218 WISCONSIN PHYTOPLANKTON 



PLATE 33. 



Page 



Figs. 1-2. Quadrigula Pfitzeri (x 1000) 138 



Fig. 3. Quadrigula Chodati (x 1000) 138 



Figs. 4-6. Quadrigula lacustris (Fig. 4, x 500; figs. 5-6, x 1000) 139 



Fig. 7. Elaktothrix viridis (x 825) 140 



