\ 
54 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- 
. 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 ¢en denticules, each of which is mammil- 
lated with small points, five 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. Jatidens. 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 differs 
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 an 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. : 
——— 
ree Vide Trans. Ge eolog. 3. Soc, London, Vol. vir, p. =o 
