COSMARIUM. <;7 



Cells minute, about as long as broad or a little 

 broader, deeply constricted, sinus slightly open ; semi- 

 cells transversely pyramidate-rectangular, sides very 

 slightly convex, converging upwards, basal angles 

 slightly rounded, apex widely retuse, upper angles 

 scarcely rounded. Side view of semicell subcircular. 

 Vertical view elliptic, ratio of axes about 1 : 1*6. Cell- 

 wall smooth. Chloroplasts axile with a small central 

 pyrenoid. 



Zygospore unknown. 



Length 6'8-9'G ^; breadth 7-9*6 /i ; breadth of 

 isthmus 2 '7-4* 8 p. ; thickness 4' 5-5 '5 //,. 



WALES. Llyn Bochlwvd !, Llvn Bodgynwydd !, 



/ e/ */ O / e> 



Capel Curig !, Snowdon (Ro-y), and Bettws-y-coed 

 Carnarvonshire . 



SCOTLAND.- -Xear Loch Coruisk in Skye, Inverness ; 

 near Berse Church, Cavinton Moss, near Aboyne, 

 Homehead in Cromar, Aberdeen ; Scolty Dam, Cammie, 

 Kincardine ; Glen Clova and Clova Tableland, Forfar 

 (Boy cj- Biff sett). 



IE ELAND.- -Lough Cloncarney, Donegal ! Dublin and 

 AVicklow (Archer). 



Geogr. Distribution.- -France. Silesia. Greenland. 

 Bengal. Ceylon. Siani. 



The distinctive features of this minute species are the widely 

 pyramidate semicells with slightly convex sides and retuse 

 apex. It appears to have been much confused with other 

 small species of the genus The small Cosmarium described 

 and figured by W. B. Turner (' Freslnv. Alg. E. India/ ISl'o, 

 p. 71, "t. 10, f. 25) as " C. pusillum var. retusum" is most pro- 

 bably one of the minute forms of Cosmarium Hammeri. To 

 the latter species also belongs " C. pusillum var. retusum forma 

 intermedia" Gutw. (' Flor/Glon. Okolic. Tarnapola/ 1894, p. 

 100, t. 3, f. 37). 



88. Cosmarium geometricum AYest & G-. S. AYest. 



(PL LXXI, figs. 5, 0.) ' 



Cosmarium geometricum West & GK S. West, Alg. MacLag. 1895, p. 58, t. 6, 

 f . ?>2 ; Nordst. Index Desm. 1896, p. 129 ; West & G. 

 England, 1897, p. 486. 



