SNAKES. 47 



Hyclrus gracilis, S/iaiv, Zool. iii. 560, young. Merrem, 141. Dis- 

 teira gracilis, Fitz. N. Si/st. Rept. 55. Kadell Nagain, Russell, 

 Tnd. Serp. t. 13, adult. Hydrophis Kadell, Boie, Isis, 1827, 554, 

 from Russell. 



Slate coloured, beneath paler: neck with narrow, rather distant 

 cross rings : the dorsal scales of the middle of the body smallest, 

 gradually increasing in size and in the strength of the keel as they 

 approach the ventral series ; chin shields one pair. 



a. In spirits. Young. Indian Seas. Old collection, named by 



Dr. Shaw. Hydrus gracilis, 



b. In spirits. Adult. India, Madras. Presented by J. C. Jerdon, 



Esq. 



c. In spirits. Younger. India, Madras. Presented by J. C. Jer- 



don, Esq. 



c. Scales ovate, six-sided, imbricate, keeled, or with the keel reduced 

 to a tubercle in the centre of the scale : head and yape moderate. 

 Hydrina. 



Hydrina, Gra2/, Zool. Misc. 60, 1842. Hydrophis, Daud. 

 Rept. vii. 372. 



* Labial shields occupying the greater part of the lips : eyes over the 

 fourth, or rarely over the third, or the fourth and fifth labial 

 shields : ventral shields six-sided, formed of two united scales, 

 which are rarely separated. 



5. Enhydeina. 



Head moderate, rounded in front : rostral small, erect: upper 

 labial shields, first triangular or band-like, high, margining the 

 nasal ; second, third and fourth large (fourth under the eyes) ; fifth, 

 sixth and seventh very small, triangular: temporal shields, three 

 above the latter large, unequal ; middle one large, linear, erect : 

 lower rostral elongate, sunk in a deep groove : lower labial, first to 

 fifth elongate, band-like ; the first very large; second short ; the sixth 

 and seventh low, band-like, marginal : chin shields one pair, lateral, 

 far apart; nasal shields narrowed, subacute in front: eyes rather 

 large: scales of neck narrow, of hinder parts broader: ventral 

 shields narrow, two-keeled, irregular ; of throat narrow, like the 

 scales, scarcely distinguishable. 



Hydrophis, § a, Gray, Zool. Misc. 1842. Disteira sp., Fitz. 



