Carcinological Fauna of India. 345 



dispute, and I have published my owu observations on that of 0. macrocera in the 

 Administration Eepoit of the Marine Survey of India for the year 1891-92 (re- 

 printed in the Annah and Magazine of Natural Histori/ for 1892). Dr. A. R. Anderson 

 has published a note on the sound produced by 0. ceratophthalma in this Journal for 

 the year 1894. 



My own opinion is that these crabs use the stridulating-orgau when in their 

 barrows — which undoubtedly are private property— to warn intending intruders of 

 the herd that the burrow is occupied, and thus to prevent the burrow becoming 

 crowded to suffocation-point. This, of course, need not be its exclusive use. 



Key to the Indian species of Ocypoda. 

 I. No stridulating ridge on the inner surface of [the palm : 

 eyestalks not prolonged beyond the eyes iu the form of a 



style ■.. 0, cordimanu. 



II. A stridulating ridge on the inner surface of the palm : 

 eyestalks (except sometimes iu the young) prolonged 

 beyond the eyes to form a horn or style : — 



1. Length of the stridulating organ much more thau 

 half the greatest breadth of the palm: antero- 

 lateral angles of the carapace well pronounced : — 



i. Fingers of both chelipeds pointed : — 



a. Stridulating ridge uai-row, consisting entirely 

 of small tubercles : no brashes of hairs on 



the propodites of any of the legs 0. platytarsiti. 



h. U he stridulating ridge consists of tubercles 



gradually passing into striae : the anterior 



surface of the propodites of the tirst two 



pairs of legs thickly furnished with hairs ... 0. ceiatophtlialma. 



ii. Fingers of the smaller cheliped expanded at tip : 



the stridulating ridge consists entirely of striiu... 0. macrocera. 



2. Length of the stridulating organ much less thau 

 half the greatest breadth of the palm : antero- 

 lateral angles of the carapace rounded off 0. rotundata. 



The synonomy of the species of Ocypoda has been discussed, at 

 length, by Ortmann (Zool. Jahrb., Syst., X. J897-98, p. 359), who has 

 had access to a great deal more mateiial tlian I have. It would be in- 

 advisable, therefore, for me, working on a collection made almost entirely 

 in India, to attempt any independent ciiticism of the older work; so 

 that, in dealing with the Indian species, I shall generally restrict my 

 citations to the papers of Ortmann and the other authors (Kingsley and 

 Miers) who have made a revision of the genus. 



43. Ocypoda ceratophthalma (Pallas), Ortm. 



Cancer ceratophthalmun, Pallas, Spicilegia Zool. IX. p. 83, pi. v. figs. 7, 8. ! 



Cancer cursor, Herbst, Krabbcu, T. ii. 74, pi. i. figs. 8, 9. 



Ocypoda ceratophthalma, Fahricias, Eut. Syst. Snppl. p. 347: Milne Edwards, 

 Hist, Nat, Crust. II. 48, and Cuvier Kcgue An, Crust, pi. 17: Kingsley, Proc. Ac. 



687 



