715 



is sometimes found perfectly dry. This association may be found 

 covering large stretches of rocks as a dense, moss-like mat, some- 

 times only consisting of Enteromorphæ, sometimes of Enteromorphæ 

 mingled with Prasiola stipitata etc. 



In some piaces the latter algæ, however, grow quite unmixed 

 with any other species, and often carpet the rock wilh a short, dark 



Fig. 152. Prasiola s(ipi7a(a-as.sociation. From rocky coast near Hojvig. 

 (F. B. phot.). 



green covering, as shown in fig. 152. Prasiola stipitata grows as a 

 rule on horizontal or slightly sloping sides of rocks, and prefers 

 piaces where birds live, especially the summits of rocks under 

 fowling cliffs. This alga may also be found quite dry. 



Simmons mentions (78, p. 251) an Enteromorpha -iormaiion 

 which, judging from the species mentioned by him, must at any 

 rate partly belong to the £'n/e/'omo/-jD/ia- association. But on the 

 other hånd he also mentions some Cladophora-species as belonging 

 to this association; these species, according to my observations, be- 

 long to algæ-associations which grow farlher down. 



Botanj' of the Færoes. 46 



