40 BRITISH DESMIDIACEJE. 



Denmark. Bornholm. Finland. S. Russia. Xova 

 Zembla. Franz Joseph Land. Spitsbergen. Green- 

 land. ]STew Zealand (var.). Sandwich Islands. West 

 Indies. Brazil. 



This characteristic species occurs mostly on wet rocks. It 

 requires further investigation, especially of living specimens, 

 as there is much doubt concerning the nature of its chloro- 

 plasts, and its position in the genus Cosmarium is by no means 

 certain. 



Var. elegans Xordst (PL CII, figs. 16-18.) 



C. annulatum var. elegans Nordst. Norges Desm. 1873, p. 23 ; Desm. Ital. 

 1876, p. 42 ; West, Alg. Engl. Lake District, 1892, p. 728 ; W. & G. S. 

 West, Further Contrib. Freshw. Alg. W. Indies, 1899, p. 284 ; Borg. 

 Freshw. Alg. Faeroes, 1901, p. 228 ; W. & G. S. West, Alg. N. Ireland, 

 1902, p. 42 ; Freshw. Alg. Orkneys and Shetlands, 1905, p. 23 ; Borge, 

 Beitrage Alg. Schweden, 1906, p. 36. 



Crenations distinctly but minutely bigrannlate. 



Length 40-57-5 n; breadth 17-29 p. 



ENGLAND. Borrowdale, Cumberland! Blea Tarn 

 and Pike of Bliscoe, Westmoreland ! Hawkshead, 

 Lancashire ! 



WALES.- -Moel Siabod !, Pen-y-gwryd (Ito't/), and 

 Glyder Fach !, Carnarvonshire. 



SCOTLAND.- -Aberdeen. Kincardine, Forfar, and Perth 

 (Roy fy BissetV). Kirkcudbright! 



IRELAND. Dublin and Wicklow (Archer). Slieve 

 Donard and Slieve Commedagh, Down ! 



Geogr. Distribution- -Norway. Sweden. Faeroes. 

 Italy. West Indies. 



C. annulatum var. elegans appears to be widely distributed, 

 and is a much prettier Desmid than the type. It is at once 

 distinguished from all forms of C. elegantissimum by its broadly 

 truncate, smooth apex, and by the scarcely evident median 

 constriction. 



245. Cosmarium elegantissimum Lund. 

 (PI. CII, fig. 19.) 



Cosmarium elegantissimum Lund. Desm. Suec. 1871, p. 53, t. 3, f. 20 ; 



Wolle, Desm. U. S. 188-4, p. 78, t. 14, f. 8-9 ; Johnson, Eare Desm. 



U. S. II, 1895, p. 292, t. 240, f. 27 ; Nordst. Index Desmid. 1896, p. 116. 

 Cosmaridium elegantissimum Hansg. Prodr. Algenfl. Bohm. 1886, p. 246. 

 Pleurotaeniopsis deyfinlissima De Toni, Syll. Alg. 1889, p. 909. 



