NO. 1 DAWSON : MARINE RED ALGAE OF PACIFIC MEXICO 79 



Type: Holotype is Loomis 5330, July 22, 1934, in the private 

 collection of Mrs. Nina Loomis, 1324 North Ogden Ave., Hollywood, 

 California. Isotype preparations are on slides 1187-1188 in HAHF. 



Type locality: In beach drift, Anaheim Landing, Orange Coun- 

 ty, Calif. 



Mexican distribution : Pacific Baja Calif. — D. 264, 8 km. south 

 of Punta Descanso, Jan.; D. 10394, Punta San Eugenio, Nov. 



The Mexican plants compare favorably in all essentials with the type 

 of the species. The characters which differentiate it from Pterocladia 

 pyramidale are to be found in the basal cystocarps, the linear, extensive 

 tetrasporangial and antheridial sori, and in the near-unity ratio of sexual 

 to asexual plants. Several characters considered distinctive by Loomis, 

 namely, the relative thallus size, color, number of cortical layers, and 

 the size and shape of medullary rhizoidal filaments, do not seem to hold 

 good when compared in series with P. pyramidale. 



Pterocladia pyramidale (Gardner) Dawson 



Dawson, 1945, p. 93; Dawson, 1945b, p. 65; Dawson, 1949, p. 228. 

 Gelidium pyramidale Gardner, 1927a, p. 273, pis. 36, 37, fig. 1, 45, 46, 

 fig. 2. Geliditim okamurai Setchell & Gardner, 1937, p. 75, pi. 6, fig. 16, 

 pi. 17, fig. 38. Pterocladia okamurai (S. & G.) Taylor, 1945, p. 161. 

 Pterocladia okamurai forma densa Taylor, 1945, p. 161, pi. 37, fig. 1.. 

 Pterocladia mexicana Taylor, 1945, p. 159, pi. 35. Pterocladia robusta 

 Taylor, 1945, p. 160, pi. 36. Gelidium pulchrum Gardner, as to Cedros 

 Island specimen interpreted by Dawson, 1949, p. 229. 



Thalli 10-25 cm. high, consisting of several abundantly, irregularly 

 but distichously branched erect axes arising from a holdfast of entangled 

 stolons; erect axes compressed to strongly flattened, 0.6-1.5 mm. broad 

 in lower parts, 120-220 (350) /x thick, 0.6-0.3 mm. broad above and 

 often becoming reduced and attenuated to 100 /a wide or less; branching 

 commonly irregularly alternate, but often opposite in part or nearly so, 

 moderately loose and open with intervals of 2-3 mm. between branches, 

 or sometimes densely, congestedly branched above, the filiform branchlets 

 becoming entangled and somewhat matted ; branchlets tapered to a con- 

 stricted base ; transection elliptical in older parts, consisting of a medulla 

 of rather thick-walled cells 12-20 ju. in diameter grading into a pig- 

 mented cortex of about 3 layers, the outermost of cells slightly anti- 

 clinally elongated, to 5.0-6.5 fx high, the medulla provided with a moder- 

 ate to large number of rhizoidal filaments, these concentrated in the 



