74 Guide to Crustacea. 



Table-case are almost entirely terrestrial in habits. The carapace is more or 

 No. 16. jggg transversely oval, and the front is of moderate breadth. The 

 branchial regions of the carapace are generally swollen, and the 

 lining membrane of the gill-chamber is richly supplied with blood- 

 vessels, and acts as a lung. Typical genera are Geocarcinns, Car- 

 diso))i((, and Uca. 



The Crabs of the family Cirapsidac are the most typical Cato- 

 nietopa. The carapace is nearly quadrilateral, with the front very 

 broad, and the orbits near the antero-lateral corners. Many 

 species are estuarine or fluviatile in habitat. The species of 

 GrapsHs and allied genera are common shore Crabs in all the 

 warmer seas. 



Tlic genus Sesaruia and its allies include, for the most part, 

 amphibious fresh-water Crabs, abundant in the tropical regions of 

 the Old and New Worlds. 



Varuna littcrata is widely distributed throughout the Indo- 

 Pacific region, and seems to be equally at home in freshwater and 

 in the sea. It is often found clinging to drift-wood at the surface 

 of the sea. 



The little Planes mi nut us also lives at the surface of the open 

 sea, clinging to floating weed or drift-wood, or to the bodies of 

 large marine animals such as turtles. It is especially abundant 

 in the Sargasso Sea, but is widely distril)uted in the warmer regions 

 of all the oceans, and is occasionally carried to the South and West 

 coasts of the British Islands. It is related of this species that 

 " Columbus, finding this alive on the Sargasso floating in the sea, 

 conceived himself not far from some land, on the first voyage he 

 made on the discovery of the West Indies " (Sloane, Nat. Hist. 

 Jamaica, ii. p. 2). 



In the family Ocypodiclac the front is generally narrow and the 

 eye-stalks are often very long. Most of the species are amphibious 

 shore Crabs, burrowing and often gregarious in their habits. 

 Several species of the typical genus Ocijpoda are exhibited. 



The species of Gclasimns, often called "Fiddler Crabs" or 

 " Calling Crabs," are common on most tropical shores, living in 

 vast numbers in salt marshes or between tide-marks, wdiere they 

 make Imrrows in the sand or mud. A group of specimens of two 

 species is mounted in Wall-case No. 5. The genus is of interest 

 ■ as exhibiting in an extreme degree two characters which are more 

 or less marked in nearly all Crabs — the unequal development of 

 the chelae or pincers on the two sides of the liody, and their 

 greater size in the male sex. The large, brightly coloured claws 



