REPTILIAN LIVERIES. 159 



that a truly terrible aspect is assumed, calculated, 

 especially when backed by the very serviceable 

 looking teeth, to make most foes deliberate before 

 pressing attack further. 



That signs other than colour are sometimes 

 adopted for warning purposes we have just seen 

 in the case of the frilled lizard. The deadly 

 Eattle-snakes (Crotalus) and the equally poison- 

 ous Cobra (Nqja\ are further cases in point. 

 Protective coloration has been adopted, as in 

 the foregoing instances, as a first-line of defence, 

 and when this is broken through, they fall back 

 upon the second warning tactics. The device of 

 the rattle-snake is the production of peculiar 

 shrill sounds produced by a number of horny 

 "bells" loosely jointed and fitting closely one 

 into the other. These bells, which may be as 

 many as twelve in number, have a curious origin. 

 "The oldest terminal bell," says Dr Gadow, "is- 

 in reality the horny covering or tip of the tail, 

 and with each moult or shedding of the skin the 

 youngest bell becomes loose, but is held by the 

 new covering which has been developed in the 

 meantime. There is thus produced an ever- 

 increasing number of loosely joint ecj bells, but 

 every now and then most or all the bells break 

 off, probably when they are worn out, and a new 

 set is developed." The noise made by this rattle, 

 when the weather is dry is very considerable ; 

 so much so that in a room a vigorous snake can 

 make conversation almost impossible for half an 

 hour or more. During this time the rattle is 

 kept in such rapid vibrations that it shows only 

 as a blurred image. By this means possible 



