1920] Setchell-Gordner: Chloroplujceae 171 



ture of tlie water at that point, we suspect tliat tlieir plants may 

 belong rather to C. Rittcri than to C. itiamillosum which is a sub- 

 tropical species. 



3. Codium fragile (Suring.) Ilariot 

 Plates 28. 29 



Fronds one to several from a broad spongy disk, cyliiidi leal, 

 profusely and dichotomously branched, 25-40 cm. high, 2-10 mm. in 

 diameter, glossy, dark green, finely rugose on the surface oi-, at times, 

 densely tomentose with h)iig hyaline hairs; utricles cylindric elavate, 

 150-350/u. (occasionally G8()/x) in maximum diameter, and 5-10 tiiius 

 as long as broad, provided (at least when young) with a mor'.' or 

 less distinct muero; gametangia ($ ?) fusiform, 1-3 to each utricle, 

 250-450/A long and 75-150/^ in diameter. 



Growing on exposed rocks and in small pools in the littoral belt. 

 Ala.ska to Mexico. 



Hariot, Algues du Cap Horn, 1889, p. 32 ; De-Toni, Phyc. Japon. 

 Novae, 1895, p. 64. Acanthocodkiin fragile Suringar, Algarum 

 Japonicaeuni, Index praec. 1867, (hid., Hedwigia, vol. 7, 1868, p. 55; 

 Algae Japonicae, 1870, ]). 23, pi. 8; ihid., Hedwigia, vol. 9, 1870, 

 p. 133. Codium mucronatuni J. Agardh, Till. Alg. Syst., 5th jiart, 

 1886, ])]). 43, 44; Hurd, Pug. Sound Mar. Stat. Publ., 1916rt, vol. 1, 

 pp. 109-135, pi. 19-24; Setehell and Gardner, Alg. N.W. Amer., 1903, 

 p. 232; Saunders, Alg. Harriman Exp., 1901, p. 416. Four Siphon. 

 Alg., 1899, p. 1, pi. 350, f. 1 a, b, c, d; Collins, Green Alg. N. A., 1909, 

 p. 389; Collins, Holden and Setehell, Phyc. Bor.-Amer. (Exsicc), 

 no. 229. Codium tomentosum Tilden, Amer. Alg. (Exsicc), no. 281 

 (not of Stackliouse). 



The mucronate tip of tlie uli-iclc of this plant is a prominent 

 specific character, but tliis character is subject to extreme variation. 

 J. Agardh (1886, pp. 43, 44) separated the species into three varieties 

 based chiefl^^ upon the character of the mucro. We have studied and 

 compared plants from a considerable number of different localities 

 ranging from Ala.ska to Mexico, and have come to the conclusion that 

 the species cannot be split into varieties based upon that character. 

 Single plants may be found producing mucronate tips covering the 

 entire range of shapes, as regards thickening of the walls and acute- 

 ness of the tip, that have been used to designate the varieties. Miss 

 Hurd (1916a, p. 109) made a critical study of the species as occurring 



