THE SNAKES 215 



Number 



of Distribution 



species 



Genus Bitis 8 species Africa. 



Genus Pseudocerastes 2 species Persia. 



Genus Cerastes 2 species Northern Africa; Arabia; 



Palestine. 



Genus Echis 2 species So. Asia; Africa north of the 



equator. 



Genus Athens 3 species Tropical Africa. 



Genus Atractaspis 11 species Tropical and South Africa. 



Subfamily Crotalince (Vipers 

 with a deep pit between the 

 eye and nostril. New and 

 Old World). 



Genus Ancistrodon i 10 species Eastern North America; Mex- 

 ico and Central America; 

 borders of the Caspian Sea; 

 Asia. 



Genus Lachesis i 40 species Central and South America; 



S. E. Asia. 



Genus Sistrurus 3 species U. S.; Mexico. 



Genus Crotalus 15 species United States; Mexico; Cen- 

 tral America and South 

 America. 



Family Typhlopidce: The small, shining, burrowing 

 members of this degenerate family are more like worms 

 than snakes, looking like many of the degraded lizards 

 we have previously noted. The entire body, both above 

 and beneath, is covered with smooth, rounded, overlap- 

 ping scales ; the eyes are hidden, really buried under the 

 head shields ; the tail is short and stubby. As compared 

 with other snakes, the skull is very simple — not at all 

 fitted for the swallowing of large prey. The jaws are 

 altogether toothless with the exception of a few teeth 

 on the transverse edges of the maxillary bones — these 

 situated almost over what corresponds to the palatine 

 region; in consequence, the prey is restricted to insect 



i Further investigations of anatomical characters may render it advisable 

 to separate the New and the Old World species into distinct genera, this 

 relating particularly to Anciai-^don. 



