260 BRITISH DESMIDIACE^E. 



absent from the centre. Chloroplasts axile, with one 

 pyrenoid (or sometimes with two ?). 



Zygospore unknown. 



Length 35-42 /x; breadth 28-33 //, ; breadth of isth- 

 mus 8'5-loju-; thickness 16-18/x. 



ENGLAND.- -Bog, 2 miles S. of Clapham, W. Yorks ! 



IRELAND. Carrantuohill, Kerry ! 



Geogr. Distribid ion. --Germany (var.). Hungary. 

 Italy. Norway. Sweden. Finland. Poland (var.). 

 Russian Lapland. N. Russia (a form). Nova Zerabla. 

 Spitzbergen. Greenland. Australia (var.). New 

 Zealand (var.). United States. 



Forma granulata Nordst. (PI. XC, figs. 11, 12.) 



C. nasutum forma granulata Nordst. Desm. Spetsb. 1872, p. 34 ; Wille, 

 Ferskv. Alg. Nov.' Semlj. 1879, p. 42, t. 12, f. 30 ; Boldt, Desm. Gron- 

 land, 1888, p. 24; Liitkem. Desm. Attersees, 1892, p. 555 ; Borg. Ferskv. 

 Alg. Ostgronl. 1894, p. 14; Boy & Biss. Scott. Desm. 1894, p. 169; West 

 & G. S. West, Notes Alg-. I, 1898, p. 334 [recorded as type] ; Alga-fl. 

 Yorks. 1900, p. 86 [recorded as type] ; Larsen, Freslrvv. Alg. E. Green- 

 land, ]904, p. 86. 



Semicells with a narrow transverse band of 6-8 

 granules (generally in pairs) above the emarginate 

 wart which lies adjacent to the isthmus. 



Zygospore globose, with rather few mamilliform 

 protuberances (about 9 visible in the periphery), each 

 protuberance furnished with a short, thick, somewhat 

 uncinate spine. 



Length 33-50 ; breadth 28-38 p. ; breadth of 

 isthmus 10-18 ju ; thickness 16'5-26/tt; diam. zygosp. 

 without spines 34-35 ju, with spines 45-47 ft. 



ENGLAND. Cowsdll Wold Moss on AYiddale Fell, 



a 



W. Yorks (with zygospores) ! 



WALES.- -On dripping rocks, Glyder Fach, Carnar- 

 vonshire ! 



SCOTLAND. --Corrie Etchachan 011 Ben Macdhui, and 

 near the summit of Lochnagar, Aberdeen (Roy fyBissett). 



Geogr. Distribution- -Austria. Bornholm. Finland. 

 G-reenland. Spitzbergen. Nova Zembla. 



C. nasutum is one of the most characteristic of the rare 

 alpine and arctic Desmids. It probably occurs in most of the 



