54 COLUBEROIDEA. 



in common, that it is not easy to seize upon any sufficiently distinct and important 

 to arrange them in separate genera. Thus the teeth, Avhich are the basis of such 

 arrangements in the mammaha, are here nearly similar in all — simple, solid, and 

 fixed to the bones — consequently do not afford characters sufficient for classifi- 

 cation. 



Other characters have, consequently, been sought, as the form of the head, 

 whether distinct or not from the body — the form of the cephalic plates — the shape 

 of the body — the number of abdominal plates — the form of the dorsal scales, 

 whether carinated or not; the number of sub-caudal scutellse or bifid plates, &c. 

 These characters, though of less consequence than those drawn from the teeth 

 of mammalia, are here tolerably constant. 



In fact, it is the want of obvious determinate characters, proper for the 

 establishment of genera, that has led to so much confusion in this department 

 of herpetology by introducing a useless number of genera, almost as many as 

 there are individuals in the family. 



