NO. 1 DAWSON : MARINE RED ALGAE OF PACIFIC MEXICO 159 



Thalli 4-9 cm. high, consisting of a number of much-branched, non- 

 percurrent, bushy erect parts from a crustose basal stratum; erect parts 

 cylindrical or subcylindrical at the very base, then compressed and flat- 

 tened above, 500-700 ix thick; branching abundant, mostly at intervals 

 of 3-6 intergenicula, both dichotomous and pinnate more or less irre- 

 gularly mixed throughout, but alternate or opposite pinnate branching 

 tending to predominate; intergenicula bluntly sagittate, usually a little 

 broader than long, 1.5-2.5 mm. broad, 1.2-2.0 mm. long, rather thick 

 and vi'ith short, subacute, distally projecting wings, not overlapping each 

 other or rarely so; midrib absent or indistinct; genicula unizonal, 200- 

 250 II long; asexual conceptacles domoid, 600-750 ju, in diameter, the 

 ostiole frequently excentric, 1-2 or up to 5 on flattened intergenicular 

 faces, bearing bispores or tetraspores ; sexual plants not seen. 



Type: Holotype is Cooper 545, March 5, 1947, on sheet 14521 in- 

 cluding slide 1412 in HAHF. 



Type locality: In protected tide pools, Playa Rosarita, Baja 

 California, Mexico. 



Additional material: California — Silva 5927, Mar., D. 5823, 

 Dec, Santa Cruz Island (large, luxuriant plants) ; Silva 1697, West 

 Anacapa Island, Mar.; D. 10268, La Jolla, Mar. Pacific Baja Calif. — 

 Cooper 774, Punta Santo Tomas, Mar.; D. 1172, Punta Baja, April. 



This plant shows considerable resemblance to Bossea orbigniana in 

 size and in the bluntly sagittate shape of the intergenicula, but differs 

 sharply in the conspicuous alternate and opposite pinnate branching. 

 From other pinnate species such as B. insularis it is distinguished by its 

 differently shaped, narrow, more acutely lobed intergenicula which are 

 little broader than long. From B. ligulata it is distinct in its narrower 

 intergenicula, its frequent dichotomous branching, and in its denser 

 branching in upper parts. 



A specimen dredged from 20-25 meters off San Pedro, California 

 seems by its branching to be referable to B. coo peri rather than to the 

 commoner sublittoral B. orbigniana. 



Bossea insularis Dawson et Silva sp. nov. 

 Plate 8, figs. 5-6 ; Plate 25, fig. 2 



Bossea gardneri Manza, as interpreted by Taylor, 1945, p. 194, pi. 

 57; Dawson, 1951, p. 53. Bossea plumosa Manza, as interpreted by 

 Dawson, 1949, p. 227. 



