744 



this takes place generally nearer the nioiiths of the fjords, where 

 the sea-water inundates its habitat at high tide. 



As mentioned already Pelvetia grows uppermost. On a sheltered 

 coast and at or a little above the highest water mark, it constitutes 

 an association which may spread far horizontally, but which is 

 vertically most often only one foot broad (see plate XXII). When 

 moist, it is of a light yellowish, olive-brown hue, but in calm 

 weather it is often liable to be dried; Pelvetia may be found quite 

 dry and stiff, and is then of a blackish hue. In tideless bays, it is 

 of course very liable to be drained, and circumstances are on the 

 whole less favourable to it here than in piaces which are subject 

 to a regular tide. This is quite clear from its slighter development; 

 specimens from the Kalbakfjord for instance, especially those growing 

 highest, were often but one inch long and consisted almost entirely 

 of receptacles, a form which has been called f. minima by Simmons. 

 Yet this dwarlish growth here in the fjords, may perhaps be partly 

 due to the great amount of fresh water which flows constantly 

 from the rivers, and which makes the surface-water with which Pel- 

 vetia comes in contact, very fresh. On coasts subject to the tide, 

 a much more vigorous and better developed Pe/f;e/m-association is 

 found. Other algæ are but rarely found in the 7^e/pe//«-association 

 as Simmons (p. 251) has pointed out, probably because only a few 

 algæ are able to grow so far above the level of the sea in sheltered 

 placfes. Ulothrix flacca and Ectocarpiis litoralis are however some- 

 times found epiphytically on Pelvetia, on the rock we fmd a sub- 

 vegetation of Verrncaria and Hildenbrandia rosea, and in cracks in 

 the rock, Rhodochorton Rothii and Ectocarpiis litoralis. 



Below this association, a Fiiciis vesiciilosns-Ascophylliim nodosiim- 

 association grows on a sheltered coast. It is very common and on 

 slightly sloping rocks it is widely distributed horizontally; a specially 

 luxuriant growth of these algæ seems to be found on coasts with 

 boulders and fragments of rocks of different sizes. On these stones, 

 Fiiciis vesiciilosus generally grows uppermost, in large dense clumps 

 and facing landward; below, Ascophylliim hangs down the sides 

 of the stones (see plate XXIV). Yet Ascoplujllum may also be found 

 growing above Fiiciis vesiciilosus. This I have seen in the Vestman- 

 havnbugt, for instance. Strømfelt likewise writes (80, p. 10), that 

 Ascophylliim grows uppermost, and Fucus vesiculosiis farther down ^, 

 whilst Rosen vinge reports that F«r«s vesiciilosus grows uppermost 



^ According to Jonsson's observations (41, p. 192 — 193), it is usually tlie reverse. 



