420 SNAKES OF CEYLON. 



It appears to be fairly abundant in the Malay Archipelago. 

 It is common further east around the Philippines, and I had 

 no less than seven specimens in a small collection from that 

 locality. It does not seem to have been recorded from the 

 Chinese Coast, and I think when Flower includes the Chinese 

 sea within its limits he means the southern part of that sea. 

 Stejneger says that its claim to be considered a Japanese snake 

 is dubious. It was not represented in the two large collections 

 of seasnakes made by Owston around Japan and the Loo Choo 

 Islands, which formed the subject of my papers published in the 

 proceedings of the Zoological Society of London in 1903and 1905. 

 There is no record from Ceylon, and it is only included in 

 this list by me because it has been found in the Bay of Bengal. 



Genus HYDRUS. 



(Greek '' hudros " water-snake.) 



General Characters. — Length rather small, about 2 feet. 

 Habit robust. Slightly attenuated anteriorly, its diameter 

 about two-thirds the extreme depth posteriorly. 



Cranial Osteological Characters. — Nasals : Sutured to pre- 

 frontals and frontal ; longer than frontal. Prefrontals : 

 Not meeting parietal, meeting postfrontals. Frontals : 

 Breadth three-fourths its length, meeting postfrontals at 

 rim of orbit. Parietal : Strongly keeled interiorly. Quadrate : 

 Oblique from above backwards ; extreme length superiorly 

 half its depth. Maxilla : Not extending beyond palatine 

 anteriorly ; extending beyond palatine posteriorly. 



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

 Postnodal, 8 to 10 ; isodont. Palatine : 6 to 7 ; anododont, 

 scaphiodont ; no edentulous space posteriorly. Pterygoid : 

 23 to 27 ; anododont, isodont ; posterior quarter edentulous. 

 Mandibular : 16 to 18 ; anododont, scaphiodont. 



There is one species, viz., platurus. 



Hydrtts platurus (Linne). 



(Greek " platus " flat, and " oura " tail.) 



Linne 's Seasnake. 



Synonymy. — Anguis platura, Hydrus bicolor, Pelamis 



schneideri, P. ornata, P. platurus, P. bicolor, Hydrophis 



platura, H. pelamis, H. bicolor. 



