CHAPTER I 

 INTRODUCTION 



In most persons the word reptile incites only feelings of disgust 

 and abhorrence; to many it means a serpent, a cold, gliding, 

 treacherous, and venomous creature shunning sunlight and always 

 ready to poison. Our repugnance to serpents is so much a part 

 of our instincts, or at least of our early education, that we are 

 prone to impute to all crawling creatures those evil propensities 

 which in reality only a very few possess. Were there no venomous 

 serpents — and there are but two other venomous reptiles known — 

 we should doubtless see much to admire in those animals now so 

 commonly despised; because a few dozen kinds, like the rattle- 

 snakes, copperheads, and cobras, protect themselves in ways not 

 unlike those used by man to protect himself, we unjustly abhor 

 the thousands of other kinds, most of which are not only innocent 

 of all offense toward man, but are often useful to him. 



There are now living upon the earth more than four thousand 

 kinds or species of cold-blooded animals which we call reptiles, all 

 of which are easily distinguishable into four principal groups : the 

 serpents and lizards, the crocodiles, the turtles, and the tuatera. 

 Their habits and forms are very diverse, but they all possess in 

 common certain structural characters which sharply distinguish 

 them from all other living creatures. A reptile may be tersely 

 denned as a cold-blooded, backboned animal which breathes air 

 throughout life. And yet, it is not quite certain that this defini- 

 tion is strictly correct when applied to all the reptiles of the past, 

 since it has been believed that certain extinct ones may have been' 

 warm-blooded. By this definition, short as it is, we at once 

 exclude a large number of cold-blooded, air-breathing, backboned 

 animals which were formerly included by scientific men among the 

 true reptiles, and even yet are popularly often so included — the 

 amphibians or batrachians. These animals, now almost wholly 

 represented by the despised toads, frogs, and salamanders, were, 



