APPENDIX. 333 



Indeed to look at the head and tail, it would be said to be a 

 normal Hydrus, but the scales are all smooth and polished 

 like the vermiform land-snakes, and the genus Aipysurus, 

 and those of the body are broad and six-sided, and it has 

 broad band-like ventral shields, so that, in fact, it embraces 

 the peculiar character of both genera; but it differs from 

 them both in the broad ventral plates being folded together 

 on each side of the sharp central ventral keel. 



Genus Hypotrophis. — Gray. 



Head rather depressed, broad, rounded in front. 



Head shields numerous, unequal, smooth, polished, pa- 

 rietal largest. 



Supra orbital 3-3, front small, hinder largest. 



Nasal large, superior ; anterior ocular 1, posterior 

 ocular 3, unequal ; lateral shields, large high, the middle 

 ones reaching to the lower edge of the orbit ; rostral square, 

 large convex, inferior rostral small, triangular, with a 

 rounded notch above. 



Temple and throat, covered with six-sided imbricated 

 scales. 



Nostrils semilunar, superior, valvular in the middle of the 

 nasal plates. 



Eyes moderate, rather superior. 



Body elongate, rather compressed ? covered with small 

 polished six-sided imbricated scales. 



Belly compressed, strongly keeled. 



Ventral shield band-like, transverse, side folded together 

 with a central notch in the middle of the hinder edge. 



Tail strongly compressed, oblong, covered with a series 

 of more or less broad transverse scales, the upper and lower 

 edge strongly keeled, and covered with folded scales — the 

 tip torn, covered with a single large compressed conical 

 scale. 



