THE BKYOl'HYTA OF ICELAND 643 



albescens, Scapania remota, Dilrichiiin nivale, Pohlia polymorpha, P. 

 Lndwigii and Brachythecium (jlaciale) have not been found below 

 the upper limit of the birch. 



In the Mountain region the number of species is as follows: 



42 Hepatica3 



5 Sphagna 



134 Musci veri 



181 Total species. 



Of these, however, 10 Hepaticse and 31 Musci veri have been 

 found only in the lowest part, at the boundary towards the Low- 

 land region, whereby the number of species which in reality bi- 

 long to the Mountain region, is reduced to 140. Of these, 2 He- 

 paticse, viz. Gymnomitrium varians and Scapania remota and 3 Musci 

 veri, viz. Ditrichiun nivale, Pohlia polymorpha and P. Ludwigii have 

 been found only in this region. 



In the Snow region the number of species is as follows : 

 16 Hepaticse, 42 Musci veri, total 58, of which, 6 Hepaticas and 10 

 Musci have been found only in a few localities and cannot be re- 

 garded as belonging to this region. In all, 42 species remain, of 

 which, however, only 8 Hepaticse and 20 Musci veri are fairly fre- 

 quent, while the others have been found only in a few localities. 

 The majority of the species belong to those which are of equal 

 frequency at all altitudes, and only 4 species (Pleiiroclada albescens, 

 Dicranum falcatum, Pohlia cucullala and Pohjtrichnm sexangulare) 

 can be designated true Snow-region species. 



The number of species decreases rapidly as the height above 

 sea-level increases, and even at the upper limit of the heather moor 

 the number falls to about 40 % of the total number of species. 

 Above a height of about 600 metres the number scarcely reaches 



u v 



15 % of all the species. 



