THE BRYOPHYTA OF ICELAND 665 



The rocky flat is very widely extended in NW. Iceland, since 

 it comprises all the flåts and plateaus above the mountain slopes, 

 and on the north side of the mountains descends as far downwards 

 as to the sea-level. Several rocky-flat piants are therefore more 

 widely distributed liere than in the other districts of Iceland. Oligo- 

 trichiini hercyniciim, Rhacomitriiim siideticiim , Conostomiim boreale, 

 Lesciiræa Breidleri, Gymnomitriiim concinnatiim and Pleiiroclada al- 

 bescens are very conimon. Sphenolobiis politiis, Haplozia sphæro- 

 carpa, Gymnomitriiim revoliitiim and G. varians have been found 

 only on the rocky flåts of NW. Iceland. 



Lesciiræa filamentosa is very common and found fruiting on 

 detached blocks and on rocks, and L. patens is also frequent and 

 likewise sets fruit. 



Some few species, which are widely distributed elsewhere in 

 Iceland, are absent here, for instance Scapania dentata, Radiila com- 

 planata, Gymnostomam riipestre, Campylopiis Schimperi, Sælania cæsia, 

 Mnium Seligeri, Hypniim cnpressiforme and Hypniim paliistre, whilst 

 others are rare, for instance Preissia commiitata, Leptobryiim pyri- 

 forme, Catoscopiiim nigritiim. Timmia aiistriaca and Hypniim falcatiim. 

 The comparatively abundant occurrence of species of Sphagnum, 

 and the lesser frequency of the last-mentioned lime-loving species, 

 appear to indicate that the soil here is less calcareous than in the 

 other districts of Iceland. 



The Bryophyte vegetation of NW. Iceland has, on the whole, 

 a more decidedly xerophilous and Arctic character than that of the 

 rest of Iceland. 



West Iceland has, with the exception of the southern part 

 as far as Borgarfjordur, been very superflcially investigated and, 

 apart from a few scattered collections made by Helgi Jonsson, 

 especially in Biidahraun on Snæfellsnes, and my own collections 

 near Stvkkisholmur, the whole stretch of coast norlh of Hvalfjordur 

 and around Breidifjordur is, from a bryological point of view, quite 

 unknown. 



Several of the species characteristic of South Iceland occur here 

 also, partially decreasing in frequency throughout West Iceland, for 

 instance Thiiidiiim delicatiilnm , Hylocomium loreiim, Eurhynchiiim 

 piliferiim and (in the South-west) Madotheca Cordæana. Some species 

 have a decidedl}'^ westerly distribution in Iceland, being of almost 

 equal frequency in West and South-west Iceland and a few also in 



The Botany cf Iceland. Vol. I, part II. 43 



