120 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 24 



Merus of chelipeds covered with large flattened granules; anterior 

 margin with a small, strongly projecting, rounded, granular lobe. Carpus 

 about one and a half times as long as wide, finely granular, armed on 

 anterior margin with a broad, strongly projecting lobe occupying the 

 proximal two-thirds of margin, this lobe rounded on its proximal side, 

 forming an obtuse angle on its distal side, its edge sometimes obscurely 

 subdivided into three parts ; dorsal surface with a distinct median longi- 

 tudinal crest ; posterior margin markedly convex, with an obliquely ru- 

 gose crest ending distally in a very small tooth, this crest sometimes 

 covered with small crowded granules instead of rugae; the distinct 

 groove between posterior and median crests with scattered granules a 

 little larger than those on rest of dorsal surface and on lobe, this groove 

 sometimes very broad, the median crest then correspondingly narrow; 

 another broad groove sometimes present anterior to median crest, ex- 

 tending for only about distal half of carpus ; a few scattered hairs some- 

 times present near posterior margin. Manus finely granular, heavy, sur- 

 face swollen, the swollen area often lightly, longitudinally grooved to 

 form two low, close-set crests ; outer margin with a distinct rounded 

 crest, defined by a strong, broad groove near outer margin and usually 

 extending well onto pollex. Fingers finely granular; curved at tips, 

 meeting entire length in one cheliped, usually shorter and slightly gap- 

 ing in the other; dactylus usually deeply grooved along center; gape 

 with a short, thick pubescence, usually extending to tips of fingers. 

 Ventral surface of chelipeds smooth. 



Merus of walking legs unarmed, anterior margin with a short, thick 

 fringe of plumose hairs, that of leg 3 slightly inflated ; other segments 

 thickly covered with tufts of long non-plumose setae. 



Measurements: Holotype male: length 8.0 mm, width 7.2 mm. Para- 

 types: males, 3.0 to 8.6 mm; non-ovigerous females, 4.2 to 6.5 mm; 

 ovigerous females, 3.6 to 7.9 mm. 



Color: Specimens preserved in alcohol were pale orange, with 

 lighter spots on the carapace and chelipeds. 



Ecology: Usually occurring in the littoral, under stones. It was 

 taken once by the Velero III from a sand and shell bottom at 10 fath- 

 oms. 



Relationships : This new species is allied to Petrolisthes crenulatus 

 Lockington, P. ortmanni and P. hians Nobili, P. lewisi (Glassell), 

 and P. cocoensis, new species. It may be readily distinguished from 

 these forms by its narrower, more produced and less deflexed front. 



