1896.] A. Alcock — Carcinological Fauna of India. 271 



front is broadish and broadly bilobed, and does not project as far as 

 the salient edges of the afferent branchial canal. 



The orbits are deep and completely conceal the eyes, their outer 

 wall is marked by 3 closed sutures, the surfaces between which are very 

 convex ; there is a widish gap at tbe inner canthus where the antennae 

 with their small flagellum are found. The antennules fold obliquely. 



The external maxillipeds are sunk altogether or in part a good deal 

 below the level of the sharp edges of the buccal cavern : they are 

 longitudinally hollowed or grooved along their inner border, the merus 

 more deeply than the ischium : the last-named joint is about twice the 

 length of the narrowly-triangular merus. 



The chelipeds are hardly stouter than the slender legs : and are 

 markedly less than twice the length of the carapace : the distal half of 

 the hand is almost filiform : the fingers are hardly half the length of 

 the hand, are filiform, and open in a vertical plane. 



The abdomen of the male has the 3rd 4th and 5th segments coales- 

 cent, that of the female has the 3rd-6th coalescent. 



Key to the Indian species of Ixa. 



I. Channels of carapace with very definite under- 

 mined edges : lateral processes with very abruptly 

 acuminate tip : buccal frame distinctly trian- 

 gular : exognaths with the surface concave and 



almost devoid of granules I. cylindrus. 



II. Channels of carapace simply grooves of no very 

 remarkable appearance : lateral processes gradu- 

 ally tapering : buccal frame quadrangular : exo- 

 gnaths with the surface, in the basal three-fourths, 

 tumid and covered with a mosaic of large 

 granules I. inermis, 



95. Ixa cylindrus, (Fabr). Leach. 



Cancer cylindrus, Fabricius, Mantiss. Ins. I. 323, and Enfc. Syst. II. 456. 



Cancer cylindricus, Herbst, Krabben, I. ii. 109, pi. ii. figs. 29-31. 



Leucosia cylindrus, Fabricius, Enfc. Syst. Suppl. p. 352 : Bosc, Hist. Nat. Crust. 

 I. 237 : Latreille, Hist. Nat. Crust et. Ins. YI. 119. 



Ixa cylindrus, Leach, Trans. Linn. Soc. Vol. XI. 1815, p. 334: Bell, Trans. 

 Linn. Soc. Vol. XXI. 1855, p. 311 {'part): Miers, ' Challenger ' Brachyura, p. 301 

 and footnote. 



Ixa canaliculata, Leach, Zool. Miscell. III. p. 26, pi. 129, fig. 1 : Desmarest, 

 Consid. Crust, p. 171, pi. xxviii. fig. 3: Milne Edwards, Cuvier, Regne An., Crust, 

 pi. xxiv. fig. 1, and Hist. Nat. Crust. II. 135 : A. Milne Edwards, in Maillard's 

 l'He Reunion, Annexe F, p. 10. 



