PLATE CXXI. 



FIGS. PAGK 



1-2. Staurastrum conspicunm W. & Gr. S. West, x 520 143 

 3-6. St. lanceoltum Arch. 3 and 4, x 400 (after- 

 Archer) ; 5 and 6, x 500. 4 and 6, zygospores 149 

 7. St. lanceolatum var. compressum W. & Gr. S. West. 



x 520 . . . . 150 



8-9. St. parhyrhynchum Nordst. &, x 400 (after 



Noi-dstedt) ; 9, x 520 . . 151 



