PART 1 GARTH : PACIFIC OXYRHYNCHA 307 



lesser granules between these and also on the dorsal branchial surface. 

 A transverse row of four small tubercles at protogastric level, a single 

 low metagastric tubercle, a pair of cardiac tubercles, and a pair each of 

 inner meso- and inner metabranchial tubercles ; besides these paired intes- 

 tinal tubercles and a row of lesser postlateral granules. Intestinal region 

 not protruding appreciably beyond posterior margin of carapace. 



Basal antennal article broadened anteriorly as well as posteriorly, 

 anteroexternal spine acute and incurving, lateral marginal spine smaller, 

 rounded. First two movable articles of antenna flattened, second over- 

 reaching rostrum. A spine external to the base of the immovable article 

 and a group of three spines at pterygostomian level. External maxilliped 

 remarkably broadened and flattened, ischium not grooved, merus with 

 both internal and external angles broadly produced and almost no inden- 

 tation for insertion of palpus. 



Chelipeds of male massive, devoid of pubescence, and porcellanous in 

 texture. Merus cylindrical, unarmed except for a few proximal tubercles ; 

 carpus shallowly sulcate above; manus smooth, greatly elongated, and 

 swollen internally; dactylus occupying about one-third of total length, 

 bearing one molariform and one simple tooth in gape, a tooth of the 

 pollex interposing between them, tips incurving, crenulate, excavate, and 

 setiferous. 



Ambulatory legs much shorter than cheliped in male, sparsely setose ; 

 meri shortening abruptly from first to last, broadening distally, anterior 

 borders spinulous ; carpi deeply sulcate ; propodi of relatively equal length, 

 cylindrical ; dactyli longer than in related species, spiniform beneath, tips 

 curving. 



Male abdomen seven-segmented, otherwise unremarkable. Male first 

 pleopod with tip slightly recurving, a setiferous fold occupying the shal- 

 low concavity and concealing the opening. (See Plate S, fig. 2) 



Female with cheliped little if any longer than first ambulatory leg; 

 manus not greatly elongated ; fingers distally denticulate, proximally 

 gaping slightly, gape without enlarged tooth or teeth. Meri of ambu- 

 latory legs of the first two pairs less attenuated than in male. 



Material examined: 180 specimens from 29 Galapagos stations. (See 

 Garth, 1946, p. 381) 



Measurements: Male specimen: length 13.0 mm, width 10.8 mm, 

 rostrum 1.3 mm, width 1.4 mm, cheliped 22.3 mm, chela 12.0 mm, 

 dactyl 4.3 mm, height of palm 2.7 mm, ambulatory legs 17.5, 15.0, 14.0, 

 and 11.5 mm, respectively. Largest male: length 15.7 mm, width 13.0 

 mm. Largest female: length 15.4 mm, width 12.3 mm. 



