HOW ANIMALS DIGEST. 



603 



ing the huge mouthful down its throat. But how shall the act be ac- 

 complished with no limbs to assist ? As the under jaw divides in front, 

 and articulates with the skull by the intervention of extra movable 

 bones, the mouth and throat can stretch enormously. The sharp, coni- 

 cal teeth are recurved, acting like the barb of an arrow to hold what- 

 ever position is gained. Each side of the jaw is pushed forward in 

 turn and gains a new and further hold on the carcass, which by suc- 

 cessive slight movements is slowly pulled head first down the gullet. 

 The common striped snake seizes a toad or frog, however he can catch 

 him, usually by one or both hind legs, and immediately proceeds to 

 " take him in," despite all protests and struggles. 



Fig. 2. Skuli, op a Serpent {Python) : 6, articular portion of the lower jaw ; a, quadrate bone ; 



c, squamosal portion of the temporal bone. 



As the opposite of the enormous throat of the snake, the bulky 

 whalebone whale has the smallest throat, proportionate to its size, of 

 any animal just large enough to admit the tiny creatures which are 

 its food. We see in this a fine example of Nature's economy. 



The alligator has a curious way of preventing the admission of water 

 when swallowing prey. Seizing a fish or other small creature, the rep- 

 tile rises to the surface of the water and flings it into the air ; then, 

 before it reaches the water, catches it and gulps it down. If the prey 

 is too large to handle in this manner, it is carried to the shore to be 

 devoured. 



Ingluviation. Many animals can not procure their particular food 

 at all times. Such either can endure fasting, like members of the cat 

 tribe, or have a special reservoir, as shown in the crop of a fowl. This 

 crop is only a dilatation of the gullet. In the cormorant, the whole 

 gullet is very capacious, for the purpose of storing fish; on account of 

 which habit the bird has become a type of voracity. The pigeon has 

 its crop divided into two perhaps to give a better form for flight. 

 The pelican has a bag beneath the lower jaw. Many small animals, 

 insects especially, have crops. Similar in purpose is the first stom- 

 ach, or paunch, of a cud-chewer. Birds which eat fruit, insects, or 

 other food readily procured, and of a character which needs no delay in 

 digestion, have usually no crop, or but a rudimentary one. 



