18 



GUIDE TO KEPTILES AND AMPHIBIANS. 



Cases 11, 

 12, and 15. 



With the family Colubridce 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 (Boidce) nor 

 Vipers (Viperidce). 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 Snake (Coronella mistriaca), 

 A (No. 261)> an d the Common Snake (Tropi- 

 donotus natrix), B (No. 240)- 



Heads of the three British Snakes. 



Head of the Viper 



(Viper a berus). 



(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. Acrochordince. 



„ 2. Colubrincc. Common Snake, Eat-Snake, etc. 



„ 3. Dasypeltinw. African Egg-eating Snake. 



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



upper jaw grooved. 

 Sub-family i. Dipsadomorphinm. Indian Tree-Snakes. 

 „ 5. Elachistodontince, Indian Egg-eating Snake. 



„ 6. Homalopsina. Oriental Water-Snakes. 



C. Peoteeoglypha . The front upper teeth grooved or perforated. 



Sub-family 7. Elapinca. Cobras and Kraits. 

 „ 8. Hydrophiinm. Sea-Snakes. 



