North American Fresh-icater Ostracoda. 439 



Second pair of antennae five-segmented ; natatory setae 

 reaching to or barely beyond the tips of the terminal 

 claws. Mandibular palp not extending beyond tips of 

 mandibular teeth; first mandibular process armed with 

 two biarticulate spines, which are commonly toothed. 

 Branchial plate of first maxilla large, bearing stiff plu- 

 mose setae. 



The second foot ends in a bill-shaped segment (as in 

 Cypridopsis) and a strong chitinous claw. 



Caudal rami stout, ending in two long slender claws 

 and a terminal seta. Dorsal seta always near the sub- 

 terminal claw. 



The males are as yet unknown. At least eight species 

 occur in America, of which two are herein added to the 

 list for the first time: C. reticulata Zaddach, not pre- 

 viously reported from this country, and C. testudinaria^ 

 described as new, 



KEY TO SPECIES OF CYPRIS. * 



1 (6). Both spines on the first process of the first pair 



of maxillae smooth. 



2 (5). Terminal claw of the second foot as long as the 



last segment. Shell noticeably less than three times 

 as long as high. Terminal seta of caudal ramus a 

 third as long as the terminal claw and of same 

 length as the dorsal one. 



3 (4). Caudal ramus straight; subterminal claw two 



thirds the length of the terminal one. Shell four 

 ninths as high as long. C. clavata Baird. 



4 (3). Caudal ramus bent, weakly S-shaped; subter- 



minal claw half the length of the terminal one. Shell 

 two thirds as high as long. C. virf:xs Jurine. 



5 (2). Terminal claw of second foot twice as long as 



the terminal segment. Shell fully three times as long- 

 high. Subterminal claw of caudal ramus half as long- 

 as the terminal one; terminal seta three times as 

 long as the dorsal one, which is set closely against 



* Partly a modification of Vavra's Icey (68, p. 83). 



