NO. 1 DAWSON : MARINE RED ALGAE OF PACIFIC MEXICO 153 



Bossea orbigniana (Decaisne) Manza 



Manza, 1937A, p. 563; Manza, 1940, p. 304; Smith, 1944, p. 235, 

 pi. 51, fig. 3; Dawson, 1945b, p. 60, 65 ; Doty, 1947, p. 168. Amphiroa 

 orbigniana Decaisne, 1842, p. 124; Harvey, 1847, p. 100, pi. 38, figs. 

 1-6. 



Thalli saxicolous, to 14 cm. high, consisting of several much-branched 

 erect parts from a crustose basal stratum; erect parts dichotomously, 

 more or less divaricately branched in one plane throughout at intervals 

 of 0.6-2.0 cm., or with occasional widely divergent, unbranched, op- 

 posite or alternate pinnate branches; segments cylindrical at the very 

 base, but otherwise strongly compressed or flattened throughout, broader 

 than long, markedly cuneate, sagittate, the acute, swept-back wings 

 giving the branches a serrate appearance, 2-5-3.0 (or to 4.5) mm. wide, 

 usually with a thickened midrib; genicula unizonal, 200-250 ^ long; 

 intergenicular medulla multizonal, the filaments straight; tetrasporang- 

 ial conceptacles domoid, about 750 /* in diameter, usually one on either 

 side of the midrib, irregularly aggregated on older intergenicula ; car- 

 posporic plants not observed. 



Type: Holotype not designated. D'Orbigny's specimen was not 

 found in the Natural History Museum of Paris in 1950. Isotype ma- 

 terial may be in the Harvey Herbarium, Trinity College, Dublin, Ire- 

 land. 



Type locality: Shores of Patagonia and Chile. Southern Chile. 



Without a study of the type material and of other material from 

 Chile one cannot be certain to what plant this name applies. Although 

 Harvey's figure shows much resemblance to our Pacific Coast plants 

 referred here, it fails to show several essential details. Furthermore, 

 Harvey's figure may not have been drawn from d'Orbigny's specimen, 

 but from one of Darwin's. Pending the necessary critical review of 

 Amphiroa orbigniana Dec'ne it seems best to recognize the entity de- 

 scribed above under this name. 



Pacific coast distribution: Oregon — In the vicinity of Cape 

 Mears and Cape Arago, fide Doty, I.e. California — not recorded from 

 northern California; known in the vicinity of Monterey only from the 

 infratidal; Silva 5352, Pismo Beach (covered with hydroids indicating 

 sublittoral ) is the only other record north of Point Conception ; common 

 both intertidally and infratidally from the northern Channel Islands to 

 southern California. Pacific Baja Calif. — D. 4268, Isla Los Coronados, 

 June (dredged) ; D. 5188, just north of Bahia de Todos Santos, Sept.; 



