LIST OF ILLUSTRATIONS 



PLATES 



I-III. Skulls of Weasels. 



IV- VI. Skulls of Bears. 



VII. Bat, Thyroptera discifera. 



VIII-X. Skulls of American Squirrels. 



TEXT FIGURES 



Figure 1. Enamel pattern of lower molars of Si/iuijjlomys and M'lctomys 



2. Enamel pattern of molars oi Sijnapomys. 



3. Skull of Synaptomijit helaletes. 



4. Enamel pattern of molars of Midomys. 



5. Skull of Midomys -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. 

 IL Skull of Sonora Grizzly. 



12. Skull of Rocky jNIountain Grizzly. 



13. Skull of Sonora Grizzly from the Co})permines. 



14. Skull of Sonoi-a Grizzly from Nogales 



15. Skull of California Grizzly. 

 16-17. Skull of Barren Ground Bear. 



18. Teeth of Thyroptera discifera. 



19. Head of Thyroptera discifera. 



20. Foot and uropatagium of Thyroptera discifera. 



21. Right foot of TJiyroptera discifera. 



22. Maxillary teeth of Desmodvs rufus. 



23. Mandibular teeth of Desmodus rufiis. 



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 So7-ex rnacrurus. 



29. Rostrum of Sciuropteras silus. 



30. Rostrum of tSciuropterus volans. 



31. Audital bulla of Sciur opt erus volans. 



32. Audital bulla of <S'cmropto'rts V. querccli. 



33. Sternum of Romerolagus nelsoni. 



34. Sternum of Lepus timidus. 



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