614 University of California Piihlications in Botany [Vol. 8 



figs. 6-13, Kelps of U. S. and Alaska, 1912a, pp. 155, 156; Setchell 

 and Gardner, Alg. N.W. Amer., 1903, p. 266 ; Collins, Holden and 

 Setchell, Phyc. Bor.-Amer. (Exsice.), no. XXXVI. Fucus Clatlims 

 Gmelin, Hist. Fuc, 1768, p. 211, pi. 33. 



The juvenile blade disintegrates in the center, back to the stipe, 

 after which two meristems are established at the base and along the 

 margin of the remaining two partial blades. For a time these continue 

 to develop together but sooner or later one takes the ascendancy and 

 becomes erect while the other usually degenerates sooner or later. As 

 the blade continues to grow, it rolls and thickens along the margin, 

 leaving behind a false stipe, which branches here and there, the 

 branches developing numerous small blades. 



46. Agarum (Bory) Post, and Rupr. 



Holdfast composed of small branched hapteres ; stipe compara- 

 tively small, cylindrical or flattened, at times fimbriated ; blade rela- 

 tively thin, with narrow to broad percurrent midrib and perforated 

 alae; sori broad. 



Bory, in Diet, class., vol. 9, 1826, p. 193. 



The genus Agarum was founded by Bory (Joe. cit.). He enum- 

 erated five species, as follows: A. quinquecostatum, A. cribrosum, 

 A. escidentum, A. Belisei, and A. Pylaii, all but one of which have 

 since been distributed between two other genera, the first one to 

 Costaria, the last three to Alari<a, thus indicating that he had a much 

 broader generic concept than can be accepted by later algologists. 

 Thus Agarum cribrosum, though imperfectly described specifically by 

 Bory, is the type of the genus as reconstituted by Postels and Ruprecht 

 (1840, p. 11). They enumerated five species, as follows: A. Gmelini, 

 A. Turneri, A. pertusum, A. platyneurum, and A. hrassicae forme, all 

 of which were reported within our territory with the exception of 

 A. Tiirneri. 



Key to the Species 



1. Stipe cylindrical, not fimbriate; blade with two basal scrolls 



1. A. cribrosum (p. 615) 



1. Stipe flattened, with fimbriate margins; blade with rounded or cordate base .... 



2. A. fimbriatum (p. 616) 



