6io 



FRESH-WATER BIOLOGY 



FIG. 937. Stephanoceros eich- 

 hornii Ehr. X 60. (After 

 Weber.) 



IIG. 938. Apsilus bucinedax Forbes. 

 Ventral view. X6s. (After Stokes.) 



FIG. 939. Alrochus tentaculatus 

 Wierz. X35- (AfterWierzejski.) 



FIG. 941. Acyclus in- 

 quietus Leidy. X 12. 

 (After Leidy, from Hud- 

 son and Gosse.) 



FIG. 940. Pompholyx 

 complanata Gosse. 

 X24S. (After Hud- 

 son and Gosse.) 



FIG. 942. Pterodina patina Ehr. A, Dorsal view of female. 

 X 225. (After Weber.) B, Dorsal view of the male. (After 

 Marks and Wesche.) C, Corona, showing the two wreaths of 

 cilia. (After Wesenberg-Lund.) 



