258 THE REPTILES 



The Adder, or Common Viper, is the only poisonous reptile 

 indigenous to Great Britain. Its favourite haunts are dry heaths, 

 sandy wastes, open woodlands, and sunny slopes where rank 

 grass and brushwood form a cover. It is very variable in colour, 

 some specimens being nearly olive brown, others a dirty brownish 

 yellow. The head is almost oval, depressed, and widening behind 

 the ears. The gape of the mouth is great, and there are no teeth 

 in the upper maxillary bones except the poison fangs. The neck 

 is smaller than the back of the head, and the body increases in 

 girth nearly to the middle, slightly diminishing to the vent, then 

 becoming abruptly smaller and lessening to the extremity of the 

 tail. These snakes are by no means uncommon in the New Forest, 

 but as they are generally shy, slipping quietly away through the 

 undergrowth when disturbed, they are not often seen. The real 

 danger is the possibility when crossing the warm, dry heath lands 

 of stepping upon one, or in sitting down in the long, rank grasses 

 of placing the hand on one that may be concealed asleep, when 

 it is very likely to turn and bite. Although the bite is rarely fatal, 

 it is a dangerous experience, and produces a greater or less amount 

 of pain and general constitutional disturbance. The Viper preys 

 upon mice and small rats, so that it does good in helping to 

 decrease the number of these vermin ; and it also takes toll of 

 the nestlings of those birds which build their nests on the ground: 

 Of the African Vipers, the Horned Viper, the Puff Adder, and the 

 River Jack Viper are familiar examples, frequently to be seen 

 in zoological collections. 



The Pit Vipers are so called from the presence of a little depres- 

 sion on both sides of the face between the eye and the nostril. 

 Most of the Pit Vipers have large heads, which may be completely 

 or not at all covered with large plates. To this group of very 

 poisonous snakes, all of which have a canal in the poison fangs, 

 the Rattlesnakes belong. They are readily recognised by the 

 curious appearance of the end of the tail, which is made up of a 

 number of horny, round, and flat pieces capable of making a sharp 

 sound, not unlike that produced by a large grasshopper, by their 

 friction during the rapid vibration of the tail. An average specimen 

 of the Common Rattlesnake (Crotalus durissus) measures about 

 4 feet in length and 6 inches in girth, and the length of the nine 

 rattles is about 2 inches. It lives upon rabbits, rats, and other 



