332 APPENDIX. 



No. VII. 



DESCRIPTION OF A NEW GENUS OF SNAKES, 



BY J. E. GRAY, ESQ. F.R.S. F.Z.S. &c. 



The Sea Snakes (Hydridce) form a very distinct group of 

 Reptiles, easily known at first sight, by their compressed 

 tail and large superior operculated nostrils. The greater 

 part of these animals have their abdominal surface much 

 compressed, and covered on each side with a series of 

 scales like the rest of the body, which are often united 

 together, forming a narrow shield. 



The well known genus Aipysurus is one of the abnormal 

 forms of this family, having the broad band-like shield and 

 the smooth scales of the vermiform land snakes, with the 

 compressed tail, the nostril, the marine habit of the 

 normal Hydridce ; but the transition of the Aipysuri to 

 the Hydri was so abrupt, that it was to be expected, that 

 there must exist some genus which had hitherto escaped the 

 observation of naturalists, which would shew the gradual 

 approximation ; such a genus has at length been discovered 

 by Mr. Jukes on Darnley Island. 



This new genus, which I propose to call Hypotrophis, 

 has the large blunt depressed head, covered with numerous 

 head shields of the true Hydri, and like them, has the very 

 high lateral shield; the throat covered with numerous im- 

 bricated scales ; the eyes small, round, high up, and sur- 

 rounded by several ocular plates, and the nostrils superior 

 lunate and valvular, and the tail broad and compressed. 



