214 



VERTEBRATA 



than the lizards, and with the exception of very few species 

 possess no remnants of hind limbs. 



The family Colubridce includes most of our harmless 

 snakes. The commonest of our garter snakes (Thnmnophis 

 sirtalis) frequents yards, gardens, and fields hi search of 

 mice, frogs, and insects. Like all snakes, they swallow 



their prey whole 



and sometimes 

 alive. The lower 

 jaw is so loosely 

 attached to the 

 skull as to permit 

 the throat to be 

 greatly enlarged 

 and the alimentary 

 canal may likewise 

 become much ex- 

 panded owing to 

 the fact that the 

 ribs are not artic- 

 ulated to a breastbone, as in birds and mammals, but 

 terminate freely. The prey after being swallowed may 

 remain alive some time in the stomach. I once shot a 

 water moccasin (Natrix sipedon) and upon opening the 

 stomach an hour later found seven fish, three of which 

 swam away when placed in water. 



The milk snake or spotted adder (Lampropeltis triangu- 

 laris) frequents the neighborhood of houses, and is often 

 mistaken for the copperhead pilot. When disturbed it 

 mimics the poisonous snakes, but is entirety harmless. The 

 black snake or blue racer (Bascanion constrictor) frequents 



FIG. 245. A garter snake two feet long and the 

 frog which it swallowed. Photograph. 



