24 TUSKS AND THEIR USES. 



purposes, and are thus in this respect analogous to the 

 antlers of many stags. In other instances, however and 

 this in all the groups in which they occur they have 

 undergone a still further serni-monstrous development, 

 rendering them if not actually harmful, probably in some 

 cases inconvenient to their owners. Lastly, the independent 

 acquisition in closely allied or widely separated groups of 

 mammals of tusks of very similar structure and appearance, 

 shows how little reliance is to be placed on external 

 characters as indicative of relationship. 



