THE VIPERS 2601 



inhabits the desert regions of Northern Africa, Southwestern Asia, and India, 

 being replaced in Arabia and Palestine by E. colorata. 



The most remarkable peculiarity of this viper (which, however, it may possess 

 in common with the horned vipers, since the scales of the latter have a similar 

 structure) is its power of making a curious, prolonged, almost hissing sound, 

 produced by rubbing the folds of the sides of the body one against another, when 

 the serrated lateral scales grate together. That this is the true cause of the sound 

 may be proved by twisting the body of a dead specimen, and thus causing friction 

 between the scales. Sir J. Fayrer writes that this species is a very fierce and vicious 

 viper; it throws itself into an attitude of defense and offense, coiled up like a spring, 

 rustling its carinated scales as it moves one fold of the body against another. It is 

 aggressive, and does not wait to be attacked before darting its head and body at its 

 enemy, the mouth wide open, and the long fangs vibrating, thus presenting a most 

 menacing appearance. It is very poisonous, and there can be little doubt that it 

 destroys many human lives, as men are much more exposed to contact with this 

 species than with Russell's viper. 



The dreaded rattlesnakes of the New World are our first repre- 

 sentatives of the subfamily of pit vipers ( Crotalincs) , which are com- 

 mon to Asia and America, and are characterized by the presence between the nostril 

 and the eye of a deep pit in each loreal shield, the physiological significance of 

 which is still unknown. All have triangular broad heads and short thick bodies. 

 The Asiatic representatives of the group are less deadly serpents than their Ameri- 

 can relatives; while the only vestige of the rattle of the latter to be found* in the 

 former is a small horny spine at the end of the tail of one species. Many of the 

 Indian species are arboreal in their habits; their coloration assimilating to that of 

 the foliage and boughs among which they dwell. As regards their geographical 

 distribution, pit vipers present a curious similarity to bears and deer; and since 

 they are most abundant in the Oriental region, and also more numerous in North 

 than in South America, Mr. Wallace is of opinion that the group originated in the 

 Indo-Chinese countries, and thence spread northeastward to North America, and so 

 onward to the southern half of the New World, which area, having been the last to 

 receive the group, has not had time, in spite of its extreme fitness for reptilian life, 

 to allow it to attain its full development. 



The rattlesnakes are sufficiently distinguished from their allies by the jointed, 

 horny appendage at the end of the tail from which they derive their name. In the 

 young rattlesnake the tail terminates in a somewhat nail-like "button,"' which in 

 a perfect rattle remains at the tip, the various rings, which may reach to twenty or 

 more in number, being gradually interpolated between this and the scaly portion of 

 the tail. More or less symmetrical in form, the rattle is composed of hollow, horny 

 rings, somewhat like quill in substance, which are interlocked with one another, 

 and are yet so elastic as to allow a considerable amount of motion between them. 

 The various rings do not appear to be formed with any regularity, sometimes sev- 

 eral being added in a single year, while at other seasons but one is developed; 

 neither does there seem to be any relation between the growth of the rattle and the 

 changing of the skin. That very large rattles must, however, belong to old snakes 



