LACERTILIA AND CROCODILIA. 411 



arches are present in a rudimentary condition. Its appearance is 

 completely serpentiform, and it is vulgarly regarded as a dan- 

 gerous and venomous animal, but quite erroneously, as it is 

 even unable to pierce the human skin. It is a perfectly harm- 

 less animal, living upon worms, insects, and snails, and hyber- 

 nating during the winter. It derives its specific name of frag- 

 ilis from the fact that when alarmed it stiffens its muscles to 

 such an extent that the tail can be readily broken off, as if it 

 were brittle. 



Numerous other small Lizards are referable to the ScincidcSj 

 but it is only necessary to mention the Skinks themselves 

 (Scincus), in which both pairs of limbs are present in a well- 

 developed state. The Skinks are found in almost all the 

 warmer parts of the Old World, and closely-allied forms (such 

 as the West Indian " Galliwasp ") are found in the New World. 



The next family is that of the Lacertidce, 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 

 tongue is slender, bifid, and protrusible. The only truly Brit- 

 ish Lizards are the Sand-Lizard (Lacerta agilis\ and the Vivi- 

 parous Lizard (Zootoca vivipara); 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 Varanidcz or 

 Monitors, which indeed are only separated by the compara- 

 tively trivial fact that the abdomen and head are covered with 

 ordinary scales, and not with large " scuta." The Monitors 

 are exclusively found in the Old World, and are the largest of 

 all the recent Lacertilia; the Varanus Niloticus of Egypt at- 

 taining a length of six feet, and the Varanus bivittatus of Java 

 attaining to as much as eight feet. 



The Gcfkatida form a large family of Lizards, comprising a 

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

 world. One of their leading characters is to be found in the 

 fact that the eyes are not furnished with movable eyelids, but 

 are covered by a transparent fixed eyelid, resembling the 

 " antocular membrane " of the Snakes, behind which the eye 

 moves freely. The tongue, too, is short, fleshy, and only pro- 

 trusible to a very limited extent. They feed on insects, and 

 are found in abundance in the warmer parts of both the Old 

 and New Worlds. 



