122 BRITISH DESMIDIACE^E. 



ENGLAND.- -Keigliley Moor, W. Yorks ! 

 SCOTLAND.- -Harris, Outer Hebrides ! 

 Geogr. Distribution.- -France. Galicia in Austria. 

 Australia. 



This small species is probably much more widely distributed 

 than is indicated by the above records, as it is only very 

 recently that we have realized its specific distinctness. It 

 stands nearest to C. Norimbergense Reinsch, but is distin- 

 guished by its deeper constriction and by the obliquely 

 truncate angles of the semicells. Owing* to the latter cha- 

 racter the semicells possess a very characteristic outline. 



131. Cosmarium subdanicum West. 

 (PI. LXXXV, figs. 25, 26.) 



Cosmarium subdanicum West, Alg. W. Ireland, 1892, p. 150, t. 21, f. 4 ; 



Nordst. Index Desm. 1896, p. 245. 

 C. humile (Gay) Nordst. var. subdanicum (West) Selimidle, Beitr. alp. 



Alg. 1895, p. 389. 



Cells very small, about as long as broad, very deeply 

 constricted, sinus narrowly linear with a slightly 

 dilated apex; semicells widely truncate-pyramid ate 3 

 basal angles rectangular and retuse-emarginate, apical 

 angles slightly rounded, sides very slightly convex and 

 with a small emarginate wart in the middle, apex 

 widely truncate and triundulate, centre of each semicell 

 furnished with a small granule. Side view of semicell 

 circular, with a small granule at the middle on each 



o 



side. Vertical view elliptic, with a small granule at 

 the middle on each side, ratio of axes about 1 : 1'G. 

 Cell- wall smooth. 



Z y go s pore un kn o w n . 



Length 16'4-17'5/x; breadth 1 3*5-14 /x; breadth of 

 isthmus 3-4 JJL; thickness 8*2-8*5 /x. 



IRELAND.- -Ballynahinch, Gralway ! 



This small species has been regarded as one of the series of 

 forms including C. humile (Gray) Nordst., C. danicum Borg., 

 C. striatum Boldt., and C. substriatumNovdst., all of which are 

 merely forms of C. humile. (Consult p. 221 et seq.) Schmidle 

 has stated that C. subdanicum should be placed as C. humile 

 var. subdanicum, but we think it quite distinct from C. humile 



