COSMAEIUM. 179 



Side view of semicell very broadly elliptic. Vertical 

 view broadly elliptic, ratio of axes about 1 : 1'2. Cell- 

 wall uniformly granulate ; granules large and flattened, 

 causing the margin of the semicells to appear undulate, 

 about 22-24 visible at the periphery of one semicell, 

 disposed in indistinct oblique series (about 11 visible 

 in front view), sometimes almost entirely without any 

 regularity of arrangement, at the central part of the 

 apex often reduced. Chloroplasts axile, with 'two 

 pyrenoids. 



Zy go spore unknown. 



Length 60-63 & ; breadth 38-40 ,u ; breadth of isth- 

 mus 15-20 ^t; thickness 27-31 /u. 



ENGLAND.- -Strensall Common, N". Yorks ! 



SCOTLAND. Rhiconich, Sutherland ! Lewis and 

 Harris, Outer Hebrides ! 



IRELAND.- -Near Lough Grlentornan, Donegal ! Ar- 

 derry Lough, Gralway ! Cromagloun, Tore Mt., Grlen 

 Carao'h, and Castletown, Kerry ! 



o / 



This species appears to be principally confined to the bogs 

 of the old rocks of the western British areas. It occurs in 

 association with Xanthidium Smithii, Euastrum eras-sum var. 

 scrobiculatum, Penium adelochondrum, Cosmarium commissu- 

 rale var. crassum, and many other rare Desmids. It should 

 be compared with Cosmarium Logiense Bissett and C. prse- 

 grande Lund., from both of which species it is easily 

 distinguished. 



171. Cosmarium Wittrockii Lund. 

 (PI. LXXVIII, fig. 19.) 



Wittrorkii Lund. Desni. Suec. 1871, p. 31, t. 3, f. 14 ; Kirchn. 

 Alg. Schles. 1878, p. 152 ; Wille, Ferskv. Alg. Nov. Semlj. 1879, p. 44 ; 

 Merges Ferskv. Alg. 1880, p. 24 ; Boldt, Siber. Chloropliy. 1885, p. 108 ; 

 ? Benn. Fresh\v. Alo-. Engl. Lake Distr. 1886, p. 10, t. 1, f. 15 ; Cooke, 

 Brit, Desm. 1887, p. 118, t. 42, f. 8 ; De Toni, SyU. Alg. 1889, p. 964; 

 Schmidle, Beitr. Algenfl. Schwarzwald. ti. Eheineb. 1893, p. 99, t. 4, 

 f . 23 ; Boy & Biss. Scott. Desm. 1894, p. 177 ; G-tifrw. Flor. GMon. Okolic 

 Tarnapola, 1894, p. 87, t. 3, f. 17 ; Xordst, Index Desm. 1896, p. 272. 



Ursinella Wittrockii Kuntze, Eevis. gen. plant. 1891, p. 925. 



CosYii--ii-iv.-,;i Witti-ockii Lund. var. Schmidlei Borge, Sverig. Chloropliy. II, 

 p. 16 [= C. Wittrockii figured by Schmidle, 1. c. 1893]. 



C. pseudorthopunctatum West & G-. S. West, Freshw. Chloropliy. Koh 

 Chang, 1901, p. 89, t. 2, f. 12-13. 



