466 REFERENCES TO THE PLATES. 



Fig. 5. Last lower true molar without its hinder lobe, from the left side. 



Fig. 6. Outer view of the same tooth. 



Fig. 7-10. Parahippus cognatus. See page 314. 



Fig. 7. Three upper molars of the left side, apparently of the temporary series, viewed ou their tritu- 

 rating surfaces. 



Fig. 8. The second of the series, viewed externally. 



Fig. 9. The first lower temporary molar of the right side, viewed upon its triturating surface. 



Fig. 10. The same tooth, viewed externally. 



Figs. 11, 12. Hypohippus affinis. See page 311. 



Fig. 11. A second or third left upper molar of the temporary series, viewed on its triturating surface. 



Fig. 12. The same tooth, viewed externally. 



Fig. 13. Anchifpus texancs. See page 312. 



Greater portion of an upper left molar tooth, viewed on its triturating surface. 



Figs. 14-19. Leptochcerus spectabilis. See page 197. 



The figures twice the diameter of nature, except 16, 17. 



Fig. 14. The last premolar and the succeeding two true molars, of the upper right side, a, premo- 

 lar ; li, r, true molars. 



Fig. 1.5. The same teeth, contained in a fragment of the jaw, viewed externally. 



Fig. 16. An inferior true molar, apparently the first of the left side, viewed on its triturating surface, 

 and magnified three diameters. 



Fig. 17. Portion of the right side of a lower jaw, containing the last two premolars and the second 

 true molar, of the natural size, a, h, premolars ; f , second true molar. 



Fig. 18. The same premolars, viewed from above and magnified two diameters. 



Fig. 19. The second true molar, from the same jaw fragment, viewed ou its triturating surface and 

 magnified two diameters. 



Figs. 20-27. Perchceriis probus. See page 194. 



Fig. 20. Fragment of the left side of a lower jaw, containing a portion of the last temporary molar 

 and the succeeding two permanent true molars. 



Fig. 21. Triturating surfaces of the latter two teeth. 



Fig. 22. Last permanent premolar, inner view, removed from beneath the last temporary molar of 

 the specimen represented by figure 20. 



Fig. 23. The same tooth viewed from above. 



Fig. 24. An upper left true molar, probably of the same animal, reversed and viewed externally. 



Fig. 25. Triturating surface of the same tooth. 



Fig. 26. A last upper molar, probably of the same animal, viewed on the triturating surface. 



Fig. 27. Fragment of a lower jaw, right side, of the same animal, containing the last temporary 

 molar and the succeeding permanent true molar. 



Figs. 28-30. LoPHioDON occidentalis. See page 239. 



Three views of a last inferior molar of the right side. 



Fig. 28. External view. Fig. 29. Internal view. 



Fig. 30. View of the triturating surface. 



Fig. 31. Equus excelsus. See page 266. 



Fragment of the right side of the upper jaw, containing the back four molars. 



Figs. 32, 33. Merychippus mirabilis ? 



Fig. 32. An inferior temporary molar, viewed on the triturating surface. 



Fig. 33. The same tooth viewed externally. 



