North American Fresh-water Ostracoda. 459 



Second pair of autennge five-segmeDted, natatory setae 

 reaching beyond the terminal claws (except in one variety). 

 Second pair of maxilla? very characteristic; palp rudi- 

 mentary, two-segmented; branchial plate formed of six 

 plumose setae. 



Second foot five-seguiented, terminal segment short, 

 provided with two long, unequal, backwardly directed 

 setae and a rather short forwardly diiected seta. 



Caudal rami stout; dorsal seta distant from the sub- 

 terminal claw\ 



This genus contains but one known species^ which as 

 jet has not been found in America. 



XII. Cypria Zenker. 



1785-1854. Cypris, auctorum. 



1820. Ifonoculns, Jurine (36, p. 178). 



1854. Cypria, Zenker ((75, p. 77). 



1889. Cypria, Brady & Norman (9, p. 68). 



1891. Cypria, Vdvra (68, p. 62). 



I give the following general description of the genus 

 from Vavra's emendation (68). 



Second pair of antennae five-segmented in the female 

 and six-segmented in the male; distal extremity of the 

 fourth segment in the male provided with two special 

 sense organs ; natatory setae, on the end of the third 

 segment, extraordinarily long, reaching far beyond the 

 tips of the terminal claws. 



Mandibular palp, also that of the first maxilla, unu- 

 sually well developed. Second maxilla with a well- 

 developed branchial plate; palp unsegmented in the 

 female, ending in three bristles; right and left palps of 

 male different in shape, each forming a hooked prehen- 

 sile organ. 



Terminal segment of second foot small, about a third 

 as long as the fourth segment, bearing two nearly equal 

 backwardly directed setae, which are comparatively short, 

 and a lono; forwardlv directed seta. 



