COSMARIUM. 185 



Length. 44-48^; breadth 33-3<r5 p ; breadth of 

 apex 21/x; breadth of isthmus 7 '0-9* 6 /A; thickness 



O()_00 ,. 







ENGLAND.- -Elter Water, Westmoreland! (Biwtt). 

 Keighley Tarn, W. Yorks ! Great Slmnnor Fell, 

 N. Yorks ! Thursley Common, Surrey ! Hants 

 (Joshua). Cornwall (Joshua). 



WALES.- -Moel Siabod!, Capel Curig (Goolte fy Wills), 

 and Llyn Teyrn on Snowdon ! , Carnarvonshire. 



SCOTLAND.- -Sutherland ! , Ross, Inverness, Aberdeen, 

 Kincardine, Forfar, Perth, Argyll, ArTan (Roy fyBissett). 

 Orkneys ! 



IRELAND. Xear Loughs Mao-rath and Grlentornan, 



o o 



Donegal ! Oorid Louoii and Ballvnahinch, Galway ! 



O O / t/ 



Glen Caragh, Castletown, and Lower Lake of Killarney, 

 Kerry ! Dublin and Wicklow (Archer). 



Geogr. Distribution. France. Germany. Galicia in 

 Austria. Norway. Sweden. Denmark. Poland. 

 S. Russia. Faeroes. Ceylon. United States. 



C. Nymannianum bears considerable resemblance to 

 C. Hammeri, but can be distinguished by its punctate cell- 

 wall and by the large scrobiculation in the centre of the semi- 

 cells. 



Joshua reports the zygospores of this species from Alton,, 

 Hants, and from Cornwall,, but neither describes nor figures 

 them (vide Joshua, ' Xotes Brit. Desm. II / 1883). 



39. Cosmarium trilobulatum Reinsch. 

 (PI. LXII, figs. 28-30.) 



Cosmarium trilobulatum Reinsch, Spec, Gen. Alg. 1867, p. 118, t. 22 A II, 



f. 1-6 ; Lund. Desm. Snec. 1871, p. 42 ; De Toni, Syll. Alg. 1889, p. 960 ; 



West, Alg. W. Ireland, 1892, p. 143 ; Alg. Eng. Lake Distr. 1892, p. 724 ; 



Roy & Biss. Scott. Desin. 1894, p. 176 ; Nordst. Index Desm. 1896, p. 250 ; 



West & G. S. West, Alg. S. England, 1897, p. 485. 

 Didymidium (Cosmarium) trilobulatum Reinsch, Algenfl. Franken, 1867, 



p. 116, t. 9, f. 6. 

 Ursinella trilobulata Knntze, Revis. gen. plant. 1891, p. 925. 



Cells very small, a little longer than broad up to 

 almost 1-J- times longer than broad, deeply constricted, 

 sinus narrowly linear with a slightly-dilated extremity; 



