1920] Seichell-Gardner: Chlorophyceae 269 



margins plane or slightly undulate; membrane 45-90/a thick, thicker 

 in the center and thinner near the margins ; cells elongated vertically, 

 up to two and one half times as high as broad in the thicker central 

 portion, nearly square at the margins. 



On rocks in the lower littoral belt. Central California (San Fran- 

 cisco) to southern California (Pacific Beach). 



Setchell and Gardner, Phyc. Cont. I, 1920, p. 284. Phycaseris 

 lohata Kuetzing, Spec. Alg., 1849, p. 477, Tab, Phyc, vol. 6, 1856, 

 p. 10, pi. 27. Ulva fasciata f, lohata Setchell, in Collins, Holden and 

 Setchell, Phyc. Bor.-Amer. (Exsicc), no. 863; Collins, Green Alg. 

 N. A., 1909, p. 216. 



Among the TJlvae of the Californian coast is one of moderate size 

 (up to 30 cm. or more long and to 15 or more cm. broad) which is 

 distinct in general appearance. It is attenuate at the crisped base, 

 broadening above and usually lobed or divided into several broad 

 divisions. The margins are either plane or slightly undulate. Like 

 U. expansa it is thicker in the center with palisade-like cells (in sec- 

 tion) and thinner on the margins where the cells are nearly square 

 (in section). It bears a striking likeness in every way to Kuetzing 's 

 figure (1856, pi. 27) of his Phycoseris lohata from Chili. We have, 

 therefore, referred it to his species with some doubt. 



Ulva lohata belongs to the same group of species as U. expansa 

 but is generally firmer in substance, slightly thicker, never reaches a 

 great size, and is less deeply or conspicuously ruffled. It is well repre- 

 sented by the specimens distributed in . the Phycotheca Boreali- 

 Americana (under no. 863). 



The most typical plants are those of the central Californian coast 

 (San Francisco to Monterey). "We have referred here also • one 

 plant from southern California, but with some doubt. 



9. Ulva rigida Ag. 



Frond low, at first lanceolate or ovate-lanceolate, firm and stiff, 

 with distinct stipe, later broader and irregularly deeply divided ; 

 membrane 60-llOjj. thick, varying with age and position in the frond ; 

 cells, in section, vertically elongated, one and one half to three times 

 as high as broad. 



Growing attached to rocks and other algae, upper littoral belt. 

 Alaska (Uyak Bay) to Mexico (La Paz). 



