List of Freshwater Algæ. 73 



out the discovery of the genus Spirotœnia, which up to the present 

 had not been recorded from East Greenland or Greenland on the 

 whole. The species found was Sp. condensata Bréb. which is well- 

 known in arctic countries, e. g. in Nova Zembla and Spitzbergen. 



Of high-arctic species hitherto not found in Greenland may be 

 mentioned Euaslrum tetralobum Nordst. which is known only from 

 Spitzbergen and Nova Zembla. 



Further may be named Cosmarium spetsbergense Nordst. also a 

 true arctic species, which has earlier only once been found in East 

 Greenland (Hurry Inlet); elsewhere it is only known from Jan Mayen, 

 Spitzbergen and Nova Zembla. 



Of the genera which I have mentioned in my above-mentioned 

 paper, namely: Mesotaenium (1 species), Penium (5 species), Cylindro- 

 cystis (1 species), Closteriiun (6 species), Pleurotœnium (1 species), 

 Cosmarium (42 species), Arthrodesmus (2 species), Xanthidium (1 spe- 

 cies), Staurastnim (29 species), Euastrum (6 species), Gonatozygon 

 (1 species), Desmidium (1 species), Gymnozyga (1 species), Hyalotheca 

 (1 species), Sphaerozosma (I species) the following genera have not 

 been discovered here : Mesotaenium, Arthrodesmus, Xanthidium, Gonato- 

 zygon, Gymnozyga and Sphaerozosma. Of Closterium only two species 

 were present and of Euastrum 4 species only : 3 of the 6 species 

 mentioned in my earlier paper have disappeared but in return the 

 quite arctic species Euastrum tetralobum has been added and this 

 confirms the fact first pointed out by Boldt, later by me, that the 

 large Euastrum-sytecies are wanting in the true arctic regions; the 

 interesting find of E. oblongum in Jameson Land by Larsen makes 

 this species an exception. 



With regard to the most of the above-named genera the com- 

 plete disappearance of some and the reduction in the number of 

 species of others is in good accordance with what w^e know about 

 the distribution of the plants in question, which all disappear or 

 are very seldom in the arctic regions ^ 



The remaining green algæ are of little interest. Of bluish-green 

 algæ Nostoc commune seems to be common. Even very large 

 specimens are found along the border of lakes or on places quite 

 laid dry in summer. Stones on the bottom of lakes when dry were 

 found covered by blackish crusts of different bluish-green algæ e. g. 

 G/œoca/)sa-species and Calothrix etc. 



No material of snow-algæ was brought home. 



Robert Boldt. Grunddragen af Desmidieernas Utbredning i Norden (Bihang till 

 k. svenska Vet.-Akad. Handl. Bd. 13, Afd. III, No. 6, Stockholm 1887). 



