202 PROCEEDINGS OF THE ACADEMY OF 



like other head scales, orbit surronncled by scales, labials not 

 pitted. One pair of geneials. Scales of body subeqnal, keeled, 

 without apical pores. , 



The above generic characters ^111 indicate to the zoologist a 

 type of whose affinities I have been quite uncertain. Its superficial 

 characters remind one at once of the Peropoda, and the double 

 urosteges suggest the Pythons. Examination shows that it does 

 not possess the essential characters of the division, lacking all 

 external trace of posterior extremities, and having the mandi- 

 ble constructed on the Colubrine type, thus lacking the coro- 

 noid bone. The form of the postfroutal bone is, however, sig- 

 nificant ; it is of considerable size, and sends forwards along the 

 external margin of the frontal a process, as far as the prefrontal. 

 This structure is characteristic of the family Aclwochordidse,^ 

 which embraces the genera Ghersydrus and Achrochordiis. The 

 present genus differs in the possession of ventral shields, where- 

 fore it may be referred to a new family under the name of the 

 NoTHOPiD^. I should not be surprised to find that the genus 

 Xenodermus of Reinhardt belongs to it. 



The allies of this genus, then, are exclusively Old World, and 

 confined to farther India and the Archipelago. 



Cha7\ Specif. — Head rather small ; neck and tail rather slender. 

 Scales of body in twenty-nine rows, all strongly keeled, those of 

 the seven median rows a little broader than the lateral, and more 

 Strongly keeled. The scales of the inferior series are more acute 

 than the superior. A broad shallow groove extends throughout 

 the length, between the keel of the first row and the angle of the 

 gastrosteges. The difference between the dorsal and lateral series 

 of scales is more distinct posteriorly, which, with the angulation 

 of the vertebral line, gives the animal a pentagonal section. The 

 scales of the head are smaller than those of the body, not imbri- 

 cate, and keeled ; but one row separates the orbit from the labials. 

 Muzzle rounded, a little projecting. Rostral plate not visible 

 from above, subtriangular, broader than long. Nasal subparal- 

 jelogrammic, the upper anterior angles nearly meeting above the 

 rostral, the inferior approaching near to the labial margin. Supe- 

 rior labials small, twelve, seventh under orbit ; inferiors fourteen 

 or fifteen, the inferior four in contact with the geneials. First 



' See Proc. Acad. Nat. Sci., 1864. 



[October 24, 



