34 THE RATTLESNAKE AND NATURAL SELECTION. 
supposed that its persistent rattle was only the whirring of a locust. 
The range in pitch in the rattling sound of the snake is quite 
great ; it is even difficult to understand how sharp it can be from a 
study of the sound made by the animals tamed by captivity, 
at the same time the note of the locust is also very variable so 
that one is not able to discriminate by this means. The reader 
will doubtless have caught the main point towards which these 
facts so plainly tend, namely, that the imitation of the note of the lo 
cust may possibly be of high value to the rattlesnake. The Ci- ; 
cada furnishes the most satisfactory mouthful to many of our birds. 
Almost every observer of the life of our woods and fields, has seen : 
determined notes, are easily misled by sounds which approach 
even though imperfectly, the calls of their species or the sounds 
of their prey, so that the imperfections in the note of a& rat- 
tlesnake when considered as an imitation of the Cicada cannot 
count much as an argument against this view. F 
If this view be correct, then we must regard the rattle of the 
rattlesnake as a useful appendage, and not an instrument cale 
lated to do it injury by warning its prey of its presence.t Bu 
ŽI had an opportunity, recently, of seeing a living Cobra di Capello in a state of © 
The first impression was how entirely unlike any other serpent it was. 
like serpents, would be easily misled by the strange shape of the cobra and fail to $ 
it or even be attracted to 
closely or even smell any strange object. $ 
t Rattlesnakes of the genus Crotalophorus make little or no noise with the im 
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