THE RATTLE, 



305 



cela s'observe dans ceux des animaux ruminants dont la corne 

 revet les chevilles osseuse du veritable coronal prolonge en pointe 

 et devenu de cette fagon une arme d'attaque, et surtout de 

 defence. ' ^ 



Dumeril also tells us that the peculiar structure of those 

 few terminal vertebrae, with their knobs or pads (' botirrelets ') 

 upon which the skin is moulded, tends to a movement lateral 

 rather than up and down, — that quick action which we 

 perceive when the rattle is being vibrated. Thus the horny 

 covering takes the form of this bone with its lobes or bulges, 

 which instead of permitting the supposed cup-like nail to fall 

 off as in our finger illustration, causes the links as they arc 

 pushed out to hang or cling together ; and we can only 

 suppose that the constant action loosens, and not only loosens 

 when dead or detached, but loosens, that is to say, enlarges, 

 the link while growing. For if you examine the spine of a 

 skeleton Crotalus and the rattle that grew upon that spine, 

 you will perceive that the links are a great deal larger than 

 the ^ pihe osseuse stir laqiielle elle a ete en qtielqiie sorte inoulee' 



There is one other peculiarity observable in a detached 

 rattle, which I cannot pretend to explain in any way. If 

 you hold one up by its base or largest link, you will find it 

 invariably hangs in a slight curve and not perpendicularly. 

 You can straighten it, but you will not be able to curve it in 

 the opposite direction, proving that it naturally inclines one 

 way, whether to the right or the left of the animal while living, 

 I cannot assert. But it is a curious feature, and one that 

 can no doubt be accounted for by scientific observers. Thus, 



* Erpetologie generale, tome vii. part, ii, p. 1457, par MM. Dumeril et Bibron, 



Paris. 



U 



