122 EXPLANATION OF THE PLATES. 
In the specimen, a large mass of matrix occupies the inner surface of the right zygoma, which is allowed 
to remain so as to give strength to the latter. 
Fig. 2. Fragment of the lower jaw of the right side, exhibiting the basal apophysis, and also presenting 
to view the greater portion of the last temporary molar, beneath which is exposed the last permanent pre- 
molar, and posterior to it the protruded first permanent true molar. 
PalieAs SEE) Sake 
Archaeotherium Mortont. Figures 1 to 3 are half the diameter of nature, and the remaining figures are 
of the natural size. 
Vig. 1. View of the right side of the skull. The orbital entrance is entire; and in the upper jaw the 
posterior two temporary molars and the anterior two permanent molars are seen. ‘The dotted line represents 
the upper part of the face restored from another specimen. 
Vig. 2. Upper view of the same specimen represented in figure 1. The ossa nasi are represented, in dot- 
ted lines, from another specimen. 
Tig. 38. View of the left side of a facial fragment, from an old individual, containing the posterior two 
permanent promolars. 
Tig. 4. View of the triturating surfaces of the teeth represented in figure 3. 
Fig. 5. View of the triturating surfaces of the anterior two permanent true molars of the left side of the 
upper jaw; from an adult individual. 
PAD) ex 
Figs. 1-7. Archaeotherium Mortoni. All the figures of the natural size except 6 and 7. 
Tig. 1. Outer view of the last two premolars and the true molars of the left side of the upper jaw, from 
the same specimen as Plate VIII., figure 1. 
Fig. 2. Outer view of the last premolar and the true molars of the left side of the lower jaw. 
Fig. 3. View of the masticating surfaces of the same teeth represented in figure 2. 
Fig. 4. Inner view of the last premolar of the left side of the lower jaw; from the same specimen repre- 
sented in figure 2. 
Rig. 5. Inner view of the penultimate premolar of the left side of the upper jaw; from the same speci- 
men represented in figure 1. 
Fig. 6. Half the diameter of nature. View of the inion or occipital region. Upon the right of the figure, 
when placed in proper position, the large infundibular expansion of the root of the zygomatic process is 
observed. 
Fig. 7. Half the diameter of nature. Inner view of the angular portion of the right side of the lower jaw. 
Near its middle the entrance to the dental canal is observable. 
Figs. 8-13. Archacother’um robustum. All the figures of the natural size. 
Fig. 8. Outer view of the crown of a canine. 
Fig. 9. Anterior view of the same specimen as the preceding. ; 
Fig. 10. View of the triturating surface of a fragment of an inferior second true molar of the left side. 
Vig. 11. View of the outer surface of the same specimen represented in figure 10. 
Fig. 12. View of the triturating surface of a fragment of an inferior last true molar of the left side. 
Fig. 15. View of the inner surface of the same specimen represented in figure 12. 
Figs. 14-21. Anchitherium Bairdii. All the figures are of the natural size. mn 
Vig. 14. Outer view of the posterior five inferior molar teeth of the left side. The last of the series has 
lost its hinder lobe. 
Fig. 15. View of the masticating surface of the posterior three inferior molars of the left side. From 
an older individual than the preceding specimen. 
Fig. 16. Outer view of an unworn inferior molar of the right side. 
Fig. 17. Inner view of the same specimen as figure 16. 
