NO. 2 DAWSON: MARINE RED ALGAE OF PACIFIC MEXICO 271 



medulla of sparse filaments ; cortex of 3-4 layers of cells, the outermost 

 anticlinally elongate, 3-6 /x broad and about 7 /* long, the innermost 

 ovoid or spherical, 8-10 /x in diameter, not stellate; medullary filaments 

 sparse, slender, of cells to 10 times as long as broad, little branched, 

 interwoven, but the majority extending perpendicularly from cortex to 

 cortex; tetrasporangia cruciate, 20-25 by 11-14 /*, scattered through the 

 unmodified cortex; cystocarps abundant, scattered, embedded beneath a 

 prominent, pit-like ostiolar opening about 50 yu, in diameter at the surface, 

 surrounded by poorly developed perithecial filaments; carpospores in a 

 compact, subspherical mass 80-110 fi in diameter, angular, 9-11 ju, in 

 greatest diameter ; antheridia unknown. 



Type: Holotype is Hollenberg 3038 in the Dudley Herbarium, 

 Stanford University, California. 



Type locality: Drift, Moss Beach, San Mateo County, Cali- 

 fornia. 



Mexican distribution: Pacific Baja Calif. — D. 1567, drift, 

 Bahia Ositos, near Punta Maria, April. 



This single cystocarpic Mexican collection is in close agreement with 

 the original description of Smith and Hollenberg. It seems to differ only 

 in having slightly smaller cortical cells and scattered rather than ag- 

 gregated cystocarps with more prominent ostioles. The gonimoblast 

 development appears to be virtually the same as in other species reported 

 here. The plant is readily recognized by its broadly falcate blades. 



A fragmentary blade of a tetrasporangial plant from drift at Punta 

 San Quintin, near Isla San Martin, Baja Calif., appears to belong here. 

 It is very broadly falcate, 12 cm. broad, and structurally similar to the 

 Punta Maria specimen. 



Halymenia abyssicola Dawson 

 PI. 3, figs. 22-25 



Dawson 1944, p. 278. 



This species was somewhat inadequately and incorrectly described 

 by the writer in 1944. Reexamination of the type material has revealed 

 developing carposporophytes which are in general agreement with those 

 of Halymenia. In the light of the now fairly ample Halymenia collections 

 from the Gulf of California, some clarification of the circumscription of 

 the species is presented below. 



Thalli plane, membranous, rose red in color, exceeding 8 cm. in 

 length and breadth, with entire margins, but the attachment and the 

 shape of the whole thallus unknown, 300-400 fi thick ; transection show- 



