Introduction. 



1 have been charged with the determination of the hitest 

 collections of marine algæ from East Greenland. These collections 

 have been procured by Mr. C. Kruuse, and the material dates 

 from Amdrup's expedition in which Mr. Kruuse as well known 

 took part, and from Kruuse's own expedition to the district of 

 Angmagsalik. After the publication of L. K. Kosenvinge's 

 exhaustive works on the Marine Algae of Greenland (Grl. Havalg. 

 and Deux. Mém.) several important papers have been written 

 which have greatly altered the view regarding the limitation of 

 species in some genera, such as Acrosiphotiia, Ulothrix and 

 Sphacelaria] therefore I have moreover been charged with a 

 second examination of all the Greenlandic material of the genera 

 Acrosiphonia^ Ulothrix and SpJiacelaria. In revising this 

 material I have met with some new habitats of some intermingled 

 species, as may be seen by the following list. 



According to Rosenvinge's statement^) 83 species were 

 previously known from East Greenland. To this number one 

 species, Actinococcus siibcutaneus, should be added, it is regarded 

 by Rosenvinge (Deux. Mém. i as the nemathecia of P//y//opAora 

 Brodiæi and thus not included in the number of species. Of 

 the 85^) species gathered by Kruuse 29 were not previously 



CD ') L. Koldeiup Rosenvinge, uni Algevegetatioiien ved Grönlands Kyster, 

 '"" Særtryk af »Meddelelser om Grönland» XX, Kjöbenhavn 1898, p. 180. 

 *) In Kruuse's collection there were moreover found two species, Eciocar- 

 pna tonientosiis (Huds.) Lvngb. and Ectocarpus fascicnlaltis (Griff.) Harv. 



