IOWA ACADEMY OF SCIENCES. 



173 



West Okoboji, fifteen to twenty 

 feet below surface 



f Dapbnella bracbyura. 

 Daphnia kal. , vai-iety retrocurva. 

 Simocepbalus serrulatus. 

 Ceriodapbnia consors. 

 Eurycercus lamellatus. 

 Danhevedia setiger. 

 Cbydorus spbaericus. 

 Cbydorus globosus. 

 Camptocercus rectirostris. 



( Sida crystallina. 

 Ceriodapbnia reticulata. 

 Ceriodapbnia consors. 

 Dapbaia kal., variety retrocurva. 

 Daphnia byalina 

 Macrothrix laticornis. 

 Eurycercus lamellatus. 

 Cbydorus spbaericus. 

 Leydigia quadrangularis. 



r Dapbnella bracbyura. 



below surface ] Dapbnia kal., variety retrocurva, 



I Cbydorus spbaericus. 



East Okoboji, surface . 



Spirit Lake, ten to fifteen feet 



Raccoon River, Adel, Iowa. 



Raccoon River at Sac City. 



I Ceriodapbnia reticulata. 

 J Scapboleberis mucronata. 

 I Iliocryptus sordidus. 

 [_ Pleuroxus denticulata. 



( Scapboleberis mucronata. 



Simocepbalus serrulatus. 

 < Cbydorus spbaericus. 



Pleuroxus denticulatus. 

 [_ Alona sp? 



THE ANATOMY OF SPH^RIUM SULCATUM LAM. 



BY OILMAN A DREW. 



For a number of years the embryology of the Cyrenidas has 

 been attracting considerable attention, but little has been 

 added to our knowledge of the general anatomy since Dr. 

 Franz Leydig's publication in 1855 (No. 5), who recorded such 

 anatomy as could be made out from young and rather trans 

 parent specimens.* 



It is my present intention to continue the work here begun 

 on Sphsorium to a comparative anatomy of the Cyrenidse, but in 



*I find a reference to a paper by Temple Prime, entitled: Notes on the Anatomy of 

 the Oorbiculidas and Translation from the Danish of an article on the Anatomy of 

 Cyclas by Jacobson. Bui. Museum Comp. Zool., Cambridge, Vol. V. This volume 

 unfortunately is not to be found In the reference libraries of Baltimore. 



