NO. 2 DAWSON : MARINE RED ALGAE OF PACIFIC MEXICO 267 



No new material of this species has come to hand^ and nothing more 

 can be added to the description of the type material which is here quoted : 



"Fronds erect, cylindrical and rigid below, flat and ligulate above, 

 2.5 cm. high, the ligulate portion 1-1.5 mm. wide and 125-150 ft thick, 

 subdichotomously branched ; medulla occupying approximately Yz of the 

 thickness of the flattened portion and composed of compound fibers 5-7 

 II diam. ; cortex composed of anticlinal filaments with 4-6 color-bearing 

 cells; tetrasporangia numerous, in nemathecia on both sides and near 

 the apices of the terminal segments, 25-30 /i, long, 10-13 fx. wide, cru- 

 ciately divided ; cystocarps and antheridia not observed." 



Type: Holotype is Howell 462a, Mar. 24, 1932, on sheet 236505 

 in the Herbarium of the California Academy of Sciences, San Francisco, 

 California. 



Type locality: On rocks, Bahia Sulphur, Isla Clarion, Mexico. 



In the original account, and in Taylor 1945, pp. 208, respectively, 

 comparisons have been made between Polyopes bushiae Farl. and P. sin- 

 icola S. & G., and between P. clarionensis and P. sinicola. The name 

 Polyopes sinicola was given to a plant from the upper Gulf of California 

 which, upon reexamination, has proved to have nothing to do with 

 Polyopes or with any other red alga. The type specimen of P. sinicola 

 actually is a good example of the brown alga Ishige foliacea Okamura 

 which has been collected repeatedly by the writer in the northern Gulf 

 of California during the past dozen years. 



Key to the Mexican species of Halymenia 



1. Thalli dichotomously branched, at least in part, the segments 



generally less than 1 cm. broad 2 



1. Thalli not dichotomously branched, with broad membranous 



blades (3 cm. wide or more) 3 



2. Segments subterete; apices blunt . . , H. agardhii 

 2. Segments flat; apices acute or bif^ircate . . H. bifida 



3. Blades broadly falcate; cystocarp ostioles prominent, pit-like 

 H. californica 



3. Blades not falcate, but elliptical, orbicular or reniform; cysto- 

 carp ostioles inconspicuous 4 



1 Since this was written, luxuriant, fertile material which corresponds with the 

 type except for larger size has been examined from Oahu, Hawaiian Islands. The 

 largest specimens, collected by M. S. Doty on wave dashed, exposed rocks in a 

 sandy beach at the mouth of "Bellows Field Creek," Dec. 6, 1952, range from 6 to 

 13 cm. in height and to 3 mm. wide. The writer collected young examples 4.5 

 cm. tall at exposed Laniloa Point, May 30, 1953. 



