27 



Fig. 21. Cyclotella ocellata , ( 3), cells 6-20u in diameter; 

 central area with 3-^ ocelli. X 1000. In Great 

 Lakes. 



valve views 



Notes 



Fig. 22. Cyclotella pseudostelligera , (7), 

 cells 7-Su in diameter; has 

 marginal spines. X 3000. Widely 

 distributed. 



Notes : 



valve view 



Fig. 23. 



Cyclotella stelligera , (3), cells 

 5-25m in diameter. X 1000. Abun- 

 dant in the southeast. 



Notes : 



valve view 



