1895.] A. Alcock — Carcinological Fauna of India. 193 



Sphenocarcinus, A. Milne-Edwards. 



Sphenocarcinus, A. Milne-Edwards, Miss. Sci. Mex., Crust., I., p 135. 

 Sphenocarcinus, Miers, Journ. Linn. Soc, Zool., Vol. XIV. 1879, p. 663; and 

 1 Challenger ' Brachyura, p. 34. 



Carapace elongate sub-pentagonal, broad behind, tapering in front 

 to a long rostrum formed of two spines (fused together to near the tip). 

 The surface of the carapace is symmetrically and deeply honey-combed 

 by broad deep channels which leave symmetrical tubercles with over- 

 hanging edges between them. 



There are no true pre-ocular and post-ocular spines, but the eye is 

 deeply sunk between two low smooth excrescences which are pre-ocular 

 and post-ocular in position. 



The basal antennal joint is truncate-triangular, and the antennary 

 flagella are completely hidden beneath the rostrum. The epistome is 

 long and narrow. The external maxillipeds have the merus as broad 

 as the ischium, somewhat dilated at the antero- external ang-le, and 

 somewhat excavated at the antero-internal angle for the insertion of the 

 small palp. The chelipeds are not much stouter, and not much shorter 

 than the next pair of legs, which are the longest : the dactyli of the 

 legs, though stout recurved and prehensile, are not toothed along the 

 posterior edge. Abdomen, in both sexes, seven-jointed. 



Oxypleurodon Miers ('Challenger' Brachyura, p. 38) differs from 

 Sphenocarcinus only in the form of the rostrum, the spines of which are 

 divergent instead of convergent and more or less fused. I much suspect 

 the generic value of this character. If, however, the two forms be iden- 

 tical, then Sphenocarcinus would have to be removed to the next sub- 

 family, in which case the sub-family Acanthonychina? would be perfect- 

 ly homogeneous. 



Sphenocarcinus cuneus (Wood-Mason). 

 Oxypleurodon cuneus, Wood-Mason, Ann. Mag. Nat. Hist., (G) VII. 1891, p. 261. 



Carapace elongate sub-pentagonal, narrowing to a long tapering 

 cylindrical rostrum, which, in the male, is longer than the carapace and 

 only emarginate at the extreme tip, but, in the female, is shorter than 

 the carapace and distinctly bifid at the end. 



The carapace is symmetrically honey-combed by deep channels, 

 which leave between them great symmetrically undermined islets, as 

 follows : — one, very elongate-oval, on the gastric region ; one, triangu- 

 lar, on the cardiac region ; one, somewhat semilunar with one horn 



