718 



A summer vegetation of Porphyra as liixuriant as that of the 

 Færoes will most likely only be fonnd in more nortliern parts 

 of Norway. As to Nordland, Kleen for instance writes, that Por- 

 phyra iimbilicalis is found at the highest level, often far above the 

 highest water mark. That it may be found luxuriant even in 

 summer, in the Færoes, is certainly due to the faet that the 

 sea is almost always stormy. Even in calm weather there is most 

 often a swell and therefore surf along the coast. And even when 

 it happens that the sea is quite calm for some time, the littoral 

 algæ-vegetation is not in great danger of being dried up, because 

 the air is very moist, the weather often cloudy, and fogs and rain 

 frequent. That it, however, may happen, that the littoral algæ-ve- 

 getation, to which the Porp/jf/ra-association belongs, may be found 

 dried on sunshiny days has already been mentioned. 



The lowest limit of the Po /-jo/jz/ra-association is determined by 

 Boye to lie at the highest usual water mark, which is almost 

 identical with the sharply-marked, white line formed by the Bala- 

 nus, as he likewise points out. As may be seen in my illustration 

 from Midvaag (see plate XVII), his view agrees with observations 

 from the Færoes, although only in somewhat more sheltered 

 piaces. In more exposed piaces, the Porjo/iyra-association is replaced 

 here by other algæ, and is not found until far above the highest 

 water mark. In these exposed piaces it may extend far in a ver- 

 tical direction, sometimes even to many metres, thus Simmons' 

 remark, that the Porp/iyra-association has »nur eine recht geringe 

 vertikale Verbreitung«, holds good only in the case of somewhat 

 sheltered piaces. 



The Rhodochorton- Association. 



The P/?oG?oc/70/'/o/j-association commonly forms a kind of close 

 felt, reddish-brown to crimson, on stones and rocks, but in piaces 

 where it is apparently more exposed to be dried up and to the 

 surf, it may be found on the rocks in small firm lumps resembling 

 peas (f. globosa). It often grows on the underside of rocks and 

 stones, in clefts in the rocks, and in the caves (about which 

 more will be said presently); but it may also be found growing in 

 full daylight. 



It is found partly in the littoral region, especially in its higher 

 part, and partly far above the highest water mark, especially in 

 the caves. 



