204 U.S. NATIONAL MUSEUM BULLETIN 292 



Note: Not included in preceding key Is Uca maracoani (Latreille, 1802-1803), which Is confined chiefly to 

 the South American mainland from Venezuela to Rio de Janeiro. Crane (1958) records this species from 

 Cocorite Swamp on the Trinidad coast of the Qulf of Paria, only a few miles from the shores of Venezuela. 



Genus Ocypode 



83. Ocypode quadrata (Fabricius) 

 FiGUBES 68, 69 



Cancer quadratus Fabricius, 1787, p. 315 [type-locality: Jamaica]. — Hemming, 



1954, pp. 297-327. 

 Ocypode quadrata. — Fabricius, 1798, p. 347. — Chace, 1956, p. 159. — Holthuis 



1959, p. 259, pi. 9: fig. 3. 

 Ocypoda albicans Bosc, 1801-02, p. 196 [type-locality: "la Caroline"]. 

 Ocypode albicans. — Latreille, 1802, p. 48. — Rathbun, 1918, p. 367, pis. 127, 128. 

 Ocypode arenarius Say, 1817, p. 69 [type-locality: United States]. 

 Monolepis inermis Say, 1817, p. 157 [type-locality: eastern shore of Maryland]. 

 Ocypoda arenaria. — H. Milne Edwards, 1837, p. 44, pi. 19: figs. 13, 14. 



Diagnosis. — Carapace subrectangular, nearly nine-tenths as long 

 as wide in adults, strongly convex longitudinally, nearly semicircular 

 in midline, surface granular, without pubescence; fronto-orbital 

 distance slightly less than maximum carapace width in adults; front 

 very narrow, subspatulate, width between posterodistal angles of 

 basal segments of eyestalks, with eyes retracted, about one-fourth of 

 fronto-orbital distance; lateral marginal ridges converging slightly 

 in posterior two-thirds. Cornea markedly swollen, occupying con- 

 siderably more than half of extensor surface of distal segment of eyestalk. 

 Chelipeds distinctly dissimilar and unequal in both sexes; fingers of 

 major chela shorter than palm, spinose. Second, third, and fourth 

 pereiopods bearing rather long, silky, erect hairs, especially numerous 

 on extensor and flexor margins of carpus and propodus. Hair-frmged 

 ventral opening present between coxae of third and fourth pereiopods. 

 Denuded first pleopod of male terminating, in posterior view, in sharply 

 recurved blunt tip directed proximolaterally (fig. 69a). A fairly large 

 species, maximum carapace length in midline about 45 mm. 



Color in life, — There are apparently two color phases of Ocypode 

 guadrata on Dominica. The familiar off-white phase frequents the 

 beaches on which there is light-colored sand, but on the black beaches 

 a brown phase exists. A male of the latter was transfered first to a 

 white background and allowed to remain on it for tliree days in antici- 

 pation of its altering its dark color. When it failed to change its color- 

 ation or pattern, a blue background was substituted but with the 

 same result. In view of the positive indication of color change obtained 

 by Green (1964) from his study of light and dark populations of 

 Ocypode ceratophthalma in Hawaii, it is very possible that more ex- 

 tensive investigation of 0. quadrata might yield similar results. 



