SNAKES. 47 
Hydrus gracilis, Shaw, Zool. iii. 560, young. Merrem, 141. Dis- 
teira gracilis, Fitz. N. Syst. Rept. 55. Kadell Nagam, Russell, 
Ind. Serp. t. 13, adult. Hydrophis Kadell, Bote, 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. 
e. In spirits. Younger. India, Madras. Presented by J. C. Jer- 
don, Esq. 
c. Seales 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, Gray, 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. ENHYDRINA. 
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. 
