REPTILIA 



393 



The Lacertilia include, beside the types commonly known as lizards, the 

 chameleons, horned-toads, and the glass snake a legless lizard. They subsist 

 largely on insects and the eggs of other animals. Only one species is known to be 

 poisonous the "Gila monster" of New Mexico and southward. The glass snake 

 possesses in a high degree a power more or less common among lizards of breaking 

 loose from the tail when struck, or held by that organ. In some species, at least, 

 a new tail may be regenerated. Most lizards are terrestrial, though a few are 



FIG. 198. 



FIG. 198. 



Swift Lizard (Sceloporus undulatus). Adult. 

 Shufeldt. 



Photographed from life by Dr. R. W. 



aquatic. They run, burrow, and climb. One species (Fig. 199) has a membrane 

 from the sides, supported by ribs, that serves as a parachute. 



Order III. Ophidia (Snakes'). Reptiles with elongated bodies covered by 

 fold-like epidermal scales which may be shed as a single "cast." Limbs are 

 wholly wanting. The mouth is capable of great extension on account of the great 

 movability of the quadrate and other bones. Teeth are numerous and fused (not 

 in sockets) to the bones bearing them. Sternum wanting. There are no movable 



