PLATE CXL. 



FIGS. PAGE 



1-2. Staurastrum scabrum Breb. X 520 . . 81 



3-4. St. subscabmm Nordst. 3, X 400 (after Nordstedt) ; 



4. X 520 . . .82 



5. St. subscabrum forma scabrior West. X 400 . 83 

 6-7. St. acarides Nordst. 6*, X 510 ; 7, X 570 (after 



Nordstedt) . . . .73 



8-10. St. acarides var. eboracensis West. 8*, X 510 ; 

 9, X 400 ( in outline only) ; 10, forma hexagona 

 in vertical view, X 400 (in outline only) . 74 



11-13. St. asperum Breb. 11*, X 510; 12 and 13, X 520 74 

 14*. St. spongiosum Breb. X 510 . . 76 



15. -St. spongiosum, var. Griffithsianum (Nag.) Lagerli. 



X 600 (after Nageli) . . .78 



16*. St. spongiosum var. perbifidum AVest. X 510 . 78 



