THE GBAPSOID CRABS OF AMEEICA. 25 



Genus GONEPLAX Leach. 



Goneplax LEACH, Edinburgh Encyc., vol. 7, 1814, pp. 393 arid 430; type, 

 Ocypode bispinosa Lamarck, lS01=C'ancer rhomboidcs Linnaeus, 1758 

 (on p. 393, spelled " Goneplat " by typographical error) ; Trans. Linn. 

 Soc. London, vol. 11, 1815, pp. 309 and 323; Nouv. Diet. Sci. Nat, vol. 

 13, 1817, p. 295. 



Gonoplax LEACH, Encyc. Brit., Suppl. to 4th, 5th, and 6th ed., vol. 1, 1816, 

 p. 413 ; Malac. Pod. Brit., 1816, pi. 13, and explanation of plate. 



FreviUca A. MILNE EDWARDS, Bull. Mus. Comp. Zool., vol. 8, 1880, p. 15; 

 type, F, barbata A. Milne Edwards. 



Carapace subquadrilateral, with the antero-lateral angles acute and 

 the lateral borders posteriorly convergent, a good deal broader than 

 long, moderately convex, regions faintly indicated. 



The front and orbits occupy the whole anterior border of the 

 carapace; front square cut, laminar, obliquely deflexed, occupying 

 from a fourth to a third of the anterior border of the carapace, the 

 rest being occupied by the trenchlike orbits. 



Eyestalks typically long and slender, but sometimes strongly en- 

 larged at the cornea ; the antennules fold transversely ; the antennae 

 have a short basal joint and a slender flagellum of good length, stand- 

 ing in the orbital hiatus. 



Buccal cavity square or anteriorly widened, well separated from 

 the prominent epistome ; efferent branchial channels not well defined. 

 The merus of the outer maxillipeds is square and bears the palp at 

 the antero-internal angle. 



Chelipeds in both sexes much more massive than the legs, which 

 are long and slender. 



The abdomen in both sexes consists of 7 separate segments ; in the 

 male the third segment either covers or nearly covers the sternum 

 between the last pair of legs. 



Distributed along the east coast of America from Gulf of Mexico 

 to Rio de Janeiro ; in the northeast Atlantic and Mediterranean ; and 

 in the Indo-Pacific from the Persian Gulf to Japan. 



KEY TO THE AMERICAN SPECIES OB 1 THE GENUS GONEPLAX. 



A 1 . Carapace with 2 lateral teeth or spines. 



B 1 . Sides of carapace strongly convergent posteriorly. 



C 1 . Notch in upper margin of orbit. Oblique ridge on branchial region. 



barbata, p. 26. 

 C 2 . No notch in upper margin of orbit. No oblique ridge on branchial 



region sigsbci, p. 26. 



B 2 . Sides of carapace almost parallel. 



C 1 . A tuberculiform swelling on margin of carapace between exorbital tooth 



and next lateral tooth rosaea, p. 27. 



C*. No tuberculiform swelling on margin of carapace between exorbital 



tooth and next lateral tooth hirsuta, p. 28. 



A*. Carapace with 3 lateral teeth or spines tridentata, p. 29. 



