THE SNAKES 



317 



ored to impart a clear idea of the general distribution 

 of well-defined groups. A glance over the thoroughly 

 representative series of illustrations showing the Viper- 

 ine forms will do more for the student than a long 

 description in print. Vipers have either keeled or 

 smooth scales — mostly the former; the plates under the 

 tail may be in one or two rows — the former the com- 

 moner character. 



The family Viperidce is divided into two subfamilies, 

 thus : — 



No head pits. 



Subfamily Viperince. 

 The Teue Vipers. 

 Distribution: Confined to the 

 World. 



Examples. 



European Viper. 

 Old Sand Natter. 

 Tic Polonga. 

 Rhinoceros Viper. 

 Puff Adder. 



A deep pit between the eye and nostril The Rattlesnakes. New World. 



— on each side of head. 



Subfamily Crotalince. 

 The Pit Vipers. 

 Distribution: New and Old World. 



Copperhead Snake. 

 Water Moccasin. 

 Fer-de-lance. 

 Bushmaster. 

 Tree Vipers. 



New World. 

 New World. 

 New World. 

 New World. 

 Old World. 



In the United States and in Europe the poisonous 

 snakes belong to the Viperidce, 1 those in the former 

 country representatives of the Crotalince; the European 

 poisonous snakes represent the subfamily Viperince. 

 Rattlesnakes abound in many parts of the United States, 

 while frequenting the swamps of the southeastern por- 

 tion is a semi-aquatic Crotaline snake that is highly 

 dangerous; northward, the place of the latter reptile is 

 taken by the formidable copperhead snake. The Euro- 

 pean poisonous snakes are not nearly so large or dan- 



i Except two small Elapine snakes in the United States. 



