OF MASTODONS, WITH REMARKS, ETC. 
9 
The third tooth (Plate XXVI. c) is three inches and one-tenth long, 
and two inches and two-tenths broad. This tooth has three denticules, 
with two points each. On the anterior surface of the crown, it has a 
fold of enamel rising up in a small point; and along the base of the 
crown posteriorly there is an horizontal ridge, consisting of a number 
of very small mammillaform processes. This tooth has three roots cor¬ 
responding to its denticules. 
The fourth tooth (d) is three inches and seven-tenths long, and two 
inches and eight-tenths broad ; it has three denticules, each of which 
is divided by a deep groove into two rather flattened points, of which 
the inner is the broader; each of these is again superficially divided 
by a slight groove. At the base of the crown, both anteriorly and 
posteriorly, there is a ridge of very small mammillaform points. Each 
denticulehas on its external point, both on its anterior and posterior sur¬ 
face, a ridge of enamel, which commences at the base of the process 
near the central groove and passes upwards and outwards. This ridge 
appears to exist on all the teeth until it is worn down by use, and we 
find traces of it also in the teeth of the M. giganteum. The crowns 
of all the teeth rise on their inner surface nearly perpendicularly, but 
on the outer side they slope obliquely inwards. 
The tusk belonging to this jaw is so accurately described by Dr God- 
man, and so correctly represented in the plate to his paper, that there 
is no necessity for my doing more than to refer to it. (See Vol. III. 
N. S., Plate XVIII. fig. 2.) 
The tusk represented in Plate XXVI. fig. 3, is that of an adult ani¬ 
mal. It is eleven inches long, and its largest diameter is two inches, 
its section is oval. This tusk consists of a central column composed 
of thin plates nearly parallel to its base; the whole covered with a coat 
of enamel, which becomes very thick towards its projecting extremity. 
The enamel is entirely worn off to the termination of this tusk, and even 
the central bony column is evidently worn down and smooth, as if from 
use by the animal; it is also worn at one side. This tusk belongs to 
the collection of J. P. Wetherill, Esq.* 
* There is in the cabinet of the Academy of Natural Sciences, deposited by Mr J. Fisher, 
by whom it was obtained at Big-bone lick, a tusk much smaller than the one we have de¬ 
scribed—it is also much less perfect. 
3* 
