128 



are often very long and the zygospore is large and ellipsoidal, frequently with 

 one or two mamillate protuberances at the poles ; length of zygosp. 35 72 /x, 

 breadth 1640 /* (fig. 46 A). D. Icevis (Kiitz.) W. & G. S. West is a larger 

 species with shorter cells, which are 20 26 p in thickness and 2| 4 times 



Fig. 46. A, Debarya glyptosperma (De Bary) Wittr., from Fairfield, Westmoreland 

 (x275). B, D. calospora (Palla) W. & G. S. West, from Pilmoor, N. Yorks. 

 ( x430). C E, D. leevis (Kiitz.) W. & G. S. West, from Mitcham Common, 

 Surrey; C, x!80; D, x250; E, mature zygospore, x 430. F I, D. Desmidi- 

 oides W. & G. S. West, from near the Lizard, Cornwall ( x 430). 



longer than the diameter. The zypospore is ellipsoidal (44 50 p. x 29 36 fi) 

 with a scrobiculate middle coat (fig. 46 C E). D. calospora (Palla) W. & 

 G. S. West is 11 13 /x in diameter; the zygospores are subglobose or ellip- 

 soidal, 18 26 fj. in diameter, and ornamented with large scrobiculations 



