— 49 — 



A contribution to the knowledge of the 

 marine Alga vegetation on the coasts of 

 the Danish West-Indian Islands. 



By 



F. Børgesen. 



Our knowledge of the algoid vegetation of the tropical seas 

 as seen from an ecological point of view, is still very inconsider- 

 able. In his large new Geography of plants S c h imp er 1 ) in 

 mentioning the Alga vegetation of the tropical seas writes p. 827: 

 „Die Benthosvegetation der tropischen Meere ist zur Zeit noch sehr 

 ungenau bekannt. Kein wissenschaftlicher Reisender scheint ihr bis 

 jetzt eine genauere Untersuchung gewidmet zu haben." I have to 

 acknowledge that I am not able to give an exhaustive description 

 of the associations of Algae on the shores of the Danish West-Indies, 

 for that my observations are still too few; yet some contributions 

 I think I am able to make, especially with regard to the vegeta- 

 tion in the lagoons and in shallow water in general. I have, it is 

 true, also tried to dredge in deep water, but with no great result, 

 as the comparatively small dredge I carried with me constantly 

 became entangled in numerous corals, and thus deprived me of 

 the inclination for more thorough examination. 



The same characters that obtain for the tropical Alga vegetation 

 in general and among w r hich I particularly will remark, that the tropical 

 Algae commonly are much smaller than those from the temporate 

 and arctic seas, all large Phæophyceæ not occurring there, and that 



l ) A. F. W. Schimper: Pflanzen-Geographie auf physiologischer Grundlage. 

 Jena 1898. 



Botanisk Tidsskrift. 23. Bind. 4 



