10 ALLAN HANCOCK ATLANTIC EXPEDITION REPORT 



Chelipeds robust, unequal, devoid of hairs. Merus rugose on dorsal 

 and smooth on ventral surface; a projection on distal half of anterior 

 margin, covered with rough granules. Carpus covered on dorsal surface 

 with coarse granules, which are larger toward outer margin; nearly 

 smooth on ventral surface; anterior margin thin and raised into a crest, 

 along which is a row of about five to eight pointed or rounded teeth, the 

 proximal ones crowded closer together. Manus of major cheliped thick, 

 heavy, without a crest on outer margin ; completely and evenly covered 

 with large, coarse granules, which are more flattened on the ventral 

 surface; fixed dactyl with about four large, low teeth on cutting edge, 

 the proximal one the largest; movable dactyl with a large projecting 

 tooth at proximal end of cutting edge, followed by about four low teeth. 

 Manus of minor cheliped without a crest on outer margin ; completely 

 and evenly covered with coarse granules, smaller than those on manus 

 of major cheliped; granules more flattened on ventral surface; dactyls 

 with tips crossing; cutting edge of movable dactyl with a large, pro- 

 jecting tooth followed by a row of about six to nine low teeth, finely 

 serrate on edges ; cutting edges of fixed dactyl with a row of about nine 

 similar teeth. 



Walking legs very faintly rugose, almost devoid of hairs. Lower 

 surface of propodus with three small spines at distal and one near prox- 

 imal end. Lower surface of dactyl with a row of three small spines. 



Telson of abdomen with five plates. 



Remarks. — Schmitt (1935) included Cartagena, Colombia, among 

 known localities for Pachycheles serratus (Benedict). This record was 

 based on material of P. chacei in the U. S. National Museum ; the 

 specimens were examined by the writer and are here designated para- 

 types. 



Pachycheles chacei is similar in general appearance to only tvvo other 

 western north Atlantic porcellanids, Pisosoina angustifrons Benedict and 

 Pachycheles serratus (Benedict). From Pisosoma angustifrons it may be 

 distinguished immediately by the generic character of the divided side 

 walls of the carapace. It is close to Pachycheles serratus but differs in 

 several respects: there are five plates in the telson of the abdomen, in- 

 stead of seven ; the orbits are somewhat shallower and less rounded than 

 in P. serratus, and the front is narrower in proportion to the carapace 

 width ; the carapace is devoid of hairs, whereas in P. serratus it is 

 sparsely hairy, especially on the frontal region; the chelipeds are also 

 devoid of hairs, instead of being sparsely or thickly hairj^- the teeth on 

 the anterior margin of the carpus are not divided by three notches into 



