BRITISH DESMIDIACE.E. 



51. Cosmarium Holmiense Lund. 

 (PI. LXV, figs. 1, 2.) 



Cosmarium Holmiense Lund. Desm. Suec. 1871, p. 49, t. 2, f. 20 ; Nordst. 

 Desm. Ital. 1876, p. 31 ; Cooke, Brit. Desm. 1886, p. 96, t, 37, f. 15 ; 

 Hansg. Prodr. Algenfl. Bohm. 1888, p. 197 ; Boldt, Desmid. Gronland, 

 1888, p. 11 ; De Toni, Syll. Alg. 1889, p. 944 ; West, Alg. W. Ireland, 

 1892, p. 143 ; Eoy & Biss. Scott. Desm. 1894, p. 103 ; Nordst. Index 

 Desmid. 1896, p. 140 ; West & G-. S. West, Alga-fl. Yorks. 1900, p. 80 ; 

 Freshw. Alg. Orkneys and Shetlands, 1905, p. 21. 



Euastrum (Cosmarium) Holmiense Gray, Monogr. loc. Conj. 1884, p. 60. 



Cosmarium Holmiense a. Lundellii Eacib. Nonn. Desm. Polon. 1885, p. 80. 



C. Holmiense b. Nordstedtii Eacib. 1. c. 



Ursinella Holmiensis Kuntze, Eevis. gen. plant. 1891, p. 924. 



DyspMnctium Holmiense (Lund.) Sclimidle, Beitr. alp. Alg. 1895, p. 349. 



Cells of medium size, about If times as long as 

 broad, moderately constricted, sinus narrow and 

 linear; semicells broadly pyramidate, basal angles 

 slightly or considerably rounded, sides straight or 

 slightly concave, faintly creimlate towards the apex, 

 upper angles moderately rounded, apex broadly trun- 

 cate, somewhat produced and slightly biundulate. 

 Side view of semicell quadrate-elliptic, with a convex- 

 truncate apex. Vertical view broadly elliptic, ratio 

 of axes about 1:1-4. Cell-wall smooth or delicately 

 punctate. Chloroplasts axile, each with one pyrenoid. 



Zygospore unknown. 



Length 43'2-66 u ; breadth 26'4-40 p ; breadth of 

 isthmus 14-4-21 M ; breadth of apex 21-29^; thicknes 

 19-2-28 t,. 



VOL. III. 



