126 TYPES OF ANIMAL LIFE 



moult, while more than one moult takes place in each 

 year. Thus the rattle ultimately consists of a number of 

 dry, hard, more or less loose, horny rings. The older of 

 these wear away in time and are lost, but a snake may 

 have as many as twenty-one rattling rings. 



It is the shaking of these rings by a violent and 

 rapid wagging of the end of the tail that produces the 

 noted sound a sound which may be compared to the 

 rattling of peas quickly shaken in a paper bag But this 

 habit of shaking rapidly the end of the tail is by no 

 means peculiar to the rattlesnake. It occurs in many 

 other species of serpents, both venomous and harmless 

 ones. It is probably a natural and spontaneous result of 

 emotional excitement, like the wagging of a dog's tail. 

 Any nervous excitement tends to produce some bodily 

 movement, and naturally results in the motion of any 

 part most easily moved as the end of the tail, whenever 

 a due supply of muscle exists to produce it. The mean- 

 ing or use of the rattle is a problem still awaiting solution. 

 It has been supposed to be useful in paralysing animals, 

 through terror excited by the sound ; in arousing curiosity 

 and so bringing animals within its reach ; as enabling 

 the sexes to find each other; or by saving the snake 

 from attack when its power of offence temporarily has 

 been exhausted. But no sufficient evidence known to us 

 lends adequate support to any of these ingenious specu- 

 lations. 



Among the various species of rattlesnake is the kind 

 called the "horned rattler," on account of a pair of 

 horny prominences it possesses, one above each eye. It 

 is found in California and Mexico. 



The deadly bite of the rattlesnake is effected by means 

 of a very ingenious and simple mechanism. It is a 

 popular error to suppose that the rapidly vibrating cleft 



