144 TYPES OF ANIMAL LIFE 



We have now advanced considerably in reply to our 

 question: "What is a rattlesnake"? We have seen 

 what it is in itself and what is its position in the whole 

 order of serpents. We now know that rattlesnakes form 

 a portion of that subordinate division of viperine snakes 

 which are known as pit vipers. We know that, poisonous 

 as they are, they are not more so than some kinds of the 

 great group of mostly harmless snakes, which goes by 

 the name of colubrine. We have seen their relation to 

 the other sections, and how they differ from the boa-like 

 snakes and worm-like snakes. It only now remains to 

 consider what a rattlesnake is in so far as it is a snake, 

 and what are the relations which it thiis bears to other 

 reptiles. 



Reptiles are creatures which form a class by them- 

 selves, but one which had very special relations with the 

 state of this planet at epochs so remote that the imagina- 

 tion has no warrant for an attempt to express it even 

 in centuries. Of all reptiles, some of the most important 

 orders — flying reptiles, marine reptiles — have entirely 

 passed away and left no living representative. 



Now, on the principle of evolution, the most important 

 and interesting questions are : How snakes came to be ? 

 and. What creatures may regarded as their special 

 ancestors ? 



Ancient fossils throw but little light on these questions, 

 for although the secondary period may be called the age 

 of reptiles, snakes are not known with certainty to have 

 had any place in it, nor yet any creatures which can be 

 affirmed to have been the special predecessors of serpents. 

 Nevertheless, in the latter part of the secondary deposits 

 (which deposits ended with the chalk) a few reUcs have 

 been found in Europe, and more in America (New Jersey, 

 Alabama, and Kansas) of certain four-limbed reptiles 



