729 



me/jza-thallus. In the illustration (fig. 160, p. 756), a great part of the 

 vegetation which is seen above the surface of the sea, is Rhody- 

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

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

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

 luxuriant vegetation of epiphytes, mostly species of Ectocarpns and 

 Myrionema, Chantransia, etc. S i m mon s also mentions this littoral 

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

 taria latifolia^ in numbers on the Laminæ oi Laminaria hyperborea 

 and saccharina ; to this epiphytical association he moreover refers a 

 great many other algæ, e. g. Dictyosiphon foeniculaceus, D. hippuriodes, 

 species of Ectocarpns, 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-Forincdion 

 or the Lomentaria-Corallina-formaiion, will in much exposed piaces 

 reach upwards into the Callithanmion-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 piaces, 

 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 piaces« ^. 



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

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

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

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



^ Cailed P. plantag inea bj^ Simmons (compare mj^ Algæ-Flora, 7, p. 436). 



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

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

 animals, can hardl}^ be supposed to afford anj' 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 

 thailus, together with the low, gregarious growth of the plant, must necessarily 

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



