202 WISCONSIN PHYTOPLANKTON 



PLATE 79. 



All figures x 500. 



Page 



Figs. 1-5. Staurastrum Johnsonii W. & G. S. West 104 



Fig. 6. Staurastrum Johnsonii forma parvum 105 



Figs. 7-11. Staurastrum Johnsonii var. depauperatum var. nov 105 



Fig. 12. Staurastrum natator W. West 106 



Figs. 13-15. Staurastrum natator var. crassum W. & G. S. West 107 



Figs. 16-18. Staurastrum urinator sp. nov 107 



