464 MANUAL OF ZOOLOGY. 



It attains a length of eight or nine inches, and was formerly 

 used in various diseases as a remedy. 



The next family is that of the Lacertida, comprising the 

 typical Lizards, in which there are always four well-developed 

 limbs, each terminated by five free toes of unequal lengths. 

 The body is covered with scales, which assume the form of 

 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 

 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 



Fig. 201. The common Skink (Seine us officlnalis). 



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 Varanida 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 bivittatus 



