. oy Lilljeborg, p. 105, pl. VI. figs. 20-21. as Graeter, p. 499. ie Byrnes, p. 31, pl. XV, figs. 1-9. The cephalothorax (Pl. LX XX, fig. 1) is elliptical; its breadth is two thirds of its length. The first segment comprises nearly one-half of its length. The fifth segment is armed pos- teriorly with a row of spines. 1100 Wisconsin Academy of Sciences, Arts, and Letters. The abdomen is broad (Pl. LXXX, fig. 6), its first seg- ment being only slightly smaller than the last cephalothoracic segment. Schmeil states that the second and third segments of the female and the second, third and fourth of the male are serrate on their posterior borders. I find some variations in these serrations in our forms. The furcal rami are short, broad and tapering. They are armed upon their surfaces with rows of spines. The lateral setae are well towards the end, with spines at their bases. Of the terminal armature, the outer is a broad, stout spine, the inner a slender, short seta. The median setae are long and stout. The inner margins of the rami are ciliate. The first antennae (Pl. LX XX, fig. 3) reach beyond the middle of the first cephalothoracic segment and, in American specimens are commonly composed of eleven segments. Herrick and Forbes claim to have collected mature specimens with ten segmented antennae. The eighth segment has a sensory hair. The second antenna (Pl. LX XX, fig. 4) is short and broad. Besides the rows of small spines on the surface of the second segment, there is upon the anterior margin a row of curved tooth like spines. Near the end of the second segment is a stout spine, and a similar spine is located near the end of the third segment. The spinous armature of the terminal segments of the exopodites of the swimming feet is 3, 4, 4, 3. The outer mar- gins of the segments of the feet are armed with stout spines, and the first basal segment is armed posteriorly with a row of small spines. The fifth feet (Pl. LX XIX, fig. 9) are widely separated from each other and each consists of a broad plate armed with three stout setae. The form of the receptaculum seminis is shown in Plate LXXX, fig. 5. The egg-sacs lie rather close to the abdomen. Length of female about 1.2 mm. according to Schmeil, but American forms average somewhat smaller. Cyclops phaleratus occurs in shallow lakes and stagnant Se ee Raitt | . . | 4 { Marsh—North American Species of Cyclops. 1101 pools, and is world wide in its distribution, although not abun- dant anywhere. The question of the identity of our form with that of Europe has been discussed by Schmeil, and I think we must agree with his conclusion. Really the only reason for separating our form is the fact that it ordinarily has eleven segments in the antenna. If we recognize this as a specific difference we should call the American form perarmatus Cragin. CYCLOPS VARICANS Sars. 1862. Cyclops varicans Sars, p. 252. 1875. zt orientalis Uljanin, pp. 33-34, pl. VII, figs. 10 and 11; pl. X, figs. 8-13; pl. XI, figs. 1 and 2. 1890. ‘“ paricans Lande, p. 64, pl. XVIII, figs. 81-90. 1891. 53 B Schmeil, p. 33. 1892. oe a Lande, p. 164. 1892. a i Schmeil, p. 116, pl. VI, figs. 1-5. 1893. eB ny Richard, p. 8. 1895. ee 2 Herrick, p. 116, pl. XIX, figs. 12-13; pl. XXX, figs. 2-8. 1895. Pe on Richard, p. 1. 1897. Us es Forbes, pp. 63-64. 1897. i a Matile, p. 130, pl. II, fig. 17. 1897. ts ie Scott, p. 322, pl. IX, figs. 26-28. ‘1901. ne ie Lilljeborg, p. 72, pl. IV, figs. 23, 24. 