plate 46. Fig. i. Head of Protoceras celer. Fig. 2. Skull 

 of Protoceras celer as Seen from Above. Fig. 3. 

 Skull of Protoceras celer as Seen from Below. 



47. Restoration of Protoceras celer (Male and Fe- 



male). 



48. Skeleton of Promerycochoerus carrikeri. (This 



plate properly comes between plates 44 and 45). 



49. Skeleton of Oxydactylus longipes. 



50. Fig. 1. Petrified Birds Egg. Fig. 2. Stylemys 



nebrascensis, the Commonest Fossil Turtle of the 

 Big Badlands. 



Page 

 Figure i. Occupied Land in and near the Big Badlands 



of Eastern Pennington County 13 



2. The First Fossil Discovered in the Big Bad- 

 lands 16 



3. The Earliest Badland Fossil Described by Dr. 

 Joseph Eeidy 17 



4. Map of North America in the Tertiary Period 24 



5. Diagram Showing the Strata of the Western 

 States in which Fossil Mammals are Found 28 



6. Section near Adelia, Neb., Showing Chadron, 

 Brule, Gering and Arickaree Formations. . 36 



7. Section of the Arikaree near Harrison, Neb. . 41 



8. Section of the Rosebud (Arikaree) near Por- 

 cupine Butte 43 



9. Section Showing Daemonelix Series as Given 

 by Prof. Barbour 52 



10. Hypothetical Continental Outlines During the 

 Oligocene .' 70 



1 1 . Skeleton of Hyaenodon cruentus 78 



12. Skeleton of Cynodictis gregarius 80 



13. Skeleton of Dinictis squalidens 82 



14. Skeleton of Steneofiber fossor 86 



15. Skeleton of Hyopatamu's (Ancodon) brac- 

 hyrhynchus 107 



16. Skeleton of Agriochoerus latifrons no 



17. Head of Poebrotherium wilsoni (eximium) 116 



18. Skeleton of Blastomeryx advena 118 



19. Head of Stylemys nebrascensis. (Three views) 120 



20. Head of Rhineura hatcheri 121 



