THE OPHIDIA IN THE MONNOW VALLEY. 208 
2. The chances of catermination or survival. —In 
the case of the adder civilisation is the worst enemy 
to be feared—man is the greatest danger. It may even 
be said that, excepting the severity of climatic condi- 
tions, the adder usually dies a natural death, unless 
at the hand of man. If, then, the adder has as its 
habitat a locality where man is chiefly conspicuous 
by his absence, the chances of survival are at their 
maximum. This condition is present in the Monnow 
Valley—that is, man is nearly absent. A few scat- 
tered farms, mostly rearing cattle and sheep, and 
therefore with fewer hands than a more corn-growing 
district, are all that are met with in the way of 
human habitations in a drive through this valley. 
The gamekeepers kill a considerable number of 
adders every spring (the woods on both Garway Hill 
and The Graig are heavily preserved with pheasauts), 
but apart from this the adder population is very 
secure. This partly accounts for the exceptional size 
of adders here: they live to a good old age and attain 
their full erowth. And when it is remembered that 
twenty female adders will in a season bring forth 
somewhere about 260 young ones, it 1s not hard to 
account for the fact of their being fairly common. 
3. Food-supply.—This is an all-important question 
in the distribution of a species. It has been seen that 
the food of adders consisted mainly of mice, slow- 
worms, small birds and their eggs, newts, water-voles, 
and erubs. All these are in abundance in this valley, 
