REPTILES AND SNAKE-STONES. 5 



not trouble us to investigate, the above broad fea- 

 tures of distinction being sufficient for general 

 purposes. Huxley appaars to rely chiefly upon this 

 distinction, that Reptilia are " devoid through life of 

 any apparatus for breathing the air dissolved in 

 water," and the Amphibia are "always provided at 

 a certain period, if not throughout life, with bran- 

 chiae." 



The heart and blood are two important points of 

 difference between reptiles and batrachians and the 

 higher vertebrate animals. These former are all cold- 

 blooded. They possess a heart, it is true; but, as 

 compared with higher organisms, an imperfect one, 

 inasmuch as it has but one ventricle ; the result of 

 this is that respiration is imperfect, and as respira- 

 tion gives heat to the blood, which in turn sustains 

 the heat of the body, it follows necessarily from their 

 organization that the temperature should be very 

 low. Let a frog leap upon your hand, or take a 

 newt between your ringers, and the chilly, smooth, 

 apparently slimy appeal to the sense of touch will 

 carry conviction far swifter than argument. 



In being oviparous, or producing their young from 

 an egg, these creatures agree with birds as well as 

 fishes ; but in some instances the outer covering of 

 the egg, then only a thin membrane, and not a hard 

 shell, is broken at the moment it issues into the 

 world, and the lively young escape, in all respects 



