PLATE CXXIV. 



FIGS. PAGE 



1. Staurastrum sultpi/gmaBum West var. subangu- 



latumW. & G. S. West, x 520 . . 163 



2-4. St. inelegant W. & G. S. West, x 520 153 



5_9 t j$f, t orbicularev&r. hihernicurn'W. & G. S. West. 

 5, x 400 ; 6, x 520 ; 7-9, x 640 (after Nord- 

 stedt) . . . .156 



10-11. 8t. orlic-ular* Ralfs. 10, x 400 (after Roy and 



Bissett); 11, x 520 . . . 155 



12-16. 8t. orbicular* var. h'alfsii W. & G. S. West. 12, 

 x 400 (after Ralfs); 13 and 14, x 520; 15, 

 x 400; 16, zygospore, x 400 . . 156 



Fig. 14 is " forma major 3 . . .157 



17-19. St. tirbiculare var. depressum Roy & Biss. 17, 

 x 460; 18, x 600 (after Roy and Bissett); 

 19, x 520 .... 158 



