THE ADDER. 93 
half an inch to an inch and a half longer than the 
imales in the same place. Thus in South Hereford- 
shire adult male adders average 24 inches, adult 
females 254 inches in length. All the exceptionally 
long specimens that have come under my own 
notice have been females, but it should be men- 
Fic, 20.—Smootu Newrts. 
tioned that Mr Boulenger did not find this difference 
to be constant in a series he examined. 
Length of tail.—This is a constant sexual differ- 
ence, the tail in the males being invariably longer 
than in the females. Speaking generally, the male 
2 Or" 
> 
adder’s tail is 8 inches long, the female’s tail 24 
inches. But the Jeneth of the tail of course varies 
