CLASS REPTILIA: ORDER OPHIDIA. 



173 



walls and run along ^^- ^^■ 



ceilings, with its back 



downward. 



Ameividse. — The 

 Lizards of the New 

 World are small, and 

 useful as destroyers of 

 noxious insects. 



Scincidae. — The 

 Glass Snake of the Mis- 

 sissippi Valley is one of the aberrant forms belonging to this 



Platyclaetphis seychellensls, Gecko. }. 



Armiva sexlineata, Striped Lizard, i. 



Ophisaurus ventrdlis. Glass Snake. 



family. When frightened, it contracts its muscles so vio- 

 lently that its tail will break off as if it were brittle. 



ORDER OPHIDIA. 



G-eneral Characteristics. — Serpents are distinguished 

 by their dilatable mouth and the absence of a sternum. 

 They crawl by using the movable ribs and under scales as 

 legs.* The vertebrae are joined to each other and to the ribs 



* The method is easily realized by allowing; one of the non-venomous kind tc 

 crawl over the palm or back of the hand. 



