NO. 10 DAWSON : MARINE ALGAE, GULF OF CALIFORNIA 307 



forms of which are now recognized under several names such as B. occi- 

 dentalis and B, leptopoda, and to which the present species is taxonomi- 

 cally equal in magnitude. 



Genus RHODYMENIA Greville 

 Rhodymenia divaricata Dawson 



Dawson, 1941a, p. 141, pi. 23, fig. 31. 



D. 53 (AHF no. 1), dredged in 4-6 meters, mud bottom, Guaymas 

 Bay, Jan.; D. 257, dredged from sand and coralline bottom in 12-22 me- 

 ters off Mejia Island, Puerto Refugio, Jan. 



Rhodymenia rosea Dawson 



Dawson, 1941a, p. 141, pi. 24, figs. 32, 33. 



D. 266 (AHF no. 2), dredged in 12-22 meters off Mejia Island, 

 Puerto Refugio, Jan. 



Rhodymenia Hancockii Dawson 



Dawson, 1941a, p. 146, pi. 20, fig. 20, pi. 26, fig. 38. 



D. 252 (Type AHF no. 3), dredged in 42 meters, west side of bay, 

 over shell bottom, Puerto Refugio, Jan. 



Rhodymenia lobata Dawson 



Dawson, 1941a, p. 147, pi. 19, figs. 12, 13, pi. 28, fig. 41. 



A sterile plant with extensive branched stipes, narrowly cuneate 

 blades, narrow segments, and thin blades was dredged in 10-18 fathoms 

 near Isabel Island, Sinaloa, Mexico, April 2, 1937. In the sterile state it 

 cannot be distinguished from Rhodymenia lobata, known hitherto only 

 from the sublittoral of central California, and is tentatively placed under 

 that name, awaiting fertile examples. 



Rhodymenia ? tepocensis sp. nov. 

 Plate 65, Fig. 1 



Frondes 12-18 cm. altae, circa 200 |x crassae, valde complanatae, partibus in- 

 ferioribus exceptis, iis ad basem subteretem copiose ramosam valde attenuatis, 

 superne 2-3 mm. latae, remote dichotomae, in planitie una ramosae; segmentis 

 acute ascendentibus, axillis anguste acutis; apicibus 2-6 -acute divisis. 



Plants 12-18 cm. high, strongly flattened except in lowermost parts, 

 very much attenuated to a subterete branching base, but holdfast un- 



