PLATE LIIL 



FIGS. PAGE 



1-2. Micrasterias Cnix-Melltensis (Ehrenb.) Hass. 1, 



x 520; 2, x 400 . 116 

 3. M. Crux-Melitensis. Form showing further divi- 

 sion of lateral lobules, x 400 . .116 

 4-5. M. Americana (Ehrenb.) Ralfs. 4, x 520 ; 5, x 



400 . . . . . 117 



6. J/. Americana var. Boldtii Gutw. x 400 120 



