360 OPHIDIA. 



HYDROPHIS. 



Hydrophis, sp., Baud. 



Posterior part of the body strongly compressed. Head short or of mode- 

 rate length, shielded above ; only one pair of frontals ; nostrils superior, in 

 a single nasal shield, both nasals being contiguous to each other. Scales 

 imbricate or not imbricate, not polished, generally with a tubercle or with a 

 keel. Ventral shields very narrow, or quite rudimentary, or entirely absent. 

 Lower jaw without notch in front. 



Synopsis of the Species. 



I. Scales more or less distinctly imbricate. 



A. Scales large, in not more than seventeen longitudinal series round the neck : Kerilia, Gray. 

 Head short H.jerdonii, p. 362. 



B. Scales much imbricate, rather small, in forty-three to forty-seven series round the neck ; ventral 



shields split into two: Hydrus, {Shaw) Gray. 

 Body stout H. stokesii, p. 363. 



C. Scales in tiventy-three to thirty-eight series round the neck; head not very small : anterior part 



of the body {neck) not, or moderately slender: Hydropliis, {Daiid.) Gthr. 



Head rather short and broad ; neck and body of moderate length. One 



postocular. Belly with only a few ventral shields H. major, p. 363. 



Head of moderate size and width ; neck and body not elongate. One post- 

 ocular. Ventrals broad, 310 H. robusta, p. 364. 



Head of moderate size and width ; neck and body of moderate length. Two 

 postoculars. Ventrals broad, 317; scales w"ith a short keel; terminal 

 scale of the tail very large H. belcheri, p. 364. 



Head rather small ; neck and body somewhat elongate. One postocular ; 

 scales strongly keeled. Ventrals not much larger than the adjoining 

 scales H. ccerulescens, p. 365. 



Head of moderate size and width ; neck and body somewhat elongate. Two 

 postoculars ; scales strongly keeled, the keel of each scale with two tuber- 

 cular prominences H. aspera, p. 365. 



Head of moderate size and width ; neck and body somewhat elongate. One 

 postocular. Back with a series of round black spots, alterjiating with 

 black cross bands H. spiralis, p. 366. 



Head of moderate size and width ; neck and body rather elongate. Two 

 po.stocukus ; scales faintly keeled. Ventrals broad, 320— 4'J6 ; terminal 

 scale of the tail small or of moderate size H. cyanocincia, p. 367. 



Head rather small and short ; neck and body elongate. One postocular ; 

 twenty-seven series of scales round the neck. Ventrals twice as large 

 as the adjoining scales. Trunk with sixty broad black rings, nearly sup- 

 pressing the ground-colour H. mehuiosoina, p. 367. 