1903. 4 iS Graeter, p. 528, pl. XV, figs. 22, 25. 1905. i os Van Douwe, p. 682. 1906. He ee Pearse, p. 249. 1909. us bicolor Byrnes, p. 29, pl. XIII, figs. 1-3. This is a species of world wide distribution, and it would be expected in our American fauna. I have never found it in any of the collections that have come under my observation. It is mentioned by Herrick, E. B. Forbes and Pearse as being found in America. Herrick states that he found it but once. His figures are not exact, but he gives twelve segments in the antenna of the female which should distinguish it from the closely related form bicolor. Forbes speaks of it as fairly common in America, but he gives neither description nor figures. Pearse states that he found it on Nantucket Island, but he too, gives neither description nor figures. 8—S. & A.—3 1102 Wisconsin Academy of Sciences, Arts, and Letters. The bicolor of Miss Byrnes has antennae of twelve segments and must be considered as varicans. Because of the very close resemblance of this species to bicolor one cannot help being a little skeptical in regard to some of these recorded occurrences, in spite of the fact that it might be expected to be a member of the American copepod fauna. CYCLOPS BICOLOR Sars. Plate LXXX, figs. 7-9; Plate LXXXI, figs. 1 and 2. 1863. Cyclops bicolor Sars, p. 253. 1880. S ‘* Rehberg, p. 547. 1884. ¥ ‘* Herrick, p. 160, pl. R, fig. 12. 1885. io ‘* Daday, p. 246. 1885. oe brevisetosus Daday, p. 255, pl. ILI, figs. 3, 5 and 10. 1887. ‘* — diaphanus Herrick, p. 16, pl. VII, figs. 3 a-e. 1888. ye bicolor Lande, p. 67, pl. XVIII, figs. 91-98. 1891. mad ‘* Schmeil, p. 34. - 1892. mS ”. | Schmeil, p. 115, pi VE figs: G2t5 1892. ag ** Wamdle, yp: 165: 1893. es Harsh spsseile: 1895. a ‘* Herrick, p. 118, pl. X VIII, figs. 3-3e, pl. XXI, figsdz 1895. rf ‘“ Marsh, p. 20. 1901. rs ‘* Lilljeborg, p. 78, pl. IV, figs. 27 and 28. 1903. ee ‘* Graeter, p. 533, pl. 15, figs. 34-36. Cephalothorax oval, its breadth being slightly more than one- half its length. The first segment comprises considerably more than one half of the cephalothorax. The cephalothorax is rather more than twice as long as the abdomen exclusive of the furcal rami. The fifth cephalothoracic segment bears upon each side a long seta. The first abdominal segment (Plate LXXXI, fig. 1) is somewhat enlarged anteriorly and equals in length the re mainder of the abdomen exclusive of the furcal rami. The last segment is armed with small spines on the ventral surface and is coarsely dentate on the dorsal surface. The furcal rami do not equal the length of the last two abdominal segments. The lateral seta is at about three-fourths Marsh—North American Species of Cyclops. 1103. of its length. The first and fourth of the terminal seta are short and slender, the inner exceeding the length of the outer. The antennae (Plate LX X XI, fig. 2) have eleven segments, the third and seventh being the longer. The swimming feet (Plate LX XX, figs. 7 and 8) are com- posed of two segments. The spinous armature of the terminal segments is 3, 4, 4, 3. The fifth foot (Plate LX XX, fig. 9) consists of a single seg- ment. It is slender and bears at the tip a single seta. Average length of mature females .5mm. Cyclops bicolor occurs in stagnant pools, and is widely dis- tributed, although nowhere common. I have notes of a mature female with antennae of ten seg- ments. In this female the egg sacs contained only four