58 ORAL EQUIPMENTS. 



has many analogies to the molar of the Elephant to which I 

 now propose to refer. 



I have already referred to the Elephant's tusk, or lateral 

 incisor tooth ; its molars also are quite unique. The molars 

 of the African species are larger than those of its Indian 

 brother ; the tubercles or cusps are fewer in number in the 

 African and are joined to one another by enamel; whereas 

 in the Indian species, each ridge seems distinct, and in reality 

 they are ; each of the lozenge shaped ridges is as it were a 

 distinct tooth composed of dentine and enamel, and they are 

 all bound together into one immense compound tooth by 

 cementum. Now singular as this arrangement is there is 

 another peculiarity about the Elephant's molars which attains 

 in no other living mammal, though its remote ancestor the 

 Mastodon had the same peculiarity in some of the molar 

 series, but not in all. 



The germs of the teeth instead of developing in the 

 substance of the jaw, and then erupting vertically, develop 

 in the back portion, and as they develop migrate forwards, 

 and being worn down in front, as they gradually wear away 

 and eventually disappear, their place is taken by the next in 

 turn. Thus we find one and a half or a portion of another 

 molar in each jaw (of course on each side also) in functional 

 condition at one time. The deciduous molars are displaced 

 in a similar fashion by the permanent set. If a young 

 Elephant be killed and its jaws examined, it will be found 

 there are a number of " toothlets," if I may be permitted to 

 coin a word, lying loosely in the substance of the bone in 

 a cavity, waiting their turn to assume their coat of mail (the 

 investment of cementum) and march forward to the fray to 

 take the place of their fellows already sacrificed in the battle 

 for life. The peculiar semi-circular form of the jaw enables 

 this to be brought about. In the Mastodon, the eruption of 

 the teeth is of a mixed kind ; some of the molars erupting 

 vertically, and some as in the Elephant succeeding from 

 behind. He who runs may read in this a significant fact in 

 evolution. 



One more, and very singular specimen of differentiation of 

 oral structures, and I must bring this paper, already too long 

 I fear for your patience, and yet all too short for the vastness 

 of the subject, to a close. 



In the ordinary "Baleen or Whalebone Whale," we 

 find a perfectly unique arrangement for the prehension 

 and retention of prey. Who would think to look at a 

 piece of whalebone that it is in reality a part of a tooth. 



