252 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 12 



large firm-walled colorless cells three or four cells thick, rather gradually 

 graded to the cortex of two or three layers, the outer cells small; tetra- 

 sporangia in very small sori about 1-2 mm diam., at the tips of somewhat 

 blunt terminal segments; cystocarps chiefly marginal or submarginal on 

 slender upper segments, prominent, to 1.0-1,25 mm diam., the ostiole a 

 little produced, the carpospore mass largely filling the cavity and attached 

 to the base by one large cell. 



Mexico: Baja California, dredged off Point Hughes, Cabo San 

 Lazaro, no. 34-602 (TYPE), 7 Mar. 1934. 



Rhodymenia Palmetta (Esper) Greville 



Plants stoloniferous below, the creeping parts wiry, at intervals bear- 

 ing single erect blades which have slender stalks 2-3 cm long, gradually 

 expanded to membranous blades with a total length of 8-10 cm; blades 

 tapered to the stalk, flat, irregularly 1-6 times dichotomously forked, the 

 divisions gradually tapered upward, not cuneate at each segment, the 

 width below 4-6 mm, above 2-3 mm, the tips rounded, forming an addi- 

 tional blade occasionally as an outgrowth from the upper end of the 

 stalk, the margin of the primaiy blade near the base, or the sinus of the 

 first forking; tetrasporangia in sori at the rounded or spatulate branch 

 tips, 2-3 mm diam., with spore discharge breaking away to leave a per- 

 foration or the sharp lateral sterile margins of the tip intact, in section 

 showing no distinctive modification of the cortex in the sorus area, where 

 it is only one or, occasionally, two cells thick. 



The identity of these plants is puzzling. When collected, they were 

 assumed to be juvenile plants of Dendrymenia flabellifolia. However, no 

 intergrades were to be found, especially regarding the prominent erect 

 axis so characteristic of that species. These are reproductively mature 

 plants. The writer was unable to find any feature by which they could be 

 distinguished from R. Palmetta, most characteristically a north European 

 species. Wyatt's Algae Danmoniensis no. 109 (seen in the author's her- 

 barium and in Herb. Kew.) is certainly essentially the same, and so are 

 specimens collected by Griflith from Kilkee, Co. Clare, in Herb. Kew. 

 The European specimens vary greatly in breadth and taper of the seg- 

 ments. However, with more (and especially cj^stocarpic) material for 

 comparison, tangible characters justifying segregation, now lacking, may 

 be found. They also resemble R. attenuata Dawson (1941, p. 139, pi. 19, 

 figs. 10, 11, pi. 25, fig. 35) except that they are not so slender, particularly 

 near the base of the blade, and in the sorus area there is none of the nema- 

 thecioid modification with stimulation of the cortex to produce anticlinal 

 rows of cells. 



