HTBEENATION AND SLOUGHING. 63 



different species is said to vary, that of the smooth 

 snake being less than that of the adder.^ Dr Opel 

 observed that the hibernation of the smooth snake 

 was neither so prolonged nor was the degree of tor- 

 por so great as in some otlier serpents. This snake 

 exhibits another interesting peculiarity, in that in- 

 stead of covering itself up in holes and corners it 

 hibernates on the surface of the ground. In this 

 country the favourite places for adders and ring snakes 

 to choose for their winter quarters are holes in old 

 trees, crevices in rocks, under masses of dead leaves in 

 the woods, in fern or bracken, and, as we saw in the 

 incident at Llanelly, in old quarries. A favourite 

 retreat for adders when hibernating is amongst the 

 roots of go'rse. Where these bushes are large a space 

 is formed round the larger roots by the action of the 

 wind swaying the roots about, just as a hole is made 

 with a crowbar. Into these holes both adders and 

 ring snakes will withdraw on being disturbed, and 

 will also hibernate in them. Mr Eees tells me that 

 on one occasion when uprooting gorse near a wood at 

 Gwern Efa, Llantrisant (Glamorgan), for the purpose 

 of clearing the land, a large number of ring snakes 

 were found thus hibernating together. 



Frequently they are found entwined together in 

 masses — for warmth, presumably. A correspondent 

 of mine, to whom I owe the knowledge of many in- 

 teresting adder incidents, writes me the following, 



^ Natural History (Vertebrates) of the British Islands. 



