124 THE MEANING OF EVOLUTION 
deadly work as almost any instrument of destruction 
known to animals below the grade of man. But, after 
all, this is an old-fashioned method, and the rhinoceros 
is a relic. 
Among the carnivorous animals the teeth, which 
were developed first chiefly for the tearing of flesh in 
its consumption, became effective for their courageous 
owners. Because these tearing teeth are well devel- 
oped in the dog they have come to be known as canine 
teeth. Usually where an animal can use its teeth ef- 
fectively for offense or defense, it is the canine teeth 
that are thus modified. The cat has developed them 
better than the dog, and one of the cats of a bygone 
geological period had canine teeth so magnificently 
enlarged and so sharp at the back as to give this 
frightful creature the name of the saber-toothed tiger. 
The long teeth in the upper jaws of the elephant, com- 
monly known as tusks, are not canine teeth. The ele- 
phant has completely lost his canines. His tusks are 
his incisors, and they have developed as have almost 
no other teeth in the mammals. 
These are only a few of the numberless devices na- 
ture has evolved for furthering the success of her chil- 
dren. There are so many others that to many of us 
they form almost the chief point of interest in our 
study of a new animal, or our closer observation of an 
old friend. 
