154 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 24 



tubercles, larger and more projecting toward posterior margin, with 

 tufts of long, stiff, non-plumose setae surrounded by clumps of short 

 plumose hairs arising from their bases; posterior margin often with a 

 fringe of long plumose hairs. Manus and fingers of both chelipeds cov- 

 ered with tubercles and hairs similar to those of carpus; granules along 

 outer margins of manus elongate and pointed, forming a serrate edge. 

 Fingers with a row of rounded or pointed tubercles near outer margins, 

 usually in the form of spines ; gaping in major cheliped, meeting for 

 entire length in minor cheliped, gape with short plumose and non-plu- 

 mose hairs. 



All segments of walking legs with long plumose hairs, and a few 

 long, scattered non-plumose setae. 



Telson of abdomen seven-plated in males, five-plated or incompletely 

 seven-plated in females. No pleopods in male. 



Material examined: See Table 48. 



Measurements: Males, 2.4 to 7.3 mm; non-ovigerous females, 2.9 

 to 5.8 mm; ovigerous females, 3.5 to 8.2 mm. The male holotype is 

 7.3 mm in length, 7.7 mm in width. 



Color: Alcoholic specimens are reddish orange, tips of fingers white, 

 setae straw-colored. 



Ecology : Occurs in the intertidal zone, occasionally under stones but 

 more often in coral heads; it has been taken from coral to depths of 4 

 fathoms. Two specimens were recovered from sponge dredged in 1-4 

 fathoms at Acapulco, Mexico. 



Ovigerous females have been collected in January, February, March, 

 and April. 



Relationships: Pachycheles spinidactylus is most closely related to 

 two Atlantic species, P. pilosus (H. Milne Edwards), 1837, from South 

 Carolina, Florida, and the Caribbean area, and P. barbatus A. Milne 

 Edwards, 1878, from west Africa. All three species are distinguished by 

 the presence of long, stiff, non-plumose setae and short plumose hairs 

 on the chelipeds, tubercles on the surface of the carpus, and three or 

 more teeth on the anterior margin of the carpus. The two Atlantic 

 species differ from P. spinidactylus in having a five-plated telson in 

 both sexes. P. pilosus has no tuft of mixed plumose and non-plumose 

 hairs on the front as in P. spinidactylus, but instead has short, non- 

 plumose bristles over the surface of the carapace, more concentrated in 

 the frontal region. In P. barbatus male pleopods are present. 



