886° THE AMERICAN NATURALIST.  [Vow. XXXIII. 
46. Claw of last joint of the second foot three times as long as the 
last segment. Dorsal edge of caudal ramus armed with five 
comps of eche n 3.0284 is « E. reptans (Baird)* 
aaa. Length between one mm. and two mm. 
4. Dorsal sete of caudal ramus transformed into a short spine or 
claw, situated near the subterminal claw. Shell seven thir- 
teenths as high as long . Æ. olivacea (Brady and Norman) 
bb. Caudal ramus with only the terminal claws developed, lacking 
oth the terminal and dorsal seta. Shell two and a half to 
three times as long as high . E. minnesotensis (Herrick) 
10. Ilyocypris Brady and Norman, 1889. 
Shell oblong, with a transverse median depression, coarsely punctate and 
tuberculate. Second antennal sete non-plumose, few; reaching a little 
beyond the apex of the terminal claws. Mandible palp four-jointed, with a 
setose branchial appendage. First pair of maxilla composed of four seg- 
ments, and a large branchial appendage bearing numerous terminal and 
about five reflexed basal sete. Second pair of maxille consisting of a 
conical lobe, which bears numerous short marginal sete, at the apex four 
stout plumose setz, and at the base an appendage of four radiating plumose 
filaments and a biarticulate process bearing three apical sete, one of which 
is plumose. The penultimate joint of the second foot has two marginal 
sete ; the last joint three long apical seta, but no claw. Caudal rami end- 
ing in two long and equal claws and one very short seta, marginal seta 
long, and attached near the middle of the ramus. No American forms 
11. Notodromas Lilljeborg, 1853. 
Shell of male and female unlike. Second antenne of both male and 
female six-jointed, natatory sete extending beyond the tips of the terminal 
claws. No branchial plate on the second maxilla; palp of same two-jointed 
in the female; in the male the terminal segment forms a scythe-shaped 
appendage. Second foot five-jointed, abdominal ramus long and slender. 
Eyes two, separate. Males numerous. 
a. Shell subquadrangular, surface smooth and shining. In the female, 
the caudo-ventral angle of the shell terminates in a horizontal, 
backwardly projecting, squamous, spine-like plate 
N. monacha (O. F. Mueller) 
12. Potamocypris Brady, 1870. 
Second antennæ four-jointed ; natatory seta numerous but short, not 
reaching beyond the middle of the terminal claws ; last joint with two 
