ENTOMOSTRACA OF MINNESOTA. 207 
These curious animals are often found at great depths in the larger 
lakes, though they may also occur in weedy localities. They are poor 
swimmers and rarely caught in the net. 
*Bosmina cornuta Jurine. 
PLATE LXV, Fies. 3-5. 
Oval, almost spheroidal. Head high, concave below the eye, 
Beak long, its flagellum midway between the eye and end of beak. 
Hye large. Antennules curved like a hook composed of 10 or 11 seg- 
ments. Antenne as long as the end of the antennules, three-jointed 
ramus with five sets, the four-jointed ramus with three sets. Shell 
high, greatest height in middle of the length. Back uniformly curved 
and forming an obtuse angle, with the straight caudal margin. 
Spines at the caudo-ventral angle short, turned dorsad. Shell hex- 
agonally reticulate. Post abdomen short, truncate and excavated api- 
cally, with two anal spines. Claws finely pectinate. Length 0.4 to 
0.54 mm. 
* Bosmina longirostris O. F. Miiller. 
PRATES XchV~ Bie 2°) LX V;, Pre. s2: 
General form oval, shell highest in the middle. Head high, beak 
short, flagellum arising from near the end of the beak, front pro- 
tuberant. Antenne longer than in B. cornuta, three-jointed ramus 
with five, four-jointed with four setw. Spines of shell short and 
Straight. Post-abdomen short, truncate, unarmed. Claws on a pro- 
tuberance, pectinate. Length 0.31 to 0.35 mm. 
Bosmina longicorpis Schoedler. 
Very similar to B. longirostris, but the front is not protuberant, the 
flagellum is midway between eye and end of beak. The spines of 
the shell are long, toothed ventrad and directed obliquely dorsad. 
Shell unmarked. The finely pectinate claws have at their base sev- 
eral large accessory spines. Length 0.36 mm. 
Bosmina brevicornis Hellich. 
A large species with depressed head having a uniformly rounded 
front. Shell higher than long and coarsely reticulate, spine short 
and curved. The beak is short and little curved, the flagellum being 
quite near the eye. The antennules have seven segments. The post- 
abdomen is large without anal spines and the claws are simply pectin- 
ate. Length 0.55 mm. Hellich says this differs from B. brevirostris 
P. E. Mueller, which has a protuberant front and long serrate spine 
and the claws have seven accessory spines. 
