PETERSON: A REVISION OF THE ENTELODONTID® 89 
of the border of the orbit, and the lower margin descends rapidly to form the 
dependent, broad, and laterally compressed process, which is in Dinohyus consider- 
ably smaller than is the case in many earlier species. This anomalous process is 
directed slightly outward as well as downward, and no doubt varies in shape in 
different species, if not in different individuals; at all events this appears to be true 
of the Oligocene forms.” Superiorly the jugal sends out a postorbital process, which 
is codssified with that of the frontal, as stated above and the posterior process is 
received by the zygomatic process of the squamosal (see Pl. LV). 
The lachrymal covers a considerable portion of the side of the face and articu- 
lates anteriorly with the maxillary, superiorly with the frontal, not with the nasal, 
and inferiorly with the jugal. The bone supplies a portion of the anterior border 
of the orbit. The lachrymal tubercle is quiet prominent. 
The long and slender nasals articulate superiorly with the spear-shaped proc- 
esses of the frontals, and laterally with the maxillaries and the premaxillaries. 
At their junction with the frontals the median area of the nasals is very convex 
transversely and on the sides of the muzzle the nasals have a slight inward bend to 
accommodate them to the concave sweep of the muzzle in front of the orbits. More 
anteriorly the nasals are regularly convex from side to side and gradually decrease 
in width; their anterior ends are slightly damaged in the type, but it is seen that 
their free ends are slightly separated in the median line, and also that they projected 
slightly beyond the superior border of the premaxillaries. 
The premaxillaries are more truncated anteriorly than in the known Oligocene 
forms. This causes the reduction of the median pair of incisors stated above, and 
the anterior border ascends slightly more rapidly than in the earlier forms. Super- 
iorly the premaxillaries have a long contact with the nasals and posteriorly they 
are received by the oblique border of the maxillaries. The premaxillaries are of 
large size, but are relatively smaller than those in Hippopotamus and Sus. The 
incisive foramina are large and the palatine processes of the premaxillaries are only 
thin bony bridges, which are suturally connected in the median line, and extend back 
Opposite the posterior portion of the canine. 
The maxillaries have a great antero-posterior diameter and the sides of the long 
and comparatively narrow muzzle are largely made up of these bones, although the 
lachrymal and the jugal cover a considerable space. The alveolar border forms an 
almost straight antero-posterior line until the canine is reached ; at this point the 
maxillary has a rapid outward curve to accommodate the root for the large canine. 
The maxillo-premaxillary suture is somewhat short in comparison with that in older 
‘These processes are present in all of the American species, of which complete material, representing this por- 
tion of the skull, has been found. 
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