North. American Centropagidce. 229 



of Illinois, Indiana, Ohio, Michigan, Washington, Oregon, 

 Montana, Wyoming, Idaho, and Nevada. 



Through the kindness of Professor Smith I was able to 

 examine collections from Lake George and Lake James in 

 Steuben County, Ind., in which I found specimens of Epis- 

 chura lacustris and Diaptomus oregonensis. Mr. Chancey 

 Juday, Curator of Collections, University of Indiana, kindly 

 sent me collections from Tippecanoe Lake, Eagle Lake, and 

 Turkey Lake, in Indiana, in which occurred Epischura lacus- 

 tris, Diaptomus sicilis, D. oregonensis, and 1 >. siciloides. I also 

 acknowledge my indebtedness to Prof. G. 0. Sars, who kindly 

 furnished me with specimens of Limnocalanus grimaldii, thus 

 enabling me to compare them with L. macrurus — also fur- 

 nished by him to the Illinois State Laboratory of Natural 

 History; to Herr S. A. Poppe, for specimens of Limnocalanus 

 sinensis', to Professor Lillejeborg for Epischura nevadensis; 

 and to Dr. C. A. Kofoid, Superintendent of the Illinois Biolog- 

 ical Station at Havana, to whom I owe thanks for his many 

 kindnesses during my stay at the Station in July, 1896, and 

 while at the University. 



No illustrations accompany this paper, since the species 

 treated may be identified by figures already published. 



OSPHRANTICUM Forbes. 



Osphranticum, Forbes. '82a, p. 645. 

 Potomoichetor* , Herrick, '82, p. 23. 



< Osphranticum, Herriek, "84, p. 134. 

 Osphranticum, Herrick, "87, p. 12. 

 Osphranticum, de Gnerne et Richard, '89b. p. 149. 

 Osphranticum, Herrick and Turner, '95, p. 85. 



Cephalothorax compact, six-segmented, the first two seg- 

 ments continent above, the last segment produced into a 

 bluntly-rounded lobe on each side. Abdomen (furca in- 

 cluded) composed of five segments in the female, of six in 

 the male. Furcal rami hairy on the inner margins ; armed 

 with five plumose seta3, the second from within the longest, 

 and with a delicate smooth seta on the inner margin of the 



*Spelled Potamoichetor in Ilerrick's subsequent references. 



