260 University of California Publications in Botwny [Vol. 8 



Kuetzing, Phyc. Gen., 1843, p. 300, pi. 20, f . 1 ; Collins, Green Alg. 

 N. A., 1909, p. 198. Entero'Tuorpha compressa f. sub-simplex Tilden, 

 Amer. Alg. (Exsice.), no. 264 (not of J. G. Agardh). 



In Enteromorpha pluniosa, we find the counterpart of E. crvnita, 

 as mentioned under that species, except that the chromatophore, as 

 seen from surface view, does not fill the cell. This is a character 

 sometimes difficult to determine in dried specimens and may possibly 

 be variable under different conditions of metabolism. Thus far it has 

 been generally accepted since its suggestion by J. G. Agardh (1882, 

 p. 151), but cultural experimentation to determine its constancy is 

 desirable. J. G. Agardh {loc. cit.) prefers Enteromorpha Hopkirkii 

 McCalla (cf. Harvey, 1849, p. 215, 1851(?), pi. 263) for reasons 

 which we can not comprehend. Kuetzing's figure (1843, pi. 20, f. 1) 

 seems to us definite and exact. 



16. Enteromorpha clathrata (Roth) Grev. 



Frond filiform, cylindrical or compressed, much branched in all 

 directions, the branches tapering from base to summit, but not ending 

 in a single series of cells ; cells rectangular, usually longer than broad, 

 always in longitudinal series, the chromatophore noticeably smaller 

 than the cell. 



Forming large, floating masses in warm, quiet waters. Alaska 

 (Sitka) to central California. 



Greville, Alg. Brit., 1830, p. 181 ; Collins, Green Alg. N. A., 1909, 

 p. 199, Mar. Alg. Vancouver Is., 1913, p. 101. Conferva clathrata 

 Roth, Cat. Bot., 1806, III, p. 175. 



This species is the counterpart of E^iteromorpha erecta, but with 

 the chromatophore not filing the cell. Enteromorpha clathrata and 

 y E. erecta bear a similar relation to, one another to that borne by E. 



crinita to E. plumosa. The identification of Roth's species seems to 

 rest with Mertens, who is followed by J. G. Agardh (1883, p. 153) 

 and, in turn, by all recent writers. 



20. Ulva L. 



Frond membranaceous, flat, consisting of two layers of cells usually 

 closely applied throughout, but in some species separating at the base 

 and margins ; zoospores or gametes formed from any cell except those 

 of the thickened, or hollow, stipe and escaping through an opening 

 in the surface of the frond. 



