154 ANIMAL LIFE OF THE BRITISH ISLES. 



Viper or Adder ( Vipera lerus, Linn.). 



At a superficial glance the Viper is quite distinct from our 

 other Snakes. Instead of the long, gracefully tapered body of 

 these, the Viper is short and thick in the body with a short tail. 

 So far as the length is concerned, the average Viper is less 

 than two feet. A few exceptionally large females have been 

 recorded measuring two feet eleven inches ; but the female is 

 always slightly longer than the male usually about an inch 

 more. Two feet three inches may be regarded as the ordinary 

 maximum for a female. The head is flatter above, and it 

 broadens behind the eyes, so that it is very distinct from the 

 body ; further, the shields on the head are very much smaller 

 than the corresponding plates of the Grass Snake. The iris of 

 the eye is coppery-red, and the pupil is vertical which usually 

 denotes nocturnal habits, but the Viper is active by day as well 

 as by night, and is fond of basking in the sunshine. 



Respecting colour, there is a considerable range of variation, 

 much of it sexual ; but, generally speaking, it may be said to 

 be some tint of brown, olive, or grey, and this ground colour 

 may be so dark that the darker markings are scarcely per- 

 ceptible on a cursory view. Along the sides there are whitish 

 spots, sometimes reduced to mere dots. The brown, red-brown, 

 or olive males have black markings ; the grey or whitish males 

 are marked with brown or black, and have the underside black, 

 The throat is black, or whitish with scales spotted or edged with 

 black. 



The females if brown or brick-red have dark brown or red 

 markings ; olive females have brick-red bands or spots. The 

 yellowish-white chin and throat are sometimes tinged with red. 

 The eyes of the female are smaller than those of the male. 



The markings are subject to a good deal of variation as well 

 as the ground colour. The usual wavy or zigzag line down the 

 centre of the back, with a series of spots on either side, may be 



