884 THE AMERICAN NATURALIST. [VoL. XXXIII. 
c. Dorsal seta the width of the ramus from the subterminal 
claw. Terminal claw of second foot nearly straight 
C. pellucida Sharpe 
cc. Dorsal seta at least twice the width of the ramus from the 
subterminal claw. Terminal claw of the second foot 
strongly curved .. . . C. incongruens Ramdohr 
bb. Dorsal seta of caudal ramus not more than half the length of the 
ramus. 
c. Dorsal seta the width of the caudal ramus from the sub- 
terminal claw. Shell yellowish brown, marked with bluish 
black longitudinal stripes on the dorsum and sides, covered 
with coarse hairs, shell thin C. durlingtonensis Turner 
cc. Dorsal seta of the caudal ramus twice the width of the 
ramus from the subterminal claw. Color yellowish green, 
shell reticulated with contorted lines which are most dis- 
tinct on the cephalic portion of the valves. Shell thin 
crena Turner 
8. Cypris O. F. Mueller, 1785. 
Second antennz five-jointed, natatory sete extending to the tip of the 
terminal claws. Mandibular palp not extending beyond the tip of the man- 
dibular teeth, the first mandibular process armed with two biarticulate 
thorns. Branchial plate of the first maxilla large, bearing stiff, plumose 
seta. Second maxilla provided with a branchial plate. Caudal rami 
stout. Parthenogenetic. 
a. Length three mm. or more. 
6. Both spines on the first mandibular process of the first maxilla 
smooth, dorsal margin of shell ie! convex. Marked with 
dark bands . . . C. herricki Turner 
66. Both spines on the first ‘gandibalar process of the first maxilla 
toothed, dorsal margin of shell ed en marked with 
dark banda : . . na . . CC. perelegans Herrick 
aa. Length between one and two mm 
4. Both spines on the first mandibola process of the first maxilla 
smooth. 
c. Terminal claw of the second foot as long as the last joint. 
Shell noticeably less than three times as long as high. 
d. Caudal ramus straight; subterminal claw two thirds as 
long as the terminal. Shell four ninths as high as 
lbag so ee as . C. clavata Baird* 
dd. Caudal ramus weakly S-shaped 
g. Subterminal claw of the caudal ramus half as long 
as the terminal. Shell two thirds as high as 
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