CONTENTS 



Page 



Introduction i 



Acknowledgments 2 



History of investigation 3 



Geographic and geologic occurrence 6 



Environment 8 



Relationships 9 



Classification 16 



Systematic revision 22 



Dichobunidae 22 



Homacodontinae 23 



Helohyinae j^y 



Hypertragulidae 43 



Hypertragulinae 43 



Agriochoeridae 47 



Oromerycidae 68 



Camelidae "jj 



Poebrotheriinae yy 



Leptomerycidae 80 



Leptotragulinae 80 



References gi 



Explanation of plates 94 



ILLUSTRATIONS 



Plates 



(All plates following page 96) 



1. Mytonomeryx from the Uinta upper Eocene. 



2. Homacodonts from the Uinta upper Eocene. 



3. Homacodonts from the Uinta upper Eocene. 



4. Protorcodon from the Uinta upper Eocene. 



5. Protoreodon from the Uinta upper Eocene. 



6. Protoreodon from the Uinta upper Eocene. 



7. Protorcodon from the Uinta upper Eocene. 



8. Diplobunops from the Uinta upper Eocene. 



9. Diplobunops from the Uinta upper Eocene. 



10. Diplobunops from the Badwater upper Eocene. 



11. Diplobunops from the Badwater upper Eocene. 



12. Diplobunops from the Badwater upper Eocene. 



13. Protylopus? from the Uinta upper Eocene. 



14. Protylopus? from the Uinta upper Eocene. 



15. Oromeryx and Pocbrodon from the Uinta upper Eocene. 



16. Malaqiiiferus from the upper Eocene of the Wind River Basin. 



17. Leptotragulus from the Uinta upper Eocene. 



18. Leptotragulus and Leptoreodon from the Uinta upper Eocene. 



Charts P^^^ 



1. Suggested phylogenetic arrangement of North American Eocene Artio- 



dactyla following 15 



2. Suggested sequential arrangement of Eocene agriochoerids 67 



! "^^ 



