NO. 2 DAWSON : MARINE RED ALGAE OF PACIFIC MEXICO 299 



articulated corallines and debris, and attaching by means of peg- or disc- 

 like outgrowths from the under surfaces ; texture usually lubricous ; erect 

 parts primarily dichotomous but ± provided with pseudo-pinnate 

 branchlets through asymmetrical growth ; segments mostly 4-9 mm. wide, 

 the intervals in mid-parts mostly 1-2 cm., the angles usually narrow; 

 terminal segments subsimple and blunt, a few times incised or lobed; 

 thickness of mature thalli 320-380 /a; cortex of about 3 layers, the outer- 

 most of anticlinally elongated cells about 5 /x, wide ; cystocarps scattered, 

 embedded in the medulla, not projecting but causing a moderate eleva- 

 tion of the surface, 1.0-1.5 mm. in diameter, usually with a single, 

 prominent but non-rostrate ostiole ; tetrasporangia cruciate, 30-35 /jl 

 long, 12-14 fx wide, scattered through the cortex which shows slight 

 nemathecial modification ; antheridia unknown. 



Type: Holotype is Dawson 9095, Apr. 27, 1950, on sheet 59352 

 in HAHF. 



Type locality: Intertidal, south shore, Isla Este, Islas San 

 Benito, Baja California, Mexico. 



Additional Mexican material: Pacific Baja Calif. — D. 276, 

 5 miles south of Punta Descanso, Jan.; D. 8869, Jan., D. 1252, Apr., 

 Punta Baja; D. 1548, Bahia Ositos, near Punta Maria, Apr.; D. 1493, 

 Punta Santa Rosalia, Apr.; D. 9831, Isla Cedros, Apr.; D. 9172, Bahia 

 Asuncion, Apr.; D. 9503, Punta Abreojos, Apr.; D. 9309, Punta 

 Entrada, Isla Magdalena, May. 



This species appears to be of wide distribution along Pacific Baja 

 California, being confined to the lowermost intertidal habitats. It usually 

 does not attach itself directly to rocks, but rather to the short, turf- 

 forming algae, mostly articulated corallines. The peculiar manner of 

 attachment of the thallus by prostrate, complanate branches with numer- 

 ous holdfast discs is distinctive of this plant. The external morphology 

 most nearly resembles that of dwarfish specimens of C. obtusifolia. 



Gallophyllis pinnata Setchell & Swezy 

 PI. 5, fig. 41 ; pi. 40, fig. 87 



Setchell 1923, p. 400; Dawson 1945c, p. 60, 66, figs. 8-9. 



Thalli 20-30 cm. tall, usually epiphytic, dull rose-red in color, con- 

 sisting of one or a few erect, complanate, branched blades from a small, 

 discoid holdfast; blades scarcely stipitate, 5-6 times dichotomously 

 branched at intervals of 2-10 cm., the longest segments usually subulti- 

 mate; primary segments mostly 0.8-1.5 cm. wide, the ultimate ones with 

 rounded apices ; margins entire but at least in part provided with minute 



