PROBOSOIDEA. 
307 
This species belongs to the genus defined by Dr. Falconer as possess¬ 
ing three crests to the third, fourth, and fifth, or intermediate molars, which 
also includes the M. oMoticus and M. angustidens, on which the genus was 
originally established, and for which the name Mastodon should therefore 
be retained. It is much more nearly related to the latter than to the former 
of these species. 
The mandibular ramus is not elevated, but it is more so just behind 
the symphysis than at the origin of the coronoid process. At the latter 
point, its transverse exceeds its vertical diameter. This form is due to the 
external convexity at this point, which is, at the middle of the ramus, but 
little marked. The inner wall slopes very obliquely inward and upward 
at the last molar tooth, approximating the inner alveolar borders. These 
are nowhere widely separated, and in the specimen are continued on each 
side in front of the fifth (anterior) molar, one-fourth its length, as an acute 
ridge. The symphysis is produced as a beak with subparallel borders, and 
is deflected at an angle of 35° with the long axis of the ramus. Its inferior 
border is continuous with that of each ramus without interruption. On 
the superior face, the alveolar ridges converge, inclosing a narrow gutter, 
narrower than the inferior face, and then diverge and disappear before 
reaching the end of the beak. Thus the superior surface, from being 
grooved, becomes flat or slightly concave. The inferior surface displays a 
slight longitudinal concavity, which occupies the space between the alve¬ 
olar ridges of the inclosed tusks. The rather large dental foramen is situated 
below the angle formed by the deflection of the alveolar ridge at the base 
of the beak. Its distance anterior to the anterior (fifth) molar exceeds the 
length of the latter. 
The symphyseal tusks are depressed or transversely oval in section; 
their adjacent sides being flattened. Their length is slightly unequal, and 
they are worn obliquely posteriorly from the inner to the outer side. The 
dentine is longitudinally, weakly, closely striate. It is usually covered by 
a thin layer of cementum. The anterior or fifth molar of the inferior series 
is much worn by use, and in a bad state of preservation on each side of the 
jaw. Its crests have become confluent by attrition, both lengthwise and 
crosswise, leaving entering bays of enamel to mark the valleys, dfliese 
