GECARCINIDAE. 



The Gecarcinidae are the true land-crabs, which are mostly characterized by a very 

 thick cephalothorax, with inflated branchial regions, the lateral margins are not defined and 

 keeled only behind the little projecting external orbital angles, the pterygostomial regions are 

 thickly hairy; the orbits are small, the carapace is much vaulted in a longitudinal sense, 

 especially anteriorly, with the reg^ions scarcely or not at all indicated, the penultimate segment 

 of the abdomen of the cf is much longer than the preceding, and the dactyli of the walking 

 legs are long, slender and spinous. 



The species are scarcely observed to go ever into the water (though the young are probably 

 hatched out in the sea), but spend their lives in hiding during the day among grass, stones, 

 fallen trunks etc., rambling about in the night. Pearse ^), who studied with so much success 

 the life of the fiddler crabs {Uca = Gelasimus), also gave us a pretty account of the habits 

 of Caf'disoma [C. guanliumi Latreille). Like Uca it lives on the same mud-flats, and likewise 

 digs burrows, but in digging it makes largely use of its great claws and not of the walking legs. 

 The largely-inflated branchial cavities are lined internally with a thick vascularized membrane, 

 that enables the animal to directly breathing the air, but the same occurs in some species of 

 Sesanna, that even climb trees, and in Geograpsns. The hairs of the pterygostomial regions 

 retain water a long time, that is continuously o.Kidized by the air. 



The carapace is generally of a bluish, violet or reddish colour, sometimes mottled by 

 yellow patches; the legs are mostly of the latter hue, and the chelipeds are scarlet-red. 



The four Indo-Pacific genera, Cardisonia^ Gccarcoidea, Epigrapsus and Grapsodes are 

 readily to be distinguished by the key of Alcock -). 



Epigrapsus Heller. 



1862. Epigrapsus Heller. Verb, zool.-bot. Ges. Wien, Bd 12, p. 522. 

 1865. Nectograpsns Heller. Reise '■Novara", Crust., p. 56. 

 1865. Grapsodes Heller. Reise "Novara", Crust., p. 58. 



Epigrapsus and h> cctograpsus are identical, being based on the same species. As to 

 Grapsodes, it has been treated of as an independent genus, but I agree with Alcock that it 



1) Proc. U.S. Nat. Mus., v. 49, 1915, p. 553—554. See also Ortmann (Zool. khib., Syst., Bd 10, 1897, p. 338— 340), Gravilr 

 (Bull. Mus. Paris, t. 12, 1906, p. 498) and Gardiner (Transact. Linn. Soc. London (2) v. 12, 1907, p. 47), 



2) Journ. As. Soc. Bengal, v. 69, prt 2, 1900, p. 440—441. The author, following Miers, writes: Geocaicinidae and Caiuiiosoma, 

 which is undoubtedly right from an orthographical point of view, but the genus that gaves the name to the family has been spelled 

 Gecarcimis by Leach, and Latreille writes Cardisoma. 



