142 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 24 



gin in addition to terminal claw ; telson five-plated ; no pleopods in 

 male. 



Description: Carapace markedly broader than long (1.1 or 1.2 times 

 in males, 1.3 to 1.5 in females), very strongly convex front to back; 

 posterolateral regions plicate, carapace otherwise smooth, shining, de- 

 void of hairs. Front transverse in dorsal view, in frontal view faintly 

 trilobate or transverse with a slight median projection. Outer orbital 

 angle forming a small, sharp tooth. Separated portion of side wall con- 

 sisting of one small irregular-shaped piece. 



Text-fig. 4. Dactyl of walking leg of Pachycheles crassus, x 84. 



First movable segment of antenna with a low tubercle at anterior 

 margin ; second and third smooth ; flagellum naked. 



Chelipeds appearing devoid of hair, but under magnification show- 

 ing a low pile between granules. Merus rugose, with a low rugose crest 

 on anterior margin. Carpus armed on anterior margin with four or 

 five smooth-margined teeth, the proximal one broad and truncate, 

 sometimes tending to be divided into two, the others narrow, conical, 

 and progressively smaller in size; surface covered with large, rather 

 flattened and scale-like granules. Manus heavy, swollen, covered with 

 large, coarse granules, more rounded than those of carpus, those to- 

 ward outer margin often pointed, giving the margin a serrate-edged 

 appearance. Fingers covered with granules similar to those of manus; 

 pollex short, conical, and flattened, dactylus strongly curved; fingers 

 meeting for entire length in both chelipeds, gape without pubescence. 



Walking legs almost devoid of hairs, a few scattered setae on pro- 

 podus and dactylus only. Dactylus with two strong fixed spines on 

 posterior margin in addition to the terminal claw; proximad to them 

 a single movable spinule (see text-fig. 4) . 



Telson of abdomen with five plates. No pleopods in male. 



Material examined: Balboa, Canal Zone, Panama, on reefs; M. 

 Ward, collector; one male, one ovigerous female (U. S. National Mu- 

 seum Cat. No. 77509). 



