208 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 
Bosmina bohemica Hellich. 
Body large, slender. Head high, front uniformly rounded, flagel- 
lum nearer the end of beak than the eye. Beak short, rounded. 
Antennules long and arched, composed of 16 or 17 segments. The 
triangular spine above the sensory filaments large and acute. Shell 
as long as high, highest in the middle. Spine long, curved dorsad 
and toothed. Shell irregularly reticulate and longitudinally striate. 
Post-abdomen large, truncate and excavated. Inferior angle ciliate. 
Claw protuberance long, unarmed. Claw with six spines at the base. 
Length 0.6 mm. 
Bosmina microps P. E. Mueller. 
Oblong, length much greater than height. Front not protuberant. 
Caudo-ventral angle of the shell without the spine, rectangular. An- 
tennules long, nearly straight, flagellum nearly midway between beak 
and eye. Length 0.5 mm. or less. The shell is reticulate and the 
antenne are very short. 
Bosmina maritima P. E. Mueller. 
Oblong, longer than high, front moderately protuberant. Shell 
strongly arched above; spine long, directed obliquely ventrad. An- 
tennules slender, gently curved; flagellum near the beak. Shell 
smooth. Length 0.5 mm. 
Bosmina brevirostris P. E. Mueller. 
Oblong, length greater than height, front greatly protuberant. 
Shell arched above, strongly spined. Antennules moderate, straight- 
ish but inclined caudad. Flagellum near end of beak, sensory sete 
remote. Length 0.6 to 0.7 mm. Color reddish. 
Bosmina diaphana P. E. Mueller. 
Gibbous, length greater than height, front not protuberant. A 
slight sinuosity in the dorsal outline over antenne. Shell very 
strongly arched without the spine, smooth. Antennules very long, 
curved, converging at the ends. Flagellum near the end of the beak. 
Length 0.6 to 0.7 mm. 
Bosmina lilljeborgii Sars. 
PLATE XLYV, Fia. 3. 
Very gibbous dorsally, length and breadth nearly equal, front not 
protuberant. Dorsal outline sinuous over the antennz. Spine ab- 
sent. Antennules longer than the body, straight or slightly curved, 
divergent. Flagellum near end of beak. Length 0.6 to 0.75 mm. 
a 
