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fangs, as in the deer. In Merycochoerus they are longer, and protrude more 

 gradually as they are worn away. The face is more abruptly prolonged in 

 front of the orbits ; the infra-orbital arches are proportionately of much greater 

 depth; and the infra-orbital foramina situated much further back. While the 

 fore part of the upper jaw of Oreodon is constructed in the more ordinary 

 manner of many animals — suilline pachyderms, carnivora, &c. — that of Mery- 

 cochoerus is more like that of the tapir. 



Merychyus, so fixr as known, is intermediate in character witli Oreodon and 

 Merycochoerus. Its molar teeth are like those of the latter ; its face appears 

 not to be so abruptly narrowed; and the infra-orbital foramina hold an inter- 

 mediate position. 



Another member of the oreodont family, from a formation probably of 

 equivalent age to that which has yielded the remains of the Oreodons, has been 

 named Leptauchenia. Its molar teeth agree in character with those of Mery- 

 cochoerus and Merychyus, but are more strongly folded internally in the case 

 of the lower ones, externally in the case of the upper ones. The face is more 

 like that of Oreodon ; has the infra-orbital foramina in the same relative posi- 

 tion, but has large unossificd spaces at the upper part of the face. 



Oreodon superhus, the name which appears at the head of this chapter, was 

 applied to a species, indicated more recently than any of the preceding, from 

 specimens belonging to Mr. Condon's collection of Oregon fossils. The species 

 exhibits characters which make it somewhat peculiar, and place it in a position 

 intermediate to the White River Oreodons and the genus Merycochoerus. It 

 is exemplified by a number of specimens, among which is the mutilated skull, 

 represented, one-half the natural size, in Fig. 1, Plate I. Other specimens, 

 consisting of detached mutilated crania, portions of others, and fragments of 

 jaws and teeth, pertain to half a dozen or more individuals. 



The skull of Oreodon superhus is about the size of that of Merycocharus 

 proprius. In form, proportions, and constitution, and in the number, relative 

 position, and construction of the teeth, it nearly resembles the other known 

 species of the genus from the Mauvaises Terres of White River, Dakota. 



The cranium proper is a magnified likeness of that of Oreodon Culbertsoni 

 or O. ?n(iJor, and more especially agrees with the latter in the possession of 

 large inflated ear-capsules. It presents the same kind of variation in different 

 specimens observed in O. Culbertsoni. In most of the specimens the tempo- 

 ral surfaces slope from the sagittal crest with a slight sigmoid curve. In one 



