244 VERTEBRATE ANIMALS. 



venomous, there are large, grooved fangs placed far back in 

 the mouth upon the upper jaw. 



Of the non-venomous, harmless snakes, we have an excel- 

 lent instance in the common Ringed Snake [Coluber natrix), 

 which is of frequent occurrence in most parts of Europe. 

 Like all the snakes, it is strictly carnivorous, having a special 

 liking for frogs, which it swallows whole. It often takes to 

 the water, and can swim rapidly and gracefully, though, in 

 this respect, it is excelled by the true venomous water-snakes 

 {Hydrophidm), which are adapted to an aquatic life by having 

 a compressed swimming-tail. A well-known American exam- 

 ple of this group is the common Black Snake (Bascanion 

 constrictor). It attains a length of from three to five feet, but 

 is perfectly harmless so far as man is concerned. Other non- 

 venomous snakes, such as the Boas and Pythons, though des- 

 titute of poison-fangs, are, nevertheless, highly dangerous and 

 destructive animals. Their bite is harmless, and they seize 

 their prey by coiling themselves round it in numerous folds. 

 By gradually tightening these folds, they reduce their victim 

 to the condition of a shapeless bolus, which they finally pro- 

 ceed to swallow whole. In this way, a large Python or Boa 

 will certainly succeed in disposing of an animal as large as a 

 sheep or calf, and it has been asserted that human beings, 

 and even oxen, can also be swallowed by unusually large 

 specimens of this family. 



The Boas and Pythons have a horny spur on each side of 

 the vent, and the tail is prehensUe. Their dental apparatus is 

 extremely powerful, giving them a firm hold for the constric- 

 tion of their prey. They are the largest of all the serpents, 

 attaining a length of thirty to forty feet. The true Boas 

 and Anacondas belong to the New World, but the Pythons 

 are confined to India, Africa, and the Indian Archipelago. 



The poisonous snakes are represented by the GrotalidoB 

 of the New World and the Viperidm of the Old World. The 

 common Rattlesnake ( Crotalus horridus) of the United States 

 has the extremity of the tail furnished with a " rattle " or 

 horny appendage composed of several membranous cells of a 

 pyramidal shape articulated one within the other. Before 

 striking its prey, it throws itself into a coil, and shakes its 

 rattle. Another highly-dangerous species is the Copperhead 

 ( Trigonocephalm contortrix). The common European viper 

 {Pelias berus) is hardly fatal to adults, but its bite causes 

 serious inflammation. Highly deadly, however, is the Cobra 

 di Capello or Spectacled Snake [Naja tripudians) of India, as 



