LACERTILIA AND CROCODILIA. 439 



shields or "scuta" over the abdomen and on the head. The 

 tail is rounded. The tongue is slender, bifid, and protrusible. 

 The only truly British Lizards are the Sand-lizard {Lacerta 



Fig. 171. — The common Skink {Scincus officiiialis). - 



agilis), and the Viviparous Lizard (Zootoca vivipard); and the 

 commonest form upon the Continent is the graceful little Green 

 Lizard {Lacerta viridis), which also occurs in Jersey. The 

 Lizards of the Old World are represented in America by the 

 Ameivce, some of which attain a length of several feet 



Very closely allied to the true Lizards are the Varanidce or 

 Monitors, which indeed are chiefly separated by the compara- 

 tively trivial fact that the abdomen and head are covered with 

 ordinary scales, and not with large "scuta." The tongue is 

 protrusible and fleshy, like that of the Snakes. The teeth are 

 lodged in a common alveolar groove, which has no internal 

 border ; and there are no palatal teeth. The tail has a double 

 row of carinated scales, and is cylindrical in the terrestrial 

 forms, and compressed in those whose habits are aquatic. The 

 Monitors are exclusively found in the Old World, and are the 

 largest of all the recent Lacertilia ; the Varanus Niloticus of 

 Egypt attaining a length of six feet, and the Varanus bivittatiis 

 of Java attaining to as much as eight feet. The Safe-guards 

 {Salvator) are the Monitory Lizards of the New World, and are 

 also of large size. 



The Geckotidce form a large family of Lizards, comprising a 

 great number of species, occurring in almost all parts of the 



