OXYSTOMATOUS AND ALLIED CRABS OP AMERICA 7 



Carapace remarkably elongate, but not covering the abdominal 

 terga, the first four or five of which he exposed in the dorsal plane 

 of the body. The last pair of legs also is raised in the dorsal plane 

 of the body. Antennae large; antennules also large, but they do not 

 fold into fossettes. The vasa deferentia protrude through the bases 

 of the fifth pair of legs; the oviducts pierce the basis of the third 

 pair of legs. The sternum is broad anteriorly, very narrow or linear 

 posteriorly. A pair of respiratory orifices between the tergum of the 

 first abdominal segment and the coxae of the last pair of pereiopods. 

 The external maxilHpeds completely cover the buccal cavern, and 

 their palp is concealed in repose; their exopodite is but little longer 

 than the ischium. The branchiae are less than nine in number on 

 either side. (After Alcock.) 



Manus very flat, terminating in a finger so bent that the movable 

 finger is applied against the anterior border of the hand. 



KEY TO THE AMERICAN GENERA OF THE FAMILY RANINIDAE 



A'. Fronto-orbital border more than half width of carapace. 



B'. Orbits of moderate size, slightly oblique, situated on anterior 



border of carapace. Last pair of legs slender Baninoides (p. 7) 



B2. Orbits very large, deep cavities in lower side of carapace, 

 which form a V, with point at rostrum. Last pair of 



legs not unusually slender Ranilia (p. 17) 



A^. Fronto-orbital border less than half width of carapace. 



B'. Carapace smooth. Chelae broad and flat Lyreidus (p. 21) 



B2. Carapace eroded. Chelae elongate, manus swollen, fingers 



long and slender Symethis (p. 24) 



Genus RANINOIDES Milne Edwards 



Raninoides Milne Edwards, Histoire naturelle des Crustac^s, vol. 2, p. 196, 

 1837 [type, R. loevis (Latreille)]. — Alcock, Journ. Asiat. Soc. Bengal, vol. 

 65, p. 292, 1896. 



Carapace elongate-obovate, strongly convex from side to side, 

 often nearly twice as long as broad, its surface for the most part 

 smooth, regions undefined. Fronto-orbital border slightly less than 

 greatest width of carapace. Eyes typically small but distinct, eye- 

 stalks broadly dilated at base, orbits slightly oblique. Antennules 

 about equal in size to antennae; antennae with a stout peduncle and 

 slender flagellum, the peduncle not concealing the antennulary 

 peduncle. Merus of external maxillipeds usually shorter than 

 ischium, its edges slightly thickened and raised. Sternum broad 

 between chelipeds and as far as the bases of the second pair of true 

 legs, then becoming extremely narrow. Last pair of legs abnormally 

 short and slender, arising much in advance of the penultimate pair. 

 Abdomen of both sexes with seven separate segments. (After 

 Alcock.) 



Atlantic and Pacific coasts of America; Indian Ocean; East Indies. 



