THE MAMMALIA OF THE UfNTA FORMATION. 



460 



two horizons, Plesiarctomys, Mesonyx, Triplopus, Aviynodon and Orotherium, while 

 on the other hand no genus passes through from the Uinta into the White River, 

 unless one agrees with Cope (!N'o. 2, p. 455) in regarding Metamynodon as identical 

 with Amynodon. While this is true, the Uinta fauna is no less clearly the forerunner 

 of the White River fauna ; what there are strong reasons for believing to be the an- 

 cestors of the hyracodonts, the titanotheria, the rhinocei'oses, horses, tapirs, camels 

 and creodonts, the dog-like carnivores, and the sciuromorph rodents of the White 

 River, all ai'e to be found. We cannot therefore agree with Schlosser (No. 13, p. GO) 

 in regarding this formation as Oligocene, which in fact seems to be an unnecessary 

 term in the classification of our Tertiary lacustrine deposits, the division between the 

 uppermost Eocene, lepresented by the Uinta, and the lowermost Miocene, represented 

 by the White River, being quite sufficiently clear. 



The following partial list of genera will indicate the relations between these 

 three formations. The Wasatch genera, which penetrate only into the Wind River 

 beds, are omitted from the list : 



Bkidger. 



Dinocerata 



Tillodonlia 



Slvpoloplius 



Jli'sonyx 



Itliacis 



Oxyjpna 



Protopsalis 



Antiac-odon 

 Anisacodnn 

 Passalacodon 



Ictops 

 Plesiarctomys 



C'olonymys 

 Mysops 



Omoinys 



Hyop^odiis 



Tomitlieriiim 



Liiiinollieriiim 



Microsyops 



Xipliacodon 



lliloliyus 



Hoinarodon 

 Arliiunudnn 



Uinta. 



Mesonyx 

 ? Miacis 

 ? 



? 

 Plesiarctomys 



Uyopsodus 



t 



Protoreodon 



1 

 Lcptolragiiliis 



? 



Larobdotlipriiiiii 



A. r. 9. — VOL. XV r. 3h. 



WlUTIC RiVKK. 



Hyfcnodon 



DapliiPnus (Ainpliicyou) 



Cyiiodiclis 



Diniclis 



Iloplophoneiis 



Lcptictiii 



Ictops 



Sciurus 



Gymnoptyclius 



Ileliscoinys 



Iscliyromys 



Eiimya 



Palicocastor 



Paltuolagus 



Laopilliecns 

 Mfiiotherium 



Didelpliys 



Oreodon 



AiirinchnTU'* 



I'di'liroilicritiin 



Enlclndon 



Pi-rcluiTiiM 



Li'plocliD'riis 



IlyopotaiiHis 



Li'l)loiii<'ryx 



IIypi^*odu8 



