REPTILIA 557 



In the United States there are 234 recognized species and subspecies 

 of snakes. Of this number, 51 species and subspecies are venomous 

 but 13 of these are too small or rare to be considered dangerous to 

 man. Hence, there are 38 kinds in our country that we must avoid. 



Family Leptotyphlopidae (worm snakes).- — Three species belong- 

 ing to this family are found in southwestern United States. In 

 Mexico, Central America, Asia, and Africa, there are about thirty 

 species. One of these, a Syrian species, is the smallest of all adult 

 snakes. Those found in our own country are small, seldom attain- 

 ing a length of more than a few inches. They are all plain flesh, 

 or various shades of pale pinkish lavender in color. An iridescent, 

 silvery sheen extends over all. The head is blunt and of the same 

 diameter as the neck and body. The small eyes are covered by 

 translucent scales. It is probable that they have very poor powers 

 of vision. The tail is likewise blunt and very short. There is a 

 vestige of a pelvis present in some members of the family. 



All of the North American species are burrowers, making long 

 tunnels in which they find insect larvae and worms. They seldom 

 come to the surface except when forced out of their burrows by 

 heavy rains. 



Family Boidae (boas and pythons). — There are sixty to seventy 

 species in this family, some of which are found in all tropical parts 

 of the world. In the United States there are three species, all found 

 in southern California or neighboring desert regions. Our species 

 are all small, but the largest of living snakes are members of the 

 family. There are authentic records of specimens 30 feet long and 

 weighing approximately 300 pounds. There is usually some ex- 

 ternal evidence of vestigial limbs present. Though none are venom- 

 ous, many species have elliptical pupils. All members of the family 

 are constrictors in feeding habits, preferring warm-blooded animals 

 as a rule. The females lay eggs and some species are known to 

 coil about them until the young are hatched. 



Family Coluhridae. — This is the largest of all the families of 

 snakes, containing 90 per cent of the living species. In the United 

 States more than 100 species of snakes belong to this family. Mem- 

 bers of the family range farther north and south of the equator 

 than those of any other family of snakes. Being so numerous and 

 widespread, it is not surprising that some species should have 

 adopted every available habitat. Hence, the variety in size, form. 



