REPTILES AND AMPHIBIANS 139 



releases it. Very large lizards often escape death in 

 this way. 



The defenceless frog, on the other hand, is completely 

 at the mercy of its enemy, the ringed adder. When 

 one is after him, he makes desperate efforts to escape, 

 his usual measured jumps becoming gigantic in his 

 anxiety. A plaintive cry comes from his throat, and 

 he often abandons himself to his fate by crouching 

 down, when he is seized by the snake. If the snake 

 grasps his head the end is comparatively speedy, but it 

 often seizes the foot first. It then forces itself, as it 

 were, over the leg, its teeth gripping further and further 

 forward ; as these do not serve for masticating but 

 merely for holding, in the snake, and as they are 

 directed backwards, they easily allow anything to enter 

 the mouth but prevent it from dragging or falling out. 

 When one leg has disappeared down the snake's throat, 

 it tries to grasp the other by a quick jerk, and if it 

 succeeds its teeth go farther over the frog's body. The 

 head of the snake swells prodigiously, there is a last 

 desperate croak from the frog, and the jaws close over 

 it like a living tomb. Surprise is often felt that such 

 large frogs can be taken into the small head of the 

 snake, but it is capable of enormous distension at the 

 back ; the anatomic foundation of this is that the bones 

 of the lower jaw articulate with those of the upper jaw, 

 which are drawn out far behind, and enlarge the gullet 

 considerably when they open across. 



Poisonous snakes go to work in a different way. 

 These hunt almost entirely during the night, as they 

 are generally nocturnal animals. The best way to catch 



