XXI. SNAKE8, TURTLES, LIZARDS, CROCODILES 



Chordata {continued) 



Class IV. — Reptilia {creeping animals) 



The i-eptile,^ are cold-blooded animals that differ markedly 

 from the amphibians in many important respects. The 

 life history of a i-e]itile is comparatively simple, for no rep- 

 tile passes throngh the i-emarkalile changes that are char- 

 acteristic of most of the amphibians. The majority of 

 reptiles possess an outside coveiing of scales, or horiw 

 plates, or, in the case of turtles, of a l)ony Iiox, while am- 

 phibians, for the most ])art, are smooth skinned. Super- 

 ficially, some reptiles I'esemlile certain amphibians and vice 

 versa, some amphibians are often mistaken for rei)tiles. 



.\n ExA^rPLi: OF THE ClASS — THE SiX-LINED LiZARD 



External features. — The body is long, slender, and more 

 or less cylin(h-ical. It presents four divisions — head, neck, 

 trunk, and tail, ail of A\'hich are clothed A\'ith scales. This 

 contrasts quite strongly with tiie smooth, short, broad, and 

 tailless body of the frog. Like the frog, the lizard has four 

 legs, but they are moi'c nearly equal in size and none of them 

 are fitted for leaping. Each leg terminates hi five digits 

 fuiTiished with claws. 



The eyes. — The eyes are conspicuous, Jnil they do not 

 protrude. Ivicli has an opa(|ue upper and under lid and a 

 nictitating mi^iiibr.-me. The latter ma)' be drawn completely 



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