CHAPTER XXIII 

 SNAKES, LIZARDS, TURTLES, AND CROCODILES 



The large class, Reptilia, including the turtles and tortoises, 

 crocodiles and alligators, lizards and snakes, is composed of 

 animals differing in general appearance but possessing many 

 characteristic features that show their close relationship. Most 

 of them are terrestrial in habitat. All are cold blooded and 

 almost all breathe by means of lungs, those that spend part of 

 their life in water coming to the surface to breathe. Nearly all 

 creep or crawl, dragging the body on the ground or close to it. 

 The body is covered with scales or with large plates. The rep- 

 tiles pass through no metamorphosis during their develop- 

 ment, the young when born or hatched from the egg resem- 

 bling the adult except in size. Most reptiles lay eggs, as do 

 the birds, and so are called oviparous. But the common 

 garter-snakes and some other species, retain the eggs within 

 the body until they are hatched, and so are said to be 

 ovoviparous. The eggs are usually laid in the earth or sand 

 or in vegetable mould and given no further care by the 

 mother, but some species show great solicitude for the 

 eggs, guarding them jealously until they hatch. 



In general appearance some of the lizards resemble the 

 salamanders and other amphibians more than they do other 

 members of their own class, and the reptiles are usually closely 

 associated in the common mind with the amphibians. A study 

 .of their body structure, however, shows that they are really 

 more closely related to the birds than to the amphibians. In 

 some of the extinct orders of reptiles the resemblance to birds 

 was quite remarkable from the fact that their whole body was 

 modified to fit them for flight. Some of these flying reptiles, 

 the Pterosauria, attained a great size, having a wing expanse 

 of twenty feet, But that was during the Cretaceous epoch, or 



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