SNAKES OF OEYLON. 375 



Cranial Osteological Characters.— ^osaZs .• Sutured to pree- 

 frontals and frontal ; longer than frontal. Praefrontals : 

 Meeting parietal and postfrontals. Frontal : Breadth three- 

 fourths the length ; not meeting postfrontal at rim of orbit. 

 Parietal : Not keeled inferiorly. Quadrate : Oblique from 

 above backwards ; extreme length superiorly half its depth. 

 Maxilla : Not extending beyond palatine anteriorly ; extend- 

 ing beyond palatine posteriorly. 



Dentition. — From three skulls in my collection. Maxillary : 

 Postnodal, 13 to 17 ; * isodont. Palatine : 7 to 8 ; anodo- 

 dont, isodont ; no edentulous space posteriorly. Pterygoid : 

 19 to 25 ; anododont, feebly scaphiodont ; posterior half 

 edentulous. Mandibular : 22 to 26 ; anododont, isodont. 



There is one species, viz., cserulescens. 



POLYODONTOGNATHUS C^RULBSCENS (Shaw). 



(Latin "cserulesco " I become blue, implying bluish.) 



Merrem's Seasnake. 



Marathi : " minerrh " and " mathera " of Bombay fishermen. 



Synonymy. — Hydrus cserulescens, Enhydris caerulescens, 



Distira cosrulescens, HydropMs obscurus, H. cyanocincta. 



History. — The type which is in the British Museum was 

 obtained by Dr. Patrick Russell. It received its official 

 baptism in 1802 at the hands of Shaw. 



General Characters. — It is a small species growing to about 

 2 J feet in length. Head small, rather elongate, not depressed. 

 Snout of moderate length, hardly projecting, declivous, 

 obtusely rounded terminally. Eye small. Commissure of 

 mouth slightly turned up posteriorly. Neck not constricted. 

 Body slender and cylindrical in its anterior two-fifths ; 

 stoutish and compressed in the posterior three-fifths ; the 

 extreme depth being two or three times that of the slender 

 anterior part. The scales are very rough, especially in old males. 



* I have examined these in over twenty specimens. 



