224 BRITISH DESMIDIACE.E. 



Var. substriatum (Nordst.) Sclimidle. (PI. LXXXV, 



fi g- 20 



Cosmarium substriatum Nordst. in Wittr. & Nordst. Alg. Exsic. 1889, no. 



977 ; fasc. 21, p. 42 (c. fig.) ; West, Alg. W. Ireland, 1892, p. 149 ; Alg. 



Engl. Lake Distr. 1892, p. 726; Roy & Biss. Scott. Desm. 1894, p. 175 ; 



Nordst. Index Desm. 1896, p. 247 ; West & G-. S. West, Alg. S. England, 



1897, p. 488 ; G-. S. West, Alga-n. Cambr. 1899, p. 217. 

 C. humile (Gray) Nordst. var. substriatum (Nordst.) Schmidle, Beitr. alp. 



Alg. 1895, p. 389 ; W. & G. S. West, Alga-fl. Yorks. 1900, p. 77 ; Alg. 



N. Ireland, 1902, p. 37 ; Freshw. Alg. Orkneys and Shetlands, 1905, 



p. 20; Borge, Beitriige Alg. Schweden, 1906, p. 34. 



Cells commonly larger than, in the type, lower parts 

 of sides of semicells retuse, apical angles rounded, apex 

 without undulations but with two series of granules 

 within the margin, granules within the sides more clus- 

 tered and restricted. 



Length 17-28/x; breadth 14-24 /A ; breadth of 

 isthmus 5-8 /x; thickness 11 14 /A. 



ENGLAND.- -Cumberland ! Westmoreland! AY., K"., 

 and E. Yorks ! Lincolnshire ! Cambridgeshire ! 



o 



Oxfordshire ! Surrey ! Hants ! Devon ! Cornwall ! 



WALES.- -Llyn Ogwen, Llyn Bodgynwydd, and Llyn- 

 an-afon, Carnarvonshire ! 



SCOTLAND. Rhiconich, Sutherland ! Craig-an- 

 Lochan, Perth ! Cumbrae, Ayr ! Orkneys ! Shetlands ! 



IRELAND.- -Donegal ! Mayo ! Gralway ! Kerry ! 



Geogr. Distribution.- -QeYm&ny, Galicia in Austria. 

 Sweden. Patagonia. 



This variety differs from the type in the retuse lower parts 

 of the lateral margins of the semicells, in the rounded angles, 

 and in the different and more restricted disposition of the 

 grannies. 



Var. danicum (Borg.) Schmidle. (PL LXXXV, 



fig. 19.) 



Cosmarium danicum Borg. JBornholm. Desm.-fl. 1889, p. 145, t. 6, f . 6 ; 

 Borge, SiissAv. Chlor. Archang. 1894, p. 26 ; Roy & Biss. Scott. Desm. 



1894, p. 45 ; Nordst. Index Desm. 1896, p. 97. 



C. humile (Gray) Nordst. var. danicum (Borg.) Schmidle, Beitr. alp. Alg. 



1895, p. 389. 



Lower parts of sides of semicells retuse, apical 



