HIPISTES HYDRINUS. 287 



narrow, divided into three portions by a pair of sharp lateral ridges, the 

 central portion beiny; much the largest ; anal bifid ; subcaudals two-rowed. 

 Maxillary with a grooved tooth behind ; two or three strong teeth in the 

 palatine series. 



Only one species is known. 



HiPiSTES HYDRINUS. (Plate XXIV. fig. H.) 



Homalopsis hydrinus, Cantor, Mai. Rept. p. 104. fig. 4 (head). 

 Hipistes fasciatus, Gray, Viper. Snakes, p. 78. 

 Bitia hydroideSj Gray, I. c. p. 63. 



Rostral shield small, as high as long ; anterior frontal short, cuneiform, broadest behind, 

 much longer than broad; posterior frontals very small, hexagonal; vertical bell-shaped, 

 elongate, broadest behind ; supraciliaries elongate ; two pairs of small occipitals, one pair 

 behind the other, with a small central shield; sometimes the occipitals are more irregularly 

 arranged. Nasal shield nearly twice as large as a posterior frontal, with the nostril behind its 

 middle. Loreal large, subquadrangular ; one prseocular, extending on to the upper surface 

 of the head, but not reaching the vertical ; two postoculars, the lower of which is the larger, 

 extending forwards and meeting the prsBocular. Seven upper labials, the fourth being below 

 the suture between the prae- and post-ocular ; the fifth, sixth, and seventh are the largest, 

 higher than long. Temporals 2 + 3, the anterior being in contact with the postoculars, the 

 posterior scale-like. One pair of long chin-shields, in contact with six lower labials. There 

 are about six series of scales between the chin-shields and the first ventral. Scales smooth, 

 without apical groove, elongate-ovate ; the apex of each scale, however, being turned inwards, 

 and not overlapping the root of the following scale, small square grooves remain between the 

 scales. The ventrals are narrow, with a sharp ridge on each side, 153-161 ; subcaudals 34-35. 

 Each maxillary is armed with twelve teeth gradually increasing in length posteriorly, the last 

 being grooved. Pale ash-coloured above, with a few blackish specks on the neck, and with 

 about forty-eight black cross bars on the back of the trunk and tail, each about half as wide 

 as the interspaces of the ground-colour. Lower parts white. 



This appears to be a semipelagic species, resembling a true Hydrophis in general appear- 

 ance and colours ; its discoverer has made the following observations : — " Of three individuals 

 observed, two were captured in fishing-stakes placed in the sea off the shores of Keddah ; a 

 third was washed on shore by the waves on the coast at Pinang. The largest male was 

 19f inches long, the tail measuring 2| inches. It moved actively and without difficulty on 

 the sand, and did not offer to bite. In one examined the stomach contained remains of two 

 small pelagic fishes." It appears to be a scarce snake. 



We have given two views of the head, and figures of portions of the trunk and belly, to 

 show the peculiar structure of the shields and scales, and the coloration. The figures are of 

 the natural size. 



