286 University of California Publications in Botany [Vol.7 



species. Both are characterized by long, narrow fronds or laciniae, 

 much thicker along the middle and with thinner, very much crisped 

 margins. One of these, Ulva dactylifera, possesses a comparatively 

 broad, though sliort, undivided basal portion from which arise the 

 several, narrow, elongated, crisped laciniae. Neither the basal portion 

 nor the laciniae show distinctly toothed margins. The other species, 

 Ulva taeniata, is either simple, long, slender, plane and dentate below, 

 but with crisped margins above, or divided to the very disk itself into 

 two or three such divisions. The "midrib" portions differ slightly 

 in thickness in tlie two species and the cells of the "midribs" differ 

 in ])roportions. 



Ulva dactylifcra has been distributed under no. 221 & (sub "Ulva 

 fasciata") of tlie Phycotheca Boreali-Araericana. Unfortunately the 

 plants under this number are not uniform. We have examined no. 

 2216 in two copies. In one the plant is certainly, although not 

 typically, U. dactylifcra. In the other it seems rather to be a form 

 of Ulva Lactuca. 



Ulva dactylifcra is nearest to U. fasciata f. costata Howe (1914, 

 p. 20, pis. 1, 2, figs. 10-23), but differs as to the basal portion, thick- 

 ness, and possibly also in proportions of cells. It differs from U. 

 fasciata Delile, so far as descriptions and figures indicate, in branch- 

 ing, in ruffling, and probably in thickness. It is a very much thinner 

 plant than U. ncmatoidca Bory, judging from the dimensions given 

 by Bornet (1892, p. 36 or 196). 



Ulva taeniata (Setchell) comb. nov. 



Plate 28 



Frond elongated, up to 1 to 2 M. long, simple or split to the very 

 base into long, narrow segments, plane below and coarsely dentate, 

 densely crisped and ruffled on the margins above, with a plane, thiekei- 

 midrib ; membrane up to 140/x thick as to the midrib, and down to 40/i 

 thick on the margins; cells of the midrib vertically elongated, in 

 section, up to two and one-half times as high as broad, l)ut becoming 

 nearly square towards the margins. 



On rocks in the lowermost littoral or upper sublittoral belts. 

 Central California (Tomales Bay to Monterey.) 



Ulva fasciata f. taeniata Setchell, in Collins, Holden and Setchell, 

 Phyc. Bor.-Amer. (Exsicc), no. 862; Collins, Green Alg. N. A., 1909, 

 p. 216. 



