CHAPTER VII 



ADAPTATIONS 



Adaptations to the general conditions of the Environment: Ter- 

 restrial types. Arboreal types. Climbing types and effect on tail and feet. 

 Running types. Bipedal types. Flying types. Swimming types. Sail-backed 

 lizards. Limbless types. Burrowing types. Modification of the eye and ear. 

 Dermal armour. 



LIZARDS and crocodiles present what may be called the 

 -/ ordinary or typical form of body among reptiles — a 

 form so familiar to all that nothing in the way of de- 

 scription is necessary. If, however, we examine a large series 

 of reptiles in a museum (exclusive of those which have lost the 

 limbs and assumed a snake-like form of body) we shall find 

 that there are two distinct and well-marked modifications ot 

 this typical shape; the one pertaining to species which are 

 terrestrial, and the other to such as are more or less completely 

 arboreal in their mode of life. In all the purely terrestrial 

 types, such as the common agama lizards, or stellions, of the 

 Old World, for instance, the body is more or less markedly 

 depressed, or flattened from above downwards, and much ex- 

 panded laterally, so that the sides form comparatively sharp 

 edges, while the limbs, which are generally short, thick, and 

 powerful, are widely sundered from one another at their points 

 of origin from the shoulders and haunches. Only a moment's 

 reflection is required to show that such a construction of body 

 and limbs is obviously the one best adapted to enable the owner 

 to escape detection from enemies by squeezing itself as flatly 

 and closely as possible upon the rock or sand upon which it 

 happens to be resting, more especially when (as is almost in- 

 variably the case) its colour harmonises with that of its sur- 

 roundings. The above-mentioned agamas, or stellions, for 

 instance, are generally coloured some shade of mottled grey, 

 brown, and blackish, so as to harmonise closely with the lichen- 



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