PLATE XII. 



FIGS. PAGE 



1-5. Closterium didymotocum Corda. 1 and 2, x 

 400 ; 3 and 4, x 200 (after Kali'*) ; 5, apex 

 of semicell, x 700 . . .116 



6-7. Cl. didymotocum vav. asperulatum West & Gr. S. 



West. 6, x 220; 7, x 520 . .118 



8-10. CL macilentnm Breb. 8 and 9, x 200 (after 



Brebisson) 10, x 220 . . .118 



1-13. CL angitxtatum Kiit/. 11 and 12, x 220; 13, 



x 520 119 



