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 Pterodactyls had no more tail than the 



Fig. 44.— Pterodactyl 



modern birds (Fig. tttt), but another kind, called the 

 Rhmnphorynchiis^ had a most preposterous racket- 

 shaped affair, like that of a windmill, which must 

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

 ture ao;ainst the wind, in which direction onlv could 

 they probably fly (Fig. 45). 



