XIV 



This list contains 22() (+15) species of Rhodophyceæ and 181 

 (+ 9) species of Phæophyceæ, in all 407 (4- 24) species. Regarding 

 the investigation of the distribution of the different species we have 

 laid the greatest stress upon finding the southern boundary of 

 those species which belong most strictly to the colder waters or 

 the Arctic Sea, and the northern limit of those characteristic of the 

 Boreal Region of the Atlantic, viz : the area which is limited to the 

 south by the tropic of cancer and to the north by the Arctic Sea. 

 With regard to the southern distribution of the Boreal Algæ we have 

 as the following grouping will show, not followed them farther 

 southwards than to the Mediterranean and the Atlantic coast of 

 North Africa, as we thought that this area would be sufficient to 

 give an opinion on their phytogeographical significance in regard 

 to our papers on the Algæ-vegetation of Iceland and the Færoes. 

 In the following grouping of the Algæ we have taken no considera- 

 tion of the Algæ strictly belonging to America, as we did not think 

 our knowledge of their distribution sufficient, but we have how- 

 ever included them within a paranthesis in the groups to which 

 they appear to belong. 



With regard to the following grouping we shall mention more 

 particularly the Arctic group and especially the southern limit of 

 the area of the Arctic Alga-flora. 



The polar circle has previously (e.g. by Kjell man and Reinke) 

 been regarded as the southern limit of the Arctic Alga-flora as re- 

 gards the Norwegian coast, while the limit near to the American 

 coast has been set much more southwards (e.g. Kjellman and Ro- 

 senvinge). The Arctic Alga-flora has thus been limited in highly 

 different manner on either side of the Atlantic. No doubt the limit 

 as regards the American coast is almost correct, while the polar 

 circle cannot be used as a limit next to the Norwegian coast \ as 

 may be seen from the hydrographical conditions of the north of 

 Norway and from the Algæ-flora of Nordland and Finmark. The 

 Alga-flora of the north of Norway belongs phyto-geographically to 

 the Boreal area of the Atlantic, and it passes without any distinct 

 limit into the arctic Alga-flora to the north and east of Norway. 

 The south limit of the Arctic Alga-flora thus goes to the north of 

 Norway, and following it westwards we shall see, that it turns con- 

 siderably southwards and touches the south-east point of Iceland, 

 where the boundary both hydrographically and phytogeographically is 



1 This has been pointed out by Simmons (Bot. Not. 1904 p. 216). 



