A MONOGRAPH OF THE SEA-SNAKES (HYDROPHIIN). 251 
are from 230 to 267 of these scales in the series. The number of costal rows exceeds 
that of nearly all the other species of this subfamily, the exceptions being Hydrus 
platurus, Enhydrina valakadyn and Thalassophis annandale:. The head shields vary 
much in individuals, and the supralabials are especially prone to division. 
Description.—The neck is more than half the extreme body depth. 
Rostral,—touches four shields; the portion visible above is about half the 
suture between the nasals. Prafrontals,—usually touch the second labial only 
(sometimes the third also, rarely none). Postoculars,—two usually (sometimes 
three). Temporals,—absent, replaced by scales of which there are two or three 
superposed between the parietals and subjacent labials. Supralabials,—eight to 
eleven, very irregular, the third, fifth and succeeding members of the series frequently 
divided into an upper and lower part. The fourth is not divided in any of these speci- 
mens, but from analogy there is every reason to believe this merely a coincidence. 
The fourth, fifth and sixth are the usual ones to find contact with the eye. Infrala- 
bials,—Very irregular, all are prone to division, but the first, second or third may be 
entire. Marginals,—a row succeeds the first, second or third infralabials. Sublin- 
guals,—absent, replaced by small scales. Here from analogy I would expect to see 
specimens in which the anterior and possibly the posterior of these shields are suffici- 
ently developed to merit the name; this is justified from the condition of these shields 
in individuals of wiperina, cerulescens, and ornata. Costals,—anterior 41 to 48, 
‘midbody 48 to 59, posterior 41 to 50, strongly imbricate everywhere, the last rows 
irregularly dentate, marginally and apically emarginate. Ventrals,—230 to 267 
(Boulenger). Absent, replaced by pairs of scales similar in size and shape to the 
adjacent costals except they are more pointed. (Anteriorly there are generally a few 
entire shields similar to those seen in other species). 
Colour.—Yellowish with black bands, or more frequently bars. Often there is a 
dorsal and a ventral series of bars in mid and posterior body which alternate costally. 
The ventral series is sometimes modified into several series of spots of variable size, 
H. guttata (Murray). A dorsal line occurs between the bars or bands usually. 
Ranges between the Mekran Coast and Australia, but appears to be decidedly 
rare everywhere. 
