1925] Setch ell-Gardner: Mehmophi/ceae 569 



This is by far the largest species of Desmarestia yet discovered, 

 and seems, as far as known to us, to inhabit relatively quiet water, at 

 times merely resting on mud flats where the water is rarely disturbed 

 except as it rises and falls with the tidal movements. One of its dis- 

 tinguishing characters is its very large size. The most noticeable 

 feature about it, however, is its exceedingly fragile nature. It is very 

 crisp and brittle, wholly unable even to bear more than a fraction of 

 its own weight without being ruptured. It is further characterized by 

 the paucity of branches, as a rule bearing only a few primary laterals. 

 This plant fully merits the name Desmarestia latissima, as already 

 given by us, and is a plant of entirely different color, texture, habit, 

 and place of growth from our D. munda. 



10. Desmarestia foliacea Pease 



Fronds membranaceous, unbranched, attached by a small disk, 

 tapering below to a very delicate cylindrical stipe, up to 1 m. long, 

 15 cm. wide, margins irregularly sinuate with occasional sinuate teeth, 

 midrib evident, with opposite branches which break up into fine 

 veinlets. 



Growing in the upper sublittoral belt. San Juan County, Wash- 

 ington. 



Pease, P.S.B.S. Publ., vol. 2, 1920, p. 322, pi. 58, figs. 5-10, pi. 61, 

 figs. 1-5. Desmarestia tabacoides Pease, P.S.B.S. Publ., vol. 1, 1917, 

 pi. 84, figs. 2-7. 



We are not acquainted with this plant and know it chiefly through 

 the above mentioned publications. There is a plant in the Herbarium 

 of the University of California (Gardner, no. 2321) dredged in ten 

 fathoms off Canoe Island, San Juan County, Washington, which may 

 possibly belong here. The plant was attached to a clam shell by a 

 relatively small, flat disk, has a small cylindrical stipe, a blade about 

 four meters long and three decimeters wide. There are, however, a 

 few small, short branches arising near the base, differing in this 

 respect from the type material as described by Miss Pease. 



Through the kindness of Miss Pease, we have received, since writing 

 the foregoing, two sheets of specimens of Desmarestia foliacea from 

 Professor Josephine Tilden, of the University of Minnesota. The 

 species seems closely related to D. tabacoides Okam., but differs in size, 

 shape, lobing and venation. 



