4-8. CROTALUS 



ment, and was regulating his rattle to a considerable extent 

 by what he saw, was manifest from the crescendos and dimin- 

 uendos corresponding to my alternating periods of move- 

 ment and perfect quiet. But there were diminutions, intensi- 

 fications and momentary cessations in the rattle beyond the 

 variations in my movements. My impression was that the 

 tail vibration tended to be irregularly rythmic independently 

 of the stimulus, though my observations were not sufficiently 

 full to establish this surmise. 



"The snake was coiled when I first saw him, but the coil 

 was not the strike coil. Nor did he change his position as 

 long as I watched him. Even the head was moved very 

 little, if at all. So far as I could make out, the only part 

 of him in motion was the tip of his tail. Thinking that as 

 good a test as I could make of my presence as a rattle entic- 

 ing stimulus would be to move slowly and quietly awayj 

 this I did. At about 80 paces from the snake, the trail, 

 curving around a steep slope, took me out of sight of his 

 position and beyond the sound of his rattle. The sound 

 became so faint at this point that I could not decide posi- 

 tively whether it actually stopped or continued but inaudibly 

 to me. I am quite sure, however, from its evenness, that 

 its general intensity of the whir gradually diminished as I 

 moved away. Nor could I tell certainly whether I was in 

 range of his vision the whole time. 



"Why I so unfortunately failed to return a little later 

 to see what was going on, and to take other means of testing 

 the snake's behavior, I do not now recall. Probably I imagined 

 I had more important duties elsewhere, though now I doubt 

 this. The entire time of the observation was something 

 more than 20 minutes. 



"At the time of rattlesnake encounter thus narrated, 

 I was greatly interested in the different behavior of this 

 individual from that of one of the same species I came 



