68 



CEXOZOIC MAMMAL HORIZONS 



Tapiridse) similar to those of the Brule clay, m others (e. g., Rhinoce- 

 rotoidea, Rodentia) more advanced than those of the upper Brule 

 clay and " Protocerds sandstones." This more or less progressive 

 character is illustrated as follows: Among Perissodactyla-Rhinoce- 

 rotidae Diceratherium is more advanced, with well-developed horn 

 cores; among Tapiridae Protapirus is similar to that in th-e ^^Proto- 

 ceras sandstones;" among Equid^e browsing horses, small and similar 

 to those of the Protoceras sandstones." Among Artiodact^da 5 

 families: Elotheriid?e, Hypertragulidae, Oreodontid?e (Eporeodon, 

 Agnoch<Lrus) , Dicotylidae, Camelid^e (not certainly present). Among 

 Camivora-Fehdae {Archmlurus , Nimravus) ; among Canidae Nothocyon, 

 Temnocyon, Mesocyon, PMlotrox. Among Rodentia Leporidae (Lepus), 

 Castoridae (Steneofiher) ; also two new and peculiarly American rodent 

 families, Geom^ddae (pocket gophers) and Haplodontidae (sewellels, 

 Meniscomys). 



The conclusion is that the middle* John Day deposition partly 

 overlaps and is partly sequent to the deposition of the upper part of 

 the Brule cla}' and the Protoceras sandstones." 



UPPER OLIGOCEXE, LATEST PHASE (EUROPE, ETAGE AQUITANIEN). 

 12. UPPER PART OF JOHN DAY FORMATION; PROMERYCOCHCERUS ZONE. 



(Figs. 1, 10, 11; PL I.j 

 HOMOTAXIS. 



Xortli America (provisional). — Great Plains: 1, Lower portion of 

 Rosebud, of Matthew. 2, Gering, of Peterson's Running Water sec- 

 tion. (See fig. 13.) 3, ? Gering, of Barton's Scotts Bluff section. 



FAUXA,'^ EARLY PHASE. 



The fauna of the upper part of the Jolm Day formation is rich, but 

 the levels have been certainh' recorded only in the case of the follow- 

 ing animals: Among Rodentia, Lepus, Entoptychus, Mylagaulodon. 

 Among Carnivora-Canidae, Nothocyon, Mesocyon, Temnocyon. Among 

 Perissodactyla, (a) Equidae, Anchitherium prsestans, Mesoldppus acu- 

 tidens; (h) Tapiridae, Protapirus; (c) Rhinocerotidae, ? Diceratheriinae, 

 ? Accra theriinae. Among Artiodactyla, (a) Elotheriidae, (h) Dicoty- 

 lidae, (c) Oreodontidae, PromerycocJicerus, 4 species, Eporeodon, (d) 

 Hypertragulidae, (e) Camelidae, Paratylopus stemhergi, P. cameloides.^ 



TRANSITION FROM L'PPER OLIGOCENE TO LOWER MIOCENE IN UPPER 

 PARTS OF JOHN DAY, GERING, AND HARRISON AND LOWERMOST PART 

 OF ROSEBUD. 



From the preceding American Oligocene (upper part of Brule clay 

 or LeptaucJienia zone, and lower and middle parts of the John Day) 



a See Appendix, p. 91. 



b The only camels from the John Day obtained hy the University of California expeditions came from 

 the top of the formation. The matrix of the type of P. stfrribergi shows that it is not from the middle 

 John Day, as Wortman supposed (Sinclair, November, 1906). 



