1925] • S etch ell-Gardner: Melanophyceae 717 



Farlow, List of Mar, Alg. U. S., 1876, p. 706 (nomen nudum), in 

 FarloAV, Anderson and Eaton, Alg. Exsicc. Amer.-Bor., no. 103, MS ; 

 Collins, Holden and Setchell, Phyc. Bor.-Amer. (Exsicc), nos. 179 and 

 CXVIII; J. G. Agardh, Sp. Sargass. Aust., 1889, p. 93; Grunow, Add. 

 cog. Sargass., 1915, p. 401. 



The type locality of S. Agardhianum is San Diego, California. 

 The form of the species is considerably modified by habitat. It is 

 common in rather shallow rockpools in the lower half of the littoral 

 belt or in deeper pools higher up. In these situations it is always 

 covered with water and grows short and stocky with the secondary 

 lateral branches more highly developed. When growing in quiet 

 water in the sublittoral belt, it becomes much more elongated and 

 attenuated, reaching a length of nearly a meter. It grows in pro- 

 fusion on the harbor side of the government breakwater at San Pedro, 

 California, but is wholly absent on the exposed side. The antheridia 

 and oogonia in this species are often in separate conceptacles on the 

 same individual, or even in the same receptacle. 



10. Sargassum insulare S. and G. 



Fronds 7-9 cm. high, arising from a parenchymatous disk ; stipe 

 small, 5-10 mm. long; primary branches cylindrical throughout, 1-2 

 mm. diam., smooth, moderately and alternately branched ; leaves 1-2 

 cm. long, about half as wide as long, asymmetrical, the upper margin 

 concave and mostly smooth, the lower margin and apex convex and 

 crenate or dentate, ecostate ; cryptostomata sparse ; vesicles inter- 

 mingled with the receptacles, spherical or subspherical, 1.5-2.5 mm. 

 diam., short petiolate, often crowned by the remnant of a leaf; recep- 

 tacles moderately branched, standing on a single pedicel on the base of 

 a leaf, irregular in shape, clothed with scattered blunt spines, some- 

 times crowned by a rudiment of a leaf. 



Growing on rocks in the upper sublittoral belt. San Marcos 

 Island, Gulf of California. 



Setchell and -Gardner, Mar. Alg. Gulf Calif., 1924, p. 735, pi. 20. 

 figs. 67, 68, and pi. 21, fig. 78. 



