THE ADDER. 



93 



half an inch to an inch and a halt' longer than the 

 males in the same place. Tims in South Hereford- 

 shire adult male adders average 24 inches, adult 

 females 25h inches in length. All the exceptionally 

 long specimens that have come under my own 

 notice have been females, but it should be men- 



Fiu. 20. — Smooth Newts. 



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 

 adder's tail is 3 inches long, the female's tail 2J 

 inches. But the length of the tail of course varies 



