VI 



ILL USTRA TIONS. 



PT,ATE 



XVII. 

 XVIII. 



XIX. 

 XX. 



XXI. 

 XXII. 



Curves of annual distribution of Bosmina per square me- 

 ter in Green lake 33 



Curves of annual distribution of Eurycercus lamellatus 



per square meter in Lake Winnebago .... 34 



Curves of annual distribution of Chydorus sphaericus 



per square meter in Lake Winnebago .... 35 



Curves of annual distribution of Leptodora hyalina per 



square meter in Lake Winnebago 36 



Curves of annual distribution of total plankton in Lake 



Winnebago per square meter . ... . . . 38 



Curves of annual distribution of total plankton in Green 



lake per square meter 38 



