452 BULLETIN OF THE BUREAU OF FISHERIES, 



i. Sargassum natans (Linnaeus) Meyen. PI. XC, fig. i. 



Fucus natans, Linnaeus, 1753, Tom. 2, p. 1160. 

 Fucus bacciferus. Turner, 1802, vol. i, p. 55. 

 Sargassum bacciferum, Agardh, 1820, p. 6. 

 Sargassum natans, Meyen, 183?, p. 185. 

 Sargassum bacciferum, Harvey, 1853, p. 59. 

 Sargassum bacciferum, Farlow, 1882, p. 103. 

 Sargassum bacciferum, De Toni, 1895, p. 82. 

 Sargassum natans, Borgesen, 19143, p. 7. 

 A. A. B. Ex. No. 105 (in part). 

 P. B.-A. Nos. 381, 2180. 



Fronds 15 to 45 cm. long, coriaceous, shining chestnut brown; stems terete, many times decom- 

 pound; leaves lanceolate-linear, on a rather long petiole, occasionally forked, 4 to 10 cm. long, i to 7 mm. 

 broad, acutely serrate, midrib distinct, cryptostomata usually lacking; vesicles spherical, on terete 

 petioles whose length about equals that of the vesicles, usually provided with a spinelike tip; recep- 

 tacles axillary, forked, cymose, cylindrical, verrucose; usually sterile. 



Floating in North Atlantic, especially near the Gulf Stream. No specimen surely referable to this 

 species is known attached. 



Occasionally abundant in summer on Bogue Beach, Beaufort, N. C., not observed at other seasons. 

 Fairly abundant on beaches at Southport, N. C., Georgetown, S. C., and Isle of Palms in the harbor of 

 Charleston, S. C., July and August, 1909. 



Forma angustum (Collins) comb. nov. 



Sargassum. bacciferum I. angustum, Collins, in Collins, Holden and Setchell, Phycotheca Boreali- Americana, No. 833, 1901. 

 A. A. B. Ex. No. 105 (in part). 

 P. B.-A. No. 833. 



Leaves long, narrow, 2 to 6 cm. long, i mm. or less wide, in extreme cases consisting of little more 

 than the midrib, conspicuously serrate, cryptostomata lacking; vesicles spherical, sometimes tapering 

 very slightly at base, sometimes provided with a spinelike tip, petiole i to 3 times length of vesicle; 

 sterile. 



Floating in North Atlantic, with the species. 



Occasionally abundant in summer, Bogue Beach, Beaufort, N. C., not observed at other seasons; 

 probably in other localities also. 

 a. Sargassum filipendula Agardh. PI. XC, fig. 2. 



Sargassum filipendula, Agardh, 1824, p. 300. 



Sargassum filipendula, Harvey, 1852, p. 61. 



Sargassum vulgare, Farlow. i88, p. 103. 



Sargassum filipendula, De Toni, 1893, P- i6- 



A. A. B. Ex. No. 101 (S. vulgare). 



P. B.-A. Fasc. D. No. XCVH, Fasc. E. No. CXIX (S. vulgare). 



Fronds 30 to 150 cm. long, yellowish-brown; stems terete or slightly flattened decompound, smooth; 

 leaves linear-lanceolate or narrow linear, on a short petiole, sometimes forked, i to 5 cm. long, 1.5 to 12 

 mm. broad, larger and broader below, smaller and narrower above, acutely serrate or the upper narrower 

 ones subentire, midrib distinct, cryptostomata more or less conspicuous, usually occurring singly, 

 serially arranged on both sides of the midrib; vesicles spherical, on flattened petioles usually longer than 

 the vesicles, usually provided with a spinelike tip; receptacles cylindrical, verrucose, paniculate on an 

 elongated axillary branch, the lower ones pedicillate, rather simple, the upper ones confluent. 



Warm and temperate North Atlantic. 



Beaufort, N. C.: Abundant in harbor and on Fort Macon and Shackleford jetties throughout the 

 year, from low-water line to i m. below low water; abundant on coral reef offshore at depth of 24 to 25.5 

 m., May, 1907, August, 1914, and August, 1915. 



Most of the specimens from our coast which have been referred to S. vulgare Ag. belong to this 

 species or to one of its forms, but specimens of the true S. vulgare are known from the extreme south, 

 Key West, Fla., Mexico, and West Indies. The species differs from S. vulgare in having narrower 

 leaves, longer petioles of vesicles, and more racemose branching of receptacles; many specimens have 

 also less conspicuously serrate leaf margins, and the leaves less rigid and leathery. With its various 

 forms the species shows much variation in the shape and size of leaves, the amount of serration, and the 

 abundance of cryptostomata. 



