The Rattlesnakes 



of the Southwest there are few areas where more than one species 

 occurs except on the borders of the ranges of the different 

 species, where the distribution of one may extend a slight distance 

 into that of another. 



Several species of Rattlesnakes inhabit Mexico and Central 

 America that are not found in the United States. One large 

 and very handsomely coloured species is confined to South 

 America. With the exception of one Mexican species extending 

 southward into that continent, this is the only South American 

 Rattlesnake. 



The Rattle. Compared with all other genera of serpents, 

 the rattle is a unique appendage. The closest approach to it is 

 the well-developed spine existing on the tail of many snakes. 

 The natural use of the rattle remains unknown. To presume 

 that the snake is provided with this appendage to warn enemies 

 away from its formidable fangs, is to fall in line of very bold theory. 

 Nature has no apologies to make for the distribution and ex- 

 istence of Her creatures whether innocent or dangerous, and 

 She is not lavish in placing danger signals to guard the unwary. 

 The argument has been advanced that the rattle is used as a 

 call, during the breeding season, which is not illogical, as snakes 

 are not wholly deaf, although lacking external ears. They 

 appear to appreciate the vibrations of certain sounds possibly 

 with the aid of the delicate tips of the tongue or by means of a 

 sensitive development of the scales. From the examinations 

 of freshly captured snakes, it appears that the rattle is used but 

 little in a state of nature, for it rapidly shows traces of wear and 

 breakage in the frequent use of it by caged specimens, though 

 it may have been quite perfect at the time of their capture. 

 Many snakes, both venomous and innocuous, vibrate the tail 

 when greatly angered. The Rattlesnake does likewise, hence 

 the "warning" sound. There are good arguments point- 

 ing to the occasional use of the rattle to decoy prey within 

 the reach of the fangs but it is the writer's purpose to 

 explain what is actually known about the rattle and not to 

 enter into theory. 



A persistent and popular idea is to the effect that the age 

 of a snake may be told by counting the rings or segments of the 

 rattle. With the majority of specimens, such calculation is 

 impossible. In the case of certain specimens a definite idea of 



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