214 A. Alcock — Oarcinological Fauna of India. [No. 2, 



the palm, are arched, and meet only at the tip. The other legs are 

 slender, the second pair being much longer than the last three pairs 

 and longer than the chelipeds. 



The Museum possesses a specimen from Mauritius, which I have 

 included here for the sake of comparison. 



Hyastenus oryx, A. Milne- Edwards. 



Hyastenus oryx, A. Milne-Edwards, Nouv. Archiv. du Mus., VIII. 1872, p. 250, 

 pi. xiv. fig. 1. 



Hyastenus oryx, Haswoll, Proc. Linn. Soc, N S. Wales, Vol. IV. 1879, p. 442 ; 

 and Cat Austral. Crust., p 20. 



Hyastenus (Chorilia) oryx, Miers, Zool. H M. S. 'Alert,' pp. 182 and 195, 517 

 nnd 522 ; and ' Challenger ' Brachyura, p. 58. 



Hyastenus oryx, de Man, Archiv. fur Naturgesch., LIII. 1887, p. 224, taf. vii. 

 fig. 2. 



Hyastenus oryx, C W. S. Aurivillins, Kongl. Sv. Vet. Akad Handl. XXIII. 

 1888-89, No. 4, p. 50, pi. iv. fig. 4. 



Hyastenus oryx, A. 0. Walker, Jonrn. Linn. Soe., Zool., Vol. XX. 1890, p. 109. 



Carapace pyriform, little setose, crisply and rather closely tuber- 

 culated, but without any spines, the tubercles on the gastric region 

 beinw disposed in the form of a cross or anchor. The rostrum consists 

 of two slender horns, which in the male are about half the length of 

 the carapace proper, and strongly resemble the horns of an Oryx in 

 miniature : in the female they are not one-third the length of the 

 carapace, and are nearly parallel. 



The supra-ocular eave is sharply angled, but not produced, an- 

 teriorly. The basal antennal joint is sharply toothed at the antero- 

 external angle. 



The chelipeds in the male are as long as the carapace plus two- 

 thirds of the rostra' .« their merus is slender, but the palms are 

 broadened and inflated ; and the fingers, which are from half to two- 

 thirds the length of the palm, are arched, aud meet only at the tip. 

 In the female the chelipeds are considerably shorter than the post- 

 ocular portion of the carapace, and are rather more slender than the 

 ambulatory legs, the fingers being but little arched, and little separated 

 when clenched. 



The ambulatory legs are slender, with slender almost smooth 

 actyli : the first pair, which are considerably the longest, are about 

 one-fourth longer than the carapace and rostrum. 



This, like Hyastenus calvarius, is a small species, an egg-laden 

 female of average size measuring only 14 mil Km. from the tip of the 

 trum to the posterior border of the carapace. It is a common species 

 at the Andamans, and has also been taken off Ceylon at 34 fathoms, 



