COSMAELUM. 7 



Slightly larger than the type, apex of semicells still 

 more produced, and undulations of lateral margins 

 more pronounced, vertical view with blunter poles. 



Length 91-112/u; breadth 67-87 /n ; breadth of 

 apex 33-38 ILL ; breadth of isthmus 24-35 /LI. 



ENGLAND. Penyghent, "W. Yorks ! 



SCOTLAND.- -Glen Callater, beside the " Break Neck : 

 Waterfall, Aberdeen ; Canlochan, Forfar ! (Roy fy 

 Bissett). North shore of Loch Taj, Perth (Archer). 



Geogr. Distribution.- -Q&licia* (a form). Finland. 



The produced apices of this variety give it a rather remark- 

 able appearance, but this feature is not sufficient to warrant 

 its separation by Messrs. Roy and Bissett as a distinct species. 

 The specimens observed from West Yorkshire were inter- 

 mediate between the typical form and var. Archerii with 

 regard to the extension of the produced apices. The occur- 

 rence of intermediate forms of this nature (vide PL LXV, 

 fig. 9) is sufficient to show that these plants are forms of one 

 species. 



53. Cosmarium obtusatum Schmidle. 

 (PL LXV, figs. 13, 14.) 



? Cosmarium ochthodes ISTordst. var. obtusatum Gutw. Wahr. d. Prioritat, 

 1890, p. 68 ; Flor. Glon. Okolic Lwowa, 1891, p. 51, t. 2, f . 3. 



C. undulatum Corda var. obtusatum Sclimidle, Alg. Geb. Oberrheins, 

 1893, p. 550, t. 28, f. 11. 



C. obtusatum Schmidle, Ost-Africa Desmid. 1898, p. 38 ; West & G. S. 

 West, Freslrw. Alg. Orkneys and Slietlands, 1905, p. 21. 



Cells of medium size, about 1-g- times as long as 

 broad, deeply constricted, sinus very narrow with 

 dilated apex ; semicells truncate-pyramidate, basal 

 angles slightly rounded, sides convex with about 8 

 undulations, also with two similar series within each 

 margin having an appearance not unlike granules, 

 apex truncate. Side view of semicell broadly elliptic. 

 Vertical view oblong-elliptic, ratio of axes about 1 : 2, 

 poles undulate ; with four or five short parallel series 

 of undulations within each pole. Cell-wall punctate. 

 Chloroplasts axile, each with two pyrenoid; 



Zygospore unknown. 



is. 



