PLATE XC. 



FIGS. PAGE 



1-3. Cosmarium subalatum West & G. S. West. 



x 520 . . . . 255 



In fig. 2 the printer is responsible for the 

 omission of the sinus. 



4. C. hexalobum Nordst. x 570 (after Nordstedt) 257 

 5. C. hexalobum var. 'minus Roy & Biss. x 600 



(after Roy & Bissett) . . .258 



6. C. hexalobum Nordst. Small form, but not 

 agreeing with "var. 'minus Roy & Biss." 

 x 500 . . . . .258 



7. C. alatum Kirchn. x about 300 (after Kirch- 



iier's original drawings) . . . 256 



8. C. alatum var. sequatoriense Nordst. x 520 . 257 

 9-10. C. nasutum Nordst. 9, x 570 (after Nord- 

 stedt) ; 10, x 400 . . . 259 

 11-12. C. nasutum forma granulata Nordst. x 520. 



12, zygospore .... 260 

 13. C. nasutum var. asperum West & Gr. S. West. 



x 400 . . . . 261 



14-15. C. eductum Roy & Biss. 14, x 600 (after 

 Roy and Bissett); 15, x 570 (after Nord- 

 stedt) . . . .261 

 16. C. didymochondrum Nordst. x 570 (after 



Nordstedt) . . . .262 



17-18. C. subnotabile Wille. 17, x 400 (after Wille) ; 



18, x 520 . . . 263 



19-20. C. lumens Nordst, 19, x 570 (after Nord- 

 stedt) ; 20, x 520 . . 264 



