765 



Together with Ectocarpns liloralis these algæ form tough, en- 

 tangled, loose-lying masses in shallow water. Besides these algæ we 

 find Chorda filiim, Scijtosiphon lomentariiis, Ceramiiim ruhriim, Halo- 

 saccion rdinentaceiim and somelimes also other species belonging to 

 the above mentioned Stictyosiphon-assoc'iaVion. As already mentioned 

 this association together with the Stictij()sij)hon-association perhaps 

 answers to Si m mons's Ulvaceenformation. 



Th e Ha lidrys-Associa tion . 



As this association is but rarely found at the Færoes, it is of 

 minor importance there. It has only been found attached to the 

 bottom within a very limited region at Glibre in Skaalefjord on 

 Østero, but as this alga is ralher abundant in this locality and 

 agrees quite well with Hansteen's (38, p. 353), Boye's (6, p. 8) and 

 Gran's (36, p. 19) descriptions of their //a/zf/rys- formation, I think 

 that it ought to be mentioned here. It grows here on a stony bot- 

 tom at a depth of from 1/2 to 1 fathom, forming a narrow belt at 

 no great distance from the coast. The specimens are enormous, 

 almost one fathom long. It grows together with scattered specimens 

 of Laminaria digitata, L. hyperborea and L. færoensis and Chorda filiim. 



When I visited the tract in May 1898, I found several small 

 specimens of Piindaria latifolia, Chordaria flagelliformis, Ectocarpns 

 litoralis, Stictyosiphon foeniculaceus , Dictyosiphon and a great many 

 Diatoms growing epiphytically on the Halidrys. 



In August (?) Si m mons found it densely overgrown by Dic- 

 tyosiphon hippiiroides ; he therefore calls it »the Hcdidrys-Dictyosiphon- 

 formation«. 



The Laminariaceæ-Formation on sheltered coasts. 



The Lammanaceæ-formation varies much on sheltered coasts. 

 Where there is no current, Laminaria færoensis grows abundantly, 

 forming widely spread associations. But where there is a rapid cur- 

 rent, as in most sounds between the islands, L. færoensis is wanting 

 and is replaced chiefly by L. hyperborea. 



Let us first consider the Laminaria færoensis-association whicli 

 grows on sheltered coasts. This alga necessarily requires a habitat 

 where the sea is never disturbed. The large lamina which is often 

 several fathoms long and easily broken would soon be torn by the 

 surf. The slender haptera and the brittle stalk would not long be 

 able to resist the strain caused by the current. 



49* 



