DECAPOD CRUSTACEANS OF THE WEST INDIES 223 



Dominica Stations: 6, 112 (0-5 ft.). 



Remarks. — The genus currently known as Ucides has consistently 

 been assigned to the family Gecarcinidae since the "Gecarciniens" 

 was proposed by H. Milne Edwards in 1837. It seems to us, however, 

 that it should be transferred to the family Ocypodidae. The typical 

 gecarcinid genera (Cardisoma, Epigrapsus, Gecarcinus, and Gecar- 

 coidea) form a reasonably homogeneous group of species characterized 

 by gaping third maxihipeds and spinose dactyls of the walking legs. 

 In Ucides, on the other hand, the maxillipeds do not gape noticeably 

 and they rather closely resemble those of at least some of the genera 

 of the Ocypodidae; the walking legs in the males bear innumerable 

 fine stiff hairs, somewhat Kke the shorter ones in Ocypode, and the 

 dactyls are unarmed and resemble those of Ocypode and other ocypo- 

 dids; the dactyl of the fifth pereiopod even shows a tendency to 

 recurve as it does in some genera of the Macrophthahninae. The 

 first male pleopods, although seemingly of greater specific than generic 

 or famiUal significance in the grapsoid crabs, are certainly as similar 

 between Ucides and Ocypode as they are between the former and the 

 gecarcinid genera. The only important character that remains to 

 relate Ucides to the typical genera of the Gecarcinidae is the broadly 

 oval, laterally inflated carapace. Dorothy E. Bhss has confirmed our 

 impression that the "profile" of the carapace of semiterrestrial crabs 

 is markedly dependent upon physiological adjustment to environ- 

 mental factors, and we, therefore, believe that the ocypodid char- 

 acters mentioned above are considerably more important systemati- 

 cally than is the shape of the carapace. 



Although Ucides cannot be incorporated into any of the three 

 generally recognized subfamilies of the Ocypodidae as currently de- 

 fined, the two species in the genus, which occur on the Atlantic and 

 Pacific coasts of the Americas, do not seem to be sufiiciently distinct 

 to justify the estabhshment of a fourth subfamily at this time. The 

 genus certainly displays closer afiinity to the genera usually included 

 in the Ocypodinae, particularly to Heloecius, than it does to those 

 included in the Macrophthalminae or the Mictyrinae. The only 

 character, aside from the swollen carapace, that might exclude 

 Ucides from the Ocypodinae is the lack of the conspicuous brush of 

 hairs between the coxae of the third and fourth pereiopods. Although 

 this has heretofore been a convenient diagnostic character of the sub- 

 family, it hardly seems to be sufficiently important to outweigh other 

 considerations. 



