KANSAS ACADEMY OF SCIENCE. 67 



Centropages is an oceanic genus, but has been found also in the fresh-water 

 lakes of Kerguelen's Island. 



The genus Cyclops appears to have been the bHe noire of American natu- 

 ralists. Comprising upwards of sixty valid species, many of which are de- 

 scribed in Latin, German, Danish or Dutch, and several of which have been 

 locked up in the Russian language, and the separation of species usually 

 depending, not upon single gross characters, but upon sets of microscopic and 

 often recondite details, it is hardly strange that American naturalists should 

 have neglected this genus for the study of others promising their labor larger 

 and quicker returns. We are not surprised, then, to find that but three valid 

 species of Cyclops have as yet been recorded from North America, and that 

 in our latest and best zoological text-book, written by something of a specialist 

 in insects and Crustacea, the long-since defunct and quartered "Cyclops 

 quadrieornis" is cited as type of the Entomostraca. 



I have given some time, during a part of the last two years, to the study 

 of the free-swimming Copepoda of the fresh waters about Cambridge, Mass., 

 and the present paper gives the major part of the results of those studies, 

 together with a translation of the descriptions of Cyclops by Poggenpol, pub- 

 lished in the Bulletin of the Friends of Natural History, 1874, vol. X, part 

 2, page 70 et seq. The translation has been made, so far as practicable, a 

 literal one, and is the work "of Mr. Ivan Panin, A. B., of Concord, Mass., to 

 whom the Russian language is native, and whose thorough knowledge of 

 English and Latin has made it possible to obtain an accurate translation of 

 the technical terms. 



Before passing to the list of species, I would note the occurrence of Lage- 

 nella mobilis, Rehb. in North American Cyclops. Before Rehberg's descrip- 

 tion of Lagenella mobilis (AbhandL, vom naturwissch. Vereine zu Bremen, 

 Band VII, Heft 1, 1880, p. 68, Taf IV) came under my notice, I had ob- 

 served and made drawings of this curious gregarine, parasitic in Cyclops, at 

 Cambridge, Mass. Though only described in 1880, it appears to have been 

 previously noticed by Vernet (Observations Anat. et Physiol, sur le Genre 

 Cyclops), and doubtless has the same cosmopolitan distribution as does the 

 genus, its host. 



In the list which follows, the dimensions given are those of females, unless 

 otherwise stated. The apical caudal setse are numbered outward. 



Cyclops elongatus, Cls. (PI. I, figs. 1 and 19-23.) 



Observed sparingly in a rain-pool near the Cambridge Museum of Com- 

 parative Zoology. 



Cyclops isignaius, Koch, var. nov. fasciacomis. (PI. II, fig. 15.) 

 The ditches near Glacialis Pond yield a Cyclops which agrees well in 

 structural characters with C signatus, Koch, but which differs from the 

 European signatus so markedly in coloration as to constitute a distinct va- 

 riety. The color-pattern appears constant for localities about Cambridge. 



