124 BRITISH SERPENTS. 
Personally, I have seen only two, one on Garway Hill 
in Herefordshire, and the other in the anatomical 
museum at Edinburgh University, where Professor 
Sir William Turner drew my attention to it. 
This question of colour variation in adders is not 
an easy one to solve, and a very large series of 
specimens from different counties must be examined 
before a definite conclusion is come to. The fore- 
going arguments are based upon the examination of 
a series of several hundred adders, taken in such 
widely differing localities as Dorset, Herefordshire, 
South Wales, and Scotland, the observations extend- 
ing over a number of years. 
Conclusion.—From the fact of the same varia- 
tions being found in different places, it is obvious that 
the causes producing those variations must be acting 
everywhere. This does not preclude the possibility of 
adders adapting themselves in some degree to their 
environment and exhibiting some protective coloura- 
tion, but the evidence that they do so to any appre- 
ciable extent in this country is not satisfactory. In 
any case, the particular habitat can only account for a 
certain amount of resemblance ; it cannot possibly be 
responsible for differences found in adders taken in 
one spot. In other words, even if a locality produces 
a particular type of adder-colouring (which is doubt- 
ful), the same locality cannot account for the varia- 
tions in that local type. These variations are 
