700 University of California Publications in Botany [Vol. 8 



wider, slightly ovate, truncate, growing point very slightly depressed, 

 midrib moderately prominent, cryptostomata absent or very sparse ; 

 receptacles yellowish, complanate when young, frequently becoming 

 tumid at maturity, bi- tri-furcate, 4-7 cm., rarely 10 cm. long; 

 conceptacles large. 



Growing on boulders and rock ledges. San Francisco Bay, Cali- 

 fornia. 



Gardner, Genus Fiicus, 1922, p. 26, pis. 18, 19. 



This relatively small group of Fucus plants, although very much 

 circumscribed in its distribution, seems so distinctly marked off in its 

 combination of characters from other species, particularly from those 

 in the southern portion of our range, that it is worthy of specific rank. 

 The combination of characters that distinguish this species consists 

 of the following : relatively long and narrow, smooth and glossy fronds, 

 strict, even overlapping habit of the terminal and subterminal seg- 

 ments, the dark brown color with yellowish receptacles at maturity, 

 absence of caecostomata, and the cryptostomata, when present, incon- 

 spicuous. Its affinities with F. edentattis may possibly be traced, but 

 they seem too remote to merit much serious consideration. 



66. Pelvetia Dec'ne and Thur. 



Fronds of tough, firm consistency, flexuose, the whole plant when 

 young, and the young terminal growing parts considerably flattened, 

 without midrib, becoming more or less terete with age, especially 

 toward the base, arising from a solid, disk-shaped holdfast; growing 

 region apical ; branching dichotomous, usually abundant ; reproductive 

 organs, antheridia and oogonia, developed in conceptacles limited to 

 the terminal, metamorphosed parts of the branches, the receptacles ; 

 oogonia developing two viable gametes, or eggs ; monoecious. 

 Decaisne and Thuret, Rech. sur Antherid., 1845, p. 12, 

 This genus was founded on the Fucus canaliculatus of Linnaeus 

 (Syst. Nat. II, 1759, p. 716) based largely upon the fact that the 

 oogonium produces but two viable eggs instead of eight, the character- 

 istic number for the genus Fucus. Eight nuclei are formed in the 

 oogonium, but six of them are extruded between the two eggs at the 

 time of their formation and become functionless. The egga are 

 fertilized outside of the oogonia as in the genus Fucus. 