or five eggs each while the more ordinary number is from fifteen to twenty. This species, as described, does not correspond perfectly to the diagnosis of bicolor as given by Schmeil. There is a dif- ference in the form of the fifth cephalothoracic segment and in the proportions of the furea. There is, apparently some variation in the position of the fifth foot on the last cephalothoracic segment, and in some individuals, it resembles somewhat rubellus of Lilljeborg. The characters of the swimming feet, however, as given by Lilljeborg make a clear cut distinction between rubellus and bicolor. One might consider the American form a distinct species. The differences are slight, however, and besides are, for the most part, differences in structures which vary in other species, so that it seems to me better to consider our form as a variety of the European species. It may be added that because of its comparative rarity, a large number of in- dividuals have not been studied, and a larger amount of ma- terial may show a closer relationship to the European form than now appears. 1104 Wisconsin Academy of Sciences, Arts, and Letters. C. FIMBRIATUS FIscHErR. Plate LX XXI, figs. 3-7. 1853. aCe jimbriatus Fischer, p. 94, pl. II, figs. 19-28 and 30, 1863. crassicornis Sars, p. 256. 1870. ee Gredleri Heller, p. 74, pl. I, figs. 3 and 4. Nhe nn ae pauper Fric, p. 223, fig. 20. Soe crassicornis Uljanin, p. 39, pl. VILL, figs.9-16, pl. XII, fig. 1. Weiielos 1/28 crassicornis Brady, p. 118, pl. XXIII, figs. 1-6. LSSOs i Poppet Rehberg, p. 550, pl. 6, figs 9-11. LESSOR ae fimbriatus Rehberg, p. 548, nl VI, figs. 7 and 8. USB2 ei ss i Vedowsy: p. 63, pl. VII, figs. 9, 10 and 13. SS 20a crassicornis Herrick, p. 232, pl. LV, figs. 9-14. 1884. a jfimbriatus Herrick, p. 162, pl. R, fig. 11 SSocmaes ae Daday, p. 262. SSS ey margot, Daday, p. 264, pl. III, figs. 20-25. Wels, oe fimbriatus Vosseler, p. 192, pl. VI, figs. 4-8. 1888. a crassicornis Sostaric, p. 75, pl. I, figs. 23 and 24. 1890. te fimbriatus Lande, p. 79, pl. XXI, figs. 166-169. S91 ee e Schmeil, p. 35. SOU a Brady, p. 25, pl. IX, fig. 1. ISO eo ie Richard, p. 238, pl. VII, figs. 13 and 14. is ye Schmeil, p. 161, pl. VII, figs. 8-18. TSO2 of Lande, p. 173. IB ys Ay Marsh, p. 218, pl. VI, figs. 8 and 9. Histo isyg, 4 i Herrick, p 121, pl. XVII, figs. 8 and 9, pl. XXI, fie, 11, pli XXV, figs. 9214. TSN ee A ne Steuer, p. 7. 1901S ee oi Lilljeborg, p. 94, pl. VI, figs. 12-14. 19038. ‘ a Graeter, p. 503, pl. 15, fig. 1. OOO Ress Y Byrnes, p. 33, pl. XV, figs. 3-7. Cephalothorax (Plate LX X XI, fig. 3) oval, its breadth being a little more than two-thirds of its length. The cephalothorax is about one and seven tenths as long as the abdomen ex- clusive of the furcal rami. Each segment of the cephalo- thorax projects somewhat over the succeeding segment. The last cephalothoracic segment is armed laterally with rather long hairs. The anterior part of the first abdominal segment is some- what larger than the posterior part. The last segments are armed posteriorly with spines. The fureal rami (Pl. LX XXIJ, fig. 6) are commonly slender, slightly curved in outline, and with their outer extremities ee Marsh—North American Species of Cyclops. 