THE CRAB. 97 



into a beak, the ei)istoma (or i)art of the head between the 

 antenna? and mouth) very large and nearly square. This 

 family comprises three tribes, Macropodiens, Maiens, and 

 Parthenopiens. 



The Cyclometopa (or Canceridce, Portunidce, and Pilumnidm 

 Leach), have the shell very large, regularly curved in front 

 and narrowed behind ; the legs are of moderate length ; the 

 epistoma is very short, and much wider than long. The ab- 

 domen of the male occupies all the space between the hind 

 legs. This family comprises two tribes, the Canceriens and 

 the Portuniens J the former comprising three sub-tribes, 

 the Cryptopodes, Arques, and Quadrila teres. The type is 

 the common echble crab {Cancer Pagurus). 



The Catometopa {Ocypodia da Leach), have the shell qua- 

 drilateral or ovoid, with the front transverse and knotted ; 

 the epistoma very short ; the abdomen of the male not occu- 

 pying the space between the hind legs. The common pea- 

 crab {Pinnotheres Pisum) is an example of this order. 



The Oxy stoma { Corystidice and Leucosiadce Leach) have 

 the shell orbicular and arched in front, which is not produced 

 into a point. The epistoma is obsolete. This order com- 

 prises the stone-crabs. 



The animals belonging to the decapod Brachyura are 

 known under the common English name of Crabs, and to 

 which, in the Linnaean system, the name of Cancer was ap- 

 })lied. The term, however, is not exactly synonymous with 

 the latter name, as the lobster, cray-fish, shrimp, prawn, &c., 

 formed portions of the Linnaean genus. Since the time of 

 Liunseus, however, the study of these animals has greatly 

 increased, so that the animals known now by the ordinary 

 name of crabs compose the sub-order Brachyura, whilst 

 the Macroura comprise the other species above mentioned ; 

 but still, as if to show the total disagreement of the ordinary 



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