2U4 .ions. iu)Yi: iM.ri:MSi:N 



Clrows •»cnerally on cnrlli and aiiion-^ or on Mosscs. H Muricl 

 Bristol 1919 p. 99* foiiml il alivc in a s()il-sani|)it' from 184(1. 11 has 

 thiis been ra|)al)le of wilii.slaiKliiif^ l'A years lor|)or. Is luuloubledly a 

 chance j^iicst in Ihc hot sprinj^. 



Nostoc humifusum Carrnichael. 



Bornet el llahauil. Revision IV p. 201. 



S. Icel. Lanj»arvas? i^ — Laiij^arnar at Heykjavik.' ; near tlie niarj^in 

 of tiie nortiieiii si)rinfj, tcmp. 100 ('. Stp.)! — N. \V. Icel. Heykjanes in 

 Isaljan'iardjiip, iiol sprinj^ 00" Hariot (1893 p. 315, Belloc (1894 p. 6). 



Area: Hiir.. Air, Am.. Spil/.bergen. 



Tilis species is but rarely recorded in litcratiire. and its distribution 

 is undoubtedly known to a slight extent only. Most frequently met with 

 on earlh, bul also at times in water. In Iceland il was bolh times 

 Ibund al Ihe hol springs. The faet that it thrives well here may per- 

 haps be ascribed to the heated ground and tlie moisture from the va- 

 pour. Otherwise it is undoubtedly not a thermal alga. 



Nostoc commune Vauchcr. 



Bornel el Flahault. Hevision IV p. 203. 



E. Icel. Ekkjufell. Fissure in a rock with trickling waler -,7 1914. 

 Fljotsdalur. rocky wall over which water was trickling, among mosses 

 '»% 1914. Hangar 1894 (H. J.; ! — N. Icel. (Herarfos (Akureyri), on 

 rocks dashed with water ^-/t 1914. — S. Icel. Ytri Skogar 21/7 1901 

 H. J.)! Krokur ^/i 1901 (H. J.)! Grimsta6ir, on mud in a "Floi". 

 377 1905 (H. J.)! 



Area: Ubiquist. 



It is a pronounced terrcstrial and petrophilous species which but 

 as a rare e.xception is met with in water. 11 belongs to the most com- 

 mon species in arctic regions (Borge 1899 p. 7G5,. 



Nostoc sphærieum Vaucher. 



Bornel et Flahault, Revision IV p. 208. 



W. Icel. Hvalfj6rt)ur; stream at Litlisandur; on stones, lemp. 13*^ ^/s 

 1914. — S. Icel. Holmsa; on stones, temj). 14" '^/s 1914. Kambar; on 

 stones in stream, temp. 14° ^^/s 1914. (iljufurholtsa near Kotstrond; 

 slight current, tcmp. 15*^ ^^/s 1911. Varma at Reykii- in Olfi'is, temp. 

 17" '^/8 1914. ' Hofsfjall. "Ve 1897 (,6. D.)! Fossarnir in H()fsa '-/e 

 1898 fO. I).;! 



Area: Kur., Afr., .\m., Austr . .\ntarctic, Alaska, Greenland. 



To the present species 1 have referred a number of samples con- 

 taining spherical, solid iVo.s/or-colonies, 1 — 5 mm. in diameter, trichomes 

 4—6 // in diatneler, and heterocysts 6—7 11 in diameter. In no case did 

 I observe spores. Hence it is just possible that somc of the spccimens 

 mentioned above may in faet represent develo|)niental stages of other 

 Nostoc-species. 



Nostoc sphærieum has most fre((uenlly been found in still water; 

 but it also occurs on land luid has been foiind on Irunks, on soil and 



