LIST OF ILLUSTRATIONS 

 PLATES 



I-III. Skulls of Weasels. 

 IV-VI. Skulls of Bears. 



VII. Bat, Thyroptera disci/era. 

 VIII-X. Skulls of American Squirrels. 



TEXT FIGURES 



Figure 1. Enamel pattern of lower molars of Synaptomys and Mldomys. 



2. Enamel pattern of molars of Synaptomys. 



3. Skull of Synaptomys Jielaletes. 



4. Enamel pattern of molars of Mictomys. 



5. Skull of Miclomys wrangeli. 



6. Lower carnassial and last premolar teeth in different Bears. 



7. Skull of Kadiak Bear. 



8. Teeth of Yakutat Bear. 



9. Skull of Yakutat Bear. 



10. Skull of Grizzly Bear. 



11. Skull of Sonora Grizzly. 



12. Skull of Rocky Mountain Grizzly. 



13. Skull of Sonora Grizzly from the Coppermines. 



14. Skull of Sonora Grizzly from Nogales 



15. Skull of California Grizzly. 

 16-17. Skull of Barren Ground Bear. 



18. Teeth of Thyroptera disci/era. 



19. Head of Thyroptera disci/era. 



20. Foot and uropatagium of Thyroptera disci/era. 



21. Right foot of Thyroptera disci/era. 



22. Maxillary teeth of Desmodus rufus. 



23. Mandibular teeth of Desmodus rufus. 



24. Bark of Abies arizonica. 



25. Scales of cones of Abies arizonica. 



26. Skull of Sorex macrurus. 



27. Left side of upper jaw, showing teeth of Sorex macrurus. 



28. Upper jaw, seen from below, of Sorex macrurus. 



29. Rostrum of Sciuropterus silus. 



30. Rostrum of Sciuropterus volans. 



31. Audital bulla of Sciuropterus volans. 



32. Audital bulla of Sciuropterus v. querceti. 



33. Sternum of Romerolagus nelsoni. 



34. Sternum of Lepus timidus. 



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