717 



this alga together \vith Hildenhrandia and some species of Verrii- 

 caria as subvegetation, but different forms of Enteromorpha intesti- 

 nalis, Edocarpiis littoralis and others are, however, often intermingled ; 

 the Fucaceæ- formation mentioned below (page 720) likewise some- 

 times extends into tlie Porp/jyro-association. 



The Porphyra -\ege\a\ion was well developed in the months, 

 April to August, when I visited the Færoes; Mag. H. Jonsson like- 

 wise tells me, that he has found it vigorously developed when he 

 visited the Islands from October to December, 1897. Thus it 

 seems to be well developed all the year round, and is not, as 

 Simmons says (1. c. p. 250), mostly a »Winterformation« on ex- 

 posed coasts, even if it may be supposed to be still more vigorously 

 developed in the winter, judging by its growth in other piaces. On 

 coasts especially exposed to the surf it may also be supposed to 

 extend still further up above the level of the sea. In more southern 

 districts the Porjo/jyra- association is really a characteristic winter 

 vegetation. Thus when Kjell man (45) visited the »Skærgaard« 

 of Bohuslån from Dec. 1874 to Jan. 1875, he found a luxuriant 

 Porp /jy/'a-vegetation on the outer rocks facing the sea, whilst this 

 vegetation is totally wanting in summer, which I have also observed 

 during a visit to Lysekil in 1899. Neither was this alga found on 

 the rocks in the Firth of Forth at North Berwick, where I had an 

 opportunity of observing the local algal vegetation one day in 

 July 1900. In winter it is most likely vigorously developed liere also. 

 On the west coast of Norway, Boye points out (6, p. 20 — 21), that 

 Sognefjorden seems to be the southern limit of its occurrence ; he founds 

 this opinion on his own as well as on Hansteen's observations. This 

 is, however, scarcely correct. Mr. E. Norum, teacher at Haugesund, 

 has for a long time investigated the marine algæ growing on this 

 part of the west coast of Norway, and kindly reports, that Porphyra 

 umbilicalis is met with as an unmixed vegetation in much exposed 

 piaces at Haugesund and Utsire, an island about 3 miles west of Hauge- 

 sund. At Utsire, where Mr. Norum made his observations in July, 

 the Por/;/7y/a-vegetation reaches to a height of 2 to 3 metres above the 

 »Balamis-heli« on the southern and eastern sides of the island, and 

 it may be supposed that it reaches still further on its northern side. 

 At Christianssund, I have myself seen Porphyra at the beginning of 

 August, growing some few feet above the highest water mark on an 

 exposed coast ; but the association was indeed only slightly developed 

 here, compared with that of the coasts of the Færoes. 



46* 



