84 



STORY OP THE REPTILES 



tie themselves almost as if with a string while they 

 hurl their remaining length almost as a bolt upon 

 their prey below them. 



In some burrowing snakes the tails are very short 

 and blunt ; and in one family— rthe shield-tails (Fig. 

 43) — there is a shieldlike button at the end which 

 better enables them to push the body through the 



Fig. 43. — ShieM-taXl snake {Silyhuramacrolepus). These remarkable 

 snakes look as though their tails had been cut short off. In some 

 species the body ends in a naked disk, in others with a rough 

 ^homy point, in others again, as in the species illustrated, the disk 

 is covered with keeled scales. 



*arth. Others have a sort of horny tip for the same 

 purpose, as our common pine snake, and in some cases 

 in the Old "World kinds there are broad scales beneath 

 with sharp, backward -set spines on them which are 

 helpful in pushing the creature along or in. 



