352 ON THE FOSSIL BONES OF PACHYDERMATOUS QUADRUPEDS. 



■while those of which I speak have most commonly from six to ten. 

 The anteriors alone may give rise to some doubt ; but vire shall see in its 

 proper place that they are as easily distinguishable. 



It is more difficult to assign the specific characters of these diverse 

 teeth, with reference to each other, for they do not bear a perfect 

 resemblance. There is in the first place the difference of posi- 

 tion in the jaw, which may be judged of by the number of denticuli ; 

 then comes the difference of age, which may be "determined by the de- 

 gree of detrition. Let us examine and compare them successively, ac- 

 cording to those relations. 



I begin by a tooth of Simorre (plate 26, %. 4). It is the same de- 

 scribed by Daubenton, in his Natural History, Vol. xii. No. 1109. 



It is 0,1 1 6 long, and 0,06 broad, and yet is very much worn. Of its 

 six pairs of denticuli, the two anterior are confounded in a disc of four 

 lobes {a b) ; one of the middle (c) is already trefoil shaped, leaving a 

 small round isolated disc ; the other (^d) is elliptic and double lobed; 

 the last (e/) only show four discs, one of which begins to become lobed. 

 "We may see that had it been a little more worn, this tooth would have 

 had three discs of four lobes. Behind is a fang of two blunted and fur- 

 rowed denticuli, one of which (g) is higher than the other. 



This crown is less worn, and consequently higher on the side of the 

 unlobed discs (ade), which we shall soon see form the external side. 

 Two thick roots, both broken, take a backward direction. The poste- 

 idor (i) is by far the thicker; in fine, there is in front (marked k) a 

 flatness, giving rise to the supposition that this tooth had been pre- 

 ceded by another. 



I have found the same tooth still implanted in the palate. In the 

 cabinet of M. de Borda, at Dax, it has the same protuberances, the same 

 figures, and the same proportions (plate 28, fig, 2) ; it is merely a little 

 smaller and less worn ; the two anterior discs were not confounded. 



The fact is, that it was preceded by a tooth with two pairs of denti- 

 culi (a b) ; and we may observe behind (at e), that it must have been 

 followed by another. 



I have a third time found the same tooth among those which Dombey 

 brought home from Peru (plate 26, fig. 7), fixed in a portion of the 

 palate, and perfectly similar to that of Simorre in the outlines and pro- 

 portions, but a little more worn. , 



The two centre discs are at present confounded in a quadrilobed disc, 

 and the two posteriors are not far from being so. There is no appear- 

 ance of a small tooth in front; its socket has disappeared, and the body 

 of the existing tooth begins to exhibit symptoms of decay. More 

 backward, towards b, may be seen the remains of the socket of a tooth 

 which was next in succession. 



The tooth of Peru is precisely the same in length as that of Simorre, 

 although it falls short of it a little in front, and it does not exceed it in 

 breadth by more than 0,005. Thus, in spite of the distance of the 

 places, it is impossible not to recognize these two teeth as belonging to 

 the same species. Hence, setting aside the shape of the tooth, these 

 teeth go the length of proving that there were two others in the upper 

 jaw of the animal, one in front, with only four denticuli, and one be- 

 hind. They, moreover, prove that these teeth displaced each other 



