134 Catalogue of Reptiles inhabiting the 



Habit. — Sea of Malayan Peninsula and Islands. 



Bay of Bengal, Sea of Celebes, Molucca Islands, China Sea. 

 The head is much depressed, not broader than the neck ; the muzzle 

 broad, rounded; the rostral shield is large, rectangular pentagonal, broader 

 than high, the lower margin with a central point and a notch on each side. 

 The eyes are moderate, lateral, not prominent, surrounded by a prse- 

 orbital, a post-orbital, and beneath by the third and fourth upper labials. 

 The frenal shield, observed by M. Schlegel, was not present in four 

 individuals, examined in the straits of Malacca: its existence therefore 

 appears not to be constant : in all Hydri the shields of the head are 

 liable to considerable individual variations of form. Of the eight upper 

 labials the posterior three are very small, which is also the case with the 

 posterior five of the nine inferior labials. The two pairs of elongated 

 mentals are outside bordered by the three first inferior labials, inside, 

 by several small scales. In the young the neck is covered by 37, the 

 thickest part of the trunk by 40 longitudinal series of hexagonal, 

 smooth, comparatively small scales. In the older individual these 

 parts are covered by 32, and 37 large hexagonal scales, each with a 

 central tubercle. The lower series of the sides are slightly larger than 

 the rest, and vertically elongated, so as to acquire a rectangular appear- 

 ance. The central abdominal series is much smaller than the rest. Each 

 scale is either rhombic, and, as represented in the excellent plates of 

 Fauna Japonica, hemmed in between four* of the two lowest lateral 

 series, or they are absent, and their place is occupied by a pair of the 

 former, which are soldered together. In young individuals the central 

 series frequently consists of alternate broad triangular, and very minute 

 rectangular scales, both kinds smaller than the rest. The largest 

 individual of four was of the following dimensions : 



■» v 



Length of the head, ft. 1 inch. 



Ditto ditto trunk, 1 8 



Ditto ditto tail, <) 9^ 



1 ft. 11| inch. 

 Circumference of the neck, 2|, greatest do. of the trunk, 4 inch. 



* A somewhat similar disposition is observed in the central dorsal series of the how- 

 ever differently shaped scales of Xenodermus javanicus, Keinhardt. 



