SOUTHWELL— ANOMURA 107 



might be initiated, even though some of the genera are certainly very nearly related. 

 The descriptions given of many species of Porcellana are much too short to be of 

 any real value, and render the work of identification not only unsatisfactory, but 

 almost impossible. No doubt, however, much of the difficulty referred to above 

 has been due to the difficulty of access to necessary literature. 



During the examination of this Kutch collection I have had the inestimable 

 advantage of being so situated that by far the most of the species recorded in this 

 paper have been accessible to me in quantity, and in a living condition, from the 

 Ceylon Pearl Banks. 



No fact has struck me so forcibly during the examination of this collection, as 

 the extent of the variation characteristic of many species. Some species within a 

 genus may be distinguished as being more stable than others. Spines are particularly 

 liable to variation ; so, in less degree, are colour markings. Many of these variations 

 are noted in the text. This fact serves to indicate how inaccurate may be descriptions 

 of new species made from a very few specimens — and possibly young forms. 



I cannot close without expressing my indebtedness to Mr. Horn ell for his help 

 in many ways, for placing this collection in my hands, and for providing opportunities 

 for studying fresh material under conditions in which it was a pleasure to work. 



ANOMURA. 



PAGUEIDES. 



Family : Pagtteid^. 



Pagueid^ : Dana (7), Stimpson (34), Henderson (19), Stebbing (33), Ortmann 

 (29), Bouvier (6), Milne-Edwards and Bouvier (10), Alcock (2). 

 Paguroid^ : Boas (5). 

 Parapagdrid^ : Smith (31), Henderson (19), Stebbing (33). 



Diogenes, Dana. 



Dana (7), Stimpson (34), Heller (16), Haswell (14), Henderson (19), Stebbing 

 (33), Ortmann (29). 



This genus is confined to shallow water, and is characteristically Indo-Pacific. 

 There are about thirty species, three of which occur along the shores of the Atlantic, 

 one in the Mediterranean (solely), and the rest are purely Indo-Pacific. Many of the 

 species are small and very variable. The outstanding features which characterise the 

 genus are as follows : — 