1105 widely separated. Schmeil says that the length nearly equals the last three segments. In our forms this is rarely the case, the length being more generally equal to the last two and a half of the third, or about three times the length of the last segment. In some cases the rami are shorter yet, as in some specimens collected in the Saskatchewan. The lateral seta is situated at about two-thirds the length of the furea on the dorsal surface. A row of spines extends from the outer margin of the furca, on the dorsal surface opposite the seta, curving nearly to the center of the furea, and then nearly to the proximal end of the furca. Of the apical setae, the outer is spine like and short, the inner is slender and somewhat longer than the outer; the longest of the two middle ones nearly equals in length the cephalothorax. The first antennae (Pl. LX XXJ, fig. 2) of the female are composed of eight segments, are about two-thirds as long as the first cephalothoracic segment, and in repose lie nearly at right angles with the long axis of the animal. The fourth segment is the longest, and the fifth bears a sensory seta. The setae with which the antennal segments are armed, are, for the most part, long and stout. The segments near the base are quite stout, the first two being four times as wide as the terminal segment. The external margins of the segments of the swimming feet (Pl. LXXXI, fig. 5) are armed with short, stout spines. The spinous armature of the terminal segments of the exopodites of the swimming feet is represented by the formula, 3, 4, 4, 3. The fifth foot (Pl. LX XXI, fig. 4) consists of a single seg- ment, and is armed with one spine and two setae. The egg-saes, pl. LX X XJ, fig. 3, lie alongside the abdomen, and contain only a small number of eggs. The length of mature females varies from .7 mm. to .84 mm. This is somewhat smaller than the figures given by Schmeil for the European forms. Cyclops fimbriatus is not a common species, but is cosmopol- itan in its distribution. The synonomy is given before the description, and no ex- 1106 Wisconsin Academy of Sciences, Aris, and Letters. planations are required as it has been thoroughly discussed elsewhere. CYCLOPS AEQUOREUS Fiscumr. 1853. Cyclops magniceps Lilljeborg. 1860. aequoreus Fischer, p. 654, pl. XX, figs. 26-29. 1863. oe i. VGlansy ps sLOB: 1868. - a Brady, p. 128, pl. IV, figs. 9-16. 1878. i 5 Brady, p. 119, pl. XIX, figs. 8-10; pl. XXI, figs, 10-17. 1883. 3 Dumasti Joly, p. 120, figs. 1-8. 1883. ee aequoreus G. M. Thompson, p. 97, pl. XI, figs. 16-18. 1888. ry Dumasti Richard, p. 67. 1891. a aequoreus Blanchard and Richard, p. 515. 1891. * tk Brady, p. 26, pl. X, fig. 1. 1892. iy re Lande, p. 173. 1893. Hemicyclops aequoreus Claus, p. 348, pl. ILI, figs. 11-17. 1893. Cyclops aequoreus Scott, p. 74. 1895. og Herrick, p. 122,.p]. X XID, fig. 5. 1895. we #6 Scott, p. 33. 1901. ie a Lilljeborg, p. 102, pl. VI, figs. 17-19. Cyclops aequoreus was first recognized in our fauna by Her- rick. It is an inhabitant of brackish water. It has never appeared in any of my collections, but Mr. E. Foster tells me that he has collected it in Lake Ponchartrain and connect- ing waters. It seems likely that further collections in brack- ish waters will show that this is not an uncommon form. It is readily recognized by the six segmented antennae of the ‘female and the peculiar form of the fifth foot. Marsh—North American Species of Cyclops. 1107 BIBLIOGRAPHY. This bibliography includes only those papers of systematic importance in regard to the species treated of, and which have been quoted in this report. Annandale, M. 1907. The fauna of brackish ponds at Port Canning, Lower Bengal. Part J. Records of Ind. Mus. Vol. I, Part I, pp. 35-48. Baird, W. . 