54 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 17 



Thalli saxicolous, to 8 cm. high or more, from a discoid holdfast; 

 branching dichotomous or sub-dichotomous at intervals or 5-12 mm., 

 widely effuse or flabelliform above; branches 1-2 mm. in diameter, con- 

 tinuous or sometimes subarticulate and proliferous, smooth and slightly- 

 shiny where there are no spinulose cells, but dirty-chalky and farinaceous 

 where covered by spinulose cells; medullary filaments 7-12 mm. in dia- 

 meter; cortical tissue tristromatic, 48-80 ^ thick, the cells of the inner- 

 most layer subglobose or compressed, often wider than high, 20-30 ft 

 tall, 35-45 IX broad, those of the outermost layer chromatophore-bearing, 

 angular in surface view, 16-28 /x in diameter, semi-lunate in section, 10- 

 15 ju, tall; spinulose cells occurring in patches, irregularly scattered over 

 the surface of the thallus, commonly appearing on the thickened margins 

 first, or sometimes confined mostly to the margins throughout; repro- 

 duction sexual. 



Type: Holotype is a specimen under the name Galaxaura margin- 

 ata from E. Bornet, in the Herbarium of the University of Upsala, 

 Sweden. 



Type locality: Madagascar. 



Mexican distribution: Ba]a Calif, (cape district) — D. 3156, 

 near Punta Frailes, Nov.; D. 3100a, 5 km. north of Cabo Pulmo, Nov. 



These specimens agree in gross external morphology and in general 

 anatomy with Galaxaura veprecula as usually recognized, yet they have 

 the spinulose cells confined for the most part to the margins as in G. 

 ventricosa. As none of the specimens reaches as much as 2 mm. in dia- 

 meter, they fall short of the dimensions of G. ventricosa. 



As Chou suggests (1947, p. 19), the spinulose cells are variable in 

 size, shape and frequency. Kjellman's use of the occurrence or absence 

 of these cells to separate several species may be quite unwarranted, for it 

 appears that they may in some cases be only occasional or entirely lacking 

 in plants clearly of the same species and from the same collection as 

 others with well-developed spinulose cells. This appears to be borne out 

 by specimens at hand from Costa Rica in which the fronds are essentially 

 devoid of spinulose cells, though a few of them may occur here and there 

 on the margins. Accordingly, a conservative taxonomist would probably 

 be justified in reducing G. ventricosa Kjellm. and G. angustifrons 

 Kjellm. to synonymy under G. veprecula Kjellm. Taylor's specimen 

 from Nayarit identified by Chou as G. ventricosa is tentatively referred 

 here. 



