Peterson : The Agate Spring Fossil Quarry. 491 



quarry. Next in importance is the very large E/otherium which I 

 have provisionally named Dinohyiis hollandi, pending a more syste- 

 matic study of the specimen. Moropus distans Marsh is well repre- 

 sented by limbs, foot-bones, parts of jaws, teeth, etc. Merychyiis 

 Leidy and other small forms are also present. Among this general 

 mixture are found the remains of some carnivores, common in these 

 horizons. 



From this list it would appear at first sight, that the geological 

 horizon in which this (juarry is located, should be referred to the same 

 horizon as the Upper John Day of Oregon. The fact, however, re- 

 mains that the entire fauna, which is at present known from the uj)per 

 series of the Miocene section in western Nebraska and eastern Wyom- 

 ing, shows more highly specialized characters than obtained in the 

 fauna known from the Upper John Day. For example, no such 

 specialized forms among the Oreodontidse as Merychyus elegans, Mery- 

 cochceriis proprius Leidy, and the artiodactyls Merycodus Leidy, and 

 Syndyoceras Cooki, recently described by Barbour, have been reported 

 from the Upper John Day. 



Moropus distans is much larger and doubtless differs otherwise from 

 the form represented in the John Day formations. When the material 

 representing Diceratherium from the Agate Spring Quarry is prepared 

 for study, there will, no doubt, be found a number of important speci- 

 fic, if not generic differences, separating it from the material repre- 

 senting the genus in the John Day Beds. 



From these recent discoveries it appears that the Miocene section 

 from the Oligocene to the top of the Nebraska Beds, in this general 

 locality may perhaps have to be regarded as belonging to the lower 

 Miocene. From the study of the subdivisions of the Miocene strata 

 in western Nebraska, and eastern \\'yoming as distinguished by Hat- 

 cher,' we understand that the Harrison Beds represent the hiatus be- 

 tween the Upper and Lower Deep River Formations in Montana. Since 

 Diceratherium and the large Dinoliyus have been discovered in the 

 uppermost Harrison or at the base of the Nebraska Beds it would seem 

 to indicate the necessity of regarding the Monroe Creek Beds as of con- 

 siderably later geologic age than that assigned to them by Hatcher. 

 The Gering Beds which form the lowermost division in the Miocene 

 formation in this locality, would then have to be regarded as etjuiva- 

 lent to the L'pper John Day and Lower Deep River. However, a 



' Loc. cit., p. ii8. 



