25 



short shield pointed tails, and very small ventrals. 

 Some species have beautiful irridescent skins. 



6. Xenopeltidae — Only one genus, and one 

 species. A small irridescent snake, with narrow 

 ventrals, and with the outer rows of scales 

 enlarged. 



7. Coliibridae. This is by far the largest 

 family of snakes, and contains all those species 

 that have no striking peculiarities such as would 

 serve to classify them for any other family. In 

 fact, one might say that the members of the 

 Colubridae got placed in that family by the rediictio 

 ad absicrdtim method. The Colubridae are divided 

 as follows : 



COLUBRID.'E. 



I I i 



Aglypha. Opisthoglypha. Proteroglypha. 



(Solid toothed, (Back fanged, (Front fanged, 



harmless.) slightly poisonous.) very poisonous.) 



Colubrinae. Achrochordinae. 



I I 



Elapinae. Hyarophiinae. 



Dipsadinse. Homalopsinae. 



The Ao[lypha are harmless snakes with solid Sub-divisions 



4- 4-U oi the 



teetn. Colubridae. 



The Opisthoglypha have their back teeth 

 grooved for poison, and are slightly poisonous. 



The Proteroglypha have well-developed poison 

 fangs in the front of their mouths, and are ex- 

 tremely poisonous. 



The sub-family Colubrinae contains the 

 greatest number of the common harmless Colubers, 

 including terrestrial, semi-aquatic, and a few 

 arborial species (some of the latter with lateral 

 keels) ; also several intermediate genera that link 

 the Colubridae with the Earth-snakes. 



The semi-aquatic snakes (Tropidonotus, 

 Helicops, etc.) belonging to this sub-family have 

 not the construction of the true water-snake, but 

 resemble the rest of the Colubrinae, though their 