1850. Natural history of the British Entomostraca. Ray Soe. Lond. Birge, E. A. and Juday, C. 1908. A summer resting stage in the development of Cyclops bicusptdatus Claus. Trans. Wis. Acad. XOV ES oe ale Blanchard, R. and Richard, J. 1891. Faune de lacs salés d’Algérie. Cladocéres et | Copépodes. Mem. Soc. Zool. France, T 4, No. 5 pp. 512-535. Brady, G. 8S. 1878. Monograph of the free and semi-parasitic cope- poda of the British Isles. 3 vols. Ray Soe. Lond. 1891. Revision of British species of fresh water Cy- clopidae and Calanidae. Nat. Hist. Trans. Northumb. Durham & Newcastle. XI, Part I, pp. 68-120. 1906. On the entomostracan fauna of New Zealand Lakes. Proc. Zool. Soc. London pp. 692-701. Brewer, A. D. 1898. ‘a 1 ; ) : ‘ & ; \ 3 E i s - PLATE LXXVI. | Le ‘ : i PY 4 i Ht a i i it 4 t ; i ‘ . = if + \ 4 ; ‘ = . " oy can i ‘, , 4 fh . ‘ " ft & i } 4 . 1124 Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6. Fig. 7. Fig. 8. Fig. 9. Wisconsin Academy of Sciences, Arts, and Letters. EXPLANATION OF PLATE LXXYVI. Cyclops albidus; terminal segment of endopodite of fourth foot (x 340). Cyclops albidus; eleventh to fourteenth segments of antenna of female (x 212). Cyclops albidus; fourth foot (x 212). Cyclops albidus; inner maxillipede (x 162). Cyclops albidus; abdomen of female (x 108). Cyclops albidus; fifth foot (x 340). Cyclops albidus; second antenna (x 212). Cyclops albidus; sixteenth and seventeenth segments of an- tenna of female (x 216). Cyclops albidus; receptaculum seminis (x 212). Trans. Wis. Acad., Vol. XVI. Plate LXXVI- \ i Ny mt Leg ‘ ‘ \ ; * e wD. . ) 1126 Wisconsin Academy of Sctences, Arts, and Letters. EXPLANATION OF PLATE LXXVII. Fig.1. Cyclops fuscus; abdomen of female (x 108). Fig. 2. Cyclops fuscus; terminal segment of endopodite of fourth foot (x 212). Fig. 3. Cyclops fuscus; segments eight to fourteen of antenna of fe- male (x 214). Fig. 4. Cyclops fuscus; segments fifteen to seventeen of antenna of fe- male (x 212). Fig. 5. Cyclops fuscus; second antenna (x 212). Fig. 6. Cyclops fuscus; receptaculum seminis (x 168). Fig. 7. Cyclops fuscus; first segment of antenna of female (x 212). Plate LXXYEII. Trans. Wis. Acad., Vol. XVI. = ee eas ‘ — SS SS yt ote x ay ‘ PLATE LXXVIII. erican Species of Cyclops. 4 1127 1128 Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6. Brg. i. Fig. 8. Fig. 9. Wisconsin Academy of Sciences, Arts, and Letters. EXPLANATION OF PLATE LXXVIII. Cyclops modestus; female (x 103). Cyclops modestus; first antenna of female (x 212). Cyclops modestus; fifth foot (x 340). Cyclops modestus; abdomen of female (x 212). Cyclops serrulatus; fifteenth, sixteenth, and seventeenth seg- ments of antenna of female (x 340). Cyclops serrulatus; abdomen of female, slender form var. eéle- gans (x 103). Cyclops serrulatus; abdomen of female, most common form (x 108). Cyclops serrulatus; fifth foot (x 475). Cyclops serrulaius; receptaculum seminis (x 212). Plate LXXVIII. Trans. Wis. Acad., Vol. XVI. he | ae i 1130 Wisconsin Academy of Sciences, Arts, and Letters. EXPLXANATION OF PLATE LXXIX. . Cyclops prasinus; abdomen of female (x 212). . Cyclops prasinus; first antenna of female (x 212). Cyclops prasinus; fourth foot (x 340). . Cyclops serrulatus; fourth foot (x 212). . Cyclops tenuis; fourth foot (x 212). | . Cyclops viridis var. americanus; abdomen of female (x 103). | . Cyclops viridis var. brevispinosus; abdomen of female (x 103). Fig. 8. Cyclops serrulatus; female (x 103). Fig. 9. Cyclops phaleratus; fifth foot (x 340). Fig. 10. Cyclops prasinus; fifth foot (x 475). Fig. 11. Cyclops bicuspidatus var. navus; abdomen of female (x 103). ey = oq AYR T Pwo dW Plate LXXIX. Trans. Wis. Acad., Vol. XVI. nee We oe Le ey ee = PA er a scacsscht aoe << eS PLATE LXXX. 1132 Wisconsin Academy of Sciences, Arts, and Letters. Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6. Fig. 7. Fig. 8. Fig. 9. Cyclops Cyclops Cyclops Cyclops Cyclops Cyclops Cyclops Cyclops Cyclops EXPLANATION OF PLATE LXXX. phaleratus; female (x 58). phaleratus; fourth foot (x 212). phaleratus; antenna of female (x 212). phaleratus; second antenna of female (x 340). phaleratus; receptaculum seminis (x 212). phaleratus; abdomen of male (x 103). bicolor; second foot (x 340). bicolor; fourth foot (x 340). bicolor; fifth foot (x 340). Plate LXXX. XVI- Trans. Wis. Acad., Vol. UAL PLATE LXXXI. f ¥ Mie Fig. 2. Ise By Fig. 4. Fig. 5. Fig. 6. Meri. AL re ba, 5 EXPLANATION OF PLATE LXXXI. — ? a i" Cyclops bicolor; abdomen of female, dorsal surface Cyclops bicolor; first antenna of female (x 340). Cyclops fimbriatus; female (x 72). — . Cyclops fimbriatus; fifth foot (x 340). Cyclops fimbriatus; fourth foot (x 348). a7 Cyclops fimbriatus; furca (x 348). . . Cyclops fimbriatus; antenna of female (x 300). Plate LUXXN1. Trans. Wis. Acad., Vol. XVI. ent INDEX OF SPECIES. Cyclops adolescens, 1099. “_ aequoreus, 1106. agilis, 1094. orl albidus, 1087. americanus, 1073. annulicornis, 1087. A ater, 1071. “i bicolor, - 1102. Gs bicuspidatus, 1078. “I brevicornis, 1072. brevisetosus, 1102. “a brevispinosus, 1073. f canthocarpoides, 1039. #5 capilliferus, 1093. ai Clausii, 1072, 1087. coronatus, 1090. erasstcornis, 1104. a diaphanus, 1102. os distinctus, 1087. Pri Dumasti, 1106. oh edax, 1082. Sg FHintzii, 1078. = fimbriatus, 1194. a Pischeri, 1099. i fluviatilis, 1097. i Forbesi, 1079. ao gigas, 1072, 1078. Se gracilicornis, 1087. ee Gredleri, 1104. gyrinus, 1087. te helgolandicus, 1078. ingens, 1073. “ imsectus, 1073. lascivus, 1099. Leewwenhoekit, 1081. DLeuckarti, 1081. longicornis, 1097. macruroides, 1095. magniceps, 1106. magnoctavus, 1097. margot, 1104. minnilus, 1079. modestus, 1093. Cyclops navus, 1078. ee odessanus, 1078. oithonoides, 1081, 1087. orientali, 1101. 6é pareus, 1073. pauper, 1104. pectinatus, 1078, 1081. pectinifer, 1094. pentagonus, 1097. perarmatus, 1099. phaleratus, 1099. i Poppet, 1104. i. prasinus, 1097. pulchellus, 1078. 1082. quadricornis var. b, 1087. quadricornis var. c, 1090. Scourfeldi, 1082. serratus, 1079. serrulatus, 1094. serrulatus var. elegans, 1094. serrulatus var. montanus, 1094. co stgnatus, 1087, 1090. signatus var. annulicornis, 1088 . signatus var. coronatus, 1090. signatus var. fasciacornis. 1087. simplex, 1081. tenwis, 1085. tenwuicornis, 1081. 1090. Thomasi, 1078. uniangulatus, 1073. varicans, 1101. varius, 1095. ; varius var. brachyurus, 1095. varius var. denticulata, 1095. varius var. proximus, 1095. varius var. speratus, 1095. viridis, 1072. viridis var. americanus, 1076. viridis var. brevispinosus 1075. viridis var. ingens, 1075. viridis var. parcus, 1076. virido-signatus, 1088. Hemicyclops aequoreus, 1106. Monoculus quadricornis albidus, 1087. Monoculus quadricornis fuscus, 1090. Monoculus quadricornis var. viridis, 1072. reat Me ‘ a = es ee 5 MTA ~ 3 9088