The mandible is slender, with a very elongate symphysis, which measures
237 mm. The inferior outline of the ramus is strongly concave at the
middle and slightly convex posteriorly, while the symphysial portion is
bent upward. The superior outline is concave both behind and before the
tooth, and also immediately anterior to the coronoid process. At about
the beginning of the posterior fourth the outline is convex, and the
mandible at this point is nearly as deep as at the coronoid process. The
superior surface of the symphysis slopes down on each side to the median
line, but each half of the surface is itself nearly plane. (Pl. 11, figs.
1, 2, and 5.)
The alveolar groove anterior to the tooth is very distinct throughout and
is without septa and open at the bottom. It ends distally in a rounded
aperture 6 mm. in diameter, below which are several small foramina. These
lead to a very large canal which occupies all the symphysial portion of
the mandible, the walls being comparatively thin. Behind the tooth the
alveolar groove becomes narrower gradually and disappears in a length of
about 140 mm.
The mental foramen is situated in line with the anterior base of the
tooth, and is confluent with a groove which extends forward for about 80
mm. A rather shallow groove runs along the inferior margin of the
symphysis.
The coronoid process is erect and rounded, and is joined by a horizontal
ridge anteriorly.