F. Borgesen: The Species of Sargassum. 



3. Sargassum platycaipum Mont. 



Montagne, Cent. III, p. 18, n. 61. 



— , Sylloge generum specierumque Cryptogamarum, 1856, p. 385. 

 J. Agardh, Species Sargassorum Austral., p. 89, tab. VI. 

 Vickers. A., Phycol. Barbad., Part II, pi. II. 



Characteristic of this species (Fig. 2) are the rather large, often oval cryptostomata, ar- 

 ranged in a single series on both sides of the midrib. The leaves are lanceolate, den- 

 tate along the margin. The vesicles are not very numerous; in the diagnosis in 

 "Sylloge" Montagne writes 1. c: "vesiculis nullis". In iny specimens the vesicles 

 were only noticed in the fertile part of the thailus; they are globular, sometimes 

 ellipsoid, now and then with a short prolongation at the top. 



The receptacular branches are flat, bearing long pro- 

 jections at their margin. 



The species was found on rocks close to, or a httle 

 above the surface of the sea, in rather exposed or somewhat 

 sheltered piaces. 



St. Croix; Green Cay, Coakley Bay, Long Reef. 



Geogr. Distrib: West Indies and warnier shores ot America. 



4. Sargassum Hystrix J. Ag. 



J. Agardh, Nya Alger från .Mexico (Ofversigt K. Vet.-.\kad. Forhandl. 

 1847). 



— , Spec. Alg., p. 322. 



— , Species Sargassorum Australiæ, p. 91, tab. VII, figs. 

 1—6. 



Carpacanthus spinulosus Kiitz., Tab. phycol.. vol. XI, p. 15, tab. 46, 

 flg. 2. 



The few specimens found resembled the figure in Kijtzing, 

 Tab. phycol. quoted above. The leaves had an irregularly 

 serrate margin, a distinct midrib, but small and indistinct 

 cryptostomata. 



The vesicles are large, but scant. 



The receptacles are ramified, and provided with long projections along the margin. 



The specimens were collected floating in the sea to the north of St. Jan: off 

 Hermitage and Annaberg. 



Geogr. Distrib: West Indies, shores of America, etc. 



Fig. 2. Sargassum platycar- 



pumMoni. Part of a branch 



with receptacles and vesicles. 



(About Ve magnified.) 



