Natural History 471 



formed. The lower incisors strike in behind the upper ones, and 

 this keeps the enamel edge sharp. Moreover, these teeth are 

 "rootless," and go on persistently growing as they are worn away. 

 In the gap behind the incisors, where canines should be, an in- 

 folding of the skin into the mouth cavity separates a front portion 

 from a back portion. Thus material which is being gnawed, but 

 not intended to be swallowed, may be kept from going beyond 

 the front region of the mouth. Some of the rodents, like the 

 Gopher, store what they gnaw in capacious cheek-pouches, and 

 grind this with their back teeth when they get into a place of 

 safety. 



No one can look at an elephant using its trunk without 

 recognising a new idea the employment of the nose (and a 

 prolongation of the upper lip as well) as a food -getting organ. 

 This is Nature's way, making an apparently new thing out of 

 something very old ; and it is evident from the remains of extinct 

 elephants that the trunk or proboscis had a gradual evolution, 

 proceeding in correlation with that of the huge tusks which 

 prevent the mouth getting close to things in the usual way. The 

 efficiency of the trunk is greatly increased by a very mobile, 

 finger-like process at the tip, which enables the elephant to handle 

 little things as well as to lift great logs. 



The trunk of the Elephant is a masterpiece, and the initial 

 stages may be discerned, not only in the evolutionary history, but 

 in the short proboscis of the Tapir, and even in the sensitive snout 

 of the Pig, which is used for routing in the earth in search of food. 

 There is a special snout-bone (pre-nasal) in pig and mole; but 

 the risk of hasty interpretation in terms of fitness may be 

 illustrated by the fact that the same bone occurs in the Tapir, 

 which does not rout in the earth, and also in Tree-Sloths! The 

 bone in question is probably a primitive feature, for the Tapir, 

 for instance, is a very archaic mammal. In some cases, like the 

 Elephant Shrew, the proboscis is a puzzle: we do not know its 

 use. 



