138 ELEPHANTS 



process the toes may be reduced to two, or right away to 

 one, the original middle toe. There is no special difficulty 

 about tracing back the elephants in so far as this matter 

 is concerned, since they have kept (like man and some 

 other mammals) the full typical complement of five toes 

 on each foot. 



But I must explain a little more at length what was the 

 " typical dentition," that is to say, the exact number and 

 form of the teeth in each half of the upper and the lower 

 jaw of the early mammalian ancestor of lower Eocene 

 times, or just before. The jaws were drawn out into a 

 snout or muzzle, an elongated, protruding " face," as in a 

 dog or deer or hedgehog, and there were numerous teeth 

 set in a row along the gums of the upper and the lower 

 jaw. The teeth were the same in number, in upper and 

 in lower jaw, and so formed as to work together, those of 

 the lower jaw shutting as a rule just a little in front of the 

 corresponding teeth of the upper jaw. There were above 

 and below, in front, six small chisel-like teeth, which we 

 call " the incisors." At the corner of the mouth above and 

 below on each side flanking these was a corner tooth, or 

 dog-tooth, a little bigger than the incisors, and more 

 pointed and projecting. These we call " the canines," four 

 in all. Then we turn the corner of the mouth-front, as it 

 were, and come to the " grinders," cheek-teeth or molars. 

 These are placed in a row along each half of upper and 

 lower jaw. In our early mammalian ancestor they were 

 seven in number, with broader crowns than the peg-like 

 incisors and canines, the bright polished enamel of the 

 crown being raised up into two, three or four cone-like 

 prominences. The back grinders are broader and bigger 

 than those nearer the dog-tooth. The three hindermost 

 grinders in each half of each jaw are not replaced by 

 " second " teeth, whilst all the other teeth are. 



Now this typical set of teeth consisting of twenty- 



