340 SN.-UCES OF CEYLON. 



inferiorlj'. Quadrate : Vertical ; extreme length superiorly 

 equal to its depth. Maxilla : Not extending beyond palatine 

 anteriorly, but extending beyond palatine posteriorly. 



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

 Postnodal, 7 (? 6) to 10 ; feebly scaphiodont. Palatine : 8 to 

 10 ; anododont, isodont ; no edentulous space posteriorly. 

 Pterygoid : 18 to 24 ; anododont, scaphiodont ; posterior half 

 edentulous. Mandibular : 18 to 20 ; anododont, feebly 

 scaphiodont. 



There is only one species, viz., diadema. 



DoLicHODiRA DIADEMA (Gunther). 

 (Latin " diadema " a head dress, refers to the yello^^• 

 horseshoe mark on the crown.) 

 Gunther's jSeasnake. 



Synonymy. — HydropMs stricticolUs, H. obscurus, H. torquatus, 

 H. nigrociHctiis, Distira lapemidoides, D. torquatus. 



History. — Described and christened by Gunther in 1864 from 

 three specimens in the British Museum. 



General Characters. — A snake of fair proportions, growing to 

 3i feet. Head small, elongate, not depressed. Snout long, 

 bluntly conical, projecting slightly downwards. Eye small. 

 Commissure of mouth shaped like an italic /. Neck not 

 apparent. Body cylindrical and very slender in about the 

 anterior two -fifths ; compressed and heavy in the posterior 

 three-fifths. 



Identification. — The scale rows 30 to 41 two heads-lengths 

 behind the head, ventrals 374 to 460, taken with the juxta- 

 posed character of the scales on the compressed posterior part 

 of the body, will indicate the species. 



Colouration.' — Olivaceous dorsally, merging to yellowish 

 ventrally. Forty to sixty-five well-defined black rings 

 encircle the body. These are about as broad as the intervals 

 at midcosta and expand somewhat vertebrally, but remain 

 discrete ventrally. The^r are sometimes interrupted in the 

 posterior part of the body, and tend to lose definition as age 

 advances. The head is black, with a more or less distinct 

 vellow horseshoe mark above, especially conspicuous in the 

 young. 



