PART 1 GARTH : PACIFIC OXYRHYNCHA 357 



Ovigerous female: length 23.4 mm, width including spines 26.8 mm, 

 without spines 24.0 mm. 



Color in life: Crimson to maroon, mottled ventrally with a varying 

 amount of white. Chelipeds either pale cream except for crimson dactyls 

 or mottled crimson and white, or entirely crimson. Color deepest in 

 male. (Crane) 



Habitat: Coral (Pocillopora ligulata). (Crane) Of the 13 Hancock 

 expeditions stations, 7 were coral, 3 rocky substratum, 2 sandy bottom, 

 and one coralline. Serpulids and bryozoans were observed attached to 

 both Zaca and Velero specimens. 



Depth: Shore to 25 fathoms. 



Size and sex: The series includes males from 12.3 to 26.7 mm, females 

 from 14.1 to 23.4 mm, ovigerous females from 17.0 to 23.4 mm, and an 

 8.5 mm young. 



Breeding: Ovigerous females were encountered by the Zaca in the 

 Gulf of California in May (Crane) and by the Velero III off Panama 

 and Colombia in January. 



Remarks: The range of the species is extended northward from 

 Arena Bank to Perico Point, Carmen Island, in the Gulf of California, 

 and southward from Panama to La Libertad, Ecuador. These localities 

 define in the littoral the limits of the Panamic province. 



This species may be distinguished from Mithrax (Mithrax) sinensis 

 by the tuberculate rather than subacute hepatic and anterior branchial 

 prominences, by the two blunt teeth rather than three spines on the 

 basal antennal article, and by the stout and tuberculate meri of the cheli- 

 peds, rather than the slender and spinulous meri of M. (M.) sinensis. 



Mithrax (Mithrax) armatus Saussure 

 Plate V, Fig. 4; Plate 40, Fig. 2 



Mithrax armatus Saussure, 1853, p. 355, pi. 13, fig. 1. Stimpson, 1857b, 

 p. 456. A. Milne Edwards, 1875, p. 101. Miers, 1886, p. 86. 



Mithrax (Mithrax) armatus, Rathbun, 1925, p. 399, pi. 262, fig. 6. 



Mithrax (Mithrax) orcutti Rathbun, 1925, p. 397, pis. 140, 141 ; type 

 locality, Puerto Angel, Oaxaca, Mexico; female holotype, U.S.N.M. 

 No. 47110. 



Mithrax orcutti, Crane, 1947, p. 73. 



Type: Female holotype, length 47.3 mm, width 42.8 mm; not in 



Geneva Museum. 



Type locality: Mazatlan, Mexico; J. Verreaux, collector. 



