1884,] 513 [Cope. 
Academy Philada., 1858, 3892 ; 1854, 85, 157; 1857, 89; Bronn Lethea 
Geognostica, 1856, 930. Extinct Fauna Dakota and Nebraska, 1869, p .86 ; 
Pl. VI, fig. 1; VII fig. 2; IX, figs. 1-2. Merycoidodon culbertsont Leidy, 
Proceeds, Acad. Phila., 1848, 47, Pl. 11; 1850, 121; 1851, 239. Oreodon 
priscum Leidy, Proceed. Phila., Academy 1851, 238; Cotylops speciosa 
Leidy, Ibidem 239 ; Oreodon robustum Leidy, Ibidem 276. 
The White River epoch of Dakota, Nebraska, Colorado and Wyoming. 
The two sub-species are defined as follows : 
Length of superior true molar series from M. .040 to (OGRE We ees 
0. ¢. periculorum. 
Length of superior true molar series from .046 to .050.... 0. ¢. culbertsont, 
Oreodon culbertsoni periculorum Cope. 
This smaller race or sub-species has as yet only been found in the 
White River beds of Colorado and Wyoming. I do not detect any differ- 
ences between it and the Nebraska form other than those of size. The 
largest measurement of the O. ¢. culbertsont given in the above table is 
derived from Leidy ; my largest specimen gives .047 as the length of the 
true molar series. 
Oreodon culbertsoni culbertsoni Leidy. 
Very abundant in the White River formation of Dakota, Nebraska, 
Colorado and Wyoming. 
EUCROTAPHUS Leidy. 
Proceedings Academy Philada., 1850, p. 92. Ancient Fauna of Nebraska, 
Smithsonian Contrib. to Knowledge, 1853, p. 56. Hporeodon Marsh, Amer. 
Journ. Sci. Arts, Vol. ix, 1875, p. 249. 
Premaxillary bones distinct from each other. Otic bulla swollen. No 
prelachrymal or nasal vacuities. 
This genus presents us with the first step in the series of modifications 
which the primitive form underwent with the advance of geological time. 
It appeared contemporaneously with the earliest representatives of the 
family, @ ¢., in the White River epoch, but in small numbers. In the 
succeeding or John Day epoch the genus Oreodon had disappeared, and 
the present form had multiplied enormously in individuals, if not in 
species. Subsequent to that epoch it is unknown. 
The greater number of the Oreodont remains found in Oregon belong to 
this genus. The Hucrotaphus jacksont bore the same relation to the Oregon 
John Day fauna, as the Oreodon culbertsont did to that of the White River 
epoch. 
The species of Eucrotaphus are distinguished as follows : 
I. Palatonareal border well posterior to posterior edge of maxillary 
bones. 
