16 Wisconsin Academy of Sciences, Arts and Letters . 
place during the summer, the oxygen conditions in the shal¬ 
lower water would not interfere, and those individuals that are 
found in the deep water may be the descendants of those nearer 
the margins of the lake. Then, too, the reproductive period 
may come in deep water in the early part of the season before 
Corneocyclas enters its quiescent period, and both temperature 
and oxygen conditions are very favorable just after the fall 
overturn for a reproductive period at that time. 
