SNAKES 185 



segments to the rattle is impossible, as the shedding process 

 in the rattlesnakes may occur two, three, four, or even five 

 times in the course of a year, while the terminal segments 

 not unfrequently become detached in the course of their 

 existence. The utility of the apparatus to the creature is 

 somewhat problematic, but is probably of use in warning off 

 approaching enemies, these snakes being of sluggish habits 

 and unwilling to attack, except to secure their prey. Some 

 believe that it serves to call the sexes together, while others 

 suggest that the rattling sounds, which resemble running 

 water, act as a decoy to animals in search of drink. 



Rattlesnakes do not as a rule do well in captivity, for, 

 being of a peculiarly nervous disposition, they refuse 

 all food, and ultimately, unless forcibly fed, in which case 

 they frequently die of shock, starve themselves to death. 



In the snakes of the genus Crotalus the fangs are very 

 highly developed ; they inhabit dry, rocky districts, where 

 they feed almost exclusively on mammals. 



The Common Rattlesnake, C. durissus, of the South- 

 Eastern United States, is the largest species, attaining a 

 length of over eight feet. It is pale grey or light brown 

 above, with blackish rhombs, which are edged with yellow. 

 In spite of the fact that in many parts of its habitat this 

 rattlesnake is very abundant indeed, being in many places 

 the commonest species of snake, accidents from its bite are 

 of very rare occurrence. 



In Sistrurus, which differs from Crotalus in the head 

 being covered with nine large symmetrical shields, and not 

 with scales of irregular size, the fangs are of moderate size. 

 The snakes of this genus, known as the Pigmy Rattle- 

 snakes, are all quite small, attaining a maximum length of 



