106 BRITISH DESMIDIACE^;. 



the processes are similar to those of St. paradoxum var. longipes 

 Nordst. 



Var. nodulosum West. (PI. CXLVI, fig. 1.) 



St. paradoxum var. nodulosum West, Alg. W. Ireland, 1892, p. 182, t. 23,. 

 f. 13. 



A smaller variety with its processes trifurcate at the 

 apices ; cells in vertical view triangular, lateral margins 

 with two undulations. 



Length with processes, 33 \L ; without processes, 14 (/. ; 

 breadth, with processes, 27 '5-30^ ; breadth of isthmus 



5 (/.. 



IRELAND.- -Upper Lake of Killarney, Kerry ! 

 Var. parvum West. (PL CXLV, fig. 6.) 



St. paradoxum forma parva West, Alg. W. Ireland, 1892, p. 182, t. 23, f. 12 ,- 

 Roy & Biss. Scott. Desm. 1894, p. 23 : West & G. S. West, Alg. S. England,. 

 1897, p. 496. 



? St. paradoxum var. longipes forma minor Istvanffi, Diag. praev. Alg. nov. 

 Hungar. 1887, p. 11. 



Cells similar to the type form but exceedingly minute. 



Length, without processes, 9-1 6 {/. ; with processes, 

 18-35 (A ; breadth, with processes, 20-28 (JL ; breadth of 

 isthmus 3 '5-6 [I. 



ENGLAND.- -Thursley Common, Surrey ! Keston Com- 

 mon, Kent ! New Forest, Hants ! 



SCOTLAND. Common (Roy & Biss.}. Ehiconich,, 

 Sutherland ! 



IRELAND. --Near Glenties and Sproule's Lough, Done- 

 gal ! Ballynahinch, Galway ! Adrigole, Cork ! 



Geogr. Distribution.- -Finland. Hungary ? 



The dimensions given by Istvanffi for his St. paradoxum var. 

 longipes forma minor agree with those of var. parvum West, and 

 forma minutissima of Heimerl (' Desm. alpin.' 1891, p. 607) also 

 seems to be very similar to this variety. Figures were in neither 

 case given, unfortunately ; but Schmidle's figure of forma minutis- 

 sima Heimerl ('Beitr. Alg. Alp.' 1895, 1. 16, f. 16) does not exactly 

 correspond with var. parvum West. It is possible, however, 

 that both f. minor Istv. and f. minutissima Heimerl are synony- 

 mous with var. parvum West. 



