729 



;77e/?za-thallus. In the illustration (fig. 160, p. 756), a great part of tiie 

 vegetation wliich is seen above the surface of tlie sea, is Rhodij- 

 menia. So this is really a littoral, but epiphytical association. Hho- 

 dijmenia is often 2 feet long here and not short as when it grows 

 on the rocks. Its thallus, especially the older parts of it, shelter a 

 luxuriant vegetation of epiphytes, mostly species of Ectocarpiis and 

 Mijrionema, Chantransia, etc. Simmons also mentions this littoral 

 association (1. c. p. 256). In Trangisvaagfjord, he has found Punc- 

 taria latifoUa^ in numbers on the Laminae of Laminaria hijperhorea 

 and saccharina; to this epiphytical association he moreover refers a 

 great many other algae, e. g. Diciyosiphon foeniculaceiis, D. hippiiriodes, 

 species of Ectocarpus, and Scytosiphon lomentariiis. They may cer- 

 tainly be found here exceptionally in more sheltered localities, but 

 facing the open sea they are not common in this association, ac- 

 cording to my observations. 



The littoral Corallina-Formation 



or the Lomentaria-CoralUna-foTmsiiion, will in much exposed places 

 reach upwards into the CaZ/zY/zam/izon-association, thus even passing 

 the highest water mark. It however belongs mostly to the lower 

 part of the littoral region, and Corallina is found together with sub- 

 littoral species far down in this region. In more sheltered places, 

 Corallina hardly passes the lowest water mark, and is here limited 

 to the more low-lying, littoral pools which it covers with a dense, 

 pale-pink covering. As before mentioned, Corallina grows on the 

 most exposed coasts, e. g. Lille Dimon and Store Dimon, Muletangen 

 at Vaag's Ejde, Viderejde, Sumbo Holm, etc. In this respect, the 

 occurrence of Corallina (48, p. 116) does not bear out Kjellman's 

 words, that this alga »prefers sheltered places«^. 



In the more or less dense Cora/Zzna-vegetation, a great many 

 small and scattered growing algae are often sheltered. Larger algae also 

 find a favourable habitat here, occuring sometimes in such great num- 

 bers that they form their own associations, which will be described 



^ Called P. plantaginea bj^ Simmons (compare m}- Algae-Flora, 7, p. 436). 



^ It has been said bj' Wille (85, p. 14), that the chalky incrustation which 

 he is undoubtedly right in considering as a means of protection from herbivorous 

 animals, can hardh' be supposed to afford any protection from the dashing of the 

 waves. He founds this opinion on the observations of Kjellman and others. I 

 cannot fully adopt this view. It seems to me that the firm construction of the 

 thallus, together with the low, gregarious growth of the plant, must necessarih'' 

 protect it from the dashing of the waves (cf. Wille p. 37). 



