172 REPTILES AND BATRACHIANS 



are short and cylindrical, and covered with keeled scales. 

 The rather small eye is provided w^ith a vertical pupil. 

 Six species of Vipers occur in Europe, which merge into 

 each other in such a complete manner that the naming of 

 certain specimens is often a matter of some difficulty. 



The Common Viper, V. berus, the only poisonous snake 

 inhabiting the British Isles, where it may generally be 

 recognized by a dark, zigzag band which runs along the 

 centre of the back, although certainly dangerous, has 

 seldom produced death in man. The zigzag band is 

 almost invariably present in British specimens, but the 

 pattern varies very considerably on the Continent, where 

 the band may be either broken up into oval spots or trans- 

 verse bars, or may be entirely absent. The snake is often 

 stated to bear its initial on the back of the head, but this 

 V-shaped marking is likewise not constant. 



The Viper, which, in England and Scotland at least, 

 frequents dry woods and heaths, awakes from hibernation 

 quite early — towards the end of February or the beginning 

 of March, and commences to feed the following month. 

 Its principal food consists of young birds nesting on the 

 ground, voles, field-mice, and lizards ; in captivity it, 

 unfortunately, will hardly ever feed, and dies in a very short 

 time from starvation. Up to twenty young are brought 

 forth in July and August, in a very active condition, the 

 newly born snakes throwing back their heads and attempt- 

 ing to strike as soon as they have left their mother. On 

 the approach of a human being, the young frequently 

 disappear with great rapidity, this having given rise to the 

 statements that, when in danger, the young snakes arc 

 swallowed by their mother. This belief, however, is not 



