234 OPHISAURIANS. AMPHISB^ENIANS. 



brought into the same relation with the severed duct of the poison- 

 gland as the displaced fang which it succeeds, is not yet clearly- 

 understood. 



CHAPTER IV. 



TEETH OF SAURIANS. 



OPHISAURIANS. 



97. There are several genera of reptiles which, like the true snakes, 

 are externally devoid of locomotive extremities or have them indi- 

 cated only by minute rudiments, but are covered by small uniform 

 scales, and resemble the Saurians much more than the Ophidians in 

 their anatomical structure, especially in the fixed condition of the 

 jaws, which cannot be divaricated laterally or rotated backwards and 

 forwards upon a moveable tympanic pedicle : these snake-lizards have 

 always intermaxillary as well as maxillary teeth. 



AmphisbcBnians. — In these snake-like reptiles there are, as in the 

 true Saurians, both acrodont and pleurodont species : the greater 

 number belong to the latter category and have their teeth applied 

 against the internal surface of an external alveolar wall ; but in the 

 Trogonophis, the teeth are blended by their whole base with the 

 alveolar ridge, and are so closely arranged, as to cohere together. 

 They are unequal, conical, subcompressed and obtuse. The inter- 

 maxillary teeth are in unequal number, the middle azygos tooth being 

 longer than the rest. 



The teeth of the Cheirotes {Lacerta lumhricoides, Shaw,) are slightly 

 curved, simple and nearly equal, excepting the azygos intermaxillary 

 tooth which is longer than the rest : these are very small at first, but 

 increase as they are placed backwards. 



In the true AmphishcBnce the teeth present the form of short and 

 stout cones, (PL 6.5, figs. 3 & 4) : five are attached to the intermax- 

 illary bone, of which the middle tooth is the longest ; there are five teeth 



