cosMARimr. 157 



154. Cosmarium reniforme (Ralfs) Arch. 

 (PL LXXIX, figs. 1, 2; PI. LXXXII, fig. 15.) 



Cosmarium margo.ritiferum Menegh. var. reniformis Ealfs, Brit. Desm. 



1848, p. 100, t, 16, f . 2 a. 



C. margaritiferum forma genuina Xordst. Norges Desm. 1873, p. 11. 

 C. reniforme (Ealfs) Arch, in Joiirn. Bot. 1874, p. 92 ; Nordst. Desm. 



ArctoaB, 1875, p. 40; Wolle, Desm. U. S. 1884, p. 76, t. 14, f. 10-11; 



Cooke, Brit, Desm. 1887, p. 104, t. 42, f. 10 ; Haiisg. Prodr. Algenfl. 



Bohm. 1888, pp. 200, 250 ; De Toni, Syll. Alg. 1889, p. 982 ; Eoy in 



Journ. Bot. 1890, p. 337 ; West, Alg. W. Ireland, 1892, p. 153 ; Alg. 



Engl. Lake Distr. 1892, p. 727 ; Liitkem. Desm. Attersees, 1893, p. 557 ; 



Eoy & Biss. Scott. Desm. 1894, p. 174 ; Nordst. Index Desm. 1896, p. 223 ; 



West & G. S. West, Alg. S. England, 1897, p. 488 ; Schmidle, Lappmark 



Susswasseralgen, 1898, p. 34 ; West & GK S. West, Some Desm. U. S. 



1898, p. 307, t. 17, f. 9; G-. S. West, Alga-fl. Cambs. 1899, p. 217 ; West 



& G. S. West, Alga-fl. Yorks. 1900, p. 71 ; Borg. Freshw. Alg. Faeroes, 



1901, p. 227 ; West & G. S. West, Alg. N. Ireland, 1902, p. 37 ; Scott. 



Freshw. Plankton, I, 1903, p. 527 ; Borge, Alg. erst. Eegnell. Exped. II, 



Desmid. 1903, p. 87 ; Larsen, Freshw. Alg. E. Greenland, 1904, p. 88 ; 



West & G. S. West, Freshw. Alg. Orkneys and Shetlands, 1905, p. 18 ; 



Further Contrib. Freshw. Plankton Scott. Lochs, 1905, p. 485 ; Comp. 



Study Plankton Irish Lakes, 1906, p. 85 ; Borge, Alg. Argentina u. 



Boliv. 1906, p. 8 ; Beitrage Alg. Schweden, 1906, p. 31. 

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



Cells of medium size, very slightly longer than 

 broad, deeply constricted, sinus narrow and closed, 

 open outwards and widely dilated at the extremity ; 

 semicells reniform. Side view of semicell circular. 

 Vertical yiew elliptic. Cell- wall granulate, granules 

 rounded, disposed in obliquely decussating series and 

 sometimes in indistinct vertical series, about 30-33 

 showing at the margin of a semicell. Chloroplasts 

 axile, with two pyrenoids. 



Zygospore globose and smooth. 



Length 46-5 7 /x; breadth 44-54 p.; breadth of isthmus 

 14-1 7 /x; thickness 26-29 /A; diam. zygosp. 54-60 /x. 



EXGLAND.- -Cumberland ! Westmoreland ! (Bissetf). 

 Lancashire ! W., N., and E. Yorks ! Leicestershire 

 (Roy). Lincolnshire! Cambs! Oxfordshire! Surrey! 

 Kent! Hants ! (Rot/). AVilts ! Cornwall I (Marquand). 



AYALES.--Capel Curig!, Llyn Ogwen !, Yr Orsedd !, 

 and Grlyder Fawr (Roy), Carnarvonshire. 



SCOTLAND.- -General ! (Roy fy Sissett). Orkneys! 

 Shetlands ! Eare in the plankton ! Lewis, Harris 

 (with zygospores), and ^. L T ist, Outer Hebrides! 



