NO. 1 DAWSON : MARINE RED ALGAE OF PACIFIC MEXICO 155 



Aug.; Cooper 810, Punta Santo Tomas, Mar.; D. 5239, Cabo Colnett, 

 Sept. (close correspondence with type) ; D. 1563, near Punta Maria, 

 Apr. 



Bossea gardneri is so closely related to B. dichotoma that in some 

 cases it is difficult or impossible to distinguish the two. There is even 

 considerable suggestion that the two are not specifically distinct. Until 

 additional evidence is at hand, however, both names may be retained, 

 B. gardneri to represent a plant with rare or infrequent pinnate branch- 

 ing below and usually somewhat attenuated tips, B. dichotoma to repre- 

 sent a plant with frequent pinnate branching below, and sometimes 

 above, and somewhat expanded tips. B. dichotoma also tends to have 

 broader intergenicula than B. gardneri. 



In Mexico Bossea gardneri appears to be confined to the cool water 

 of the upwelling areas of northern Baja California. Although it is com- 

 mon among the northern Channel Islands and along the southern Cali- 

 fornia coast, it has not yet been obtained from the warmer waters of 

 the southern Channel Islands. 



Bossea dichotoma Manza 



Plate 8, fig. 2 



Manza, 1937a, p. 562; Manza 1940, p. 307, pi. 17; Smith, 1944, p. 

 234, pi. 54, fig. 1. Bossea frondifera Manza, as interpreted by Dawson, 

 1945, p. 65. 



Thalli saxicolous, to 8 cm. high, consisting of several to many much- 

 branched erect parts from a crustose basal stratum ; erect parts primarily 

 dichotomously and rather divaricately branched in one plane, frequently 

 with alternate or opposite pinnate branches below and sometimes above, 

 also with occasional proliferous branches from the intergenicular sur- 

 faces ; branch-intervals rather short, especially in upper parts ; branch 

 tips usually tending to be broadly rounded, not attenuated ; intergenicula, 

 except those at the very base, strongly compressed or flattened, much 

 broader than long, very broadly cuneate, with prominent wings and 

 midrib, mostly 3.0-4.0 mm. wide, mostly 1.5-1.6 mm. long in upper 

 parts of tetrasporic plants, smaller in sexual plants ; wings usually with 

 rounded or blunt tips, sometimes subacute; genicula unizonal, about 200 

 fx long or less; intergenicular medulla multizonal, of uniform zones of 

 straight filaments; tetrasporangial plants somewhat larger than sexual 

 ones; tetrasporangial conceptacles domoid, about 750 {x in diameter, 1-2 

 on either side of the midrib on flattened faces of intergenicula; tetra- 



