ON THE BONES OF THE MASTODON. 353 



from back to front, as in the elephant and the mastodon, and that the 

 anteriors disappeared at a certain period. 



I have further reason to believe that the anterior tooth was suscept- 

 ible of being replaced from top to bottom, as is the case in the hippojjo- 

 tamus, whose replacing teeth descend also. My reason for thinking 

 so is, that this little tooth of Dax is not worn as yet, and yet it must 

 have come after the great one, which is worn. 



This tooth of Dax further hel])s us to recognize a tooth of Simorre 

 of our Museum (plate 26, fig. 2). It is half worn, and presents the 

 figure of four lobes in front, and two round discs behind. 



A similar tooth (plate 28, fig. 14), but that it is not worn, and only 

 presents four cones, is in the cabinet of M. Hammer, who is unac- 

 quainted with its origin. The circumstance of its having a small fang, 

 might lead us to suppose that it belonged to the opposite jaw, conse- 

 quently to the inferior; for the tooth of Dax belonging to the upper has 

 no fang, neither has that of Simorre. Moreover, this may be a sucking- 

 tooth. 



The identity of the species of the teeth of Simorre, and of those 

 brought home by Dombey, being once sufficiently established, we 

 may proceed still farther. 



Among the specimens of Dombey is a large fragment of a lower jaw 

 (plate 28, fig. 4), at a fourth of its natural size. The fore part ter- 

 minates in a species of beak like that of the elephant and the masto- 

 don. Thus our actual species had not, like the two latter, either 

 incisors or canine teeth in the lower jaw. 



This piece contains two teeth : the posterior, 0,175 long, and 0,075 

 broad, had five pairs of denticuli, the posterior of which were the 

 shorter ; the two first are now amalgamated in quadrilobed figures, the 

 two succeeding are almost in the same predicament, the two last and 

 the fang are untouched. Such then is the posterior lower molar tooth 

 of this animal. 



In this particular it is the external side which is the most worn, con- 

 sequently the internal is the most prominent, aad this must be so to 

 enable the lower teeth to correspond with the upper, where the con- 

 trary is the case. 



It is the external denticuli which form trefoil figures, and above, it 

 is the internal : this too is the result of a general law which obtains in 

 herbivorous animals ; when both sides of a tooth do not resemble each 

 other, they are placed contipriwise in the two jaws. Thus, ruminants 

 have the convexity of the crescents of their upper teeth inside, e.nd 

 those of the lower outside. 



It is easy to see by the convexity of this long tooth being behind, 

 that it was not followed by another. That in front is so much worn 

 and mutilated, that its figure is no longer distinguishable : but I very 

 soon hit upon the means of remedying this deficiency. 



We have got in the Museum, a tooth of Simorre of six denticuii 

 (Daub. XII. No. mcx), differing from the former in its not having a 

 fang. (See plate 28, fig. 3). 



It was natural to look upon it as the corresponding tooth of the 

 former^ in the lower jaw ; this appeared, the more natural, as the last 

 lower teeth of the hippopotamus also differ from the corresponding 



