NO. 10 DAWSON : MARINE ALGAE, GULF OF CALIFORNIA 279 



Plants flat, membranous, blunt-lanceolate, to at least 1 1 cm. high, 2.5 

 cm. broad, with entire margins, narrowing gradually below to a very nar- 

 row base; basal attachment organs unknown, but lowermost parts com- 

 pressed or flattened, 0.5 mm. wide, giving rise to two erect blades; cross 

 section showing a single outer cortical layer of small, + — flattened 

 cells 4-10 fi in greatest dimensions (in surface view the smaller cells are 

 seen to be derived from the larger ones by division into 4-8 parts) ; sub- 

 cortex of about 2 layers of flattened cells, 15-20 fi in length; from these 



subcortical cells pluricellular (2-5) filaments 6-8 /x in diam., run -| 



directly across to an opposite subcortical cell, forming thus a loose medul- 

 lary tissue of usually unbranched, bridging filaments; no strictly longitu- 

 dinal filaments present. 



Type : D. 182, dredged in 24-44 m., Puerto Refugio, Jan. 26, 1940. 

 Herb. AHF no. 29. 



This species is known from a single, fairly complete but perhaps im- 

 mature plant. The very remarkable structure of the frond, together with 

 the external form, although allowing it to be classed rather well with 

 Halymenia, sets it apart from all other known species. The medulla is un- 

 usual in the absence of longitudinal or interlacing filaments. Those pres- 

 ent are mostly at right angles to the surface and form a sort of "pillar 

 eflfect" between the cortices. Relatively few run obliquely. 



Genus GRATELOUPIA C. Agardh 

 Grateloupia prolongata J. Ag. 



J. Agardh, 1847, p. 10; Kiitzing, Tab. Phyc. XVII, tab. 24; De Toni, 

 1905, p. 1565; Setch. & Card., 1924, p. 780, pi. 80. 

 On the basis of the description given by De Toni and the figure of 

 Kiitzing, Setchell and Gardner placed several Gulf specimens under this 

 name. The treatment seems acceptable in view of the type locality of the 

 species : Pochetti, Pacific Coast of Mexico, and here additional specimens 

 are recorded. This determination must stand in question, however, until 

 the type specimen of Grateloupia prolongata can be examined with refer- 

 ence to the Gulf material. Yendo, 1914, records this species from Japan. 

 He is followed in 1936 by Okamura. Yendo states that he has studied the 

 Agardhian type and finds it agrees satisfactorily with Okamura's speci- 

 mens distributed as no. 32 of Algae Japonicae Exsiccatae and sent out 

 under the name G. filicina. He further states that in the Agardh herbar- 

 ium there is a Japanese specimen sent by Farlow and named G. prolongata 

 by Agardh. 



