TAILS 85 



This horny shield reminds us that rattlesnakes 

 have a series of horny rings upon the end of the tail,- 

 by vibrating which a buzzing sound is made that is a 

 warning or threat of anger or attack. Some harmless 

 snakes rapidly vibrate the tail against a dead leaf or 

 other object and thus produce a similar sound for 

 similar purposes — ^perhaps an imitation. Many others 

 vibrate the tail, but not necessarily against anything. 



Among the extinct flying reptiles, the kind known 

 strictly as the Pterodad/yls had no more tail than the 



Fig. 44.— Pterodactyl. 



modem birds (Fig. 4A), but another kind, called the 

 RhanvphoryncJms, had a most preposterous racket- 

 shaped afEair, like that of a windmill, which must 

 have been used as the tail of a kite to hold the crea- 

 ture against the wind, in which direction only could 

 they probably fly (Fig. 45), 



