HYDROPHIS. 361 



Head rather small and narrow ; neck slender. Two postoculars ; twenty- 

 three series of scales round the neck. Ventrals not t^^nce as large as the 

 adjoining scales. Trunk with forty-one cross bauds H. subcincta, p. 368. 



Head small ; neck slender. Two postoculars ; twenty-seven to twenty- 

 nine series of scales round the neck. Ventrals not twice as broad as the 

 adjoining scales. Trunk witli from forty-three to sixty-one black rings, 

 not tapering on the sides H. nigrocincta, p. 368. 



Head rather small ; neck slender. Two postocidars ; twenty-eight series 

 of scales round the neck. Ventrals more than twice as broad as the ad- 

 joining series. Trunk with from forty-two to forty-eight cross bands . H. elegans, p. 369. 



Head rather small ; neck slender. One postocular ; thirty-three to thirty- 

 five series of scales roxind the neck ; vertical short H. torquata, p. 369. 



D. Head very small ; neck exceedingly slender : Liopala, [Gray) Gthr. 

 The Icugtli of the thin part of the body is more than one-third of the total. 



One postocular ; thirty-one to thirty-three series of scales round the 



neck. Trunk encircled by from fifty-nine to sixty-seven blackish rings . H. chloris, p. 370. 

 The length of the thin part of the body is one-third of the total. One 



postocular ; thirty-one to thirty-tliree series of scales round the neck. 



Trunk with from forty-eight to fifty-eight blackish cross bands extending 



to the middle of the side H. lindsayi, t^. 371. 



Two postoculars ; twenty-six to twenty-eight series of scales round the neck. 



Ventrals 376. Trunk with from sixty to sixty-four rhombic blackish 



cross bars; sides and belly not banded H. atriceps, p. 371. 



One postocular; twenty-three series of scales round the neck. Trunk with 



thirty-eight broad black cross bands, confluent on the back and bell}' . H. latifasciata, p. 372. 

 One postocular ; nineteen to twenty-three series of scales round the neck. 



Trunk with from fifty-three to fifty-nine complete blackish rings . . . H. coronata, p. 372. 

 Two postoculars ; thirty-three series of scales round the neck. Truidc with 



sLxty-two blackish rings H. diadema, p. 373. 



II. Scales not imbricate, placed side by side. 



A. Head very small ; neck exceedingly slender : Microcephalophis, (Less.) Gray. 

 One postocular. Ventral shields 228-294, those on the hinder half of the 



body split into two H. gracilis, p. 373. 



Two postoculars. Ventral shields 316, all undivided H. fasciata, p. 374. 



One postocular. Ventral shields 412-440, those on the hinder half of the 



body split into two H. cantoris, p. 374. 



B. Head of moderate size ; anterior part of the body not, or moderately elongate: Thalassophis, 



{Schmidt) Gthr. 



Head narrow, elongate; body rather slender. Two postoculars. Ventral 

 shields twice as broad as the adjoining scales, 350 in number . . . . H. lapemoides, p. 375. 



Head narrow, elongate ; body rather slender. Two postoculars. Ventral 

 shields twice as broad as the adjoining scales, 271 in number. Scales 

 keeled H. longiceps, p. 375. 



Head narrow, elongate; body rather slender. One postocular. Ventral 

 shields distinct, only the anterior being twice as broad as the adjoining 

 series, 398 in number H. stricticoUis, p. 376. 



Head rather narrow and produced ; body somewhat elongate. Two post- 

 oculars. Ventral shields twice as broad as the adjoining scales, 252-260 



•S A 



