112 REPTILES AND BATRACHTANS 



appear on the surface after heavy showers, when they 

 search for the worms upon which they live. Their eggs, 

 deposited in burrows several inches underground, are 

 remarkable for their large size. 



Although these worm-like creatures cannot be regarded 

 as derived from any of the lizards with which we are 

 acquainted, they show relation to them in being provided 

 with rudiments of the hip-girdle, a character in which 

 they agree with the following family — the Boid^. 



The Boa family, represented in all tropical countries, 

 includes the largest snakes, and combines, with a much 

 higher organization than the preceding, vestiges of hind 

 limbs, which in many cases terminate in a claw-like spur, 

 visible externally. 



They are all constrictors, killing their prey by throwing 

 their coils around them and crushing them to death, 

 and consequently their bodies are usually thick in propor- 

 tion to their length, owing to the presence of strongly 

 developed muscles from which they develop their crushing 

 power. The very largest of these snakes, which may 

 measure thirty-five feet in length, although able to over- 

 power very big animals, of the size of a bull, have not 

 sufficiently wide a gape, even when fully expanded, to 

 permit them to devour anything much larger than a goat 

 or small antelope, and the accounts of their swallowing 

 feats have often been much exaggerated. 



The family is divided into two sub-families — the 

 Pythonince, in which a bone above the eye, the supra- 

 orbital, is present, and the Boince, in which it is absent, as 

 in all other snakes. The allies of the Pythons may be, as 

 a rule, further distinguished from those of the Boas by 



