1920] Setchell-Gardncr : Chlorophyceue 255 



Growing on sticks and stones, sometimes floating, in quiet waters 

 and sheltered bays. From Alaska (Sitka) to central California. 



J. Agardh, Till Alg., Syst., part 3, 1883, p. 129, pi. 4, f. 103, 104; 

 Collins, Green Alg. N. A., 1909, p. 202; Saunders, Alg. Harriman 

 Exp., 1901, p. 411; Setchell and Gardner, Alg. N.W. Amer., 1903, 

 p. 211; Collins, Holden and Setchell, Phyc. Bor.-Amer. (Exsicc), 

 no. 913; Tilden, Amer. Alg. (Exsicc), no. 385. Ulva prolifera 

 Mueller, in Fl. Dan., vol. 5, fasc. 13, 1778, pi. 763, f. 1. 



We must necessarily adopt the idea of J. G. Agardh as to the 

 nature and limits of Enteromorpha prolifera, but neither he, nor any 

 other writer, as far as we know, has examined the type. The illustra- 

 tion in the Flora Danica {loc. cit.) simply shows the habit and might 

 represent either this species or some form of E. intestinalis. The 

 fronds of forms of Enteromorpha prolifera resemble those of forms 

 of E. intestinalis in habit, but are generally more proliferous. They 

 vary from tliose of E. intestinalis in having slightly smaller cells, but 

 differ particularly in having the cells arranged in longitudinal rows 

 in the lower portions, at least, and in the branches. In size and shape, 

 as well as in extent and variety of branching, there is great variation. 



Enteromorpha prolifera also resembles E. compress'a at times, when 

 the tube is collapsed, but may generally be distinguished from that 

 species by the longitudinal arrangement of cells in the branches. It 

 is closely related to E. tuhnlosa and E. flexuosa, but in these species 

 the cells are more regularly and uniformly arranged in longitudinal 

 rows than they are in E. prolifera. Enteromorpha tululosa is more 

 or less branched and the membrane is not thickened within, while 

 E. flexuosa is typically unbranched and with the membrane inwardly 

 thickened. E. prolifera may be simple at first, but is usually branched 

 later and is destitute of a thickening of the inner surface of the 

 membrane. 



8. Enteromorpha flexuosa (Wulf.) J. Ag. 



Frond cylindrical, tubular, simple, tapering to a filiform stipe 

 below, inflated above, flexuous and intestine-like; cells 8-12/i. long, 

 6-8/A wide, roundish polj^gonal, in longitudinal series; membrane 

 somewhat thickened on the inside; chromatophore filling the thick- 

 walled cell. 



Growing on rocks and on other plants. Santa Barbara, California. 



