338 



ZOOLOGY 



3. General Organisation of Recknt Eeptilia. 



External Features. — In external form, as in some other 

 respects, certain of the Lacertilia exhibit the least specialised 

 condition to be observed among the living Reptilia. Lacerta is 

 such a central type, and the general account of that Lizard which 

 has just been given applies in all the points of cardinal importance 

 to a large proportion of the Lacertilia. Modifications take place, 

 however, in a variety of different directions. Of such the following 

 are a few of the chief The tail region is usually, as in the example. 



ffiSDurl,!,,, 



Fig. ri7V.— Chamseleon vulgaris, x 5. 



(From the Cambridge Natural Historj/.) 



extremely long and tapering ; but in some groups of Lizards it is 

 comparatively short and thick ; and in others it is depressed and 

 expanded into a leaf-like form. In the Chamseleons (Fig. 977) 

 the long and tapering tail is used as a prehensile organ, the 

 coiling of which round branches of the trees in which the anims-l 

 lives aids in maintaining the balance of the body in climbing 

 from branch to branch. 



In the limbs there is likewise a considerable amount of varia- 

 tion in the different groups of the Lacertilia. Moderately long 

 pentadactyle limbs like those of Lacerta are the rule. In the 

 Chamaileons (Fig. 977) both fore- and hind-limbs become prehensile 



