A Contribution to the Knowledge of the 

 Marine Algae of Jan Mayen 



by 



Helgi Jonsson. 



The Danish Amdrup Expedition to East Greenland in 1900, 

 in which Mr. Kruuse took part, stayed at Jan Mayen from June 25 th . 

 to June 29 th . A list of the vascular cryptogams and phanerogams 

 collected has already been published 1 ). I have been charged with 

 the determining of the collections of marine algæ made by Mr. 

 Kruuse June 27 th 1900 at Jan Mayen. These collections contain 

 15 species ' 2 ). Species hitherto unknown from Jan Mayen, are in 

 the following list printed in large type. 



Rhodophyceæ. 

 Lithothamnion glaciale Kjellm. 



The plants are young and sterile and gathered in a depth of 25 

 fathoms. The specimens have kindly been determined by M. Foslie and 

 he refers them with some doubt to this species. 



Cfiioria arctica Schmitz. 



It was collected sterile in a depth of 20 fathoms. Glandular ceils 

 abundant. 



Ptilota pectin at a (Gunn.) Kjellm. 

 Some few, sterile specimens. 



Rhodochorton penicilliforme (Kjellm.) K. Rosenv. 

 With tetraspores. 



J ) Gfr. C. Kruuse: Jan Mayens Karplanter, Botanisk Tidsskrift 24. Bind. 

 København 1902. 



2 ) In G. H. Ostenfeld: Contribution à la flore de l'île Jan-Mayen (Botanisk 

 Tidsskrift 21. Bind, Kjøbenhavn 1897) L. K. Ros en vinge has enumerated 

 all the seaweeds (21 species) known from that island. 



