272 A. Alcock — Carcinological Fauna of India. [No. 2, 



Ixa megaspis, Adams and White, ' Samarang' Crust, p. 55, pi. xii. fig. 1 : Miers, 

 'Challenger' Brachyura p. 301 (var. of cylindrus). 



Carapace covered with vesiculous gi^anules between which it is 

 smooth and polished, and there are some largish smooth patches on the 

 branchial regions : tlie channels of the carapace are deep and very well 

 defined, with undermining edges, and have the floor more or less coated 

 with pubescence : the huge cylindrical lateral processes are of almost 

 the same diameter at their distal end as at their base, and their rounded 

 end is abruptly surmounted by a spine : the distance between the edge 

 of the raised plane of the gastric region and the free edge of the front 

 is nearly equal to the anterior breadth of the front : the ends of the 

 posterior margin are a little thickened and prominent, but are hardly 

 dentiform even in the young. 



The buccal cavern, though truncated, has a distinctly triangular 

 shape : the exognath, when denuded of its distal pubescence, is found 

 to have a smooth and longitudinally concave surface, the concavity 

 falling along the inner border ; and is seen to fall short of the raised 

 anterior edge of the afferent branchial channel by a mean distance 

 equal to nearly half the length of the merus : the raised outer border 

 of the ischium has a narrow band of vesiculous granules, wanting at 

 the basal end. 



Four males and four females (three adult) are in the Indian 

 Museum collection from the Andamans, and from the Madras coast in 

 the neighbourhood of Palk Straits. 



The largest female has the carapace 20 millim. long by 60 millim. 

 in extreme breadth. 



96. ? Ixa inermis, Leach. 



Ixa inermis, Leach, Zool. Miscell. III. p. 26, pi. 129, fig. 2 : Desniarest Consid. 

 Crust, p. 171 : Milne Edwards, Hist. Nat. Crust. II. 135 : Haswell, P. L. S., N. S. 

 Wales, IV. 1879, p. 59, and Cat. Austral. Crust, p. 132. 



Carapace covered with vesiculous granules between which it is dis- 

 tinctly rough : the channels of the carapace are merely grooves, and are 

 devoid of pubescence : the lateral processes are curved forwards, and 

 taper gradually to a point : the distance between the gastric region 

 (no part of which region has the form of a definitely raised plane) and 

 the free edge of the sharply bidentate front is much less than the 

 anterior breadth of the front : there is a large granular petaloid tuber- 

 cle at either end of the posterior margin. 



The buccal cavern is distinctly quadrangular, owing to the eversion 

 of the outer lip of the afferent branchial channel : the exognath in its 

 basal three-fourths is very strongly convex, the surface of the convexity 



