CLASS REPTILIA: ORDEE OPHIDIA. 



173 



walls and run along 

 ceilings, with its back 

 downward. 



A m e i v i dae. 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 



Fig. 293. 



Platydactylus seychettensis^ Gecko. \. 



Ameiva sexlinedta, Striped Lizard. 



Ophisaurus ventralis, 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. 



General 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 ia easily realized by allowing one of the non-venomous kind to 

 crawl over the palm or back of the hand. 



