42 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 24 



First movable segment of antenna with a lamellar lobe, finely dentic- 

 ulate on its margin and bearing a single spine; second granulate; third 

 nearly smooth ; flagellum naked. Outer maxillipeds rugose. 



Merus of chelipeds rugose, armed on anterior margin with a large 

 spine-tipped tooth. Carpus about one and a half times as long as wide, 

 armed on anterior margin with four or five broad teeth, denticulate 

 on their margins; surface covered with short, flattened rugae forming 

 oblique longitudinal rows; no median longitudinal crest. Manus and 

 fingers with similar rugae tending to break up into flattened granules 

 on outer half of manus, and extending obliquely on inner half; outer 

 margin of manus with a row of spines and with scattered plumose and 

 non-plumose hairs. Outer margin of pollex with a row of rough gran- 

 ules; dactylus with a forward-pointing distal spine on outer margin, 

 giving it a bifid-tipped appearance; gape with a short thick pubescence. 



Walking legs rugose, all segments with setae; anterior margin of 

 merus with one or two distal spines ; merus of leg 1 with a posterodistal 

 spine, that of leg 2 unspined at posterodistal angle. 



Abdomen and ventral surface of chelipeds and walking legs without 

 distinct striations. 



Material examined: See Table 8. 



Measurements: Males, 2.2 to 6.0 mm; non-ovigerous females, 2.7 to 

 4.5 mm; ovigerous females, 2.8 to 5.8 mm. The male holotype measures 

 5.0 mm in length, 4.8 mm in breadth. 



Color: "[In alcohol] this beautiful little crab has the appearance of 

 being embroidered in colored silks, somewhat similar in effect to the 

 Peking stitch; the plications are an orange-red, laterally merging into 

 a yellow on the median line; the subcardiac whorls, protogastric and 

 frontal ridges are a deep red. The under side of the chelipeds is a bril- 

 liant carmine, mottled with white. The propodi of the ambulatories are 

 distally banded with mottled carmine. The median line of the abdomen 

 is paralleled with red chromatophores, blending into orange. The hands 

 give the impression of being banded with orange and white." (Glas- 

 sell, 1937) 



Ecology: Petrolisthes polymitus has been taken in the littoral under 

 stones, and in corals to a depth of 2.5 fathoms. It was dredged on one 

 occasion by the Velero III from a sand bottom in 4 fathoms, and taken 

 in abundance from sponge dredged at 1-4 fathoms. 



Ovigerous females have been collected in December, January, Feb- 

 ruary, and March. 



