22 
DESCRIPTIONS OF INFERIOR MAXILLARY BONES 
EXPLANATION OF THE PLATES. 
Ml the figures are one-fourth the natural size. 
Plate XX. Two views of a fragment of the lower jaw, left side, of a young Mastodon, in 
the cabinet of the American Philosophical Society. 
Fig. 1. External view. Fig. 2. Superior view. 
m. n. o. Alveoli from which the teeth have fallen out. 
c. Molar, with three denticules. 
d. Molar, with three denticules. 
r. Mental foramen for nerve and blood-vessel. 
Plate XXI. Three views of a fragment of the lower jaw, left side, of an adolescent Masto¬ 
don, in the Wistar Museum, University of Pennsylvania. 
Fig. 1. Exterior view. Fig. 2. Superior view. Fig. 3. Interior view. 
/. Posterior molar, with five denticules and a heel. 
e. Penultimate molar, with three denticules. 
Plate XXII. Fig. 1 and 2. Two views of a small fragment of the lower jaws right side, of 
a Mastodon, in the cabinet of the American Philosophical Society. 
Fig. 3 and 4. Two views of a molar tooth, upper jaw, of a Mastodon, in the cabinet of the 
American Philosophical Society. This tooth appears to differ from any hitherto described. 
It resembles the teeth represented in Cuvier, (Ossemens Fossiles, Plate IV. fig. 1, 3,4, and 6, 
Divers Mastodontes) in the enamel being crenulated; but it differs from them in the arrangement 
of the enamel. It is probably an undescribed species, and we propose to dedicate it to our 
estimable friend, the distinguished professor of the institutes and practice of medicine in the 
University of Pennsylvania, and Vice-President of this Society, Dr Chapman. 
Plate XXIII. Two views of a portion of the lower jaw, right side, of the Mastodon gigan- 
teum, in the Baltimore Museum. 
f. Posterior molar. 
p. q. Anterior mental foramina. 
s. Foliated expansion of the chin. 
x. Depression in the articulating surface of the condyloid process. 
y. Foramen for the passage of the inferior maxillary nerve, and artery to the teeth. 
Plate XXIV. Two views of a fragment of the lower jaw, right side, of a Mastodon, in the 
cabinet of tire American Philosophical Society. 
f. Posterior molar, with four points and a broad heel. 
e. Penultimate molar, with three points. 
