450 



BULLETIN OF THE BUREAU OF FISHERIES. 



KEY TO GENERA. 



Frond flat, band shaped, dichotomously branched in one plane, furnished with a midrib 



i. Fucus (p. 450). 



Frond distinctly differentiated into stem and leaflike portions, laterally branched, floats 



developed as special organs 2. Sargassum (p. 451). 



Genus i. Fucus (Tournefort) Linnaeus. 

 Fucus, Linnaeus, 1737, p. 326 (in part). 



Frond flat, band shaped, repeatedly dichotomously branched in one plane, fur- 

 nished with a more or less conspicuous midrib, attached by a basal disk; vesicles present 

 or absent, formed from swollen portions of the frond, often in pairs on each side of the 

 midrib; cryptostomata more or less conspicuous here and there over the frond, bearing 

 tufts of paraphyses; apical cell three-sided in young stages, soon becoming four-sided; 

 receptacles formed from the more or less swollen apices; unisexual or hermaphroditic; 

 oogonia producing eight eggs, accompanied by numerous paraphyses; antheridia ellip- 

 soidal, numerous, occurring as lateral branches of richly branched filaments, producing 

 numerous sperms, accompanied by paraphyses; eggs spherical, relatively large, non- 

 motile; sperms small, pear shaped, biciliate, actively motile. 



About 1 6 species, in cold and temperate seas. 

 Fucus vesiculosus Linnaeus. PI. LXXXIX. 



Fucus vesiculosus, Linnaeus, 1753, p. 1158. 

 Fucus vesiculosus, Harvey, 1852, p. 71. 

 Fucus vesiculosus, Farlow, 1882, p. too, pi. 9. 

 Fucus vesiculosus, De Toni, 1893, p. ao6. 

 A. A.B. Ex. No. 109. 

 P. B.-A. No. 577. 



Frond dark brown or black, coriaceous, band shaped, variable in form and size, 2.5 cm. to i m. long, 

 i to 25 mm. wide; repeatedly and regularly dichotomous; tapering below to a distinct stipe; furnished 

 with an evident midrib; cryptostomata more or less conspicuous; vesicles usually present, sometimes 

 lacking, variable in form, size, and arrangement, usually occurring in pairs, one on each side of the 

 midrib; receptacles forming swollen portions at the tips of the branches, more or less conspicuous, vari- 

 able in size and form, somewhat flattened, turgid; antheridia and oogonia produced on different plants. 



North Atlantic and Pacific Oceans. 



Beaufort, N. C. : Abundant on innermost jetty, and occasional elsewhere at Fort Macon from low 

 water up to 60 cm. above low-tide line, fairly abundant in harbor along shores, occasionally fairly 

 abundant on Bogue Beach. 



Thjis is the southern known Limit of the species and of the genus on our coast. 



The species is variable in size and form, in the presence or absence of vesicles and the abundance 

 and shape of these when they are present, in the conspicuousness of the cryptostomata, and in the size, 

 shape, and conspicuousness of the receptacles. The vesicles may vary from numerous short, round ones, 

 crowded together in places so that they resemble a double chain of beads, to few long, scattered ones, or 

 they may be confluent, forming large, bladderlike structures, or may be lacking. The receptacles may 

 be lacking (in sterile specimens), or may be small, or may form large, swollen portions at the apices, or 

 may extend some distance from apices, they may be long and narrow or short and broad, their apices 

 may be acute or obtuse. The Beaufort specimens are 4 to 5 mm. wide (at the vesicles up to 9 mm. wide) 

 and 10 to 30 cm. long; the cryptostomata are inconspicuous, the receptacles are only slightly swollen 

 and extend when young 3 to 6 mm., when mature i to 2.5 cm. from the apices, they are scarcely wider 

 than sterile portions of the frond; their apices are acute. At Beaufort the plants are sterile during the 

 spring and summer, commencing to form their receptacles in August and maturing these by November. 

 Plants collected from November to January have mature fruits, those collected from April to August are 

 entirely sterile. The species was not collected in February or March, 1909, but was probably present. 

 In May, 1907, numerous small plants 2 to 3 cm. long were found, in addition to large ones up to 30 cm. 

 long; all were sterile. 



