one- horned Rhinoceios. 115 



One may follow these different states in the figures of 

 Plate I.*, one of which exhibits the teeth of a two-horned 

 rhinoceros still young, the other those of an adult unicorn. 

 One may follow there also the variations of the molar teeth 

 dow nwards, which are much less considerable. 



They are composed of two eminences turned round in the 

 form of a portion of a cylinder, and placed obliquely one 

 behind the other, in such a manner that their concavity is 

 turned inwards and a little forwards. The detrition only 

 enlarges the crescents of their summits; but this figure of 

 a double crescent is preserved until the eminences are worn 

 at the base, a period when the tooth becomes quadrangular 

 and single. 



It was for want of being well acquainted with this varia- 

 tion of the teeth by detrition, that Merck, to whom, how- 

 ever, we are indebted for the first eiforts to illustrate this 

 part of the natural history of the rhinoceros, thought him- 

 self authorised to advance, in his third letter on fossil 

 bones, a fact which Faujas inserted in his Essais de Geo- 

 logief. This fact is, that fossil teeth of the two kinds of 

 the living rhinoceros arc found in Germany. 



But, even allowing this fact to be true, it would be impos- 

 sible to prove it, because the teeth of these two species re- 

 semble each other when they are of the same age; but Merck 

 had in his possession the head of a young two-horned rhi- 

 noceros : all the fossil teeth, which resembled those of this 

 head, were considered by him as coming from the two- 

 horned rhinoceros, and those which were advanced, from 

 the one-horned. 



In reality, these teeth came neither from the one nor the 

 other, as I shall prove hereafter, but from a third species, 

 which differs from the two first in other respects than by 

 the teeth. 



We have a^iven in Plate IV. specimens of these fossil teeth 

 of the rhinoceros. It will there be seen, that, without the 

 l-ules which we have established from observation, every 

 body would be tempted to ascribe them to animals very dif- 

 ferent. 



Fig. 1 . represents a superior molar tooth of the right side, 

 very much worn : the original is in our museum. 



F'ig. 2. exhibits a portion of an upper jaw with two teeth, 

 one of which is entire and still untouched. This fragment, 

 in the cabinet of Joubert, was found near the village of 

 Issel, on the last declivities of the Black Mountain. The 

 individual must have been of a small size. 



• Given in our last Number. f Vol. i. p. 107. 



H S Fig. 3. 



