550 A. HESSELBO 



red, consisting of Hypnum ochraceum, H.falcatum, Schistidinm ri- 

 vulare, Rhynchostegium riisciforme var. atlanticum and Scapania 

 undulata. 



The Bryophyte Vegetation of Inundated Gravelly Soil (slightly 

 inclined ground and hanks of streams). 



Where the water flows down the mountain sides and spreads 

 over slightly inclined gravelly ground, ,and along the flat banks of 

 streams which are periodically inundated , a vegetation composed 

 mainly of Bryophyta is developed. The most conspicuous spe- 

 cies growing on this gravelly ground, and one which is hardly 

 ever absent, and is often the most abundant constituent of the 

 moss carpet, is Philonotis fontana, and after it this community 

 may be designated the Philonotis association (Ostf., 1907). 

 Very frequently many other species also occur, either as an ad- 

 mixture in the Philonotis carpet, or replacing it over smaller or 

 larger areas. In NW. Iceland P. fontana is often replaced by P. 

 seriata. Mniobrynm albicans var. glacialis is almost as common 

 as Philonotis; and Brynm ventricosum , B. Duvalii, Brachythecinm 

 riuulare and Acrocladium cuspidatam are also among those species 

 which are rarely absent. 



As a few examples will best show the composition of this ve- 

 getation, the following are given: 



1. The Ellidara near Reykjavik: The mossy fringe along 

 the banks consisted of Philonotis fontana, Dichodontium pellacidum 

 and Acrocladium cuspidahim. 



2. Husavik, along a stream: A broad belt of Cinclidium 

 stygium together with some Palndella squarrosa. 



3. Husavik, along the banks of smaller streams on a slope: 

 Mniobrynm albicans var. glacialis, Mninm punctatum, Philonotis 



fontana, Marchantia polymorpha together with some Brynm Duvalii 

 and Thiiidinm lanatnm. 



4. Berufjordur, along a stream: Philonotis fontana, Mninm 

 Seligeri, Hypnum giganteum and Mniobryum albicans var. glacialis. 



5. Svinaskard, along a small stream: Philonotis seriata, 

 Scapania undutata, Chiloscyphns polyanthus and Pellia Xeesiana. 



6. Kaldalon (NW. Iceland), in a small stream and on 

 gravelly ground over which water was flowing: Philonotis seri- 

 ata, P. fontana, Dicranella squarrosa, Mniobryum albicans var. 



