304 Memoirs of the Indian Museum. [Vol. V, 



at the base of the immobile finger. Near the upper edge of the palm, as in ^. cras- 

 simanus and allied species, are two depressions, one on the inner surface and one on 

 the outer : that on the inner surface is triangular in shape and that on the outer 

 more or less quadrangular. These depressions are united by the transverse groove at 

 the base of the dactylus. The inner surface of the palm, as in .4. crassimanus, bears 

 in its lower half a sharp transverse ridge near the base of the immobile finger ; this 

 ridge runs towards the prominence terminating the lower margin, but is separated 

 from it b}^ a longitudinal, infero-internal groove which extends backwards for almost 

 the entire length of the palm. There is also another ridge, transverse in direction, 

 which crosses the middle of the inner surface of the palm; it is bounded proximally 

 by a curved groove which runs to the carpal articulation and between it and the 

 more anterior transverse groove at the base of the immobile finger is a large shallow 

 depression. These ridges and grooves on the inner surface of the palm appear to be 

 characteristic of the species. Characteristic also is a very fine granulation on the 

 inner side of the immobile and fixed fingers; the surface of the former is evenly 

 rounded, but bears a short though conspicuous carina near the finger-tip. The outer 

 surface of the chela more nearly resembles that of A. crassimanus ; there is a broad 

 shallow groove on the fixed finger and a feeble depression proximal to the transverse 

 ridge which terminates on the marginal prominence at the end of the lower edge of 

 the palm. In external view the inner margin of the fixed finger is prominently angled 

 just in advance of the socket for the great tooth of the dactylus ; near the apex the 

 inner margin of the movable finger is decidedly sinuous. The fingers open somewhat 

 obliquely, that is to say, in a plane different from that of the outer surface of the 

 palm. The large chela of the female is proportionately a trifle broader than in the 

 male, but has a closely similar structure. 



As in most species of the edwardsi group the dactylus of the small chela is, in 

 the male, subspatulate in form, " Balaeniceps-shaped," whereas in the female it is 

 slender. In the male (text-fig. -^^h) the small chela is nearly five times as long as 

 broad and the fingers are about equal in length with the palm. On the upper edge 

 of the latter there is a transverse groove behind the insertion of the dactylus and in 

 lateral view the margin is consequently notched ; there is a similar notch, rather less 

 conspicuous, on the lower edge near the base of the fixed finger. On either side of 

 the upper edge is a triangular depression reaching backwards to the middle of the 

 palm and on the infero-internal aspect another longitudinal groove which extends 

 almost the whole length. The palm is quite smooth, without the granulations found 

 in A. cnphrosync. The greatest breadth of the dactylus is about one-third its total 

 length. On its upper surface at the proximal end are two low crests, short, distally 

 convergent and bearing a few setae. A sharp keel runs the whole length of the inner 

 margin. P^oth fingers are strongly curved at the tips. 



The small chela of the female is rather less than five times as long as broad and 

 the fingers are a little longer than the palm. In both sexes the chela bears scattered 

 setae, more numerous in the female than in the male. 



In the second peraeopods (text-fig. 33c) the ischium is a little longer than the 



