NO. 2 DAWSON : MARINE RED ALGAE OF PACIFIC MEXICO 297 



Thalli to 45 cm. tall, epiphytic or saxicolous, consisting of one to 

 several erect, complanate parts from a small, spreading or clasping, 

 discoid holdfast, deep, dull reddish in color; base of primary blades some- 

 what stipitate or at least narrow and thick (coompressed to flattened), 

 expanding cuneately; blades 0.8-2.0 (3.0) cm. broad, usually 300-350 

 /i thick in mature parts, dichotomously branched at intervals of 2-8 cm. 

 or more, the angles very narrow and the segments tending to lie parallel, 

 the terminal segments commonly 6 cm. long or more, lanceolate, the 

 tips simple or bifurcate and blunt, normally not incised into small seg- 

 ments; margins entire, plane or undulate, sometimes with a few small, 

 proliferous branchlets from older, lower parts; transection of younger 

 parts showing an outer cortex of a single pigmented layer of periclinally 

 flattened cells 9-16 /x, long; tetrasporangia not in sori, scattered through- 

 out mature parts of blades in the cortex which is slightly to moderately 

 nemathecially modified, 35-40 fi long, 14-20 /a wide, cruciate; cystocarps 

 scattered throughout the flat blades, embedded in the medullary area, 

 about 600 fi in diameter at first, enlarging to 1500-1800 ju,, compressed, 

 causing only moderate swelling on either side of the blade, usually with 

 1, or 2-3, non-rostrate ostioles on one side; antheridial plants tending to 

 be smaller than cystocarpic or tetrasporic ones; antheridia borne in a 

 dz continuous superficial layer over the greater part of the flattened sur- 

 faces of the mature blades, causing them to appear somewhat mottled, 

 developing from a single pigmented cortical layer without nemathecial 

 modification ; spermatia 2.0-2.5 fi in diameter. 



Type: Holotype not designated but represented by a collection by 

 Haenke in the Agardh Herbarium, University of Lund, Sweden. Tran- 

 sections are present on slide 2294 in HAHF. 



Type locality: "Pacific Ocean," but supposed to be Monterey, 

 California. 



Mexican distribution : Pacific Baja Calif. — This species is char- 

 acteristically of sublittoral occurrence in Mexico. The specimens cited 

 here were taken from drift except as otherwise indicated. D. 5278, 

 Punta Descanso, Sept.; Cooper 759, Punta Santo Tomas, Mar (inter- 

 tidal) ; D. 5148, 5184, Cabo Colnett, Sept.; D. 9647, Punta San Quin- 

 tin, Apr.; D. 1146a, 1180, Apr. (intertidal), D. 8912, Jan., Punta 

 Baja; D. 8682a, Bahia Rosario, Jan.; D. 1546, Bahia Ositos, near 

 Punta Maria, Apr.; D. 1490, Punta Santa Rosalia, Apr. 



Among those Callophyllis species with large, scattered cystocarps 

 C. obtusifolia appears to be distinguished by its entire margins, the re- 

 mote dichotomies, the narrow angles, and the long, ± attenuated but 



