CONTENTS. 5 



Chapter III. Western American Cenozjoic horizons — Continned. Pago. 

 Miocene — Continued . 



V. Fifth faunal phase — Continued. 



Last phase of Miocene of first phase o. Pliocene (etages Pontien, 



Messinien) 80 



16. Ogalalla formation (in part); Peraceras zone 80 



16a. Rattlesnake formation of John Day \'alley, Oregon. . 81 



Pliocene 81 



VI. Sixth faunal phase 82 



Middle Pliocene or second phase (etage Astien) 82 



17. Blanco formation; Glyptotherium zone 82 



Upper Pliocene or lower Pleistocene 83 



18. Elephas imperator zone 83 



Pleistocene 84 



VII. Seventh faunal phase 84 



Lower Pleistocene (preglacial) 84 



19. Equus zone 85 



Middle Pleistocene (glacial) 86 



General characters 86 



Early phases 87 



Subsequent phases 88 



Late phase 90 



Conclusion 90 



Appendix. Faunal lists of the Tertiary ]\Iammalia of the West, by W. D. 



Matthew 91 



Index 121 



