10.") 2 Catalogue of Reptiles inhabiting the [Oct. 



gradually increasing in depth towards the tail. Entire length, 1 ft. 

 3 inch. 



Adult ? — Head and back uniformly dark olive or brown, becoming 

 greyish on the posterior half, and very indistinct or obliterated on the 

 sides. In some a pale yellow spot on each side of the hindhead, and 

 a third on the frontal shields. The lateral oval spots pale sulphur 

 coloured on the anterior half, pale greenish yellow on the posterior. 

 The black of the lower surface very pale, but distinct. Iris black ; 

 tongue buff. 



Central abdominal series of larger scales, 454+60. 



Habit. — Sea of Malayan Peninsula and Islands. 



Bay of Bengal, Malabar, Sumatra, Borneo. 

 In form and number the shields of the head resemble those of 

 Hydrus nigrocinctus, so as to afford no distinguishing character. Yet 

 it may be readily distinguished from that and other species by the ex- 

 cessive slenderness of the anterior, cylindrical part of the trunk, which 

 from thence becomes much compressed, gradually increasing in bulk 

 and vertical diameter till towards the tail, where the diameter again 

 decreases. The scales of the cylindrical, anterior part of the trunk are 

 rhomboidal with rounded points and slightly imbricate ; the rest are 

 hexagonal. The central abdominal series continued beneath the tail, 

 consists of hexagonal scales, a little larger than the rest, and frequently 

 longitudinally divided. In the very young all the scales are smooth, 

 with age the central abdominal ones acquire a small tubercle on each 

 side, and those of the compressed sides and of the back each a central 

 tubercle. In the largest individuals the central abdominal scales have 

 three longitudinally placed minute tubercles on each side, and the rest 

 of the hexagonal scales three or four similar central tubercles. In the 

 new-born the neck is covered by 32, the bulkiest part of the body by 

 49 longitudinal series ; these parts are covered by 26 and 44 series in 

 the largest individual, which is of the following dimensions : 



Length of the head, ft. Of inch. 



Ditto ditto trunk, 3 2| 



Ditto ditto tail, 4 



3 ft. 7| inch. 

 Circumference of the neck, If, of greatest do. of the trunk, 3f inch. 



