OPHIDIA. 169 



Tail extremely short, truncated, scarcely tapering, generally termi- 

 nating in a rough naked disk, or covered with keeled scales* . . Uropeltid^, p. 182. 

 Ventral shields distinct ; two occipitals ; tail tapering Calamarid^, p. 194. 



II. Body rather rigid, covered with rounded, smooth scales ; ventral 

 shields developed ; head short, not distinct from neck ; teeth of the 

 maxillary few in number, the last enlarged, not grooved. 

 Rostral shield large, more or less produced backwards Oligodontid^, p. 205. 



III. Body flexible throughout ; ventral shields developed ; head more or less 



distinct from neck ; a mental gi-oove ; no rudiments of hind limbs. 



Body neither very slender nor much compressed ; nostril lateral ; no 



faug-like tooth in front or in the middle of the upper jaw . . . Colubrid^, p. 220. 



Nostrils on the top of the snout Homalopsid.k, p. 275. 



Body elongate or stout ; pupil round or vertical ; loreal region con- 

 cave ; one of the four anterior maxillary teeth is enlarged, the last 

 grooved Psammophid^, p. 290. 



Body and tail much compressed or very slender ; head elongate ; snout 



obtuse or rounded ; pupil round ; no fang-like tooth in front . . Dendrophid^, p. 293. 



Body generally excessively slender; head very long, with tapering 



snout ; pupil linear, horizontal ; last maxUlary tooth grooved . . Dryiophid*, p. 300. 



Body and base of the tail much compressed; head subtriangular, 

 broad behind, very distinct from neck, with short snout; loreal 

 region flat DiPSADiDiE, p. 307. 



Maxillary with a fang-Hke tooth in front, but without elongate pos- 

 terior tooth LycodontidvE, p. 314. 



IV. Body flexible; ventral shields developed; head thick, very distinct 



from neck ; no mental groove. 

 MaxiUary teeth very small, few in number AmblycephalidjE, p. 324. 



V. Body cylindrical, flexible ; anterior maxillary teeth unequal in length ; 

 none of the hinder teeth enlarged ; rudiments of hind limbs present. 



Tail prehensile Pythonid^, p. 328. 



Tail very short, not prehensile Erycid.e, p. 332. 



VI. Body, head, and tail covered with small, wart-like, not imbricate 

 scales. 

 Tail prehensile Acrochordid.e, p. 335. 



* See Mtlanophidium, Tp.ldS. 



