2540 SCALED REPTILES 



is the absence of typical vipers, and the abundance of pit vipers, although several 

 genera of the latter are common to Asia. Europe and Northern Asia are compara- 

 tively poor in snakes, but (next to Africa) are characterized by the number of typ- 

 ical vipers and colubrine water snakes. 



Although a few members of the suborder subsist on eggs, snakes as 

 a rule capture and devour living animals, which are in all cases swal- 

 lowed whole, as these reptiles have no apparatus for rending or masticating their 

 food. And it is in order that they may be able to swallow larger animals than 

 would otherwise be possible, that they have the power of dilating their jaws in the 

 manner already indicated. Not only can the jaws be thus enlarged, but the throat 

 and stomach are capable of dilatation, owing to the circumstance that the lower 

 ends of the ribs, from the absence of a breastbone, are quite free; and in swallow- 

 ing, a snake seems gradually to draw itself over the object to be devoured. The 

 majority of snakes devour their prey alive, and a frog may be seen struggling in the 

 stomach of a common English water snake long after it has been swallowed. Other 

 snakes, however, kill their prey either by striking it with their poison teeth, after 

 the manner of the vipers, or by encircling and smothering it in the folds of the 

 body, like the boas. Although the process of digestion is very rapid, snakes feed 

 but seldom; and it has been asserted that two or three frogs are sufficient to supply 

 the needs of the English water snake for a whole year. All snakes drink much, 

 water being absolutely essential to their existence. 



As might have been expected from their numbers, snakes exhibit great 

 diversity in their modes of life; and while those of the tropical regions remain active 

 throughout the year (unless they lie by during periods of drought) the species in- 

 habiting colder regions hibernate during the winter. The most remarkable diver- 

 sity from the ordinary mode of ophidian life is displayed by the blind snakes, which 

 lead a completely subterranean existence, very seldom making their appearance 

 above the surface. The great majority of serpents are terrestrial in their habits, 

 seldom entering the water or climbing trees; and these ground snakes, as they may 

 be called, are characterized by their cylindrical form and the width of the shields on 

 the inferior surface of the body. Tree snakes, on the other hand, which are mostly 

 remarkable for their brilliant coloration, lead an almost completely arboreal life. 

 Frequently they have the body very slender, or the shields on its under surface 

 may be keeled in order to afford a firmer hold in climbing; in other instances the 

 tail is prehensile. It is among this group that the egg-eating species are found. 

 Then, again, we have fresh-water snakes, which swim and dive with facility in the 

 waters of rivers and lakes, where they spend a large portion of their time, feeding 

 on such aquatic creatures as they can capture therein. As a rule, these snakes are 

 distinguished by having the nostrils placed at the top of the muzzle, and likewise 

 by the tapering form of the tail. Lastly we have the sea snakes, which, while hav- 

 ing the nostrils situated as in the last group, are distinguished by the lateral com- 

 pression of their tails. In all cases extremely poisonous, these snakes are almost 

 entirely pelagic in their mode of life, and seldom approach the land, although in 

 one genus the shields on the under surface of the body are sufficiently developed to 

 admit of terrestrial progression. 



