114 H. JONSSON 



The Surf- be It, as previously stated, occurs at the upper 

 boundary of the Fucus-association on rocky coasts which are very 

 much exposed. I have seen such a belt at 0ndver5arnes in SW. 

 Iceland, in the Vestmannaeyjar in S. Iceland and at Vattarnes in 

 E. Iceland. Strom felt (70) has noticed a similar belt on Seley in 

 E. Iceland. It will probably be found, on further investigation, that 

 the surf-belt is far more widely distributed along the coasts than 

 is recorded above. As a rule, the individuals in this belt are of low 

 growth; the frond is leathery, and very thick in proportion below, 

 and rounded, but tapering evenly upwards and becoming thinner; 

 above, it is often excessively branched. The height of the individuals 

 varies to some extent, f. dendroides is the highest, while f. exposita 

 attains only an insignificant height (5 — 9 cm.). A similar surf-belt 

 occurs in the Fseroes (Borgesen, 12), although the vegetation is 

 possibly more luxuriant there than in Iceland. 



The W a v e - b e 1 1 (Fig. 6) comprises the ordinary Fucus inflatus-be\t. 

 As a rule, it is exposed to the movement of the waves, a movement 

 which is often very violent indeed; more rarely it is exposed di- 

 rectly to the breakers. Here the species occurs in its typical form 

 which shows a considerable variation in the breadth and consistenc}' 

 of the thallus. In very exposed places the branches of the frond are 

 comparatively long and narrow and leathery, but where the move- 

 ment of the waves is less felt, the frond is usually broader. The 

 vegetation of this belt is generally very luxuriant, and covers the sub- 

 stratum entirely. Often, however, the vegetation occurs in patches, 

 owing to the surface-features of the shore. Such a mode of occur- 

 rence is met with, for instance, where the shore is a wild talus of 

 debris consisting of large scattered blocks of stone, or where the 

 solid rock has a similarly uneven surface owing to erosion by the 

 sea. There a belt is formed around each block of stone, while the 

 hollows between them are occupied by semi-littoral or sublittoral 

 vegetation, or by stragglers from these zones. 



The Calm Belt is lowest of all, often at the boundary between 

 the constantly submerged and the lower littoral vegetation, and some- 

 times forms small offshoots of vegetation 1 below that boundary. 

 Here the movement of the waves is least felt, and the frond of the 



1 The species varies from the principal form to two kinds of dwarf-forms — 

 a small "surf-form" of tough texture, and a small "pool-form" of delicate texture. 

 The pool-form-association (F. inflatus f. linearis) may be regarded as the fourth 

 belt, which should then be termed the Delicate Belt (see under The Vegetation 

 of Tide-Pools, p. 125). 



