A MONOGRAPH OF THE SHA-SNAKES (HYDROPHIIN 2). 203 
I find the post-chin shields separated. I can find no point of difference therefore 
between the two species. 
Daudin’s name obscura has preference over both coronata and Jlatifasciata, and 
must therefore be retained to denote this species. It is an extremely well-marked 
form, that should never be confused with any others up to now described. The scales 
in the neck alone (19 to 23) mark it off from all the other species of Distiva excepting 
gracilis, which it resembles in some ways, especially in bodily conformation, the relative 
proportions of neck and body, and in the head shields generally, but it is very definitely 
a species apart, owing to the imbrication of the costals posteriorly, the greater number 
of ventrals, the presence of marginals and the much greater length to which it attains. 
Description.—The body anteriorly varies from more than one-fourth to less than 
one-fifth the greatest body depth. I find the posterior maxillary teeth grooved, in 
specimens labelled covonata in the British Museum and my own specimens (and in 
the type-specimen of Jdatifasciata). The head shields as in the other slender-necked 
species are mostly very constant, but certain shields, notably the anterior temporal 
and the posterior sublinguals, are less so than in gracilis and cantoris. 
Rostral,—the portion visible above is from half to three-fifths the internasal 
suture. Prefrontals,—touch the second supralabial. Postoculars,—one. 
Temporals,—one large anterior succeeded by another as large or larger. Supra- 
labials,—six; the fifth and sixth usually separated by the descent between them of 
the anterior temporal ; they are not subject to division. Infralabials,—four, the 
last in contact with three or four scales behind, the suture between the first as long or 
longer than the suture between the anterior sublinguals. Marginals,—one after the 
third infralabial usually, sometimes two after the second (absent on one side in two 
examples). Sublinguals,—two well developed pairs, the fellows of each in contact. 
(Intwoexamples the posterior fellows ate separated). Costals,—anterior Ig to 23, 
midbody 25 to 32, distinctly imbricate everywhere. Ventrals, 296 to 354, entire 
throughout, and twice or nearly twice the breadth of the last costal row throughout. 
Colour,—much like the last two. The ead is uniformly black in the young, and the 
body surrounded by from 34 to 60 broad annuli which are dilated, and often more 
or less confluent vertebrally, and ventrally especially in the forebody and neck. With 
age the colour of the head may change, and become bluish or olivaceous blue, and 
acquire or retain a yellow spot or horse-shoe mark on the crown. The bands become 
less defined with age especially posteriorly. 
Habitat.—Shores between Karwar on the Coromandel Coast of India and Mergui 
on the Tenasserim Coast. Thedbald’s specimens have no habitat recorded, but are 
probably from the Burmese Coast. My figures are from a specimen of mine from Burma 
in which the scales are 21 to 22 anteriorly, 29 in midbody, and 31 posteriorly ; 
imbricate everywhere. The ventrals are 318. The neck is one-fifth the greatest 
body depth. 
DISTIRA FASCIATA (Schneider). 
? Hydrophis gracilis, Jan, Icon. Gén., 1872, 41, pl. iv, fig. 2. 
chloris, Giinther, part, Rept. Brit. Ind., 1864, p. 370 (non Daudin). 
2) 
