A MONOGRAPH OF THE SHA-SNAKES (HYDROPHIINA). 193 
Frontal,—touches six shields ; the fronto-parietal sutures are longest, the fronto- 
preefrontal shortest. Nasals,—touch the first and second supralabials ; sometimes 
two or more sutures radiate from the nostril and subdivide this shield, forming a 
pseudo-loreal or other pseudo shields. Praeoculars,—one. Postoculars,—one 
ortwo. Temporals,—one, two or three superposed small shields. Supralabi- 
als,—irregular; the anterior two to five are well developed, the rest small, occasioned 
by horizontal sub-division, the extent to which this occurs affecting the contact with 
the eye, and the number of postoculars and temporals; the third and fourth usually 
touch the eye, sometimes the fifth also, more rarely the fourth only, or none at all 
touch the eye. Infralabials,—the fourth or fifth is the largest of the series, and in 
contact with three or four scales behind. Marginals,—absent. Sublinguals,— 
imperfectly developed, but an anterior pair at least can usually be discerned, the fellows 
of which are widely separated. Costals,—anteriorly 40 to 60, midbody, 50 to 70, 
posteriorly 50 to 70; sub-imbricate, or imbricate. Ventrals,—230 to 314, little 
larger, or not as large as the last costal row. Colour,—very variable. The young 
are bluish or bluish-grey with many well defined, black annuli, often dilated vertebrally. 
As age advances these bands become more and more obscured, first disappear- 
ing ventrally, and so converted into dorsal bars, which in old specimens may dis- 
appear altogether. In old adults the dorsum 1s frequently a uniform bluish or bluish- 
grey, merging at midcosta to yellow or yellowish ventrally. Both dorsal and ventral 
hues again are subject to much modification according to whether the specimen has 
recently desquamated or is about to do so. In the latter case the yellow on the belly 
becomes often tinged with brown. 
Halitat.—From the Persian Gulf, through the Indian and Malayan region to New 
Guinea. 
The post maxillary teeth I find all grooved. 
DISTIRA. 
Having failed to discover a single species in which the posterior maxillary teeth 
are ungrooved, I have no course open to me but to unite the two genera Hydrophis 
and Distiva (held by Mr. Boulenger to be distinct on this understanding) ; and as 
Distira is the older title, I retain this name to designate the genus. 
I cannot but think, judging from external characters, that osteological differences 
will be discovered, to separate the slender-necked species from those of more even 
relative proportions, and I also expect to discover anatomical grounds for the isola- 
tion of viperima and jevdom from the other species herein included in this genus. 
There seems to me sufficient justification for doing so on external characters alone ; 
however, I prefer for the present to let them remain as placed by Mr. Boulenger. 
