194 EXPLANATION OF THE PLATES. 
PLA Ea 
Rhinoceros Nebrascensis. 
Figs. 1, 2. Two-thirds the diameter of nature. View of the left side of a much mutilated face and lower 
jaw. In the upper jaw are seven molar teeth, the triturating surfaces of which, from the same specimen, 
are represented of the natural size in Fig. 8, Plate XV. The lower jaw contains six molars entire. 
Fig. 3. The size of nature, represents the triturating surfaces of the teeth last mentioned, from the 
same specimen. 
Figs. 4-8. Different views of ‘superior molars, which had not yet protruded from the jaws, and therefore 
were entirely unworn. Of the natural size. ; 
Fig. 4. External view of the anterior four molars of the left side. 
Fig. 5. View of the triturating surfaces of the same teeth. 
Fig. 6. Internal view of the same teeth. 
Fig. 7. View of the anterior side of the third right superior molar. 
Fig. 8. View of the posterior side of the same specimen as the last. 
Fig. 9. Triturating surfaces of the teeth from the same specimen represented in the succeeding figure. 
Natural size. 
Fig. 10. Fragment of the left side of the lower jaw of a very young animal, viewed upon its outer side 
and exhibiting the last temporary molar and the first succeeding permanent molar. 
Fig. 11. One-half the diameter of nature. View of the forehead taken from the same specimen as 
figure 1. 
Fig. 12. Two-thirds the diameter of nature. View of the inion or occipital region, represented from the 
same specimen as Figs. 1, 2, Plate XV. 
Fig. 18. View of the triturating surfaces of the entire series of the superior molars of the right side, 
from a different individual from any other indicated. Natural size. 
Fig. 14. Fragment of an upper jaw of the right side of a young animal, exhibiting the triturating 
surfaces of the posterior three temporary molars. Natural size. 
- PoOATE XY: ; ~ 
Rhinoceros Nebrascensis. 
Figs. 1, 2. Two-thirds the diameter of nature. 
Fig. 1. View of the right side of a skull, with the top broken away its whole length. The specimen 
belonged to a very old individual, as the molar teeth are nearly worn away to the fangs. 
Fig. 2. View of the base of the skull from the same specimen as the last. The characteristic enamelled 
triturating surfaces of the molars are entirely obliterated. 
Fig. 8. The size of nature. It represents the triturating surfaces of the superior molars of the left side. 
PEA iy KW AS , 
Titanotherium Proutit. 
Figs. 1, 2. One-third the diameter of nature. 
Fig. 1. A portion of the right side of the lower jaw, containing the last two and part of the first molar. 
Fig. 2. A portion of the left side of the lower jaw of a second and smaller individual, containing the 
three true molars and the fangs of that in advance. 
Fig. 3. One-half the diameter of nature. View of the triturating surface of the true molars, from the 
same specimen as figure 2. 
Figs. 4-7. Two-thirds the diameter of nature. 
Figs. 4, 5. Fragment of a left posterior superior molar. Fig. 4. Outer view of the entire portion of the 
fragment. Fig. 5. View of the masticating surface of the same fragment. This last presents the external 
anterior cusp with two pits at its base, and the large internal conical lobe. 
