372 M. R. Thorpe— Aroeocyon. 



The geologic horizon of A. marshi is Middle Pliocene. 

 It was collected about one mile west of Cottonwood, on 

 the East Fork of the John Day River, Oregon. The 

 enveloping matrix was soft tuff, lying between the basal 

 conglomerate and the capping rim rock of rhyolite, about 

 3 feet below the lower edge of the latter. Merriam has 

 designated this formation by the name Rattlesnake. 



Simocyon prirnigenius was found in the Pikermi beds 

 near Athens, Greece, while the type of 8. diaphorus came 

 from the gravel deposits of Eppelsheim, Germany, the 

 deposits of both localities being of equivalent age. There 

 is a difference of opinion in regard to the geologic age 

 of these formations. The German geologist, Lepsius, 

 believes that these strata are unquestionably of the Lower 

 Pliocene epoch, and that the Eppelsheim beds present 

 the northern facies of the Pikermi beds. On the other 

 hand, the members of the French school of geologists are 

 equally positive that the entire series is Upper Miocene. 

 Whatever geologic age we ascribe to these Pikermi and 

 Eppelsheim formations, they must both be placed in the 

 same period. I incline more to the French view of con- 

 sidering them Upper Miocene, but there is not sufficient 

 space to go into details on this point. It should be noted 

 that Von Zittel places Simocyon in the Upper Miocene. 



According to Gaudry, Greece was most probably con- 

 nected with Asia by vast plains, produced by the reces- 

 sion of the sea which began in the Middle Miocene and 

 continued throughout Upper Miocene until the Mediter- 

 ranean Sea had become nearly dry and had reached the 

 stage where it was represented by only a series of brack- 

 ish lakes, with the consequence that Europe and Africa 

 were broadly connected by land masses. All of these 

 Upper Miocene deposits were apparently laid down in 

 shallow basins of fresh water, for the most part due to 

 recurrent torrential flooding, after the manner of our 

 own Oligocene deposits in the Great Plains region of 

 North America. 



The extent of these deposits shows how widespread 

 were these conditions of deposition throughout Europe. 

 The beds are more or less local areas, extending from 

 western Portugal (Archino on the Tagus River) to 

 Maragha in Central Persia, and northward to Tcherni- 

 gow in south central Russia and to Eppelsheim, near 



