31 



7b Punctae in uni seriate rows throughout; or with geometric 

 facets - COSCINODISCUS 



Fig. 31. Coscinodiscus denarius , (k), 

 cells 40-90u in diameter. 

 X 1000. 



Notes : 



facet 



valve view 



Fig. 32. Coscinodiscus lacustris , (k), 

 cells 20-50u in diameter, 

 with marginal spines. X 1000. 



Notes : 



valve view 



Fig. 33. Coscinodiscus Rothii , (8), 

 cells 25-40|i in diameter. 

 X 1000. In Red and Lower 

 Mississippi Rivers. 



Notes : 



valve view 



