128 TYPES OF ANIMAL LIFE 



traverses each of them. The feeling of anger also doubt- 

 less sets the poison glands secreting, just as the sight of 

 good food will make a hungry man's mouth water i.e., 

 will set similar glands secreting in the man's mouth. The 

 rattlesnake strikes its prey to kill it, and, having struck, 

 waits quietly till it dies. Then it begins to devour it at 

 leisure, not again using its fangs, but only the small teeth 

 before mentioned. It always devours its prey entire, 

 and can swallow an animal much thicker than its own 

 body. In fact, the creature does not so much swallow 

 its prey as slowly drag itself over the creature it devours, 

 being enabled so to do by the elasticity of its skin, 

 and by the extraordinarily loose condition of the teeth- 

 bearing bones of its jaws. Thus the two halves of the lower 

 jaw and the several pieces which compose the upper jaw can 

 be stretched far apart and separately moved, so that, while 

 the dead victim is securely held by some of them, others 

 can be moved and implanted further on, and thus, by 

 degrees, its body is drawn within the gullet of the snake. 

 Even when it has passed into the stomach the form of 

 the prey may be visible for some time, but digestion 

 takes place very quickly. The rattlesnake has no rudi- 

 ment of a limb, and its movements are effected by nothing 

 but its backbone and ribs, with the aid of the muscles 

 thereto annexed (which are very numerous and complex), 

 and that of the large transverse scales which clothe the 

 nbilomen. The ribs are very movable, and their lower 

 ends are connected to the inside of these scales. Thus 

 the snake's motion may in part be compared with that 

 of a centipede, the successive opposite pairs of movable 

 ribs practically serving as so many pairs of feet. It is 

 thus, with the aid of the ribs and scales, that the rattle- 

 snake progresses by taking advantage of the various 

 irregularities of the surface over which it moves. On a 



