THE SERPENTS OF SCOTLAND AND THEIR STUDY 93 



accountable. The serpents, which in point of view of 

 geological time are a comparatively modern type as seen at 

 present, seem to have spread over Europe from East to 

 West, the hardier species penetrating farther into the 

 colder climes than those of more warmth -loving nature. 

 Apparently only three species were on what is now Great 

 Britain when that mass of land became separated from the 

 Continental mainland. Ireland, it would appear, was already 

 an island, and the sea proved an inseparable barrier to the 

 progress of the snakes in that direction, to say nothing of 

 St. Patrick. The Isle of Man, too, was in the same position 

 probably, as there are no serpents there. Whether this at 

 all represents what really occurred or not, the fact remains 

 that three species comprise the British list of Ophidians. 

 These species are : 



1. Tropidonotus natrLv, the Ring Snake or Grass 



Snake. 



2. Corondla austriaca, the Smooth Snake. 



3. Vipera berus, the Adder or Viper. 



The first two of these, the Ring Snake and the Smooth 

 Snake, are essentially lovers of warm climates ; the Ring 

 Snake delighting to pass hours in the ponds of the south, not 

 only because there it finds its chief food, frogs, but also for 

 the simple delight of being in the water ; the Smooth Snake 

 being an inhabitant of sandy plains and warm heaths, 

 where it also finds its favourite food, the sand lizard (Lacerta 

 agilis). The Adder, on the other hand, much less sus- 

 ceptible to cold, and with a more varied diet of small 

 mammals particularly, is found far and wide, in every 

 county of England and Wales, and almost universally 

 distributed of course in varying numbers in Scotland. 

 To the extreme north it is found, and I believe I am correct 

 in saying that even in Sutherland Adders are as a rule to be 

 found active after their winter hibernation, in the month of 

 March. 



Do the other two British serpents, then, never occur in 

 Scotland ? It may be said with certainty, I think, that the 

 Smooth Snake (Coronella austriaca] was never indigenous in 

 Scotland, though it was supposed to have been recorded 



