170 WISCONSIN PHYTOPLANKTON 



PLATE 6;{. 



All figures x400. 



Page 



Figs. 1-3. Micrasterias radiata Hass 50 



Fig. 4. Micrasterias radiata var. simplex (WoUe) 6. M. Smith 51 



Fig. 5. Micrasterias americaim (Ehr.) Ralfs 52 



