~ 
BRITISH SERPENTS. 
is absent from Treland. It is frequently seen in the 
islands of Mull and Jura. 
Description. 1. S/ze.—Some confusion has arisen 
in the minds of some as to the size of the adder, from 
the fact of the small red viper not being regarded as a 
distinct species, a most excellent work on Natural His- 
tory thus making the statement that the “average size 
of the common viper is 10 inches.” The fact of the 
matter is that the small red viper averazes this figure, 
but the common adder has a very differeut measurement. 
A reference to the figures in the various counties will 
show that the average size of the adult adder in this 
country varies from 18 inches to 25 inches, accord- 
ing to the locality. When I was working up the 
Ophidia of the Monnow Valley I was very much 
struck with the laree size of the adders there, and 
wrote to G. A. Boulenger on the subject. I had 
then recently obtained a specimen measuring 283 
inches, and was anxious to know what this authority 
thoueht of it. His opinion on this matter is) prob- 
ably of more value than any other that could be 
obtained, as many of the interesting specimens taken 
in this country go to him at the British Musemn. 
Mr Boulenger says :— 
“The usual size of adult vipers in this country is 
from 20 to 25 inches, specimens of 26 inches being 
very yare. T have no British example measuring as 
much as 28 inches. The largest specimens in the 
British Museum measure 
