MARINE ALGAL VEGETATION 165 



3. Gigartina, widely distributed. 4. Corallina widely distributed, in 



Rhodymenia. a single pool Halosaccion. 



Plum aria elegans. 

 Delesseria alata. 

 Acrosiphonia. 

 Monostroma Grevillei. 

 Chsetomorpha Melagonium. 



5. Laminaria 4- Alaria. 



In another part: 



Ascophyllum in quantities between 

 1 and 2. 



Delesseria sanguinea and others. 



It would carry us too far to give several more examples from 

 the diaries, but on regarding the material taken as a whole it is 

 distinctly seen that there is no other difference of importance be- 

 tween the two districts with regard to the zonal division of the 

 algal vegetation beyond the fact that some of the communities and 

 associations occur in one place and are absent from the other. The 

 division of the belts varies somewhat in both places which is 

 chiefly due to the greater or smaller degree of exposure of the 

 locality (see Part VI). 



The most conspicuous difference in the division of the belts 

 in E. Iceland and S. Iceland is due to the enormous size of the 

 Cora//zna-belt in the latter place. This community (Gigartina, Coral- 

 lina and others; see Part VI) occurs just below the Fucus-helt where, 

 for instance, in the Vestmannaeyjar it is the dominant one; this 

 also applies to Eyrarbakki and the south side of Reykjanes, but 

 perhaps to a somewhat less degree. This leaves less room for the 

 /?/ioGh/me/?za-community (Rhodymenia, Halosaccion ; see Part VI), which 

 also forms a belt below the Fucus-belt; consequently it is not so 

 large there as in E. Iceland where it is extremely common and in 

 several places widely extended. In many places in SW. Iceland 

 the /?/7OG?z//T7e/?za-community is as large as in E. Iceland. 



The sea off the coast of S. Iceland is in movement everywhere, 

 and calm water is almost unknown. The calm-water-vegetation 

 proper, which is so common w r ithin the fjords of E. Iceland, is 

 therefore absent from S. Iceland, but is again found richly repre- 

 sented in SW., NW. and N. Iceland. 



The luxuriancy of the vegetation is somewhat similar in 

 both places; it appears, however, to be greater in the Vestmanna- 

 eyjar and the western part of the south coast. 



Depth-limit. It appears that there is reason to believe (see 

 Part V) that the algal vegetation extends to greater depths in the 

 fjords of E. Iceland than on the south coast, but as this cannot be 

 regarded as sufficiently proved I shall not enter into it more fully. 



