250 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 12 



RHODYMENIA Greville, 1830 



Plants forming moderate to large fronds, branched, the segments flat, 

 linear to foliaceous, chiefly dichotomously divided, but often proliferous 

 from the margins ; growth from an apical meristem ; structurally showing 

 a parenchymatous medulla of large colorless cells and a thin cortex of 

 small cells which becomes thickened by the formation of anticlinal rows 

 in the fertile portions ; sporangia scattered or formed in sori between these 

 cell rows, tetrapartite ; three-celled carpogenic branches and two-celled 

 auxiliary branches on the same supporting cell, with the carpospores 

 formed from the outer gonimoblast cells, the cystocarp within a some- 

 what swollen loose pericarp opening by a distinct pore. 



KEY TO SPECIES 



1. Plant decumbent, the branches narrow, very brittle R. decumbens 



1. Plant erect 2 



2. Plants to 2.0 dm tall, segments narrowly linear, 0.75-3.0 mm 

 wide R. Dawsonii 



2. Plants less than 1 dm tall 3 



3. Clearly stoloniferous, the blades with stalks 1 cm or more in 

 length R. Palmetta 



3. Not evidently stoloniferous, the blades closely dichotomous with 

 blunt tips and no considerable stalk 4 



4. Segments 3-5 mm wide R. californica 



4. Segments 1-3 mm wide R. divaricata 



Rhodymenia californica Kj lin 



Plants 3 cm tall, tufted, purplish red, 3-4 times dichotomously 

 branched at wide angles, the thin segments 3-5 mm broad, the apices 

 truncate rounded; tetrasporangia with paraphyses in sori near the tips 

 of the terminal divisions. 



Kylin 1931, p. 21, pi. 9, fig. 22. 



The scanty Post Ofhce Bay specimens are smaller than the maximum 

 of Kylin's type collections as described above, but seem in general to 

 agree with his figures and descriptions. 



Ecuador : Archipielago de Colon, dredged at 55 meters near Wreck 

 Bay, I. San Cristobal, Schmitt no. 352 A -34, 15 Dec. 1934. Ibid., 

 dredged from 27 meters off Post Office Bay, I. Santa Maria, no. 34- 

 280B, 19 Jan. 1934. 



