136 BRITISH DESMIDIACE^. 



SCOTLAND.- -Common! (Roy $ Bissett). Outer 

 Hebrides ! Shetlands ! 



IRELAND. Donegal ! Mayo ! Galway ! Kerry ! 

 Dublin and TVicklcnv (Archer). Down (up to 

 2000 ft.) ! 



Geogr. Distribution.- -France. Belgium. Germany. 

 Austria and Galicia. Norway. Sweden. Bornliolm 

 (var.). Finland. X. Russia (form). S.Russia. Faeroes. 

 Azores. United States. 



C. cselatum is one of the most characteristic species of the 

 g-enus. It is principally an upland species, where it is not 

 infrequently found 011 wet rocks, but it is not a true alpine 

 Desmid. On old heaths and commons, which are still parts 

 of the primitive country,, it often occurs in boggy springs. In 

 such situations it is usually found among large numbers of 

 Diatoms. 



The marginal granules are acute, but the basal ones are 

 rounded. Considerable variation is shown in the disposition 

 of the granules on the broad basal tumour. 



Var. spectabile (De JN T ot.) Nordst, (PL LXXVI, 



fig. 8.) 



Cosmarium spectabile De Not. Desm. Ital. 1867, p. 45, t. 4, f. 31 ; Eabenli. 



Flor. Etirop. Alg. Ill, 1868, p. 170. 

 Euastrum (Cosmarium) spectabile (De Not.) Gay, MonogT. loc. Conj. 1884, 



p. 62. 

 Cosmarium caelatum Ealfs var. spectabile (De Not.) Norclst. Desm. Ital. 



1876, p. 40 ; De Toiii, Syll. Alg. 1889, p. 1008 ; Lutkemull. Desm. 



Attersees, 1893, p. 555, t, 8, f. 8 (?) ; Boy & Biss. Scott. Desm. 1894, 



p. 44 ; Liitkem. Desm. Millstattersees, 1900, p. 8 ; Borge, Beitrage Alg. 



Schweden, 1906, p. 41. 



Scarcely to be distinguished from the typical form 

 except by its slightly greater angularity and by the 

 more band-like disposition of the granules across the 

 base of the semicells. 



Length 39-46*5 /x; breadth 35-40 /x; breadth of 

 isthmus 15-16 /A; thickness 21-22 p.. 



WALES. - - Snowdon ! and Cap el Curig ! (Roy), 

 Carnarvonshire. 



SCOTLAND.- -Frequent (Roy $ Bissett). 



Geogr. Distribution. France. Italy. Austria and 

 Gralicia. Sweden. 



