234 BRITISH DESMIDIACE^. 



Var. tatrica Eacib. (PL CLXII, fig. 19.) 



//. dissiliens var. latrica Eacib. Nonn. Desm. Polon. 1885, p. 64, t. 14, f. 5 j 

 De Toni, Syll. Alg. 1889, p. 786 ; West, Alg. Engl. Lake Distr. 1892,. 

 p. 6 (sep.) ; Nehroder, Alg. Versuchsteiche Schles. Fischereiv. Trachen- 

 berg. 1897, p. 28. 



Cells nearly as long as broad, or even up to Ij times 

 longer than broad, quadrangular, distinctly constricted 

 at the middle ; semicells about twice as broad as long,, 

 with convex sides ; forming short filaments, destitute 

 of a mucous sheath. Cells in end view either perfectly 

 circular, or of the form bidentula. 



Length 16-22[x ; breadth 16-20ri ; 



ENGLAND.- -Ha wkshead, Lancashire ! 



Geogr. Distribution. Galicia in Austria. Poland. 

 E. Africa, 



Var. hians Wolle. (PL CLXII, figs. 16-18.) 



H. dissiliens var. hian-s Wolle, Freslnv. Alg. U. 8. 1887, p. 21, t. 54, f. 14-16 ;. 

 De Toni, Syll. Alg. 1889, p. 786; West, Alg. W. Ireland, 1892, p. 116; 

 Alg. Engl. Lake Distr. 1892, p. 6 (sep.) ; West & G. 8. West, Alg. 8. Eng- 

 land, 1897, p. 497; Alga-fl. Yorks. 1902, p. Ill; Alg. Ceylon, 1902, 

 p. 195 ; Alg. N. Ireland, 1902, p. 60 ; Alg. Orkneys and Shetland*. 1905, 

 p. 28 ; Borge, Sao Paulo Alg. 1918, p. 77. 



H. Indica Turn. Alg. E. India, 1893, t. 19. f. 18 (only). 



Filaments conspicuously constricted at the joints ; 

 cells usually much broader than long, lateral margins 

 of cell very convex, with an acute median incision or 

 notch ; filaments enclosed in a sheath. 



Length 12-22[ji ; breadth at broadest part 20-32 \L ; 

 breadth at apex of semicell 15-24 [ji ; breadth of isthmus 

 18-26 [i. 



ENGLAND.- -Westmoreland ! Lancashire ! Horton in 

 Eibblesdale, W. Yorks ! Great Shunnor and Cronkley 

 Fells, N. Yorks ! Esher West End Common, Surrey ! 



SCOTLAND.- -Lerwick, Shetlands ! 



IRELAND. --Near Glenties, Donegal! Clifden, Galway! 



Geogr. Distribution.--^. Russia. Ceylon. New Zealand. 

 United States. W. Indies. Brazil. 



The turgid cells, very much constricted at their points of 

 union, and also with their prominent median incision, readily 

 distinguish this variety from the typical form. 



