COSMAKITJM. 171 



obscurely undulate, with a single radiating series of 

 about 4 granules within each marginal undulation, 

 and in the centre with 6 or 7 vertical series of granules, 

 5 or 6 in each series. Side view of semicell rather 

 broadly obovate-elliptic. Vertical view elliptic, ratio 

 of axes about 1 : 1*7. 



Zygospore unknown. 



Length 38-40 p. ; breadth 30-32 ^ ; breadth of 

 isthmus 12-1 3 p.; thickness 17'5/t. 



ENGLAND. Lano-cliffe near Settle, Cowside Beck 



O ' 



near Arncliffe, Horton-iii-Bibblesdale, Penyghent, and 

 Cowgill Wold Moss on \Yiddale Fell, W. Yorks ! 



WALES. Moel Siabod, Llvn Idwal, and Llyn Cwlyd, 



/ V V 



Carnarvonshire ! 



SCOTLAND.- -Corrie Etchachaii on Ben Alacdhui, 

 Aberdeen (Roy fy Bissett). Winter Corrie, Clova Mts., 

 Forfar ! 



IRKLAND. Carrantuohill, Kerry ! 



/ 



This alpine Desmid will probably be found to have a much 

 wider British distribution in the " corries ; and springs high 

 up on the mountains. 



163. Cosmarium Slewdrumense Roy. 

 (PI. LXXXI, fig. 6.) 



Cosmarium Slewdrumense Roy, Desm. Alforcl District, 1890,, p. 204 ; Roy 

 & Biss. Scott. Desm. 1893, p. 174, t. 2, f . 19 ; Nordst. Index Desm. 1896, 

 p. 235. 



Cells small, a little longer than broad, deeply 

 constricted, sinus linear; semicells somewhat oblong- 

 elliptic, with a flattened base, sides 4-undulate, apex 

 truncate and about 5 -undulate, with a single radiat- 

 ing series of very minute granules within each undula- 

 tion, in the centre with 4 compact vertical series of 

 minute granules, 6 in each series. Vertical view 

 elliptic, with the minute granules arranged in trans- 

 verse lines. 



Zygospore globose, furnished with somewhat distant, 

 stout, attenuated spines (about 13 visible around the 

 periphery). 



