116 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL.24 



two-thirds of anterior margin with three or four teeth, all but the dis- 

 tal one wholly or partially coalesced ; manus with two strong dorsal 

 crests and a third along outer margin ; merus of walking legs unarmed. 



Description : Carapace subquadrate, nearly smooth, with grooves 

 defining the anterior regions distinct, as in Petrolisthes I. lewisi. 

 Front, orbits, and antennae as in the typical form. 



Merus of chelipeds as in the typical form. Carpus with a similar 

 length-width ratio ; teeth on anterior margin not well separated, as in 

 Petrolisthes I. lewisi, but the proximal two or three partially coalesced, 

 or completely joined to form a narrow, strongly projecting lobe or broad 

 tooth, followed by a smaller, separated distal tooth ; dorsal and poster- 

 ior crests usually exactly as in typical form, but the oblique granules 

 sometimes low and partially obscured, the crests then appearing some- 

 what smooth. Manus with crests as in typical form, dorsal ones some- 

 times low, smooth, in latter case the groove between them somewhat 

 obscured ; distinct groove near outer margin always present, defining 

 the heavy, smooth outer marginal crest. Gape of fingers with a short 

 pubescence. Chelipeds devoid of hairs except for occasional traces near 

 posterior margin of carpus. 



Walking legs as in Petrolisthes I. lewisi. 



Measurements: Holotype male: length 4.7 mm, width 4.7 mm. 

 Paratypes: males, 3.1 to 6.4 mm; non-ovigerous females, 3.5 to 4.7 

 mm; ovigerous females, 2.9 to 6.3 mm. 



Color: No color remains on any of the preserved material exam- 

 ined, except for traces of reddish stripes on the fingers as in the typical 

 form. These stripes were present in only a few specimens. 



Ecology: As in the typical subspecies, Petrolisthes lewisi austrinus 

 occurs under stones in the intertidal zone. There is no record of its 

 association with corals. As previously noted by the writer (Haig, 

 1957b), the Askoy record of a single specimen from mud bottom in 

 24-64 meters (13-15 fathoms) was probably an error. 



Ovigerous females were collected in January, February, March, 

 September, and December. 



Remarks: The structure of the carpal teeth, which are separated 

 in Petrolisthes lewisi lewisi and coalesced in P. I. austrinus, was a con- 

 stant character in all the specimens examined. 



The two specimens from Isla Flamenco, Panama, referred by No- 

 bili (1901b) to Petrolisthes sinuimanus, were seen by the writer and 



