768 



mens ma}^ of course be sometimes found, but not in great numbers, 

 what is, however, the case on the coasts of Greenland, according to 

 Rosenvinge (71, p. 218). The name »formation of loose-ljdng Alg9e« 

 may in the Faeroes only be used of the above mentioned loose 

 masses of algae, which mainly consist of species of Enteromorpha, 

 Chcetomorpha tortiiosa, Acrosiphonia, Monostroma, etc. 



The Vegetation on soft bottom. The Zostera- Association. 



With the exception of the Cliaracea', which may be found in 

 brackish water, algae from the northern seas will not usually thrive 

 on a bottom of sand or mud^, which is therefore destitute of 

 vegetation. Only here and there, where stones are found, may 

 algae be met with, but as a soft, loose bottom is rather common 

 in the sounds between the islands and in the fjords, at any rate 

 in deep water, somewhat large, naked regions occur with only a 

 few loose drifting algae. What makes the tracts still more naked 

 is, that the Zostera marina, which has its habitat in shallow 

 water (down to a depth of from 6 to 7 fathoms in our seas) in 

 this kind of ground with loose bottom , is almost totally wan- 

 ting at the Faeroes. It has only been found at the bottom of 

 Vaag Fjord. In a small limited territory it makes an association 

 here at a depth of about 1 fathom, and at low tide, its leaves may 

 be seen floating on the surface of the sea. The Zostera here as 

 elsewhere shelters a number of different epiphytes, e. g. species of 

 Enteromorpha, Ectocarpus litoralis, Chantransia virgatnla and C. secun- 

 data, Microsyphar Zoster ce, Scytosiphon tomentarins, and so forth. 



3. The lower limit of the Algae-vegetation. The elittorai Region. 



As mentioned before, I agree with Rosenvinge in determining 

 the elittorai region as that part of the bottom of the sea where no 

 vegetation grows on the bottom ; I shall therefore leave this re- 

 gion out of consideration. At far greater depths than those at 

 which the fixed algae grow, we may of course find loose-lying algae 

 which have been carried by the current away from their habitats. 

 Such portions of algae may perhaps live for some time by con- 

 suming their reserve stores, but when these are used up they must 



^ In the tropics however we find an algse-vegetation wliich is often quite 

 dense and fastened on a bottom of sand or mud. 



