PLATE XXII. 



FIGS. 



1-3. Closterium attenuatum Ehrenb. x 220 . 169 



4_5._ Cl. turgidum Ehrenb. 4, x 200 (after Ralfs) ; 



5, x 400 . . . 170 



6-14. CL Pritchardianum Arch. 6 and 7, x 200 

 (after Archer) ; 8 and 9, outline drawings, 

 x 120; 10, apex of semicell, x 520; 11, 

 part of cell- wall showing dotted strias, x 520 ; 

 12, semicell with prominent marks, x 520 ; 

 13 and 14, zygospores, x 120; 14 is an 

 abnormal zygospore produced by the conjuga- 

 tion of three cells .172 



