no. 8 SKULL OF BRIDGER CREODONT—GAZIN 9 
taper to a point between the frontals, producing a pattern resembling 
an arrowhead pointing posteriorward. The frontals are decidedly 
broad forward but taper posteriorly toward the parietals. Between 
the postorbital processes the frontal area or plateau is slightly con- 
cave, a condition that I do not attribute to the compression which has 
taken place between this surface and the posterior part of the palate. 
At the position of the postorbital processes the frontals are bluntly in- 
flated, and moderately prominent temporal ridges extend posteriorly 
to their union forming the sagittal crest at about the juncture of the 
frontal and coronal sutures. The parietals are elongate and slender, 
and support a moderately well developed sagittal crest that slopes 
downward and backward, although increasing in depth toward the 
supraoccipital. The supraoccipital is missing from the P. ulta skull, 
but from other material of the genus it is known to extend far back- 
ward and a little upward, forming a remarkably developed inion. The 
greatest constriction of the slender braincase is across the parietals 
between the temporal part of the frontals and the anterior margin of 
the squamosals where these pairs approach each other closest. Pos- 
terior to the constriction the superior and lateral surface of the 
cranium formed by the squamosal sweeps widely out onto the broad 
and massive zygomatic processes. At the deepest part of the temporal 
fossa, a very large vascular foramen penetrates the parietals on each 
side of the sagittal crest. This is accompanied by a smaller foramen 
posterolateral to it on each side close to the squamosal but also within 
the parietal. 
Lateral aspect.—In lateral view (pl. 2) the premaxilla is seen to 
rise aS a narrow rim of bone along the anterior margin of the maxilla 
and form the lateral rim of the broad but possibly somewhat de- 
pressed anterior narial aperature. The premaxilla is rapidly pinched 
out posteriorward between the nasal and maxilla. The maxilla as ex- 
posed laterally is anteroposteriorly short, although the nasal process 
extends posteriorly above the lachrymal as it rises onto the dorsal sur- 
face, and the malar process extends prominently backward beneath 
the malar or jugal. The large infraorbital foramen penetrates the 
maxilla above the anterior root of P%, well forward of the orbital rim 
and about midway dorsoventrally. The lachrymal bone is prominently 
displayed on the dorsolateral surface of the rostrum anterior to the 
orbital rim and forms the anterior margin of the orbit. Extending 
downward to the anterior extremity of the jugal and separated from 
it by a marked notch, it almost or quite excludes the maxilla from 
participation in the formation of the rim. The lachrymal foramen is 
concealed just within the orbital fossa posterior to a small process on 
