164 A. Alcock — Carcinological Fauna of India. [No. 2, 



lateral border ; and by tliis border being elegantly beaded, raised ia 

 very stiong relief, and continued far along the edge of the lateral spine. 



In the Indian Seas this species has only been found on the Madras 

 coast. 



Although I have frequently dredged it, I have never done so in less 

 than nine fathoms. I have on more than one occasion heard it make a 

 musical noise audible at several yards distance. 



As Henderson has remarked, a Sacculina is often found parasitic 

 on the male. 



In the Museum collection are 14 adult males, 40 females, and 15 

 young males. 



Family LEUCOSIID^. 



Leucosiens, Milne-Edwards, Hist. Nat. Crnst. II. 118. 

 Leucosidea, De Haan, Faun. Japon. Crust, p. 129. 

 Leucosiidae, Dana, U. S. Expl. Exp. Crust pt. I. p. 390. 

 Leucosiadse, Bell, Trans. Linn. Soc. Vol. XXI. 1855, p 277. 

 Leiico»iidse, Miers, ' Challenger' Brachyura, p. 297. 



Carapace circular or oval or polygonal. Eyes and orbits very small : 

 front narrow but many times wider than the orbit. The antennules 

 fold more or less obliquely. The antennae are small, sometimes obsolete. 

 The external maxillipeds completely close the buccal cavern, except 

 that -YQVj commonly there is a crevice in front : their palp or flagellum 

 springs from a groove in tl^eir dorsad surface near the inner edge, 

 and is completely concealed when tlie maxillipeds are in repose: the 

 exognath is broad, sonsetimes remarkably broad. 



The afferent branchial channels occupy the sides of the endostome 

 on either side of the deep median endostomial groove which, as in the 

 CalappidaB, serves as an efferent branchial channel. The afferent 

 channels are covered in by the exognaths of the external maxillipeds ; 

 the efferent channel is covered in immediately, as in the Calaypidsey by 

 a pair of lamellar processes from the first maxillipeds. 



The chelipeds are symmetrical and have no remarkable peculiarity 

 of form. 



The abdominal terga are very rarely distinctly separate : commonly 

 in both sexes the 3rd-6th are intimately fused with obliteration of 

 sutures, sometimes however the 6th also is independent, and in a few 

 forms the sutures are not obliterated. 



The vasa deferentia emerge through the 5th thoracic sternum on 

 either side, near the bases of the 5th legs. 



The Leucosiidas are such a natural group, and the various forms of 

 which ii is conjposed show so many intergiadations, that any attempt 

 t o spilt it up into"" sub-families " must be received with caution. 



