588 A. HESSE LBO 



quinquedentata, L. uentricosa, L. Mullen, L. alpestris, Cephalozia bicns- 

 pidata, Cephaloziella Hampeana, Blepharostoma trichophyllum , An- 

 thelia jnlacea, A. Juratzkana , Scapania subalpina , -S. curia, more 

 rarely Preissia commntata, Blasia pnsilla , Eucalyx subeUipticus, Lo- 

 phozia excisa, L. heterocolpos and Lophocolea minor. The following 

 are the commonest mosses: Dichodontium pelhicidnm, Dicranella 

 crispa, Distichinm montcuuim, Didymodon nibelhis, Tortilla snbnlata, 

 Desmatodon latifolius, Tortella tortuosa, T.fragilis, Schistidium apo- 

 carpnm, S. gracile, Encahjpla ciliata, E. rhabdocarpa, the majority of 

 the species ofBryum^Leptobryumpyriforme,Pohlia commntata,P.crnda, 

 Mniobryum albicans, Mniiim pnnctatnm, Bartramia ityphylla, Philo- 

 nolis toiuentella, Timmia austriaca, Pogonatnm iirnigenim, Myurella 

 julacea, M.tenerrima, Brachythecium reflexum, Plagiothecium Roese- 

 anum, Hypnum hamulosiim, H. callichroum, H. uncinatiim, Hyloco- 

 mium loreum. Some rare species, for instance Eurhynchmm stri- 

 gosum var. prcrcox, Heterocladium squarrosiilum, Distichinm inclina- 

 tnm and Weisia viridnla are found especially in such localities as 

 those mentioned above. 



Xerophilous Bryophyte Associations. 



Heaths. 



The heath formation is extensively distributed about Iceland. 

 It occurs especially on dry slopes, and hardly ascends higher than 

 about 300 400 metres above sea-level, where it is succeeded by the 

 rocky-flat association. 



Heather-moor (H. Jonsson, 1900, p. 69). The chief heath- 

 forming plants are Empetrnm nigrnm, Vaccininm nliginosnm, V. 

 Myrtillus, Arctostaphylos nva nrsi, Betnla nana and, especially in 

 E. Iceland, Calluna vnlgaris. Mosses and liverworts often grow 

 abundantly on the ground. The Bryophyte carpet is chiefly com- 

 posed of Hylocominm spp. (especially H. prolifernm and H. parieli- 

 nnm), Rhacomitrinm hypnoidcs, R. canescens and Hypnnm nncinatnm, 

 but Dicranum spp. (D. scoparinm, D. fnscescens and others), Lopho- 

 zia spp. Ptilidinm ciliare, Frnllania Tamarisci and several other 

 species often occur in abundance. As examples will best show 

 the composition of this vegetation, the following are given: 



In North-west Iceland healh-veeetation is extensively distributed, 



<_J V 



especially around Dvrafjordur and Isafjordur. Here the heath-for- 

 ming plants are mostly Vaccininm Myrlillns, V. nliginosnm, Empe- 

 trnm nigrnm and occasionally Betnla nana. 



