NO. 1 DAWSON : MARINE RED ALGAE OF PACIFIC MEXICO 51 



caino, Apr. Gulf of Calif. — Poindexter, Mar. 1941, Punta Penasco; W. 

 Durham 12-1-40, Isia Tiburon, Dec; D. 3155, near Cabo Pulmo, Nov.; 

 D. 6755a, Cabeza Ballena, Mar. Nayarit — Taylor 39-667A, dredged, 

 Isla Maria Madre, May. 



This species appears to have a wide distribution in the Pacific Mex- 

 ican area, but it is probably ephemeral and of infrequent occurrence. It is 

 interesting to note that the two records from Pacific Baja California are 

 from the two exposed localities having the most nearly tropical intertidal 

 environment known for that region. 



Svedelius has clarified the nomenclature and distinguishing char- 

 acters of Galaxaura fastigiata which has often been combined with or 

 confused with G. oblongata. In G. fastigiata the limitation of the cal- 

 cification to the cortex with no extension into the medulla appears to be 

 the best criterion for separating it from G. oblongata, which has not as 

 yet been detected in the Mexican flora. 



Galaxaura filamentosa Chou 

 Plate 19, fig. 2 



Chou, 1945, p. 39, pi. 1, figs. 1-6, pi. VI, fig. 1 ; Taylor, 1945, p. 139. 



Thalli 3.5-5.0 cm. high, bushy, attached by a small discoid holdfast ; 

 branching more or less dichotomous, sometimes appearing trichotomous 

 by development of adventitious branches; branches terete, densely covered 

 throughout with extended assimilatory filaments; internodes 2-10 mm. 

 long, 0.5-1.5 mm. thick (excluding extended filaments) ; internal struc- 

 ture filamentous, homogeneous, without differentiation of medullary and 

 cortical layers, these filaments 16-24 ju, in diameter, their free ends ex- 

 tended into assimilatory, chromatophore-bearing filaments with poorly 

 developed or undifferentiated supporting cells; tumid basal cells totally 

 absent; shaft composed of cylindrical cells 1.5-3 times as long as broad, 

 16-18 /x in diameter below, 20-22 /a above; reproduction sexual. 



Type: Holotype is Taylor 39-46, Mar. 17, 1939, on sheet 150 in 

 HAHF. 



Type locality: In tide pools on a rocky point, Sulphur Bay, Isla 

 Clarion, Revillagigedo Archipelago, Mexico. The species is reported 

 from Costa Rica, the Galapagos Archipelago and from Formosa. It has 

 also been collected at the type locality by J. T. Howell of the Zaca Ex- 

 pedition, March 1932 (Specimen in the Herb. Calif. Acad. Sci.). 



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