588 A. HESSELHO 



qiiinquedentald, L. ventricosa, L. MiiUevi, L. alpestris, Cephalozia bicus- 

 pidata , Cephaloziella Hampeana, JUepharostoma Irichoplujlliim , An- 

 thelia jnlacea, A. Jiiratzkana , Sca])ania snbalpina , S. curia, more 

 rarely Preissia commutala, Blasia pnsilla , Eucalyx subellipticiis, Lo- 

 phozia e.vcisa, L. heterocolpos and Lophocolea minor. The following 

 are Ihe commonest mosses: — Dichodontiiim pelliiciduni, Dicranella 

 crispa, Distichiiim montaniim, Didijmodon rubeUus, Tortula subulata, 

 Desmatodon latifoliiis, Tortella lortuosa , T.fragilis, Schistidiiim apo- 

 carpum, S. gracile, Encalypta cdiata, E. rhabdocarpa, the majority ol" 

 the species oi Bryum, Leptobryum pijriforme, Pohlia conimiitata, P. criida, 

 Mniobryum albicans, Mniiim punctatiim, Bartramia ityphylla, Philo- 

 notis iomentella, Timmia austriaca, Pogouatnm urnigernm, Myurella 

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

 aniim, Hypimm hamulosiim, H. callichroiim , H. uncinatum, Hyloco- 

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

 gosum var. præcox, Heterocladium squarrosulnm, Distichiiim inclina- 

 tiim and Weisia viridiila are found especially in such localilies as 

 those mentioned above. 



Xerophilous Bryophyte Associations. 

 Heaths. 



The healh 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 succeedqd by the 

 rocky-flat association. 



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

 forming planls are Empetrum nigriim, Vaccininm nliginosiim, V. 

 Myrtilliis, Arctostaphylos iiva ursi, Betiila luma and, especially in 

 E. Iceland, Calliina vulgaris. Mossos and liverworts olien grow 

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

 posed of Hylocomium spp. (especially H. proliferiim and H. parieti- 

 num), Rhacomitriiim hypnoides, R. canescens and Hypmim uncinatum, 

 but Dicrannm spp. {D. scoparium, D. fuscescens and others), Lopho- 

 zia spp. Ptilidium ciliare, Frullania 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 heath-vegetation is extensively distributed, 

 especially around Dv'rafjordur and Isafjordur. Here the heath-for- 

 ming piants are mostly Vaccininm Myiiillus , V. uliginosnm, Empe- 

 trum nigrum and occasionally Betnla nana. 



