214 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 



Mac roth rix serricaiidata Uaday. 



Shell rounded, punctate, transparent, obtusely angled caudad. 

 Caudal part of dorsal margin serrate, ventral margin nearly straight, 

 sparsely ciliate cephalad. Antennules long, subcylindrical, attenuate 

 at the end, slightly curved, armed with minute setne. Post-abdomen 

 rounded at the end, sinuous above the anus, serrate with strong teeth. 

 Length 0.9 to 1.0 mm. This species is near to our own M. xxmper. 



*Macrothrix rosea Jurine. 



Plates LIV, Figs. 1-3; LVI, Figs. 5-7, 11, 13. 



Monoculus roseus — Jurine. 

 Lynceus roseus — Desmarest. 

 Daphnia rosea — M. Edwards, Jurrell. 

 Echinisca rosea — Lievin. 



The body is sub oval, terminating behind in an acute angle; the 

 lower margin is less conspicuously spined than the last or the following; 

 the antenniB are but slightly dilated at the end and nearly straight. 

 The longest seta of the antennae is longer than in the last, reaching 

 beyond the tips of the terminal seta^; abdomen more slender, sinuate 

 in front, beset with short hairs. 



Length 0.6 mm., male 0.3 mm. The male has small claws on the end 

 of the post-abdomen, and the antennules are curved and elongated. 



In a later publication Birge finds small claws on the post abdomen 

 of the male which resemble that of Bosmina. On the posterior side of 

 the apex of the antennules of the male is a cluster of five or six long 

 sense hairs peculiar to this species. 



*Macrothrix tenuicoriiis Kurz. 

 Plates LIV, Figs. 5-8; LVI, Figs. 13, 12, 20. 



(See Notes on Cladocera of Minnesota, p. 245.) 



The body is oval, produced posteriorly in a sharp point; the ab- 

 domen is strongly arched, while the upper outline of the head is a 

 regular curve or slightly extended in front of the eye; the antennules 

 are long, nearly straight and a very little narrowed toward the end, 

 just in front of which is a series of short teeth; there is no lateral 

 spine, but a strong terminal one in addition to the sensory filaments; 

 the pigment spot is large, the eye small and the lobus opticus well 

 separated from the ganglion; the antenna have a very powerful basal 

 joint; the elongated seta is very stout and densely spiny, with a tooth 

 at its flexure; two of the terminal sefpe are spiny, for the basal half; 

 the valves are beset with very long spines in sets of three each, all 

 having dificrent positions; the abdomen is nearly as in Jf. rosea, but 



