HIBERNATION AND SLOUGHING. 61 
when that cold is very far short of the winter tem- 
perature. I have often noticed, when snake-hunting 
in the Monnow Valley, how a change of wind affects 
the adders. Let a cold east wind strike the slopes 
of Garway Hill or the Graig, and the adders which 
yesterday were lying out on the margin of the cut 
bracken, or on the paths through the woods, are no- 
where to be seen. Even the snakiest spots, where one 
knows the reptiles are, will be searched in vain on a 
cold day. So repeatedly have I found this to be the 
case, that now I never go to certain favourite hunting- 
grounds unless I see that the wind is from a warm 
quarter. Thus it is that the time of the retirement 
for the winter varies considerably with the particular 
season: one year all the snakes will have disappeared 
by the middle of September, whilst in a warm late 
autumn they will be found active towards the end 
of October. In the same way the date of commenc- 
ing activity in the spring is found to vary according 
as that season is early or late. F. G. Aflalo! mentions 
that he has “found adders lively in the New Forest in 
the middle of April, rarely before; but Sir Herbert 
Maxwell tells me that he has seen them in Scotland as 
early as March.” In Dorset they are generally seen 
in February. Of course it is difficult to be quite cer- 
tain as to the exact date, because the snakes may have 
been moving about in any given district some weeks 
before any one happened to see one. 
1 Natural History (Vertebrates) of the British Islands, p. 305, 
