31-6 SNAKES OF CEYLON. 



My views have not been hastily arrived at, but are the 

 result of many years' special study of marine forms. Among 

 various large collections, I have examined all the seasnakes 

 in the British Museum, not once, but many of them repeatedly, 

 and side by side with the allied forms from which they are 

 supposed to differ. In the Indian Museum too I have ex- 

 amined the specimens most critically half a dozen and more 

 times side by side. 



My most recent work has been largely devoted to a study 

 of skulls and dentition, and I think the recognition of genera 

 and species should depend, if not entirely, almost entirely 

 upon these characters. I have drawn up a synopsis of these 

 characters which differentiate the genera and species I recog- 

 nize. 



In my " Monograph of the Seasnakes," published by the 

 Asiatic Society of Bengal in 1909, I pointed out that the 

 grounds upon which Mr. Boulenger based his genera Hy- 

 drophis and Distira were mistaken, and he has acknowledged 

 this in his most recent work on the Reptilia of the Malay 

 Peninsula, published in 1912, where all the species are now 

 placed in a single genus under the former title. Some other 

 mistakes pointed out by me have been therein acknowledged 

 and rectified. 



Nomenclature. — It is difficult to find appropriate English 

 names for the species. I have accordingly associated with 

 each the name of one of our best known herpetologists, as a 

 fitting memorial to his work. 



General Characters (for Indian species).— With the ex- 

 ception of the members of the genus Platurus (which are of 

 fairly even calibre and cylindrical throughout), the bodies of 

 seasnakes are cylindrical, and more or less attenuated in 

 about the anterior two-fifths, compressed and heavy in about 

 the posterior three-fifths. In some species the head and 

 forebody are remarkably slender, even amounting to one- 

 quarter the depth at the greatest girth posteriorly. Another 

 peculiarity too (excepting again Platurus) is that the dorsal 

 length over the compressed part of the body is longer than 

 the ventral length, so that a seasnake is curved like a prawn. 



