COSMARIUM. 251 



cardine, Forfar !, Perth !, Stirling, Argyll (lioy 

 Bixsett). 



IE ELAND. Carrantuohill. Kerry ! 



/ 



Geogr. Distribution. France. Italy. Norway. 

 Sweden. Finland. X. Eussia. Xova Zembla. Spitz- 

 bergen. Greenland. Sandwich Is. Xew Zealand. 



The average number of crenations on a semicell of this 



o 



variety is 20 ; but some of the smaller forms may only possess 

 16. Occasionally some of these crenations are very delicately 

 bigranulate, but this can scarcely be detected except in the 

 side or vertical view. 



Two smaller forms of this variety have been recorded by 

 Wille ('Ferskv. Alg. Nov. Semi j/ 1879, p. 41) from Nova 

 Zembla, and have been seen by others from elsewhere. 



Forma minor Wille, 1. c. t, 12, f. 28. Length 28-30 M ; 

 breadth 20-24/1; breadth of isthmus 16 /LI ; thickness 17-18^. 

 We have not observed this small form in the British Islands. 



Forma intermedia Wille, I.e. t. 12, f. 29; Boldt, Desm. 

 Gronland, 1888, p. 20 ; Borge, Chlor. Xorska Finmark. 1892, 

 p. 10; West & G. S. West, Alga-fl. Yorks. 1900, p. 85. 

 Length 38-40 M ; breadth 27-28 M ; breadth of isthmus 14-17 fi ; 

 thickness 20-25 f i. (PI. LXXXIX, fig. 7.) We have observed 

 this form from Woollev. West Yorkshire. 



/ ' 



Var. Rostafinskii (Grntw.) nob. (PI. LXXXIX, 



figs. 8-10.) 



Cosmarium Rostafinskii Gutw. Wahr. d. Prioritat, 1890, p. 67; Flor. Glon. 

 Okolic Lwowa, 1891, p. 41, t 1, f . 15 ; Nordst. Index Desm. 1896, p. 225 ; 

 West & G. S. West, Alga-fl. Yorks. 1900, p. 84. 



Semicells rather more regularly pvramidate than in 



O i> JL t/ 



typical C. speciosum, and with the apex more evidently 

 truncate. 



Length 35-46 p. ; breadth 23-31 p.; breadth of 

 isthmus 11-1 4 p. ; thickness lo'o-16'5fL. 



ENGLAND.- -Cautley Spout, W. Yorks ! 



SCOTLAND. Buirn Chalim, Perthshire ! 



Geogr. Distribution. Galicia in Austria. United 

 States (form). 



This form differs so little from C. speciosum that it is scarcely 

 justifiable to regard it as specifically distinct. 



We have described from California a Desmid which we 



