120 EXPLANATION OF THE PLATES. 
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Figures of the natural size. 
Oreodon Culbertsonii. 
Fig. 1. View of the base of a skull containing on both sides all the molars perfect, and on the left side 
the canine in the same condition. J'rom an adult male individual. The molar teeth are four premolars 
and three true molars. 
Fig. 2. View of the left side of the same specimen as the last, exhibiting the canine and the succeeding 
series of molars. 
Fig. 3. Inner view of a series of inferior molars of the right side, restored from seyeral different indi- 
viduals. The teeth consist of three premolars and three true molars. 
Fig. 4. View of the masticating surface of the same series as the last. 
Fig. 5. External view of a right posterior inferior molar, removed from its socket. 
Fig. 6. View of the masticating surface of the same tooth as the last. 
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Figures of the natural size. 
Figs. 1-5. Oreodon Culbertsonii. 
Vig. 1. Upper view of the skull, from the same specimen as figure 3, Plate IT. 
Fig. 2. View of the inion or occipital region, from the same specimen as the preceding. 
Fig. 3. View of a specimen upon the left side of the face, exhibiting the orbit and lachrymal depression 
entire. 
Fig. 4. Greater portion of the left side of the lower jaw of a young individual, containing the first pre- 
molar, the succeeding two temporary molars, and the permanent true molars, of which the last is only 
partially protruded. 
Fig. 5. View of the triturating surfaces of the premolars and Jast temporary true molar, from the same 
specimen as the last. 
Fig. 6. Oreodon major. View of the triturating surfaces of the superior true molars, of the right side, 
considerably worn. 
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All the figures are of the natural size. 
Figs. 1, 2. Oreodon Culbertsonii. 
Fig. 1. View of the left side of the skull of a young individual. The zygoma, end of the nose, and 
nearly all the teeth are broken away. In advance of the orbit is observable the large lachrymal depression. 
Fig. 2. View of the base of the same specimen as the last. Upon the right side of the jaw all the 
molars are preserved, consisting of the temporary series and the permanent true molars. The foramina 
visible at the base of the cranium, proceeding backward on each side, are the rotundum, ovale, lacerum, and 
condyloideum. ; 
Figs. 8, 4. Oreodon gracilis. 
Fig. 3. View of the base of the skull of a young animal. ‘The teeth visible on the left side, proceeding 
backward, are, a fragment of the canine, the two fangs of the first premolar, three succeeding temporary 
molars, and two permanent true molars. On the right side are preserved the last temporary true molar and 
the succeeding two permanent true molars. The oblique lines indicate a portion of the matrix, in which 
the specimen was originally imbedded. 
Fig. 4. Superior view of the same specimen as the last. It presents a remarkable degree of flatness of 
the forehead. 
