THE MASTODON 201 
the object of this being the same in both tooth 
and chisel, to keep the edge sharp by wearing 
away the softer material. In the case of the 
chisel this is done by a man with a grindstone, 
but with the tooth it is performed automat- 
_ ically and more pleasantly by the gnawing of 
food. In the mastodon and elephant the tusks, 
which are the representatives of the cutting 
teeth of rodents, are wide apart, and of course 
do not gnaw anything, but the presence of 
these enamel bands hints at a time when they 
and their owner were smaller and differently 
shaped, and the teeth were used for cutting. 
Thus, great though the disparity of size may 
be, there is a suggestion that through the mas- 
todon the elephant is distantly related to the 
mouse, and that, could we trace their respec- 
tive pedigrees far enough, we might find a com- 
mon ancestor. 
This presence of structures that are appar- 
ently of no use, often worse than useless, is 
regarded as the survival of characters that once 
served some good purpose, like the familiar 
buttons on the sleeve or at the back of a man’s 
coat, or the bows and ruffles on a woman’s 
