PLATE CLXVIT. 



FTGS. PAGE 



1-4. Oocardium stratum Nag. var. minor Carter. 1*, 

 vegetative cell, X 510 ; 2*, 3* and 4*, stages in 

 conjugation, X 510 . . . 205 



5. Euastrum montanum West. Zygospore, X 600 



(after Liitkemiiller) . . .265 



6. Roya obtusa (Breb.) West var. montana West. 



Zygospore, X 510 (after Harris) . . 260 



7. ? Staurastmm inflexum Breb. Zygospore, x 600 



(after Liitkemiiller ; see p. 109) . . 109 



8*-9*. St. Meriani Reinsch. Zygospores, X 550 . 269 



10. Spondylosium Lundellii Borge. var. triquetrum 



(Lund.) nob. x 400 . . 225 



11*. Micrasterias papillifem Breb. Zygospore, X 435 266 



