2 20 SNAKES. 



claw, as seen in the boa constrictor, the pythons, and some 

 of the blind-worms, and usually more developed in the male. 

 There is, however, the true skeleton of a claw beneath the 

 skin, composed of several bones, and presenting somewhat 

 the form of a bird's claw, hinting at the common ancestry 

 between snakes and lizards. These spurs, though mere 

 vestiges of limbs, must still be of some use to the large 

 constrictors when climbing trees and hanging from the 

 branches. They are found in the boa, python, eryx, and 

 tortrix, four groups which approach the lizard characteristics; 

 also in Boa aqiiatica, the anaconda. 



