ARCH J10THERIU M OF NEBRASKA. 



561 



suture, resembles the cat tribe, and more particularly the extinct genus Machairo- 

 dus ; while the vertical orbits are separated from the temporal fossse by post-orbital 

 arches, relatively as strong as in the Ruminants. The face posterior to the penul- 

 timate premolar is demi-cylindrical, and constructed very much like the corre- 

 sponding portion of the head of Choeropsis. The specimen indicates an animal a 

 little larger than the Choeropotamus parisiensis, Guv. 



Lateral view. — (Tab. x. 2.) — The temporal fossa has about the same length as 

 the depth, and extends antero-posteriorly from the lateral margin of the inion to 

 the posterior margin of the orbit, and in this direction measures in a straight line 

 about the middle five inches. The breadth is relatively as great as in Felis or 

 Machairodus, measuring from the upper edge of the zygomatic process two inches 

 seven lines. The temporal surface from above downwards is convex, and about a 

 third of its extent is contributed by the frontal bone. The squamous portion of 

 the temporal bone is relatively small, appearing as if it was extended outwards to 

 form the broad deep root of the zygomatic process, which, as in Sus and Dicotyles, 

 originates on a line with the lateral border of the inion. 



The squamous suture descends in an irregular convex line in an unusually abrupt 

 manner, and the coronal suture after passing obliquely backwards and downwards 

 upon the temporal surface for a little over an inch, then descends vertically an inch 

 and a half posterior to the anterior margin of the temporal fossa. 



The parietal bone has a remarkably broad descending process to join the sphenoid. 



The outer margin of the zygoma posteriorly is broken in the specimen. The 

 portion of the process which turns forward to join the malar bone, is about three- 

 fourths of an inch deep, and curves upward. 



The glenoid cavity appears to hold the same relative position as in the Peccary, 

 but this, as well as the entire base of the cranium, is still enveloped in a hard 

 matrix. 



The meatus auditorius externus and its process, also obscured by matrix, appears 

 to hold a position at the bottom of a deep fossa posterior to the glenoid articulation. 



The orbital entrance is vertically oval, and is directed outwards and as much 

 forwards as in the Cats, but not at all upwards. It is broader below than above, 

 and its supra orbital margin is prominent outwards. Internally or anteriorly its 

 margin presents a mammillary lachrymal process, above and below which it is 

 notched. 



The malar bone advances upon the face as far forward as the lower part of the 

 anterior border of the lachrymal bone. Its inferior margin ascends anteriorly, and 

 below the orbit its external face is bent upwards, and is remarkably shallow, being 

 at the narrowest part just in advance of the middle of the orbit only half an inch, 

 and behind the orbit it is as remarkably deep, measuring from the summit of the 

 post-orbitar process vertically two and one-third inches. 



The face is long, broad, and demicylindroid in form, though it appears compara- 

 tively narrow, with the great breadth of the cranium from zygoma to zygoma. The 

 sides of the face are vertically convex, and the exit of the infra-orbitar canal is a 

 large oval foramen, advancing upon a correspondingly large depressed portion of 



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