18 



GUIDE TO EEPTILES AND AMPHIBIANS. 



Cases 11, 

 12, and 15. 



With the family Coluhridce we reach the typical Snakes, which 

 comprise some nine-tenths of the Ophidia, and may be roughly 

 defined as normal Snakes which are neither Pythons {Boido'^ nor 

 Vipers (Vijjeridcc). In other words, they are Snakes with well- 

 developed eyes, without vestige of hind-limbs, and with normal 

 upper jaws, usually carrying numerous teeth. The following are 

 some of the chief characteristics of the family : A median longi- 

 tudinal groove divides the shields on the chin ; the squamosal bone 

 of the skull is horizontally elongated and movable ; and the pterygoid 



Fig. 15. 



Fig. 16. 



Heads of the Smooth Suake (Coronella austrtaca), 

 A (No. 261 )> ^^nd the Common Snake (Tropi- 

 donotus natrix), B (No. 240)- 



Heads of the three British Snakes. 



Head of the Viper 

 (Vipera berns). 



(No. 318.) 



bone reaches the quadrate. The family is divided into three series 

 and eight sub-families, as follows :— 



A. Aglypha. The teeth solid and ungrooved. 



Sub-family 1. Acrochordime. 



„ 2. Coluhrinoi. Common Snake, Eat-Suake, etc. 



„ 3. Dastjpeltiim. African Egg-eating Snake. 



B. Opisthoglypha. One or more of the hinder teeth in the 



upper jaw grooved. 

 Sub-family 4. Dipsadomorphina'. Indian Tree-Snakes. 

 „ .5. Elachistodontincc Indian Egg-eating Snake. 



„ 6. Homalopsincc. Oriental AYater-Snakes. 



G. Peoteroglypha . The front upper teeth grooved or perforated. 

 Sub-family 7. Elapince. Cobras- and Kraits. 

 „ 8. Hydrophiincc. Sea-Snakes. 



