94 THE TOWER MENAGERIE. 
deserving of notice,—is unquestionably one of the most 
difficult problems, to the solution of which the zoologist 
has to apply himself. 
In internal and anatomical structure, on which modern 
naturalists are agreed that the greatest reliance ought to 
be placed in the distinction of closely approximating 
species, there is in the various races of Wolves no devi- 
ation from the common type of sufficient importance to 
warrant their separation from each other; neither does 
their outward form, excepting only in size and in the 
comparative measurement of parts, differ in any remark- 
able degree. In colour it is true that the most striking 
variations are observable, their hair exhibiting almost 
every intermediate shade between the opposite extremes 
of black and white. But it must be obvious that on this 
character, taken by itself, it would be absurd to insist as 
a ground of specific distinction, when we reflect on the 
influence which climate and other external. accidents 
must necessarily exercise on animals so extensively dis- 
persed, and so variously circumstanced. 
There are, however, strong grounds for believing that 
the fine pair of animals, whose portraits are prefixed to 
the present article, exhibit real and substantial marks of 
distinction of sufficient value to sanction their separation 
from the other species. Considerably larger and more 
robust than the Common Wolf, and differing greatly in 
the expression of their physiognomy, neither in figure 
nor in countenance are they remarkable for that starved 
and gaunt appearance which is the common and well 
known attribute of the latter. In fact, they have alto- 
gether a more fierce and formidable, but at the same 
time a more noble and less sinister, aspect. Their hair, 
