THE present discussion is based upon material collected during three travels to the 

 Danish West Indies, partly along the coasts of the islands, and partly in the 

 Sargasso Sea. 



I. The species oi^ Saryassum 

 found at the shores of the Danish Ish\nds. 



1. Sargassum vulgare C. Ag. 

 C. Agardh Species Algarum, vol. I, p. 3. 

 J. Agardh, Species Sargassorum Austral., p. 108. 

 Vickers, A., Phycologia Barbadensis, Part II, pi. II. 

 Fucus natarts Turner, Fuci, p. 99 (101), pi. 46, fig. a. 



var. typica. (Fig. 1). 



The speciraens which I have referred to the typical form are very much like the 

 figure given by Turner (1. c). The linear-lanceolate leaves possess a dentate-sinuate 

 margin, a distinct midrib, and quite numerous, but small and irregularly placed tri- 

 chostomata; the latter are sometimes very indistinct or qvnte absent in some of the 

 leaves. 



The vesicles are sometimes few, sometimes numerous; they are globular, of the 

 size of a small pea, and most often they are without prolongations at the top; such 

 ones occur, however, now and then. 



The receptacles are cylindric, filiform and irregularly ramified. 



var. foliosissima (Lamour.) J. Ag. 



J. Agardh, Spec. Sargassorum Austral. p. 108. 



Fucus foliosissimus Lamouroux, Essai Thalassiophytes (Ann. du Museum d'Hist. nat., vol. 20, 1813, 

 p. 36, pi. 7, fig. 1). 



This form is different from the typical one by having numerous, closely packed 

 leaves which are smaller, proportionally shorter, and more or less undulate, frequently 

 somewhat twisted. 



The receptacles are shorter and similar to the vesicles hidden between the leaves. 



