SERPENTS. 385 



birds, reptiles, and even insects and worms. During the cold season 

 these Eeptiles remain benumbed in holes, where several are often 

 found entwined together. They are most frequently seen on the 

 first fine days of spring, warming themselves in the sunshine ; but 

 when the weather becomes very hot, they are rarely to be met with. 

 The bite of the Viper is very dangerous. 



The family of Boas (Boid&) contains a considerable 

 number of species, upwards of forty being described 

 in the catalogue of the British Museum. They are, 

 generally speaking, the largest of all the Serpent 

 tribe, and are characterized by several distinctive 

 marks. The greater number of them have a pre- 

 hensile tail, which, though short, is excellently fitted 

 for grasping the branches of trees. They possess 

 rudimentary hind extremities, which are developed 

 under the skin. These consist of several small bones, 



FlG. 317. VENT AND HOOK OF BOA. 



terminated by a horny spur, not unlike the spur of a 

 fowl in miniature ; these little claws project exter- 

 nally a little in front of the vent (Fig. '617). Their 

 body is well adapted for twisting and twining round 

 other objects, and the scales that cover it are small 

 and numerous. 



The Boa Constrictor has the upper jaws and palate bones lined 

 with teeth, all of which are very sharp and pointed backwards. 

 Each side of the lower jaw is likewise armed with teeth, all directed 

 towards the throat. It must be evident, from a mere inspection of 

 these teeth, that they can be of little use in holding, much less in 

 destroying such strong and large animals as the Boa devours, and 

 upon a little reflection we shall find that they are intended for a 

 very different purpose. These serpents are said to watch in the 

 forests, and especially near the drinking-places of rivers, there 

 hanging from a tree, until some quadruped passes within range. 



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