NO. 1 DAWSON: MARINE RED ALGAE OF PACIFIC MEXICO 69 



D. 10855, San Bias. Guerrero— Taylor 34-570, Bahia Petatlan. Oaxaca— 

 Taylor 34-549, Bahia Tangola Tangola. 



Centroceras bellurn Setchell & Gardner 

 PI. 27, fig. 4 

 Setchell & Gardner 1924, p. 779, pi. 26, fig. 48, pi. 40c, pi. 78. 



Thalli 1.0-1.5 cm. high, more or less prostrate at the base and 

 attached by numerous pericellular hairs (1-3 at a node), becoming 

 erect at the outer ends, completely corticated, subsecundly branched; 

 main axes 110-130 [x in diam.; branches all arising at the nodes back 

 of the growing point; tetrasporic ramuli stichidia-like, considerably 

 enlarged for some distance above the base, each tapering very gradually 

 to a blunt terminal growing cell, and more or less curved at the apex; 

 corticating cells in regular longitudinal rows on the older parts of the 

 thallus, quadrate except at the slightly swollen nodes and on the fruiting 

 part of tetrasporic ramuli where they are divided into 2-4 smaller cells; 

 tetrasporangia completely immersed, in a single whorl at each node; 

 sexual plants unknown. 



Type: Marchant 85, June, in Herb. University of California, 

 Berkeley. 



Type locality: Cast ashore at Guaymas, Sonora, Mexico. 



This species has not subsequently been found in any of the Mexican 

 collections although a specimen dredged by a Hancock Expedition from 

 15 fms. at Post Office Bay, Charles Island, Galapagos Archipelago, seems 

 to agree with it, at least in sterile characters. 



Spyridia filamentosa (Wulf.) Harv. 

 PL 30, fig. 1-3 

 Harvey 1833, p. 336; Setchell & Gardner 1930, p. 167; Dawson 1949, p. 230. 

 Fucus filamentosus Wulf en 1803, p. 64. 



Thalli bushy or tufted, 2-20 cm. high, epiphytic or on rocks, shells 

 or debris, very irregularly ramified, usually with multiple axes, the 

 branches usually multifarious; principal axes 200 /i in diam., or more, 

 gradually reduced at the tips, consisting of a row of very large axial 

 cells covered with a complete cortex composed of alternating tiers of 

 much smaller long and short cells in 1 or 2 layers; multifarious lateral 

 branchlets about 40-60 p in diam. at the base, reduced to 20 /x above, 

 simple, of cells 1.0-1.5 diameters long, provided with a single terminal 

 2-3 celled spine, each cell node with a short cortical band ; tetrasporangia 

 tetrahedrally divided, ± spherical, about 50 fi in diam., sessile from 

 the cortical bands of the lateral branchlets; sexual plants not seen. 



Type: The location of the Wulfen type is unknown. 



Type locality: Adriatic Sea. 



Mexican distribution: Pacific Baja Calif. — D. 8783, 21671, 

 21630, 21752, Bahia San Quintin (intertidal) ; D. 2612 (Williams & 



