86 
WILD BEASTS AND THEIR WAYS chap, xv 
securely lodged in thick bamboo retreats. The yak 
is another species of which I have had no personal 
experience. This beautiful animal is a denizen of 
the most lofty mountains, and is found at elevations 
that could hardly be attained by any other animal of 
its weight. It is a most sure-footed beast, and is 
used for riding among the Himalayahs in its domes¬ 
ticated state. 
There is a species of wild ox, or rather bison 
{Bison bonassus), still remaining in the forests of 
Lithuania; this was the original aurochs of Central 
Europe, which was at one time plentiful; but the 
increase of population and the invention of fire-arms 
drove these animals into the remotest forests, until 
by degrees they have been nearly exterminated. 
It may be accepted as a fact that only two species 
of the true bison are known to exist, the Bison 
Americanus (or so-called buffalo) and the European 
species, Bison bonassus , both of which are distinct 
from all others belonging to the Bovidcz , in pos¬ 
sessing fourteen pairs of ribs. 
