44 EXTINCT BRITISH ANIMALS. 
average of five feet of snow on the ground (although, 
of course, not evenly distributed), which means a 
rise of at least two feet of water in the ponds and 
lakes at the break-up of winter. How then would 
a Beaver manage this superabundance of still water ? 
You will probably say “that’s best known to the 
CRANIUM OF BEAVER FROM THE FENS. UPPER SURFACE. (§ NAT. SIZE.)* 
Beaver himself!” Just so; but we know what a 
Beaver does under similar circumstances when he 
has built his house and dam on a running brook. 
During the summer months Beavers often frequent 
ponds and lakes at a distance from their houses for 
the purpose of feeding on the stems and roots of a 
pond lily (Nuphar advena). When a Beaver’s house 
* From a specimen in the Museum of the Royal College of Surgeons. 
