136 BRITISH DESMIDIACEJE. 



WALES. Dolbadarn Castle, Capel Curig ! (Cooke 

 Wills), Llyn Idwal, Llyn-y-cwm-fTynon, Llyn Bodgyn- 

 wyd and near Conway, Carnarvonshire ! Holyhead. 

 Anglesea ! Dolgelly, Merioneth ! 



SCOTLAND. Shetlands, Sutherland !, Ross, Inverness,. 

 Banff, Aberdeen, Kincardine, Forfar, Perth and Argyle ; 

 zygospores from Scotston, Aberdeen (Roy & Biss.), 

 Lewis, Outer Hebrides ! Hoy, Orkneys ! In the plankton f 



IRELAND. - -Donegal ! Mayo and Clare Isle ! Gal way ! 

 Kerry ! Dublin and Wicklow (Arch.). Down ! 



Geogr. Distribution. - France. Galicia in Austria, 

 Turkey. Norway. Sweden. Denmark. Bornholm. Fin- 

 land. N.Russia. Spitzbergen. Turkey in Asia. Australia. 

 LTnited States. Colombia. Brazil. 



This species is very closely allied to St. bracliycerwn and St. 

 inflexum. It is a larger Desmid than either of these, however, 

 and the row of tiny emarginate granules on the apex of the semi- 

 cell is one of its distinguishing characters. Its short, stout, 

 converging processes, frequently seen in the vertical view to be 

 bent abruptly in one direction, are very characteristic. 



Var. compactum W. & G. S. West. (PL CXLIX, 



fig. 10.) 



St. cyrtocerum var. compactum West & G. S. West, Alg. Orkneys & Shetlands,, 

 1905, p. 26, t. 2, f. 29. 



Body of semicell much larger in proportion, and 

 processes much shorter. 



Length 36 [L ; breadth, including processes, 40 ^ ; 

 breadth of isthmus 1 1 (i . 



SCOTLAND. --Plankton of Loch Trebister, Shetlands I 



136. Staurastrum brachycerum Breb. 

 (PL CXLII, figs. 21, 22.) 



Staurastrum brachycerum Breb. Liste Desm. 1856, p. 139, t. 1, f. 24 ; Arch. 



in Pritch. Infus. 1861. p. 742 ; Roy & Biss. Scott. Desm. 1894, p. 180. 

 St. polymorphism var. brachycerum Rabenh. Flor. Europ. Alg. 1868, p. 210 ; 



Borge, Siisswasseralgen Franz Josefs-Land, 1899, p. 764 ; Comere, Desin. 



de France, 1901, p. 157, t. 11, f. 4. 



