THE GEAPSOID CRABS OF AMEBICA. 341 



Chelipeds much more massive than the legs, markedly unequal in 

 the American species, and differing little in the sexes. The larger 

 eheliped alters considerably with age, the arm and fingers becoming 

 elongated, and the whole hand increasing in size until it becomes 

 longer than the carapace is broad and more than half as high as the 

 carapace is long. 



Legs stout; some of their joints are fringed with bristles, and their 

 long strong dactyli are square in section and have a series of spines 

 along all four edges. 



The abdomen in both sexes consists of 7 separate segments and 

 covers the whole width of the sternum between the last pair of legs. 



The branchiae are 8 in number on either side; the gill chambers 

 are vaulted and remarkably capacious, and they are lined by a thick 

 vascular membrane folded to form a sort of pocket, and as in several 

 other crabs — such as Uca and Ocypode — that spend most of their time 

 out of water, a sort of "choroid process" of this membrane, shaped 

 like a gill-plume, projects laterally' over the j>leura of the penulti- 

 mate pair of legs. 



Tropical America, Bermudas, Cape Verde Islands, west coast of 

 Africa, Indo-Pacific from Madagascar to Hawaian Islands and Chile. 



Analogous species on opposite sides of the continent: giuinhumi 

 (Atlantic) ; crassum (Pacific), also on Atlantic side of Isthmus. 



KKY TO THE AJtEltiCA N Sl'ECIES OF THE GENUS CARDISOMA. 



A'. Extrt'iuity ol' aiipenclayes of first abdoininnl segment in male broad aiul 

 Jjlunt. Legs sparsely hairy gunnhnini. p. 341. 



A^ Extremity ()f appendages of first abdominal segment in male with 2 slender 

 processes. Legs very hairy crassum. p. 845. 



CARDISOMA GUANHUMI Latreille. 



GREAT LAND-CKAB; WHITE LAND-CRAB; MULATTO LAND-CRAB; 

 .RIEY (Porto Rico); TOURLOUROU ; GUANHUMI (Brazil). 



Plates 10(5 and 107. 



Granhunii Marcgrave dk Ltebstad, Hist. Tier. Natur. Brazil., 1048, p. 18.5. 



text-fig. ; Brazil. 

 (■ftuf/rejos Terrestrcs Parka, Descripeion de difereutes piezas de Historia 



Natural, Havana, 1787, p. 163, pi. 57. 

 Ocypode riiricola Latreille, Hist. Nat. Crust., vol. 0, 1803, p. 35. not pi. 



24, fig. 2, copied from Herbst. Not Cancer ruricola Linnaeus. 

 Ocypode cordata Latreille, Gen. Crust., vol. 1, 1806, p. 31. Not Cancer 



cordatus Linnaeus. 

 Gecareinus carnifex Latreille, Nouv. Diet. Hist. Nat., vol. 12, 1817. p. 511; 



St. Thomas. Not Cancer carnifex Herbst. 

 Cardisoma guanhumi Latreille, Eucyc. Meth., Hist. Nat., EntouL. vol. 10, 



1825. p. (585 (type-locality, Brazil; type in Paris Mus.). 



