FOOD OF REPTILES AND BIRDS 71 



widely, the two lower jaws being conneetcd by an extensile 

 elastic ligament. All the teeth are reenrvcd, and first one 

 half of the lower jaw is pushed forward and then the oilier, 

 and gradually hke a man climbing up a rope hand over hancl 

 the snake creeps over its food. When the snake has passed 

 its mouth over the victim, the neck may be tremendously 

 extended, every scale starting apart. In order to assist in 

 swallowing there is a great discharge of saliva, and in order 

 that the reptile should not be choked, the entrance to its 

 air pipe is placed far forward and can be protruded between 

 the two lower jaws while they are at work. 



Some birds and mammals are immune to snake poisons 

 and some snakes are harmless. The origin of the group is 

 obscure, but the poison habit is certainly an acquired one 

 and not inherited from their remote ancestors. Well, as 

 Sancho Panza reminds us, "we are as God made us, and 

 some of us even worse." 



Lizards vary greatly in their diet, the majority feeding on 

 insects, worms, and occasionally small birds and mammals; 

 but some are herbivorous, and then the intestine is unusually 

 long. Of the three English species, the young of the common 

 lizard, Lacerta vivipara — the only reptile foimd in Ireland — 

 feeds upon aphides and other minute insects, the adult eats 

 larger insects and the sand lizard, Lacerta agilis, feeds on 

 insects throughout its life. The slow-worm or blind lizard, 

 Anguis fr agilis, which is so often mistaken for a snake, is 

 fond of slugs. 



Birds, like lizards, are sometimes carnivorous, sometimes 

 herbivorous, and sometimes both. They do a great amount 

 of destruction in our gardens and orchards, and our cornfields, 

 but the species of birds are so numerous and their habits are 

 so diverse that it is difficult to generalize about them. As 

 they have only a beak to help them to pick up their food, they 

 prefer as a rule something easily picked up, such as seed, 

 although of course the great vultures hold their victims in 

 their claws and tear the flesh off with their beaks. Young 

 grouse feed exclusively on insects till the end of their third 

 week, when they become weaned and take to a diet of heather- 

 tops with which by accident may be mingled a certain number 



