z9^ 



2.9 5' 



Carcinological Fauna of hidia. 283 



The 9 families may be characterized as follows, their compass in 

 relation to the schemes of other authors will be noted in the sequel : — ^. , 



Family Gonoplacid^, Marine Catoraetopes closely resembling ; ^o^ 

 Cyclometopes. The pnlp of the external maxillipeds articulates at or 

 near the antero-iuternal angle of the merus, never at the antero-external 

 angle or at the middle of the anterior border : the exognath of the external 

 maxillipeds is of normal size and is not concealed. The interantennular 

 septum is a thin plate. The division of the orbit into two fossae is not 

 accented. 



Family Grapsid^, Littoral (rock-haunting), or pelagic (drift-weed 

 and timber-haunting), or estuarine and paludine, or fluviatile, or rarely 

 terrene Catometopes. The palp of the external maxillipeds articulates 

 either at the antero-external angle, or at the summit, or at the middle 

 of the anterior border of the merus : the exognath is either abnormally 

 slender or abnormally broad. The interantennular septum is very broad. 

 The division of the orbit into two fossae is accented. [Front of great 

 breadth : carapace usually quadrilateral, -with the lateral borders either 

 straight or very slightly arched, and the orbits at or very near the 

 antero-lateral angles : the buccal cavern is square and there is generally 

 a gap, -which is often large and rhomboidal, between the external 

 maxillipeds]. Male openings sternal. 



Family Geocakcinidj:. Terrene Catometopes (Land-crabs). The P*'V/ 

 palp of the external maxillipeds articulates either at the antero-external 

 angle or at the middle of the anterior border of the merus (but is 

 sometimes, though never in any Indian species, completely hidden 

 behind the merus) : the exognath is slender and inconspicuous (some- 

 times more or less concealed) and sometimes carries no flagellum. 

 The interantennular septum is very broad and the antennular fossae 

 are narrow. The front is of moderate breadth and always strongly 

 deflexed : the carapace is more or less transversely oval, the antero- 

 lateral borders being strongly arched and the fronto-orbital border being 

 very much less than the greatest breadth of the carapace. In all the 

 Indian forms there is a wide rhomboidal gap between the external 

 maxillipeds, Male openings sternal. 



Family Ocxpodid^, Amphibious littoral and estuarine crabs, 

 burrowing, and commonly gregarious. The palp of the external maxil- 

 lipeds is coai'se, and articulates at or near the antero-external angle of 

 the merus : the exognath is generally slender and often mox'e or less 

 concealed. The interantennular septum is generally broad, but in one 



625 



