DECAPOD CRUSTACEANS OF THE WEST INDIES 179 



striate laterally, obscurely granulate anteriorly; lateral margins 

 subparallel, without tooth posterior to outer orbital angle, fronto- 

 orbital distance nearly equalling maximum width of carapace; front 

 abruptly deflexed at postfrontal lobes, slightly more than half as 

 wide as carapace, margin with shallow median sinus, faintly quad- 

 rilobate in dorsal view. Eyes well developed, cornea slightly wider 

 than eyestalk. True ventral margin of orbit largely replaced by 

 nearly straight hairy granulate ridge accentuated posteriorly by 

 rather deep groove, mesial end of ridge not curving to anterolateral 

 angle of mouth area. Third maxillipeds with oblique hairy ridge on 

 merus, gaping widely, exposing mandibles. Chelipeds subequal, carpus 

 unarmed, minutely denticulate on flexor margin; palm granulate 

 with low dorsal ridge in proximal half; fingers pointed, very narrowly 

 spoon tipped, movable finger minutely tuberculate on extensor 

 margin. Walking legs flat, not very broad, merus of third pereiopod 

 one-third as wide as long, with sharp subdistal tooth on extensor 

 margin; dactyl about four-fifths as long as extensor margin of prop- 

 odus. Denuded first pleopod of male terminating in posterior view 

 in short blunt endpiece partially recessed in broad end of appendage 

 and directed anteromesially (fig. 62a). A medium-sized species, 

 maximum carapace length in midline about 16 mm. 



Habitat. — Muddy river banks. 



Distribution. — Saint Thomas and Tampico, Mexico. 



Remarks. — Comparison of the first pleopod of a male syntype of 

 Sesarma americanum (figs. 62a-c), very kindly made available to us 

 by Dr. H. Gisin of the Museum d'Histoire Naturelle in Geneve, 

 Switzerland, with that of a male paratype of S. tampicense (figs, 

 Q2d-f) indicates that the former species is a senior synonym of the 

 latter and probably not a junior synonym of S. angustipes, as sug- 

 gested by Rathbun (1918). 



69. Sesarma (Holometopus) hanseni Rathbun 



Sesarma (Holometopus) hanseni Rathbun, 1897a, p. 92 [type-localitj^ : "West 

 Indies"]; 1918, p. 315, text-fig. 152, pi. 87: fig. 1. 



Diagnosis. — Carapace subrectangular, about four-fifths as long 

 as wide, surface smooth, punctate; lateral margins converging slightly 

 posteriorly, without tooth posterior to outer orbital angle, fronto- 

 orbital distance nearly equaling maximum width of carapace; front 

 abruptly deflexed at postfrontal lobes, nearly three-fifths as wide 

 as carapace, margin with very shallow median sinus, faintly quad- 

 rilobate in dorsal view. Eyes well developed. Thu"d maxillipeds with 

 oblique hairy ridge on merus, gaping widely, exposing mandibles. 

 Chelipeds subequal; palm bearing thin denticulate crest. Walking legs 



