SNAKES i8i 



B. Tail ending in a rattle. 



1. Upper surface of head covered with nine sym- 

 metrical shields, Sistrurus. 



2. Upper surface of head covered with scales or small 

 shields, Crotalus. 



The pupil is vertical in all four genera. The fangs are 

 always highly developed. 



In Ancistrodon the body and tail are cylindrical, and 

 rather short and stout. The scales may be smooth or 

 keeled. 



The Water Viper or Moccasin, A. piscirorus, extends 

 from Carolina and Indiana to Florida and Texas ; it 

 inhabits the neighbourhood of water, being frequently 

 found on the low bushes overhanging rivers and ponds, 

 into which it dives when disturbed. The general colour 

 of this snake is of a chestnut brown above, with a series of 

 about twenty-five indistinct, dark, vertical bars on the 

 sides of the body, which sometimes unite above into an 

 arch. The head is purplish-black above, with a light- 

 edged, dark brown streak passing from the eye to the angle 

 of the mouth. 



The Moccasin is not at all particular in the choice of 

 its food, feeding on fish, frogs, mammals, and other snakes. 

 Mr. R. I. Pocock informs me that a specimen which lived 

 some years ago in the Clifton Zoological Gardens was 

 fed entirely on raw meat, which it took from a plate. This 

 snake is very hardy, surviving many years of captivity, a 

 specimen having lived for over twenty-one years in the 

 Paris Jardin des Plantes. 



The Copperhead, A. contortrix, having about the same 



