56 BRITISH DESMID1ACE.E. 



C. rectangulare Grun. var. cambrense (Turn.) West & G. S. West, Alg. 

 Centr. Africa, 1896, p. 379. 



Cells proportionately longer, about 1J times longer 

 than broad. 



Length oo^t; breadth 22^; breadth of isthmus 6 /n. 



WALES. Bog near Dolbadarn Castle, Carnarvon- 

 shire (J. H. Lewis). 



Var. hexagonum (Elfv.) nob. (PI. LXX, fig. 4.) 



C. hexagomim Elfv. Aiiteck. Finska Desm. 1881., p. 12, t. 1, f. 8 ; Haiisg. 



in Sitzungsber. d. k. bohm. Ges. d. Wiss. 1892, p. 131. 

 C. Elfvingii Eacib. Nonn. Desm. Polon. 1885, p. 83 ; De Toni, Syll. Alg. 



1889, p. 953 ; West, Alg. W. Ireland, 1892, p. 145. 

 Ursinella Elfvingii Kuntze, Revis. gen. plant. 1891, p. 924. 



Rather smaller ; cells proportionately shorter, about 

 as long as broad. 



Length 28-30 ju ; breadth 24-27^; breadth of 

 isthmus 7-8 ji; thickness 15 /n. 



IRELAND. Near Clifden, Galwav ! 



I/ 



Geogr. Distribution. Finland. Poland. Central 

 China (form). Brazil (form). 



C. Elfvingii Eacib [" C. hexagonum Elfv."] possesses no 

 characters of sufficient importance to separate it from 

 C. rectangulare Grun. It scarcely differs from the latter in 

 any respect other than its proportionately shorter cells. The 

 two varieties which have been described of C. Elfvingii are 

 referable to other species. " C. Elfvingii var. saxonicum 

 Racib." ( ( Desm. Nowe/ 1889, p. 780, t. 5, f. 14) is without 

 doubt identical with C. pseudoprotuberans Ivirchn. var. 

 angustius Norclst. ('Freslnv. Alg. New Zeal./ 1888, p. 58, 

 t. 6, f. 15, 16). " C. Elfvingii var. alt ins Schmidle ' (in 

 ' Hedwigia,' xxxiv, 1895, p. 84 cum fig'.), by reason of the 

 narrowness of its apices, its elevated semicells, and the 

 slightly retuse character of their superior lateral margins, 

 seems to us to be a form of C. grtmatum Breb. 



The Desmid described and figured by Borge (' Beitrage 

 Alg. Schweden,' 1906, p. 39, t. 2, f. 26) as " C. pseudo- 

 protuberans Kirchn. forma minor dorso semicellulse paulluni 

 truncate ; is only a form of C'. rectangulare Grun. var. 

 hexagonum nob. 



