THE LACERTIDiE, 



155 



ture imparts an additional gracefulness to these elegant 

 lizards, of which there is not a single example among 

 those vv'e have just left ; they are, moreover, without any 

 of those dorsal crests of spines on the head, back, and 

 tail, which are so common among the Iguanian lizards: 

 none of them have gular pouches, and the tail, except 

 in one or two genera, is invariably long, rounded, and 

 smooth : the tongue is very long, more or less forked after 

 the manner of serpents, and capable of much extension. 

 Most of the European, and nearly all the British lizards 

 belong to this group ; the genera and sub-genera of 

 which, however, we have only partially analysed. The 

 singular genus Leiolepis of Cuvier forms a beautiful 

 passage between these and the IguanidcB, by means of 

 Polychrus : its tongue is highly singular, and shows the 

 union of those characters which belong on the one hand 

 to the IguanidcB, and on the other to the Lacertid(B. 

 There are no very large or remarkably shaped lizards in 

 this family, except, perhaps, the Hydrosaiires, or crocodile 

 lizards, most of which are from South America. They 

 derive their familiar name from being above the ordinary 

 size, and having a low double crest of spines upon their 

 compressed tail. Like their prototypes, also, they are 

 mostly found among the rank herbage of savannahs, 

 and on the sides of rivers ; the analogy is still further 

 preserved by the scales of the Hydrosaures being irregu- 

 larly hexangular, so as to resemble the plates or buck- 

 lers with which the skin of the crocodiles . is defended. 

 One of these, indeed, the Heloderma horridum (fig. 41.) 



has the scales upon the 

 head and some parts of 

 the body raised in the 

 middle and angulated on 

 the sides, so as to give a 

 perfect miniature resem- 

 blance to the plates on 

 the shells of the tortoises. We are entirely unacquainted 

 with that genus which should fiU up the interval be- 



