214 



THE MERYCOIDODONTID/E 



Specific Characters: The skull is low and small, about the size of that of Merychyus 

 curtus. The zygomatic arches are incomplete, but they appear to have had a moderately good 

 expansion, sufficient, I believe, to have placed the skull in the upper limits of mesocephaly, or per- 



mi9, TYPE 



Y. P. M. 



Fic , 55 -Oreodontoides oregonensis Thorpe. Skull. GHT. Cat. No. 12329 Y.P.M. 2/3 nat. size. 



(After Thorpe, 1921.) 



haps in the lower range of brachycephaly. The malar is about medium in proportions and the 

 zygomatic process of the squamosal invades the malar to a point below the last quarter of the orbit. 

 There is not a trace of facial or frontal vacuities. The anterior part of the nasal bones is missing. 



12329, TYPE 

 Y. P. M 



Fig. 156.— Oreodontoides oregonensis Thorpe. Right half, inferior view of skull. GHT. Cat. No. 12329 Y.P.M. 



2/3 nat. size. (After Thorpe, 1921.) 



These bones were reduced in that they extend posteriorly only as far as a line through the middle of 

 the lacrimal fossa:. They decrease in width extremely gradually toward the rear and terminate in 

 truncated ends. The muzzle is pointed, and the face narrows rather rapidly in advance of the orbits. 



12129, TYPE 

 Y. P. M. 



Fig. 157. — Oreodontoides oregonensis Thorpe. Right half, superior view of skull. GHT. Cat. No. 12329 Y.P.M. 



2/3 nat. size. (After Thorpe, 1921.) 



The lacrimal bone is well expanded on the face, where it has a nearly square outline. A deep but 

 small lacrimal fossa occupies roughly half of its facial area. The frontals are unreduced, and 

 extend forward in the shape of a wedge on either side of the nasals to a point slightly in advance of 

 the lacrimal bones. They are somewhat depressed between the supraorbital margins. The orbits are 

 large and round, with the upper margin but little below the top of the skull; they look mainly out- 

 ward but somewhat upward and forward. The temporal ridges are but faintly defined and do not 



