PLATE LY. 



FIGS. PAGE 



1-3. Micrasterias Mahabuleshwarensis Hobson var. 

 WaUichii (Grun.) West & G. S. West. 1, 

 vertical view, x 520 ; 2 and 3, abnormal semi- 

 cells from the plankton of Loch Bhaic, Scot- 

 land, showing malformation of both lateral 

 and polar lobes, x 520 . . 122 



4. Euastrum crassum (Breb.) Kiitz. var. Taturnii 



West & G. S. West, x 520 8 



