THE BRYOPHYTA OF ICELAND 579 



Bryophyta appeared first at the edge of the outlet of the spring where 

 the temperature was 25 -40. The vegetation here resembled that 

 of wet, cold ground, and was usually composed of Philonotis fon- 

 tana, Mnium Seligeri, Hypnum stramineum , Catoscopium nigritum, 

 and in a single spot of some Sphagnum angusti folium. On drier, 

 warmer ground Hypnum imponens was found here and there in 

 company with Hypnum stramineum, Hylocominm squarrosum, Archi- 

 dium phascoides, etc. 



Of the hot springs situated at higher levels only a few have 

 been investigated. In the neighbourhood of Kolvidarhol, at an 

 altitude of about 350 metres, on the warm ground around some 

 holes whence issued vapours impregnated with sulphuretted hy- 

 drogen and where sulphur had been deposited, the following species 

 w r ere growing: Gymnocolea inflata, Haplozia crenulata, Fossombronia 

 Dumortieri, Aneura pinguis, Archidium phascoides and Polytrichum 

 commune. Here Gymnocolea inflata was not strictly confined to the 

 warm ground, but appeared rather to prefer clay, as it also grew 

 on clayey flats which had probably been warm previously, but were 

 now quite cold. 



The same species together w r ith Blasia pusilta grew also in Rey- 

 kjadalur (at an altitude of about 260 metres) on the damp base of 

 a warm slope from which vapours, containing sulphuretted hydrogen, 

 and water issued sparsely from numerous small holes. Near some 

 mud-pools on Hellisheidi only Gymnocolea inflata and Haplozia 

 crenulata occurred. 



The Sulphur Springs on Reykjanes which I myself had no 

 opportunity of visiting have been described by Ostenfeld (Bot. 

 Tids., vol. 22, p. 239). They occur in two groups, near Reykjanes 

 lighthouse and also near Krisuvik. 



The Solfataras near Reykjanes lighthouse form a large 

 group with numerous orifices of discharge, partly mud-pools, partly 

 steaming holes, everywhere around which the ground is warm 

 (20 -30). Near the outlet of the largest mud-pool, Gunna, the 

 damp ground, which had a temperature of about 30, was covered 

 with Haplozia crenulata to which, along the margin, came several 

 other species, viz. Fossombronia Dumortieri, Archidium phascoides 

 (recorded by Ostenfeld as Pohlia nutans\. filicaulis), Trichostomum 

 littorals and Bryum uentricosum, all of which, however, only occur- 

 red sparingly. Around the steaming holes grew Riccia bifurca, 

 Preissia commutata, Fossombronia Dumortieri, Archidium phascoides, 



