M Notice of the Tooth of a Mastodon. 



the central narrow, and laterally compressed. They diminish 

 somewhat in size from before backwards, but the points remain 

 uniformly four in number. The first four denticules have suffer- 

 ed more or less from attrition, the remaining ones being unim- 

 paired. 



The only description which I have been able to find, corre- 

 sponding in any degree with the above, is that of the Mastodon 

 elephantoides, described and figured* by Mr. Clift. This was 

 also brought from the valley of the Irawady river several years 

 since. '' The tooth was eleven inches long and three and a half 

 broad, has no less than ten denticules, each of which is raammil- 

 lated with small points, ^?;e being the smallest and eight the larg- 

 est number in any one denticule." It is obvious from the figure 

 which accompanies his description that the tooth was entire, as 

 the points of the denticules were but very slightly worn. He 

 further adds, " the denticules of the tooth are more compressed 

 than in the M. latidens. They form a series of plates mucrona- 

 ted with small points. There is no apparent commissure nor 

 any central depression." 



Comparing the two descriptions, it will be seen at once that 

 they differ materially in regard to the number of points compos- 

 ing each of the denticules, those of the M. elephantoides^ having 

 from five to eight, while those of the other are uniformly four. 

 The points of the former are very closely approximated, leaving 

 but a very slight depression between them, while those of the 

 latter are quite distinct. The question, how far are these differ- 

 ences to be attributed to difference in age, presents itself Now 

 it is well known that each successive tooth is larger than that 

 which preceded it, and the number of denticules in the same 

 species is in proportion to the size of the tooth. If however the 

 two specimens which we have noticed were the same, that which 

 is largest would be provided with the greatest number of denti- 

 cules, which is not the case, they being actually less in number. 



Mr. Clift considers the Mastodon elephantoides as art interme- 

 diate link between the genus Mastodon and Elephas. Should 

 the specimen here noticed prove to be a new species, it would 

 serve to fill up another gap in the transition from one of these 

 genera to the other. 



Boston, May 2d, 1840. 



* Vide Trans. Geolog. Soc. London, Vol. vii, p. 372. 



