711 



begins at a depth of about 3 to 4 feet; the Slictyosiphon-assoc'iaiion 

 growing above that would then be reckoned littoral. 



I have not, however, done this. A comparison ])etween this 

 algal vegetation and that of a sheltered tidal locality e. g. Vest- 

 manhavn, proves that under the F iicacece- f or mni'ion just below the 

 lowest water mark, a perfectly similar vegetation, the Sticiyosiphon- 

 association, is found, which is here sublittoral. 



In tliis area of tlie sea the littoral region is therefore but slightly 

 developed, only consisting of some scattered Pelvetia, Porphijra iim- 

 bilicalis, Fiiciis vesiciilosiis and a few others, besides some crusts of 

 bluish-green algae, Hildenbrandia and Rhociochorton. 



The algae-vegetation found on exposed coasts differs as a rule 

 considerably from that found on slieltered coasts; as in the former 

 a great many species occur that are not ahvays found in tlie latter 

 places, and as the species common to both places are often re- 

 presented by varying forms in each place I have divided the algae- 

 vegetation into that of exposed and that of sheltered coasts. The 

 Norw^egian investigators Hansteen and Boye have dealt in the 

 same way with the algal vegetation of the west coast of Norway. 

 We will iirst consider the vegetation of exposed coasts. 



a. Exposed Coasts. 



The Hildenbrandia-Formation, 



or the formation of the crustlike algae as well as of lichens is widely 

 spread along the exposed coasts of the Faeroes. It covers the rocks 

 wdth a dense mat of various colours to a considerably height, i. e. up to 

 more than tw^o feet above the level of the sea and down to the Coral- 

 /z77a-formation. The uppermost part of it mostly consists of lichens, 

 which, according to the Rev. Deichmann Branth, belong to dif- 

 ferent species of Verrucaria, but crusts of bluish-green algae soon 

 appear, especially Calothrix scopiiloriim, Rivularia atra etc. and the 

 crimson Hildenbrandia rosea; the last mentioned algae 1 have found 

 on the west coast of Vaago, about eight feet above the level of the 

 sea. At a shorter distance from the sea, Hildenbrandia becomes more 

 and more predominant, still crusts of lichens and bluish-green algae 

 are intermingled with it, and another crust-alga, Ralfsia verrucosa, 

 can now be found; this how^ever prefers littoral pools where the 

 ^vater is constantly renew^ed by the surf. The walls of such basins 



