210 University of California Publications. [botany 



Sound, Alaska, Saunders (1901, p. 410); Sitka, Alaska, Ida M. 

 Rodgers, No. 5723! ; Port Renfrew, B. C, Butler and Polley, No. 

 14; Esquimalt, B. C, Harvey (1862, p. 176); Idlewild, San Juan 

 Island, Wash., Tilden, Nos. 386!, 387!; Tracyton, Kitsap 

 County, Wash., Tilden, No. 260! 



Ulva Lactuca var. latissima (L.) LeJolis. 



Generally floating when mature, but in the earlier stages 

 attached to rock or wood, usually in muddy situations. Pinnacles, 

 Summer Bay, Unalaska, Alaska, A.A.L., No. 4097a!; Sitka, 

 Alaska, Saunders (1901, p. 410, under U. Lactuca myriotrema) ; 

 Norfolk Sound (near Sitka), Alaska, Postels and RuprecJit (1840, 

 p. 21); Puget Sound, Bailey and Harvey, (1862, p. 163); 

 Esquimalt, B.C., Harvey, (1862, p. 176); Whidbey Island, 

 Wash., N.L.G., No. 112!; East Sound, Orcas Island, Wash., 

 N.L.O., No. 529! ; Friday Harbor and Roach Harbor, San Juan 

 Island, Wash., N.L.G., No. 667! 



It is difficult to determine just what course to take with the vari- 

 ous specimens of Ulva which we have from the i-egion included un- 

 der this account. A very considerable study of the species of Ulva 

 along the entire western coast of North America indicates that, while 

 there may be many forms, there is probably only one species and 

 very few varieties. The habit, size, color, and even the character 

 of cell depends so much on the age and the environment of the 

 specimen, that it is possible to trace a series from the quiet water 

 inside a point of land to the exposed localities outside of it which 

 may include all the forms and intermediate conditions between 

 the most distinct species as yet proposed under the genus. We 

 have, therefore, arranged the forms of the Northwest Coast under 

 two varieties of one species. Var. rigida includes all the 

 specimens which are lanceolate in general outline, while var. 

 latissima includes all those which show a tendency to be shorter 

 than broad, and are of general expanded habit at maturity. 

 Under each of these varieties, there are numerous forms to be 

 mentioned, due to less conspicuous conditions of growth, but we 

 have decided not to attempt a separation of these in this paper. 

 Nos. 260 and 387 of Miss Tilden 's American Algae are conspicu- 

 ous on account of the long stipes which give them the appearance 



