352 Supernumerary Tooth in Mastodon giganteus. 
three inches long, and these were united inferiorly by a third ho- 
rizontal incision siz inches long. Then by cutting through the 
alveolar process, which passed across between the first and second 
fangs, the large internal plate was removed with some additional 
projections. When this bone was raised, we found a great molar 
tooth equal in size to the sixth tooth. The surface of the crown 
was in superficial extent full as large as that of the sixth; the an- 
terior part rather larger than that of the other. This crown had 
four ridges, and a talon with a longitudinal furrow through the 
centre. The ridges had each two cusps, which are unworn ex- 
cept the two anterior; the posterior ridges, not having been fully 
developed, were not covered with enamel: the talon was of good 
size and had two or three cusps. Each of the ridges was sup- 
ported as usual by a pair of fangs, the two anterior separate, the 
two posterior coalesced into one mass. The anterior fangs passed 
under the posterior fangs of the sixth tooth. The length of this 
tooth was seven inches; the width anteriorly four inches; the 
cingulum measured in circumference sitteen and one half inches ; 
from the point of the fang to the tip of the corresponding second 
internal cusp seven and one half inches. From the anterior face 
of the anterior cusp arises an additional projection or cusp. The 
bone was somewhat shattered in the operation of exposing the 
tooth, but not sufficiently to disturb that organ, which remains in 
its original situation, and has never been displaced. 
e naturally ask, whether this additional tooth is to be con- 
stance of the kind has occurred in the Mastodon giganteus. The 
M. longirostris has been shown to possess in addition to the six 
teeth a small vertical premolar above the second and third milk 
molars in the upper jaw, which gives its even teeth; no suc’ 
tooth has been discovered in the lower jaw as yet ; and none such 
in the upper or lower jaw of M. giganiteus. 
No instance of a great supernumerary ultimate molar has wee 
found in any species of Mastodon thus far with the present eX 
ception. Anomalies of the teeth both as to number and — 
well known to exist. But the laws which govern the dentition O° 
the Elephant and Mastodon are different from those which regu 
ee 
