PLATE L. 



FIGS. PAGE 



1-2. Micrasterias denticulata Bret). 1, x 200; 2, 



zygospore, x 120 . . .105 



3-4. M. denticulata var. angulosa (Hantzscli) West & 

 &. S. West. 3, x 200 ; 4, zygospore, x 200 

 (after Eoy & Bissett) . . .107 



5. M. denticulata var. angustosinuata Gay. Portion 



of semicell, x 400 . . .108 



6. M. denticulata var. notata ISTordst. Qa, x 300 ; 



66, x 180 . . . 108 



7. M. denticulata var. subnotafa West. Vertical 



view, x 220 . . . . 108 



