VOL. LXXXIX.] PHILOSOPHICAL TRANSACTIONS. 5l5 



worn down, both the fangs and the alveolar processes begin to be absorbed. Their 

 places are gradually supplied by the next laminae of the grinder, and their fangs 

 coming forward in a constant succession. When the last tooth of a grinder has 

 advanced sufficiently in the jaw, to supply the place of its predecessor, the anterior 

 tooth of the next succeeding grinder comes forward, to supply its place. 



From the peculiar manner in which the grinders are supplied from behind, but 

 never from beneath, a preceding grinder, as is the case in the human species, and 

 in most other animals, it must appear evident, that an elephant can never shed his 

 teeth ; but, from this regular succession, he may, at one period, have only a single 

 grinder in each side of either jaw; at another there may be one and part of a 

 succeeding grinder; even a still greater variety in the appearance of the grinders 

 will take place, according as the anterior one is more or less worn away, and the 

 waste supplied by its successor. In this manner, the growth of new teeth, to 

 compose a succeeding grinder, and the ossification and formation of the fangs, are 

 constantly going on, in regular succession; so that, after the 2d year, the mouth 

 of the elephant is constantly filled with as many laminae of the grinders on each 

 side as it can hold. While the grinders thus advance forward in the mouth, in re- 

 gular succession, the alveolus of each advances along with them; and as the an- 

 terior fangs are absorbed, the same process is going on in the alveoli. In the par- 

 tition between each alveolus there is a communication, which in young elephants 

 is larger than in those farther advanced in years; and it is probable, that this canal 

 or sinus between the different alveoli, admits the passage of an elongation of the 

 membrane, from the anterior to the posterior grinder. 



The time requisite for the complete formation of 1 of these cases of teeth, con- 

 stituting a grinder, varies from 2 to 6 or 8 years; and when an elephant has at- 

 tained its full size, a considerable number of the anterior laminae must be worn 

 away, and the fangs absorbed, before the posterior ones can be sufficiently advan- 

 ced to cut the gum. From the curved line in which the grinders of the upper jaw 

 advance, it must be evident, that some of the anterior laminae must be obliterated 

 before the last can come into use: this may be made to appear more clearly, by 

 drawing lines parallel to the surface of the grinder of the upper jaw; yet there are 

 10 of the posterior ones that cannot come into action, till the same number of 

 their predecessors are worn away in regular succession. Before this could have 

 happened, several years must have elapsed, during which the posterior laminae 

 would have been completed; for, in the present state, the 3 aftermost layers are 

 not even now attached to each other, or to the rest which are anterior; the 

 membrane between, and connecting these laminae, not being ossified at the time 

 of the animal's death. In this grinder, there are 23 laminae, which is the greatest 

 number I have seen. 



In the lower jaw, the same circumstances take place : the teeth of the grinders 

 rise by the addition of their fangs, force their way through the alveoli, and cut the 

 gum, as they advance forward in the jaw. The grinding surface has rather a on- 



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