940 16. CROTALWM 



them industriously, with the result that we have never seen 

 one strike more than one-third its own length. The strike 

 however, is almost too quick to be followed by the eye, 

 though the recovery succeeding it is slow. At the same time 

 the snake strikes, its mouth is opened widely and the fangs 

 are thrust forward so that the points are directed outwards 

 at right angles with the vertical roof of the mouth. The 

 mouth is kept tightly closed except during a strike, only the 

 protruding and rapidly vibrating tongue shows, so terrify- 

 ing to the average person. This tongue is a very soft and 

 delicate organ, perhaps tactile in function. 



"The food of the rattlesnake consists chiefly of mam- 

 mals. We found three snakes last summer by following up 

 the excited calls of a number of birds in a rose thicket. The 

 birds evidently had reason to fear the snakes, especially as 

 they were of species which nest on or near the ground. We 

 have never seen the rattlesnake climbing trees, though one 

 individual was climbing through a brush thicket perhaps two 

 feet above the ground proper. It is plainly of too heavy a 

 build to be enabled to climb readily. It is hard enough 

 work for it to squirm its way over the ground. We have 

 never found any bird remains in rattlesnakes' stomachs. 



"On Pine Flats, in the San Gabriel Mountains, a large 

 lazy rattler was secured which showed a tremendous bulge 

 about half-way along its body. Dissection disclosed a full- 

 grown ground squirrel (Citellus beecheyi fisheri) which had 

 been swallowed entire, as is always the case with whatever a 

 snake eats. 



"In the San Bernardino Mountains, the junior author 

 found a small rattler in the act of swallowing an adult 

 meadow-mouse (Microtus). The victim was about half- 

 way protruding from the snake's mouth, and so tightly 

 wedged in as to render the snake unable to get rid of its 

 mouthful when we began to tease it and it wanted to. We 



