64 



Dansk Botanisk Arkiv, Bd. 2. Nr. 2. 



The specimens which I have referred to this species possess 

 leaves with a distinct midrib and small, most often scattered 

 cryptostomata; these are, sometimes, arranged more or less regu- 

 larly in a single series on both sides of the midrib. 



The basal leaves are more or less dentate; the upper have 

 a somewhat sinuate to entire margin. 



The leaves are linear-elliptic 4 — 5 mm. broad, and up to 3 cm. 

 long, with a short stalk or sessile. The vesicles are scarce, often 



quite absent ; when present, accor- 

 ding to my observations, they occur 

 only at the upper end of the branch ; 

 they reach the size of a small pea, and 

 are often somewhat oval, now and 

 then provided with a small; leaf-like 

 prolongation at their apex. 



The receptacles are mostly aggre- 

 gated at the upper end of the bran- 

 ches ; they are cylindric and irregu- 

 larly branched. 



This species appears to be closely 

 related to Sargassum vulgare, repre- 

 senting probably merely variety of it. 

 St. Thomas: Store Nordside Bugt, 

 growing in a rather exposed place. 



Geogr. Distrib. West Indies, Ber- 

 muda, Teneriffa etc. 



Fig. 44. Sargassum platycarpum 



Mont. Part of a branch with 



receptacles and vesicles. 



(About 'lo magnified). 



A 



3. Sargassum platycarpum Mont. 



Montagne, Cent. Ill, p. 18, n. 51; 



Sylloge generum specierumque Cryptoga- 



marum, 1856, p. 385. J. Agardh, Species 



Sargassorum Austral., p. 89, tab. VI. 



Vickers, Phycol. Barbad., Part II, pi. II. F. Børgesen, 1. c, p. 5. 



Characteristic of this species (Fig. 44) are the rather large, 

 often oval cryptostomata, arranged in a single series on both 

 sides of the midrib. The leaves are lanceolate, dentate along the 

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

 in "Sylloge", 1. c, Montagne writes: "vesiculis nullis". In my 

 specimens the vesicles were only noticed in the fertile part of the 

 thallus ; they are globular, sometimes ellipsoid, now and then with 

 a short prolongation at the top. 



The receptacular branches are flat, bearing long projections 

 at their margin. 



