226 Illinois State Laboratory of Natural History. 



the species in question differ, however, so considerably in 

 these two articles that, as Schmeil ('98) says, nothing certain 

 can be said of this species until Herrick declares himself as to 

 which of the two sets of drawings are correct. Schmeil regards 

 Herrick's form as possibly a new species. The recent dis- 

 covery of a new species of this genus, Kurt/femora herdmani 

 I. C. Thompson and A. Scott, in the St. Lawrence River and 

 Gulf removes all doubt as to the presence of the genus in 

 American waters.* 



Of the three genera treated in this paper, Osphranticuni, 

 containing a single species, &&& Epischura, containing threei , 

 are, so far as now known, confined strictly to North America 

 and are strictly fresh- water in their habitat. Osphranticum 

 is ordinarily found in shallow or stagnant lakes and ponds 

 (Forbes] or in running water (Herrick), while Epischura 

 occurs, as a rule, in deep clear lakes. The genus Limnocalanus 

 is peculiar in its habitat. One of the two species, L. sinensis 

 Poppe, from China, is, so far as known, a strictly fresh-water 

 form, while the other, L. macrurus Sars, although found as 

 yet in America in freshwater only, occurs in Europe and Asia 

 in both fresh- and salt-water lakes and in the ocean. Since 

 there are only these two species known, it was thought best 

 to treat both in this paper. L. grimaldii de Guerne is re- 

 garded by the writer as a synonym of L. macrurus Sars^, for 

 reasons given in the discussion of the latter species. 



A brief discussion of the structural similarities and differ- 

 ences indicative of the relationships of the genera Osphranti- 

 cum, Limnocalanus, Diaptomus, and Epischura may properly 

 precede this paper, special attention being given to characters 

 which are regarded as of generic or specific value. 



Giesbrecht, in his "Monograph" ( ,( .>2), gives special rank 

 to the structure of the first pair of antenna- as a distinguish- 



■M'e "On the Plankton collected continuously during two Traverses of the North 

 Atlantic in the Summer of 1897; with Descriptions of New Copepoda: and an Ap- 

 pendix on Dredging in Puget Sound." By W. A.. Herdman, I. C. Thompson, and An- 

 drew Scott. Trans. Liverpool Biol. Soc, Vol. XII. (1897), p. 79. 



fE.fluviatilis Herrick is not considered one of these. 



i'l'lie Zoologisch.es C'entraibfatt (Jahrg., 111., pp. 4si 183J contains a review of an 

 article by X. Zograf entitled " Essaid'Explication de L'origine de la Faune des lacsde 

 la Russie ii' lairope" in which a reference occurs to /.. mad-onyx G. <». S. This is 

 probably an error, since it is the only reference toaspecies of that name which I 

 have hem able t>> find. 



