THE ADDER. 119 
any one can readily tell an old adder from a young one 
by the size and build. But assuming that the speci- 
men to be examined is undoubtedly a young one, how 
does this affect the colouring? An examination of a 
few young adders will at once show that the younger 
the specimens the more well-defined are the colours. 
By that is meant that black and yellow, green and 
brown, are seen more distinetly as separate colors. 
Of course the specimen must not be too youne to 
show this—not just after birth that is, for ab that 
time the full pigmentation has not taken place. But 
observe the young after the first spring sloughing is 
completed, and what has just been stated will be 
seen. In the same way suppose that the specimen 
under consideration is an old one. In this ease, 
too, it is not difficult to trace the effect of age. 
It is observed that the older the adders the less 
defined are the colours, and the more blending is there 
of shades. Further than this, the markings are seen to 
be less distinct. In an old female there is a tendency 
to a general greenish-brown colour all over the body, 
and in very old adders the zigzag line and the other 
marks are sometimes almost obliterated. Photographs 
do not give much idea of tint, but they do give some 
indication of the sharpness or otherwise of colours. 
Thus in the two ilustrations here shown—one a young 
male, the other an old female—the contrast of bright 
colours and dull shade is quite distinctly seen. Both 
adders were taken in the Monnow Valley. Any one 
