48 



BULLETIN UNITED STATES GEOLOGICAL SURVEY. 





LepuSj Meplias, Mastodon, Tapirus, Sus, Cervtis, Antilope, JBos, Ganis, 

 Machcerodus, Felis, Ursus. In the JEquus beds of Oregon, a few extinct 

 genera in like manner share the field with various recent ones, while not 

 a few of the bones are not distinguishable from those of recent species. 

 I give the following list, the extinct species being in italics: 



Mylodon sodalis. 

 Thomomys (nr.) clusius. 

 Thomomys talpoides. 

 Castor fiber. 

 Lutra near piscinaria. 



Auchenia magna. 

 Auclienia mtalieriana. 

 Cervus fortis. 



Canis latrans. 



Eleplias primigennis. 



Equus occidentalis. 



Eqiius major. 



Auchenia hesterna. 

 The species derived from the cave formations of the Eastern States 

 are more numerous, and differ from the Oregon fauna in many respects ; 

 yet the parallelism is close in the genera with the Equus beds on the 

 one hand and the Pliocene of Europe and South America on the other. 

 The differences distinguishing it from the Equus beds of Oregon are, 

 however, such as compel me to regard it as a distinct division of the 

 Pliocene, under the name of the Megalonyx beds. 



Megatlierium {p). 

 Mylodon (p). 

 Megalonyx (p). 

 Sciurus (s). 

 Arctomys (s). 

 Jaculus. 

 Arvicola (s). 

 Erethizon. 

 Hydrochoerus (p) 



MocJioerodus (sp). 

 Mastodon (sp). 

 Equus (sp). 

 "? Sippotlierium (s). 

 Tai)irus (s). 

 Dicotyles (p). 

 Cariacus (p). 

 Bos fs). 



Castoroides. 

 Lagomys (s). 

 Lepus (s). 

 Anomodon. 

 Scalops. 



Arctotherium (p). 

 Procyon. 

 Canis (sp). 

 Mustela (sp). 



In the above list, the extinct genera are marked in italics. There exists, 

 as a marked feature of the Xorth American Pliocene, to which I called 

 attention several years ago,* a considerable representation of the fauna of 

 the Pampean formation of South America : such are twelve genera, of 

 which six are extinct genera, and four are peculiar to that formation and 

 fauna. The genera found in the Pampean are marked(^), and those of 

 the Subapennine {s). In the list from the Oregon localities, Mylodon and 

 Auchenia were observed to be the only distinctively Pampean genera. As 

 a conclusion of the comparison of the American Equus beds in general 

 with those of Europe, it may be stated that the number of identical gen- 

 era is so large that we may not hesitate to parallelize them as stratigraph- 

 ically the same. On the other hand, the agreement with the South 

 American Pampean formation is so marked in some respects as to induce 

 us to believe that the distinction is geographic rather than stratigraphic. 

 Believing that the Pampean formation contains too large a percentage 

 of extinct genera to be properly regarded, as it has been, as Postpliocene 

 or Quaternary, its characters, both essentially and as a result of the com- 

 parison which I have been able to make, refer it properly to the Pliocene. 



*Proc. Acad. PMla. 1857, 156; Proc. Am. PMlos. Soc. 1869, 178. 



