COMPLETE HAIG : EASTERN PACIFIC PORCELLANIDAE 87 



Walking legs finely granular. Merus unarmed, with a short fringe 

 of plumose hairs on anterior margin, that of leg 3 inflated ; carpus 

 naked or with traces of setae, and with a longitudinal crest on dorsal 

 surface; propodus and dactylus with tufts of setae. 



Variations: In some specimens the lobe on the anterior margin of 

 the carpus is less produced than in others, but it always extends for 

 about two-thirds the length of the margin. 



As noted above, occasional specimens show a tendency toward a tri- 

 lobate front. They are not otherwise separable from those in which the 

 inner orbital angles are not produced, and it is not proposed at this 

 time to separate them on this basis alone. 



Measurements: Holotype male: length 10.2 mm, width 10.2 mm. 

 Paratypes: males, 2.9 to 11.6 mm; non-ovigerous females, 3.5 to 8.8 

 mm; ovigerous females, 3.8 to 8.7 mm. 



Color: After more than twenty years in alcohol, a few specimens 

 show a dark blue-violet on the metabranchial regions of the carapace, 

 ringed by a darker line of the same color; this shade of blue is also 

 present on the eyestalks, movable segments of the antennae, walking 

 legs, telson of the abdomen, and palps of the maxillipeds. This suggests 

 that in life the color of Petrolisthes tonsorius may resemble that of P. 

 violaceus (Guerin). In a few specimens there are faint traces suggest- 

 ing blotches or stripes on the fingers. 



Ecology: Most of the material examined was collected under stones 

 in the littoral. William Beebe on the Arcturus Expedition recovered 

 it from a coral rock bottom in 2^ fathoms, and the Velero III 

 dredged it from a sand and shell bottom in 10 fathoms. 



Ovigerous females were collected in January, February, and March. 



Relationships: Petrolisthes tonsorius is extremely close to P. quad- 

 ratus Benedict, 1901, a Caribbean species. P. quadratus has been recog- 

 nized but a few times and has never been thoroughly described, and the 

 types are apparently not extant. From the small sample available to the 

 writer it appears that the outer orbital angle and the front are a little 

 less produced than in P. tonsorius. There is a strong possibility, how- 

 ever, that comparison of the two populations from adequate samples 

 of each will show them to be conspecific. 



Remarks: Six specimens from Isla Hood, Galapagos Islands, were 

 reported by Boone (1932) as Petrolisthes cinctipes (Randall); her 

 description and accompanying illustration identify them with the pres- 



