THE SMALL RED VIPER. 207 
reptile that has had but httle 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, 
¢, would 
> 
if they could have been examined when youn 
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”! the 
following occurs: “Brown and brick-red specimens, 
with the markings of a more or less dark-brown, are 
Jematles.” This is absolutely true, the colours men- 
1 Zoologist, March 1892. 
