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 



