THE SMALL RED VIPER. 207 



reptile that has had hut little attention paid to it, 

 probably on account of its great rarity and its very 

 local distribution, and also, no doubt, because it is 

 very much more difficult to capture than the ordinary 

 adder. 



The small red viper resembles the common adder 

 in the arrangement of its head-plates and in the 

 number of belly-shields, and is therefore put in the 

 same species. It differs from the adder in most other 

 respects; but the differences, by an arbitrary arrange- 

 ment, are not regarded as essential. These differ- 

 ences are, however, constant, which to my mind is 

 an all-important point. It has been said that the 

 small red viper is held to be either a variety of the 

 adder or the young of the adder. The latter view is 

 the important one from the point of view of its 

 validity as a species. This opinion presumably is 

 based upon the fact that certain ordinary adders 

 exhibit a red colour. It is assumed that these adders, 

 if they could have been examined when young, would 

 have appeared to be small red vipers. But it so 

 happens that this red colour in ordinary adders is 

 characteristic of one sex only, and that the female. 

 Thus in Mr Boulenger's most valuable paper on 

 the " Variations of the Viper in Great Britain " 1 the 

 following occurs : " Brown and brick-red specimens, 

 with the markings of a more or less dark-brown, are 

 females" This is absolutely true, the colours men- 



1 Zoologist, March 1892. 



