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REPTILTA. 



Genus I. Boa, Lin. 



Under part of the tail and body furnished with a simple 

 uninterrupted band of scales ; body compressed ; two hooks 

 near the extremity ; tail prehensile. 



Genus II. Coluber, Lin. 



Plates beneath the tail, arranged in pairs. Two subge- 

 nera. The subgenus Python is of great size, and has hooks 

 near the extremity ; the subgenus Coluber proper is of small 

 size, has no hooks, and large plates upon the head. 



Section II. Venomous. 

 A gland placed under the eye secretes a poison, and dis- 

 charges it by a canal, whose extremity opens into a duct or 

 gutter channelled in certain teeth of the upper jaw called 

 movable fangs ; the animal, at will, can conceal them in a 

 fold of the gum ; besides these there are, in the upper jaw, 

 two ranges of palatine teeth. Two genera. 



Genus I. Crotalus, Lin. 



Rattles at the extremity of the tail, as many as seven or 

 eight, very rarely ten. A small rounded pit behind each 

 nostril. [America.] 



Genus II. Vipera, Daud. 



No rattles at the extremity of the tail nor rounded inden- 

 tation behind each nostril. Two subgenera. 



Subgenus Viper proper. 



Small granulated scales on the top of the head. 



Subgenus Naia. 



Head furnished with plates ; anterior limbs susceptible of 

 being raised up and drawn forwards, so as to dilate this part 

 of the body into a disk more or less broad. 



FAMILY III. NUDA. 

 Consist of a single genus. 



Cœcilia, Lin. 



So called because their eyes are so small as even to seem 

 to be wanting ; scales so small that the skin appears to be 



