NO. 10 DAWSON : MARINE ALGAE, GULF OF CALIFORNIA 303 



Plants spreading 5-10 cm. in extent, attached loosely by elongation of 

 papillae from the under surfaces or by small, branched stolon-attachments 

 from the primary base and the prostrate blades; fronds composed of nar- 

 row, complanate segments, the primary ones about 3 cm. broad, branched 

 distichously into about 3 orders of branches, successively narrower and 

 shorter and apically acute; broader parts of primary and secondary 

 branches conspicuously clothed with abundant, semiequal, slender margi- 

 nal pinnules, giving a somewhat pectinate aspect to these parts; older 

 blade-surfaces commonly with similar, shorter projections; cystocarps lat- 

 eral on smaller segments, not abundant, with a dense proper pericarp; 

 cystocarpic plants more densely branched than sterile specimens. 



Type: D. 239, cast up on shore at high tide, north shore beach at 

 Puerto Refugio, Jan. 27, 1940. Herb. AHF no. 43. 



D. 209, lower littoral rocks, Puerto Refugio, Jan. 26, 1940; Poin- 

 dexter, shore rocks, Punta Penasco, March, 1941 (juvenile). 



This species resembles in some respects young specimens of Gigartina 

 leptorhynchus of the coast of California. 



Gigartina MacDougalii sp. nov. 

 Plate 64, Fig. 2 



Frondes 6-9 era. altae laminis angustis complanatis e stolonibus valde ramosis, 

 complanatis, in massam intertextis orientes; laminis complanatis basim attenuatis, 

 semel distiche in segmenta 5-6 mm. lata et usque ad 5 cm. longa ramosis ; segmentis 

 levibus aut inferne spinulis paucis marginalibus, sed superne papillis ramosis 

 lobatis, dense intertextisque ubique indutis. 



Plants 6-9 cm. high, of narrow complanate blades from a large tan- 

 gled holdfast of many narrow, flattened, much-branched stolons; blades 

 flattened from the start, attenuated to the base, branching once distichous- 

 ly into segments 5-6 mm. wide and up to 5 cm. long, smooth or with a 

 few marginal spinules in lowest parts, thickly matted above with branched 

 and lobed papillae over all surfaces, giving these parts a spongy appear- 

 ance and obscuring the flatness of the blades; cystocarps among branched 

 papillae, with a "pericarpium proprium." 



Type: MacDougal (Univ. Calif. Herb.; isotype, AHF no. 44), 

 Puerto Libertad, Sonora, May 4, 1923. 



The tangled holdfast of branched stolons and the matted effect of 

 the papillae over the blades are the distinctive features of this remarkable 

 species. 



