ENTOMOSTRACA OF MINNESOTA. 187 



a. Eye near the end of the head inagniccps, 202^ 



h. Eye not near the end of the head. 



* Abdominal processes free kalbergensis, 203 



** Abdominal processes united cuciillata, 203 



[Not in the key: diibia, 196; peuriata and cuivirostris, 194; tliorata,197^ 

 liermani, 198; similis, 204; bolivail, 205; cariuata, 205; luiMhollzii^206.], 



Daphnia scliaifferi Baird. 



Plate LI, Figs. 15. 



Daphnia pennata — Mueller. 



Daphnia piilex — Straus, Koch (fide P. E. Mueller). 



Daphnia magna — Lilljeborg, Leydig, etc. 



The largest species of the genus, is of an elongated oval and ven- 

 tricose form. The head is short and evenly rounded. The spine is 

 entirely absent in old females and of only moderate length in the 

 young. The antennules of the male are long and have a very long 

 flagellum. The post-abdomen is narrowed suddenly below the anus 

 so that the spines consist of two sets; the terminal claws are spiny at 

 the base. The species may be recognized at once by the concavity of 

 the dorsal margin of the post-abdomen. The plate will make any de- 

 tailed description superfluous. A common species in Europe, but not 

 yet found in America. 



The sole distinction between this species and D. magna Straus is 

 found in the fact that the intestinal coeca are very long and recurved 

 in D. scluefferi and short and thickened at the free extremity in D. 

 magna. We fail to discover sufficient reason for separating them. 



Daphuia psittacea Baird. 



Baird '50; Schoedler '58; Fric'72i; Kurz '74; Hellich '77; Herrick '84; EIymann'87; 



Daday '88. 



Head short, rounded in front, beak very short. A depression sepa- 

 rates the head from the oval, ventricose body. Spine long directed 

 dorsad. Eye distant from the margin of the head. Post-abdomen 

 long, narrowed toward the end, somewhat sinuous in the caudal 

 margin. Anal teeth about ten. Claw bipectinate, rather long. 

 Length 1.8 to 1.9 mm. 



This species is at once recognized by the head, which is very short 

 and evenly curved, or nearly so, from the heart to the beak. The 

 shell is high, oval, with a rather short spine. The fornices are wide 

 and angled behind. The antennules are longer than in most species; 

 the post-abdomen is very large, but narrows toward the end and has 

 comparatively few anal teeth, which are of unequal size. This is one 

 of the largest of the genus. Not yet found in America. 



