PLATE XLIX. 



FIGS. PAGE 



1-7. Micrasterias denticulata Breb. 1, x 400 ; 2 and 



3, polar lobes of two individuals, x 220 , 



4, vertical view ; 5, side view ; 6, basal view 

 of semicell; 4-6, x 200 (after Archer). 7, 

 zygospore, x 400 (after Ealfs) . .105 



