THE GBAPSOID CRABS OF AMERICA. 423 



late; interspace very narrow and regularly diminishing. Prehensile 

 tubercles low and molariform; a prominent submarginal row of 

 granules above and below. Inner surface of palm without oblique 

 transverse ridge ; the subtriangular area forming the lower proximal 

 portion is granulate. 



Merus of first three pairs of legs much enlarged. The third to 

 sixth segments of the abdomen of the male are fused, though vestiges 

 of the sutures remain. 



Measurements. Male, holotype, length of carapace, 6.3; width of 

 same, 10 mm. 



Range. From La Paz, Lower California, to Tumaco, Colombia, 

 oh the frontier of Ecuador (Nobili). 



Material examined. La Paz, Lower California; L. Belding; 1 

 male, holotype (17500). Santo Domingo, Gulf of Dulce, Costa Rica; 

 April, 1896; H. Pittier; 1 male (19442). 



Subfamily MACROPHTHALMINAE Dana. 



Gonoplaces vigils MILNE EDWABDS, Ann. Sci. Nat, ser. 3, Zool., vol. 18, 



1852, p. 155 [119] (part). 

 MacrophtJialmincB DANA, Amer. Journ. Sci., ser. 2, vol. 12, 1851, p. 286 ; U. S. 



Expl. Exped., vol. 13, Crust., pt. 1, 1852, p. 312. AXCOCK, Journ. Asiat, 



Soc. Bengal, vol. 69, 1900, p. 290. 



Carapace usually quadrilateral, broader than long (sometimes 

 more than twice as broad as long), flattish and not very deep, the 

 regions usually well defined; front variable, but never very broad; 

 antennules with a well -developed flagellum that folds transversely, 

 interantennular septum very narrow ; eyestalks usually elongate ; the 

 external maxillipeds do not always meet across the buccal cavern, 

 though the gap between them is never very wide, their exognath is 

 not, or not entirely, concealed and has a flagellum ; chelipeds usually 

 subequal. No special recess between the bases of any of the legs. 



Genus EUPLAX Milne Edwards. 



Euplax MILNE EDWARDS, Ann. Sci. Nat., Zool., ser. 3, vol. 18, 1852, p. 160 



[124] ; type, E. leptophthalmus Milne Edwards. 

 Chaenostoma STIMPSON, Proc. Acad. Nat. Sci. Philadelphia, vol. 10, 1858, 



p. 97 [43] ; type, C. orientate Stimpson, 1858=J5. bosci (Audouin, 1825). 



Carapace not much wider than long; lateral margins dentate. 

 Eyestalks of moderate length, not overreaching the orbital angles, 

 which do not form a prominent tooth. Outer maxillipeds with a 

 rhomboidal gape. 



Distributed through the Indo-Pacific, Australia, and Chile. 



