HISTORY AND DISTRIBUTION. 13 



ooze, at the bottoms of rivers, lakes, and oceans. In the rock 

 strata below the Cretaceous we find no traces of fossil snakes, 

 so we naturally conclude that snakes were evolved from reptiles 

 with legs about this period, or Epoch, in the history of the Earth. 



From Cretaceous times up to the present, snakes have evi- 

 dently been on the increase, not only in numbers, but species, 

 judging by the comparatively few fossil snakes found. There 

 are at present about 2000 species or kinds of snakes scattered 

 over the countries of the world, with the exception of New 

 Zealand, where they have never been known to exist. Snakes 

 are most abundant in the tropical and semi-tropical portions of the 

 globe, in districts where forests and rank vegetation abound, for 

 it is there they find an abundance of food and suitable shelter, as 

 well as the necessary warmth to quicken their sluggish vitality. 



Extinct species of snakes of the Cobra family have been found 

 in the Lower Miocene rocks in Germany. Others of non- venomous 

 species have also been discovered in the same formation. In 

 Turkey and America fossil remains of snakes of the Crotaline 

 sub-family have been unearthed. 



Snakes and Lizards. 



In outward appearance the limbless lizards resemble snakes 

 in possessing tapering snake-like bodies, and being destitute of 

 legs. Nobody would mistake a lizard with legs for a snake ; 

 but to those people who have not made a study of the anatomy 

 of snakes and Hzards, those lizards which are destitute of legs are 

 invariably mistaken for snakes. 



The general appearance of any ordinary snake is such that 

 a person of average intelligence will immediately recognize it 

 correctly. There are, however, famihes of snakes known as the 

 TyphlopiidcB and Glauconiidce, which are very worm-hke in 

 appearance, and might easily be mistaken for legless lizards or 

 worms. In fact, the older naturalists classified them as lizards. 



Snakes differ from lizards in the following ways : — 



(i) The two parts of the lower jaw are attached in front by 

 elastic ligaments, permitting the separation of the two halves of 

 the lower jaw, for the purpose of permitting large prey to be 

 swallowed. In the lizards these bones are solidly united in 

 front. 



