GECKOS, LIZARDS, AND CHAMELEONS. 73 



ment. Between the typical lizard and the 

 crocodile there is an undoubtedly superficial 

 resemblance, so much so that the former is often 

 described as crocodile-like, whilst the latter is as 

 often referred to as lizard-like. The likeness, 

 however, is purely superficial, and confined to 

 the general contour of the body. 



Any one who will take the trouble to compare 

 the skeletons of the two groups, or the organs of 

 circulation or respiration, for example, will see 

 at once how widely they are separated. Conse- 

 quently, no further comparison between the two 

 need be made here. If, however, the differences 

 which distinguish the Lizards from the Crocodiles 

 are many and wide, this is by no means the case 

 between the Lizards and the Snakes, inasmuch as 

 many Lizards have come to assume a snake-like 

 form through the loss of their limbs, concerning 

 which loss we shall have much to say later on in 

 this chapter. Nevertheless, a little discrimination 

 will enable even the uninitiated to tell the limb- 

 less lizard from the snake. In the first place, the 

 two halves of the lower jaw in the lizard will be 

 found to be closely united, and the ear is usually 

 visible externally. In the snake the two halves 

 of the lower jaw are connected only by a liga- 

 ment, and there is no external aperture to the 

 ear. Furthermore, the lizards, with few excep- 

 tions, have movable eyelids, the snakes never. 



As a rule, the body of the lizard is covered 

 with overlapping scales, but in some forms these 

 become reduced to mere tubercles, whilst in 

 others they are underlain by bony scutes recalling 

 those on the back of the crocodiles. These scales 



