198 REPTILES OF THE WORLD 



being very elastic, stretches to receive it. As soon as 

 the prey reaches the snake's throat, a lateral undulatory 

 movement of the neck commences, which literally seizes 

 the creature in suctorial fashion, greatly assisting the 

 now thoroughly distended jaws. At this stage of the 

 feeding, the lever-like suspension of the lower jaw bones 

 has been greatly strained from its normal setting and it 

 is possible the lower jaw forms but a tight band about 

 the prey, the upper jaw alone pulling in the animal — 

 assisted by the movements of the neck; the eyes bulge 

 and the skin of the neck is so distended as to widely 

 separate the rows of scales; at frequent intervals the 

 snake pauses to rest, when it forces, from between the 

 animal and lower jaw, the tubular breathing appendage. 

 One or two good breaths are taken, then commences 

 again what seems like a most heroic task. Finally the 

 sinuous movements of the throat engulf the heavy prey. 

 The head quickly assumes its normal aspect, only a few 

 flabby folds of skin denoting the astounding feat that 

 has taken place. A yawn or two effaces all traces of the 

 task except the distended portion of the body, slowly 

 forcing the prey to the stomach by a combination of 

 undulatory movements and an anterior pressure caused 

 by drawing the muscles together. 



In this swallowing performance we note one of the 

 characteristics relating to the snake's anatomy that is 

 markedly different from the structure of any of the 

 lizards. Another ophidian character is the absence of 

 eyelids. Thus, the eyes of a snake are always open and 

 a sleeping serpent may be awakened by seeing a sudden 

 movement. The eye is covered with a transparent cap 

 which is shed at each casting of the skin; under this 

 glassy cap the eye is capable of considerable movement. 

 Yet another difference between snakes and most lizards 



