PLATE XXIII. 



FIGS. PAQE 



1-3. Closterium pronum Breb. x 520 . .173 



4-5. CL aciculare Tuff en West var. *ul>r-</i< /// 



West & G. S. West, x 520 . . 175 



6-8. CL Crrafinm Perty. 6, x 520 ; 7 and 8, x 400 176 



9-\4,Cl.acutumBreb. x 520; 14, zyo-<> S pore . 177 

 15. C7. acutnm var. Linen (Perty) West ct Gr. S. 



West, x 520. . . . 178 

 16-19. CL ftubulatnm Kiitz. 16 and 17, x 400; 18, 



smaller forms, x 520; 19, zygospore, x 520 . 179 



20-21. CL idiosporum West & G. S. West, x 520 . 180 



