THE PINE LIZARD AND ITS ALLIES 355 



Lizards. Most of the Lacertil'ia (Lat. lacerta, "lizard") 

 are, like the pine lizard, elongate reptiles with four limbs and 

 movable eyelids. A few families have, however, lost one or 

 both pairs of limbs in connection with their adoption of a 

 burrowing life, and the eyes have disappeared beneath the 

 skin. The covering of scales, so characteristic of reptiles, has 

 also in some cases become much reduced. Legless lizards 

 (Fig. 181) may be distinguished from the snakes, which they 



Fig. 181. The glass snake, a legless lizard. (Reduced) 



resemble, by the fact that they are incapable of opening the 

 mouth to so great an extent as snakes are. Ear openings on 

 the sides of the head and eyelids which are capable of clos- 

 ing are found in the legless lizards but not in snakes. One of 

 the legless lizards (Ophisau'rus ventra'lis (Fig. 181)) is called 

 the glass snake because its body breaks so readily. There are 

 many fables regarding the ability of the glass snake to fly 

 to pieces when struck and later to reassemble its parts and 

 crawl away. The portion of the tail broken off is replaced, 

 but only by the slow process of regeneration and growth. 



Many lizards possess the power, when seized suddenly, of 

 snapping off the tail, which may be left in possession of the 



