170 Memoirs of the Indian Museum. [Voiv. V, 



Cerberus rhynchops (Schneider). 



1912. Hurria rhynchops, Barbour, Mem. Mus. Comp. Zool. Harvard, XLJV, No. 1, p. 123. 



This species has an even wider range than Chersydrus granulatus, for it occurs in 

 all the Indian rivers and estuaries and throughout the Malay Archipelago as far as 

 New Guinea. In the extreme east of its range it is, however, scarce. 



Ivess exclusively aquatic in its habits than Chersydrus, it probably never goes far 

 from water. In estuarine tracts it is particularly abundant, but it also makes its way 

 far up rivers. In the Gangetic delta it is one of the commonest snakes in suitable 

 localities, that is to say in ditches, creeks and swamps of brackish water, in which it 

 either lies at the bottom or remains concealed among vegetation at the edge. It also 

 frequents the deep cracks formed in mud exposed to the heat of the sun at low tide. 

 I have watched it, from a stranded boat, emerging from those cracks below water as 

 the tide covered them. Round the Chilka Lake it lies under the felted algae left at 

 the edge as the water-level sinks in the dry season, and also conceals itself among 

 submerged stones on islands such as Kalidai and Barkuda. Its habits render it less 

 liable to be caught in fishermens' nets than either of the other snakes of the lake, for 

 it rarely swims in the open. On land it is less awkward than Chersydrus. 



The type-specimen of Schneider's Hydrus rhynchops was from the Ganjam 

 district. 



Subfamily HYDROPHIDINAE. 



Genus Hydrophis, Daudin. 



1890. Hydrophis and Distira, Boulenger, Faun. Brit. Ind., Kept., pp. 398, 407. 



1909. Distira, Wall, Mem. Asiat. Soc. Bengal, II, p. 193. 



1912. Hydrophis, Boulenger, Faun. Malay Peninsula, Kept., p. 181. 



Boulenger has recently accepted the view that the two genera Distira and Hydro- 

 phis cannot be separated. The former was described one year later than the latter. 



Hydrophis obscurus, Daudin. 



1890. Hydrophis coronatus, Boulenger, Faun. Brit. Ind., Rept., p. 402. 



1909. Distira obscura, Wall, Mem. Asiat. Soc. Bengal, II, p. 201. 



1912. Hydrophis obscurus, Boulenger, Faun. Malay Peninsula, Rept., p. 188. 



1914. Hydrophis coronatus, Wall, lourn. Bombay Nat. Hist. Soc. XXII, p. 374. 



There has been considerable confusion in the synonomy of this species. Wall set 

 the matter right, so far as the specific name was concerned, in 1909 and is followed 

 in this respect by Boulenger. Unfortunately the former author has revived the name 

 coronatus in a recent note ( 1914) , but without giving reasons. This name was applied by 

 Günther in his Reptiles of British India (1864) to the young snake, of which he gives an 

 excellent figure (pi. xxv, fig. M., op. cit.), and is more than half a century younger 

 than Daudin' s "obscurus" , which is wrongly applied by Boulenger, as he himself 

 has pointed out (1912) , in the ff Fauna" and the British Museum Catalogue of 

 Snakes. 



