n 



The shields on the heads of the various 

 genera of Colubridae are regular in pattern, and 

 identification of the different species can only be 

 done by minute comparisons of the comparative 

 sizes of the different shields in relation to one 

 another. The shapes of the heads in this large 

 family are very variable, some being spade-shaped, 

 some elongate, some oval, a few rounded, some 

 triangularly elongate, and some pointed. 



The Amblycephalidae have enlarged but a rough 

 regular shields, such as those found on the classification 

 Colubridae, and their heads are club-shaped. The Cf thVheads^ 

 snakes of the family Viperidae have mostly ^^^,^,^^^' 



1 11 -11 • r ^ shielding 



triangular heads, with the exception oi the found in the 

 Azemiops Feae and Echis Carinata, which have ^^^^y?^*^ 



i3.miliss 



round heads, and the Crotalinae, which have pear- 

 shaped heads. Some of the vipers have their heads 

 covered with scales, some have regular shields on 

 their heads, and others have partly-shielded and 

 partly-scaled heads. The heads of the Boidae vary 

 considerably, the shielding of the Pythons being 

 unique in its pattern, while Gongylophis and Eryx 

 have heads covered with scales. 



The Uropeltidae and Ilysiide have differently- 

 shaped shields to those of the Colubridae, the 

 shields being enlarged and straight-sided, while a 

 few shields that are present in the Colubridae are 

 missing in the Earth-snakes. The shielding on the 

 Xenopeltidae is really a mixture of the types found 

 on the two above-mentioned families and that on 

 the Colubridae. 



The shields found on the Glauconidae and 

 Typhlopidae are peculiar, and resemble the shield- 

 ing of no other family. Their heads are of a type 

 peculiar to themselves, while the heads of Urope- 

 tidae, Ilysiidae, Xenopeltidae, and Boidae resemble 

 in shape those found among the Colubridae. 



