250 University of California Puhlications in Botany [Vol.8 



tendency towards branching, but plants agreeing with it in anatomical 

 characters, but growing in brackish or fresh waters, branch abundantly 

 from the margins, the branches tapering at the tips and being usually 

 curved. Such plants are referred under the forma suhsalsa. This 

 variety occurs at times, especially in fresh water, up to 10 cm. or more 

 long. The var. bullosa which Collins distributed under no. 1067 of 

 the Phycotheca Boreali-Americana seems to differ decidedly from 

 Enteramorpha niicrococca in the size and shape of the cells and 

 approaches more nearly E. intestituiUs in structure. This variety is 

 known, thus far, only from fresh water (San Leandro, California) 

 and does not strictlv come under our consideration. 



3. Enteromorpha minima Naeg. 



Frond 1-10 cm. long, 1-5 mm. broad, simple or slightly proliferous, 

 dilated or collapsing, soft and delicate, cells angular, 5-7/^ diam., 

 arranged in no definite order; membrane 8-lOja thick, equally thick- 

 ened on both surfaces. 



Growing on stones and on wood in uppermost littoral belt. 



From Alaska (Uualaska) to Mexico. 



Naegeli, in Kuetzing, Sp. Alg., 1849, p. 482, Tab. Phyc, vol. 6, 

 1856, p. 16, pi. 43, f. i-m; Collins, Green Alg. N. A., 1909, p. 201, Mar. 

 Alg. Vancouver Is., 1913, p. 102; Setchell and Gardner, Alg. N.W. 

 Amer., 1903, p. 213. 



Enteromorpha minima resembles E. campressa but is, in normal 

 form, less likely to show any branching, is more commonly dilated, 

 and of softer and more delicate texture. The cells are also slightly 

 smaller in surface view. From E. micrococoa, this species is to be 

 distinguished by the larger cells and thinner membrane which is sel- 

 dom noticeably thickened on the inside, although Kuetzing (1856, 

 pi. 43, f. m) so represents it. Enteromorpha minima resembles E. 

 micrococca rather than E. conipressa in size, but is found in typical 

 form up to 10 cm. high. In fresh water forms attributed to this species 

 we find plants up to 20 cm. long and sometimes with the cells decidedly 

 separated from one another as in Manostroma. In a form from drip- 

 ping rocks above high water mark on San Juan Island, Washington, 

 distributed under no. 912 of the Phycotheca Boreali-Americana, the 

 plants are large and the cells small, with the membrane thickened on 

 the inside. This seems to approach very closely to E. micrococca. 



