136 Memoirs of the Indian Museum. Vor,. IV, 



1898. Odontodactylus scyllarus, Borradaile, Proc. Zool. Soc, p. 36, pi. v, fig. 6. 



1899. Odontodactylus scyllarus, Borradaile, in Willey's Zool. Results, p. 402. 

 1899. Odontodactylus scyllarus, Nobili, Ann. Mus. Civ. Genova (2), XX, p. 276. 

 1903. Odontodactylus scyllarus, Rathbun, Proc. U.S. Nat. Mus., XXVI, p. 54. 



The carapace is smooth with its antero-lateral and postero-lateral angles rounded : 

 the former more broadly than the latter. It bears no carinae and the cervical groove is 

 entirely obsolete. The rostrum is cordiform, widest a little in front of the base, and 

 is rather more than one and a half times as broad as long ; seen from above it entirely 

 conceals the dorsal processes of the ophthalmic somite. The apex is acute, depressed, 

 and ventrally thickened. 



The eyestalks are short and broad and the breadth of cornea, which is a little wider 

 than the stalk, is in large specimens contained about five times in the median length 

 of the carapace, excluding the rostrum. The antennal scale is very large, between 

 •8 and "o, times the length of the carapace, and is nearly three times as long as wide. 



The dactylus of the raptorial claw is very strongly and abruptly swollen at the 

 base ; distally it is slender and almost straight and the knife-like edge on its inner 

 margin is cut into two strong teeth, the posterior of which springs from the mid-ventral 

 point of the inflated portion, and is longer and more slender than the other. 



The thoracic somites are smooth above. The lateral margin of the sixth is truncate 

 and rounded at either angle ; that of the seventh is similar but rather less sharply 

 truncate and a trifle broader. The lateral margin of the eighth somite is produced to a 

 rounded point and is notched antero-laterally. 



The median portion of the first five abdominal somites is smooth, but on each 

 side there is a well-defined |_-shaped groove running parallel to the anterior and lateral 

 borders. On the fifth and sixth somites, also, a broad depression well above the lateral 

 margin is confined by two longitudinal ridges the innermost of which is proximally 

 notched. Traces of similar depressions are visible on the sides of the two preceding 

 somites. The postero-lateral angles become gradually more acute from before back- 

 wards, and those of the fourth and fifth somites terminate in spines. The sixth somite 

 bears four pairs of longitudinal carinae ; the submedian and lateral end in spines which 

 project beyond the posterior margin, while, of the two intermediate pairs, the inner- 

 most is entire and the outer ends in spines which fail to reach the distal edge. Between 

 the submedian and first intermediate carinae there is a prominent proximal tubercle, 

 and another which is elongated and forms a stout keel, is found between the second 

 intermediates and the laterals. 



In the single specimen examined the height of the median crest of the telson 

 above the general surface is less than one-sixth the greatest breadth of the telson, and 

 below its small terminal spine there are two blunt points. In the anterior half there 

 are on each side two closely-approximated submedian carinae which meet or almost 

 meet at the distal end of the median ridge, an intermediate which is continuous, 

 though not very clearly so, with that which runs to the apex of the submedian spine, 

 and the second lateral which fuses distally with the marginal to form the lateral mar- 

 ginal spine. The first lateral carina, found in 0. japonicus (see text-fig. 4, p. 12) 

 does not exist in the anterior part of the telson. There is a strong carina in the 



