254 BRITISH DESMIDIACE^E. 



SCOTLAND. Skye in Inverness ! Lewis, Outer 

 Hebrides ! 



Geogr. Distribution. Gralicia in Austria. United 

 States. N. Russia. Manchuria. Madagascar. New 

 Zealand. Patagonia. 



This large handsome variety has commonly 22 creiiations 

 on each semicell. Borge has recorded forms of it with a 

 length of only 58 /.t and a breadth of 41 ju. 



213. Cosmarium speciosissimum Schmidle. 

 (PI. LXXXIX, figs. 14, 15.) 



Cosmarium speciosissimum Schmidle, Beitr. alp. Alg. 1895, p. 458, t. 15, 

 f . 30-31 ; Nordst. Index Desm. 1896, p. 236 ; Gutw. in Spraw. Kom. 

 fizogr. Akad. Umiej. Krakow, 1898, p. 196 ; West & G. S. West, Alga-fl. 

 Yorks. 1900, p. 85. 



Cells rather under medium size, deeply constricted, 

 sinus narrowly linear ; semicells semi-elliptic with a 

 broadly rounded apex, basal angles subrectangular, 

 margin deeply crenate, crenations 12-14 (commonly 

 12), emarginate (or more rarely truncate) ; with radial 

 and concentric series of truncate-emarsfinate warts 



o 



within the margin, 4-7 concentric series in which the 

 warts diminish in size from the periphery towards the 



centre ; across the base of the semicell and immediately 



t 



above the isthmus with a transverse row of 6 strong 

 costas (vertically disposed). Side view of semicell 

 rectangular, basal angles tumid, sides slightly concave, 

 apical angles rounded and minutely crenulate, apex 

 faintly retuse. Vertical view elliptic, with a rounded, 

 6-crenulate tumour on each side, poles rounded and 

 crenulate. Chloroplasts axile, one in each semicell, 

 with a single pyrenoid. 



Zygospore unknown. 



Length 4(3-52 ^ ; breadth 30-36 //,; breadth of 

 isthmus 17-19/^; thickness 20-27 p.. 



ENGLAND.- -Mickle Fell, JN". Yorkshire ! 



Geogr. Distribution. Grermany. Gralicia in Austria. 



This species is the most characteristic of those which form 

 the C. speciosum-gYOup. The margin is more profoundly 



