viii INTRODUCTION 



imprisoned giants of the past. Moreover, a great num- 

 ber of the living reptiles are degenerating — adopting 

 subterraneous habits with a consequent loss of eyes and 

 ears. Others have become greatly specialized in the de- 

 velopment of adhesive digits with which to climb, or 

 wonderful instruments for the injection of a deadly 

 virus. Then, in the zenith of their perfection, some of 

 them have gradually swung into secretive habits pro- 

 ducing an incongruous mixture of degenerating form 

 attended by various highly specialized processes. 



As our living reptiles stand, the classification may be 

 outlined as follows: — 



Class Reptilia. 



Order Rhynchocephalia. Represented by a single 

 species inhabiting New Zealand. Lizard-like in form 

 but differing in skeleton and anatomy from all living 

 reptiles. It is the sole remnant of an Order long 

 extinct. 



Order Chelonia. The Turtles (semi-aquatic and 

 marine) and Tortoises (terrestrial) . Over two hundred 

 and twenty-five species are recognized. They are gen- 

 erally distributed throughout temperate and tropical 

 parts of the world. 



Order Crocodilia. The Crocodilians — Crocodiles and 

 Alligators. About twenty-three species. Tropical and 

 semi-tropical parts of the world. All are semi-aquatic. 

 They attain the greatest size and bulk among living 

 reptiles. 



Order Lacertilia. The Lizards; nearly two thou- 

 sand species. The distribution is general throughout 

 tropical and semi-tropical parts of the world — quite 

 sparing in the temperate regions. The habits may be 

 terrestrial, subterraneous, arboreal, or semi-aquatic. The 



