211 

 A descriptive list of the fossils is given below : 



MAMMALIA. 



Order Ruminantia. 



OREODON. 



Oreodon Culbertsoni. 



This species, established on a multitude of remains from the Mauvaises 

 Terres of White River, Dakota, is apparently indicated by some small frag- 

 ments of upper and lower jaws with teeth, which are labeled " Big Bottom 

 of John Day's River." One of the best-preserved and most characteristic 

 specimens consists of a jaw-fragment containing the upper last premolar 

 and the molars, the latter being represented in Fig. 12, Plate VII. In all 

 respects it is like the corresponding part in Oreodon Culbertsoni, from White 

 River. Other specimens show a slight variation in the size of the teeth. 



Oreodon superbus. 



Nearly twenty-five years have elapsed since the first fossil remains of 

 mammals from the Tertiary formations of the West were submitted to my 

 examination. To the present time they have been coming to me in constant 

 succession, so that I have had the opportunity of examining thousands of 

 specimens, the collective weight of which would amount to several tons. 

 From some of the first specimens brought from the Mauvaises Terres of 

 White River,- Dakota, after a few errors, I thought I had fixed upon well- 

 marked characters distinguishing the extinct genus of hog-like ruminants, for 

 which I proposed the name of Oreodon. Two species were described under 

 the names of O. Culbertsoni and O. gracilis, mainly from a marked difference 

 in size. 



Several detached crania, differing from that of either of the species of Oreo- 

 don in the possession of large inflated ear-capsules, at first attributed to a 

 peculiar genus with the name of Eucrotaphus, were subsequently referred to 

 Agriochcerus, which had originally been described from jaws and teeth. Later 

 this determination appeared to be confirmed by an almost complete skull in 

 which the cranium agreed with the detached specimens. 



Some small fragments, and finally a complete skull, appeared to indicate a 

 third and larger species of Oreodon, to which the name of O. major was given. 



