INTF<ODUCTION. 



This volume is the Second, hut an independent, Part of a monograph 

 of the Decapod Crustacea of that part of the Oriental Region that lies 

 within the poHtical boundaries of British India : it treats exclusively of the 

 Section Pa^uridea of the Sub-order Anomala or Anomura. 



In my Catalogue of Deep-Sea Crustacea in the Indian Museum, I have already 

 (p. 204) explained that the Sub-order Anomala of this series of catalogues 

 is that of De Haan and Boas (= Anomoura Schizostomi of Stimpson), and 

 iiave (pp. 206 — 3o8) sufficiently defined the sub-order ; and in the Introduc- 

 tion to the series (Part I. Fasciculus i, pp. 13—15) the scheme of classi- 

 fication of the Decapoda here adopted has been re-stated and tabulated. 



It is enough, therefore, for my present purpose, to repeat that the 

 Anomala or Anomura are divided by Boas into three very natural groups, 

 namely, Paguroidce . Galatheidcs, and Hippidcs. 



The present fascicle deals with the first of these — the PaguroidcB, or 

 Pagundea, a group which includes four families, namely, Pylochelidce, Paguridce, 

 Ccenobitidce, and Lithodidcs ; but as the Indian Lithodidae are entirely deep- 

 sea forms, and have already been described in the Catalogue of Deep-Sea 

 Crustacea, they will not be further noticed in the systematic part, 



General Observations on the Paguridea. 

 1. The Form of the Body. 



In the Lithodidae the body is superficially crab-like. In the other three 

 families the carapace does not cover the last thoracic segment, which, as 

 usual, is independent and freely movable ; often also it fails to cover the 

 ophthalmic somite : it is commonly elongate, retracted anteriorly, where its 

 sidewalls are deep and nearly perpendicular ; and more or less expanded 

 posteriorly, where its sidewalls may be abrupt, but more often form an 

 open curve with the dorsal surface : the dorsal portion of the region in 

 front of the well-marked cervical groove is its most strongly calcified part, 

 the lateral and especially the postero-lateral regions being often merely 

 coriaceous or even membranaceous. 



