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PL.ATE J. 



Ceriodaphnia scitula^ (small var.) ephippial female. 



Bosmina longirostris. 



Bosmina lilljehorgii. After P. E. Mueller. 



Bosmina^ hook on the first foot of male. 



Scapholeberis mucronata. 



Scapholeheris cornida, head. 



Scapholeberis angulata^ head; 7a. angle of shell. 



Pleiiroxus denticulatus^ male. 



Simocephalus americanus, head of female. 



Bosmina^ post-abdomen of male (after Weismann). 



