KEPTILIAN MODES OF EXPRESSION. 101 



What, then, is the raison d'etre of this rattle ? It is not itself a weap- 

 on, nor lias it anything to do with the mechanism or effect of the poison- 

 fangs, for it is not sounded when a stroke is made in a natural and un- 

 alarmed way, for the sake of killing food. The composure with which 

 mice and squirrels listen to this strong and characteristic racket argues 

 this by inference, as showing that they do not connect the sound with 

 any idea of harm. If it is true that the tendency to make rattles in this 

 group of ophidians has been "seized upon by natural selection and made 

 functional," then it seems to me that everything goes to show that this 

 function is not for foraging, but is, first, one of defence through a defiant 

 warning, and, secondly, a means of calling the sexes together, thus min- 

 istering to the propagation of the race. 



Fear, or the restless desire for companionship, are the only influences 

 that evoke sounds from serpents or any other reptiles. The batrachians 

 may croak and pipe for fun, but the bellowing of the pine-snake, the 

 blowing of the hog-nose,* the hissing of the black and various grass snakes, 

 is only heard when they are calling to the other sex in the pairing season, 

 or when they are attacked. The rattlesnake, however, has no voice, can 

 make none of these sounds with his throat, so that his means of communi- 

 cation and expression are confined to his rattles, and the more j 7 ou attack 

 or annoy him, the louder is his utterance of protest. This is to be seen 

 plainly with fresh captives, full of alarm at confinement and observation. 



A strong illustration occurred on one occasion when I was one of 

 a party encamped in southern "Wyoming, where these serpents were 

 most plentiful among the sage-brush. Going a short distance from my 

 tent one evening, I was suddenly moved to make a most active leap by 

 the baleful whir of a rattler just beside me. Regaining my composure, 

 and returning to the charge with my revolver in my hand, I found that 

 his snakeship had betaken himself to a gopher-hole, where I could hear 

 a lulled crepitation. Stamping above the burrow caused the tune to as- 

 sume a crescendo instantly, whereupon I sent down a long .032 to further 

 wake up the musician. His rattling now was loud and rapid. I fired a 

 second time, and the song accelerated until all rattling blended into a 

 steady buzz. If I had hit him I hadn't killed him, it was evident, so a 

 third ball and stream of fire was shot down the hole. Out of the report 



* An entertaining and suggestive account of the way this harmless snake behaves when 

 threatened with harm appears in Science, vol. iii., p. 254. Instead of fleeing, it flattens its 

 head, hisses, springs menacingly, and snaps fiercely ; its tail vibrates rapidly, and should 

 there be any dead leaves against which it may strike, the noise will be greatly similar to 

 that of the rattlesnake, which it seems really to imitate as a deliberate measure of safety. 



