NO. 1 DAWSON : MARINE RED ALGAE OF PACIFIC MEXICO 49 



The cortex is composed entirely of branched, tapering, anticlinal fila- 

 ments about 3 cells long arising from what normally would be the hypo- 

 dermal layer. The condition is somewhat near that illustrated by Setchell 

 (1914, pi. 14, fig. 47). Gulf of Calif. — More than a dozen collections 

 are at hand indicating widespread occurrence from Puerto Libertad, 

 Sonora to Punta Frailes, Baja California. Its habitat is typically in the 

 upper sublittoral from which it is often taken together with Scinaia 

 latifrons and S. johnstoniae. Male plants have been found near Guaymas 

 in November. An apparently abnormal variant of the species was found 

 near Guaymas in which the thalli are attenuated above so that the ul- 

 timate dichotomies may be only 250 ju, in diameter. 



Galaxaura arborea Kjellman 



Plate 17, fig. 2 



Kjellman, 1900, p. 72-73, pi. 11, figs. 1-11, pi. 20, fig. 39; Chou, 

 1945, p. 50-51, pi. 5, figs. 1-5, pi. 10, figs. 1-2. Galaxaura marginata 

 (Soland.) Lamx., as interpreted by Dawson, 1944, p. 258. 



Thalli saxicolous, densely bushy, deliquescent-arborescent, as much 

 as 12 cm. high, attached by a broad, mat-like or discoid holdfast; caudex 

 and basal part of branches subterete, villous with rings of extended 

 assimilatory filaments, sometimes subglabrous, above flattened, glabrous, 

 carnose-membranous, often with distinct transverse striations, at least 

 toward the distal parts of branches, continuous or with proliferations 

 encircled at the base by a tuft of extended assimilatory filaments; seg- 

 ments 3-10 mm. long, 1-2 mm. wide, with thickened margins; medullary 

 filaments 8-16 /a in diameter; cortical parenchyma tissue 20-60 /a thick, 

 1-2-stromatic, of subglobose or compressed cells 16-60 /a in radial and 

 40-60 /x in tangential dimensions, each bearing 1-2 cuneate-cylindrical 

 stalk-cells 18-25 /a tall; terminal cells of assimilatory filaments ovate or 

 clavate, 22-36 /x tall, 18-25 fx in diameter, loosely arranged, appearing 

 subglobose on the surface; extended assimilatory filaments 0.5-1.5 mm. 

 long; tumid basal cells 1-2, 50-70 ju, long, 24-40 /a in diameter; shaft cells 

 18-20 /x in diameter, 2-4 times as long as broad; reproduction asexual. 



Type: Holotype not designated, but represented according to 

 Kjellman, by a specimen under the name Galaxaura marginata in the 

 Agardhian Herbarium, Botanical Museum, University of Lund, Sweden. 



Type locality: "in Mari Australi ad Novam Hollandiam." 



Mexican distribution : Pacific Baja Calif. — D. 22-40, dredged 

 in 35-40 m., Bahia Santa Maria, Jan. Gulf of Calif. — D. 7119, Bahia 



