PLATE CXXXIII. 



FIGS. PAGE 



1. Staurastrum cuspidatum var. coronulatum Gutw. 



X ? (after Gutwinski) . . .26 



2-3. St. pseudocuspidatum Roy & Biss. 2, x 520 ; 



3, X 400 . . . .26 



4. St. tunguscanum Boldt. X 400 (after Boldt) . 28 

 5. St. Ungeri Reinsch. X 500 (after Reinsch) . 28 

 6-7. St. mbcruciatum Cooke & Wills. 6*, x 510 ; 



7, X 500 . . . .42 



8-10. St. Avicula Breb. 8, X 520 ; 9*, X 510 : 10*, 



forma, X 510 . . . .40 



11*. St. Avicula var. subarciiatum West. X 510 . 41 

 12. St. Avicula Breb. forma. Zygospore, X 400 (after 



Roy & Biss.) . . . .40 



13-14. St. denticulatutn (Nag.) Arch. 13, x 520 ; 14, X 



500 . . . . .38 



15. ? St. denticulatum. Zygospore, X 520 (from an 



unnamed drawing by Professor West) . 39 



16. St. corntitum Arch. X 600 (after Roy & Biss.) . 31 

 17-19. St. lunatum Rails. 17 and 18 x 400 ; 19, X 520 29 

 20-22. St. lunatum var. planctonicww. 20, X 500 ; 21 



and 22, X 520 . . . . 30 



