Supernumerary Tooth in Mastodon giganteus. 351 
: 
in the exposed part are of course six in number, but although ss 
developed, and above the tooth in front, they are very slightly 
Ww The principal wear is in the outer anterior cusp. 
tooth, like the last described, is slightly movable in its socket: in 
magnitude, it is about the same as the sixth tooth, and is greater 
than the fifth. In construction, it resembles the sixth more than 
the fifth, having a fourth ridge and a well marked talon. Its cingu- 
lum is accessible on the inner and anterior faces, but not on the 
outer and posterior, the last being in contact with the bone. The 
crown may be said to be well developed, and evidently has been 
in use; of course the tooth may be taken out of the category of 
teeth imbedded in the bone, as the sixth tooth is before it is fairly 
cut. In another jaw, in which the fifth tooth is fully developed, 
those in front have disappeared, and the sixth tooth is undevel- 
oped, but displayed by cutting away the bone so as to bring its 
our ridges into view. ; 
It is obvious from what has been stated, that this tooth is a 
repetition of the sixth, a superadded tooth, increasing the num- 
each other by two transverse furrows which are deep. The cusps 
i 
| ment of it remains, and this the symphysial part which does not 
| Contain any teeth, the four teeth occupying the situation in front 
having wholly disappeared in both sides of the jaw without 
ving a trace of their sockets. 
_ The remainder of this jaw has nothing very remarkable about 
it. The texture of the bone is moderately sound, and may en- 
dure for a succession of ages. The condyloid process has been 
broken off, and also the coronoid, but the cavity for the implan- 
tation of the temporal muscle is preserved, and the angle of the 
jaw is perfect. The symphysis is entire, of a wedge-like form 
rather than foliated, and presents no mark of the cavities for the 
etracaulodon sockets ; of course it is likely to have been the jaw 
ofa female. The front part of the symphysis measures 1n a per- 
Pendicular direction five and a half inches, and the back part 
Seven inches; the latter is broader than usual, and gives more 
Space for the lingual fossa. he orifices for the issue of the sub- 
maxillary and mental vessels are larger, the forefinger being read- 
ily admitted into the posterior opening. ‘The canal on the left 
Side is one inch and three eighths in diameter ; on the left portion 
18 a trace of an alveolus four inches long. Tr ee 
_ After a careful examination of the appearance of this jaw in 
its integral state I thought it best to uncover the extraordinary 
tooth, and ascertain its situation and extent. This was done not 
without hesitation, as it might alter the relation of the parts and 
bring into doubt the existence of an additional tooth. On the 
‘Mer face of the bone three incisions were made, two vertical 
