98 L. KOLDERUP ROSENYINGE. 



glacialis, which seems to be a strongly arctic species with an extre- 

 mely northern extension, at least on this coast. The occurrence of 

 Chorda tomentosa, though only in feebly developed specimens, ap- 

 pears rather surprising, as it has not hitherto been observed on the 

 East coast. Lithothamnion tophiforme may also be named, though 

 it was only represented by one specimen. Thus, a certain floristic 

 difference seems to exist between Scoresby Sound and the area 

 North of 76° Lat. N., depending principally on the absence in the 

 latter of a number of species with a comparatively southern exten- 

 sion but also on the presence of at least one species with hyper- 

 borean occurrence. 



When considering the number of species within the main groups 

 of algæ the following numbers are found for the area here in ques- 

 tion, when the two undetermined species are included: 



Number 



of p. ct. 



species 



Rhodophyceæ 23 37 1 



Phæophyceæ 23 37- 1 



Chlorophyceæ 15 242 



Cyanophyceæ 1 IG 



It is rather surprising that the red and the brown algæ are 

 found to be equally numerous in this area, as it has proved else- 

 where that the Phæophyceæ are the most numerous group of algæ 

 in the arctic regions. When comparing these numbers with those 

 found by me for the whole of Greenland (1898, II p. 173^), we find 

 that the percentage of the Rhodophyceæ has greatly increased, that 

 of the other groups more or less diminished. On the other hand, 

 we find the same proportion between the red and brown algæ in 

 Scoresby Sound, for in Hekla Havn were found 21 red, 22 brown 

 and 9 green algæ (1. с. p. 232), and including the species found in 

 the neigbourhood of Hekla Havn (1. с. p. 231) we find the following 

 numbers: 26 red, 26 brown and 10 green algæ. The relative num- 

 ber of the Phæophyceæ seems thus to be increasing and becomes 

 predominant on going from the Atlantic northwards to the Arctic 

 Sea, but it diminishes on going further northwards in the strongly 

 arctic parts of the sea, dividing the dominion with the Florideæ 

 which greatly increase in number. 



When the 60 species of North-East Greenland are divided into 

 three groups, arctic, subarctic and North Atlantic in a similar man- 



^ I take liere the numbers as I found them in 1898 without considering the later 

 additions and corrections to tlie flora. 



