PLATE LII. 



FIGS. PAGE 



1-9. Micrasterias radiata Hass. 1, x 400 ; 2, x 520 ; 

 3, basal view of semicell, x 520 ; 4 ; x 200 ; 

 5 ; specimen showing reduction of divisions of 

 lateral lobes, x 300; 6, x 200; 7, drawing 

 of an American specimen which approaches 

 M. dichotoma Wolle ; 8 and 9, abnormal con- 

 ditions of lateral lobules, x 400 . .113 



