116 BRITISH SERPENTS. 



point at issue. But I do say that adders of great 

 variety of colouring are taken in both localities. If 

 the nature of the soil or surface of the ground be the 

 determining factor, then obviously all the adders on 

 the south slope of Garway Hill ought to be the same 

 colour ; and a series from this spot should exhibit 

 little or no variation, which is not the case. Curiously 

 enough, this same correspondent mentioned above, 

 a few days after he wrote the letter quoted, sent 

 me three adders from the locality of Newcastle Emlyn. 

 One was particularly light, one was very dark, and 

 the third a medium shade of brown. I do not know 

 the nature of the soil on which they were taken, but 

 the differences may be accounted for without that. 

 The same variety of colouring is found in the Here- 

 fordshire adders, the Monmouthshire adders, and those 

 of the Brecknock Black Mountains — i.e., adders on 

 cultivated undulating land, on wooded mountains, and 

 on bare arid slopes. It would be utterly impossible to 

 say from the colour of an adder what was the nature 

 of the ground it lived on, as would be possible if the 

 colour was dependent on that ground. I am inclined 

 to go further and to say, that while the factor of 

 locality may be a very or even an all-important one in 

 the case of the trout, it plays but a small part in the 

 colour variation of adders. The proof of the contention 

 is found in the examination of a sufficiently large 

 series of specimens taken from one locality, when, 

 instead of uniformity of colouring, infinite variety 



