COSMARIUM. 147 



Ursinella Nordstedtiana Kxiiitze, Revis. gen. plant. 1891, p. 925. 

 C. cyclicum Lund. var. truncatum Borge, Siissw. Chlor. Archang. 1894, 

 p. 21 ; [vide West in Jourii. Bot. 1895, p. 67.] 



Cells distinctly hexagonal, usually a little broader 

 than long ; apices truncate or subtruncate, less crenate 

 than the lateral margins. 



Length 48-50 p, ; breadth 54-66 JJL ; breadth of isth- 

 mus 19-21 p. ; thickness 20-23 /*,. 



ENGLAND.- -Borrowdale, Cumberland ! Penyghent, 

 W. Yorks! Mickle Fell, X. Yorks ! Wimbledon 

 Common, Surrey. 



IRELAND.- -Fintowii, Donegal ! 



Geogr. Distribution. Gralicia in Austria. N. Russia. 



We have observed this variety in greater abundance than 

 typical C. cyclicum. It is well characterized by its hexagonal 

 cells with truncate apices. 



11. Cosmarium fontigenum Nordst. 

 (PI. LIX, figs. 16, 17.) 



Cosmarium fontigenum Nordst. in Wittr. & Nordst. Alg. Exsic. 1878. 



110. 171 ; and in fasc. 21 (1889), p. 43 cum fig. xylogr. ; De Toni, Syll. 



Alg. 1889, p. 1010 ; Roy & Biss. Scott. Desm. 1894, p. 101 ; West & G-. S. 



West, Alg. S. England, 1897, p. 486. 

 Ursinella fontigena Knntze, Revis. gen. plant. 1891, p. 924. 



Cells small, about as long as broad, deeply con- 

 stricted, sinus very narrow with a slightly dilated 

 extremity; semicells broadly subpyramidate, apex 

 broadly truncate, basal angles rounded, sides slightly 

 convex or almost straight, upper part of lateral margins 

 slioiitly crenate. Side view of semicell subcircular. 



O t) 



Vertical view narrowly elliptic, with a small protuber- 

 ance at the middle on each side. Cell-w^all finely 

 punctate. Chloroplasts axile, each with one pyrenoid. 



Zy go spore unknown. 



Length 20-26 JLI; breadth 20-25 /* ; breadth of isth- 

 mus 6-8 /x; thickness 11-1 3 /A; breadth of apices 

 about 8-11 p.. 



ENGLAND.- -Puttenham Common, Surrey ! 



SCOTLAND.- -Ross; Skye and near Brin, Inverness; 

 Aberdeen; Kincardine; Perth (Roy fy Bissett). 



