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- 
tordshire adders, the Monmouthshire adders, and those 
of the Brecknock Black Mountains—ze., 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 
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