550 A. HESSELBO 



red, consisting of Hypniim ochraceum , H. falcatiim, Schistidiiim ri- 

 vulare, Rhijnchostegium riiscifonue var. atlanticiim and Scapania 

 undiilata. 



The Bryophyte Vegetation of Inundated Gravelly Soil (slightly 

 inclined ground and banks ot" 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 conslituent of the 

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

 may be desigpated 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. Mniohrynm albicans var. glacialis is almost as common 

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

 rioulare and Acrocladinm cuspidatum 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 Ellidarå near Reykjavik: The mossy fringe along 

 the banks consisted of Philonotis fontana, Dichodontinm pellncidnm 

 and Acrocladinm cnspidatum. 



2. Husavik, along a stream : A broad l)elt of Cinclidium 

 stycjium together with some Pahidella squarrosa. 



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

 Mniohrynm albicans var. glacialis, Mnium pnnctatum, Philonotis 



fontana, Marchantia polymorpha together with some Brynm Dnvalii 

 and Thnidinm lanatnm. 



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

 Seligeri. Hypnnm gigantenm and Mniohrynm albicans var. glacialis. 



5. Svin ask ard, along a small stream: Philonotis seriata, 

 Scapania nndntcda, Chiloscyphns polyanthns and Pellia Xeesiana. 



6. Kai da Ion (NW. Iceland), in a small stream and on 

 gravelly ground over which water was flowing: Philonotis seri- 

 ata, P. fontana, Dicranella sqnarrosa, Mniohrynm albicans var. 



