I32 KANSAS UNIVERSITY QUARTERLY. 
corresponding portion of Bison americanus. This portion is more 
convex and the frontal eminences are more strongly marked than 
in Bos. The orbital portions are much more strongly projected 
laterally, and more roughened for muscular attachment than in 
either of the recent forms mentioned; the posterior portions are 
much broader than in Bos. The ridges, connecting the orbits with 
the bases of the horn-cores and separating the facial from the tem- 
poral portion, are not present, the two parts gradually rounding 
into each other. This ridge is strongly marked in os, while in 
Bison americanus it 1s only slightly developed or absent altogether. 
The horn-cores are proportionally longer and more robust than in 
the last mentioned species, and are directed less strongly upward 
and backward. When compared with os a marked difference in 
the position of the horn-cores is at once noticed. In this genus the 
horn-cores are situated far back and occupy the posterior angles of 
the frontals, while in the bison they are situated just over the root 
of the zygoma and are separated from the posterior portion of the 
skull by the anterior wings of the parietals. The anterior surface 
of the frontals is slightly more convex than in Bison americanus; in 
the ox this portion is slightly concave. The fronto-nasal suture is 
situated farther forward, and the lateral portions forming the nasal 
notch are not so sloping as in the ox. The venous foramina, sit- 
uated above and slightly posterior to the orbits and leading into the 
frontal sinuses, are present in all of the three forms, but are less 
numerous in the ox than in the two species of bison undex consid- 
eration. The supra-orbital notch is not present in Bison antiguus. 
Nasals. 
The nasals are more anteriorly projected than in Bison americanus, 
and are proportionally broader and less arched than in Bos /aurus. 
There seems to be no articulation with the maxilla, but on account 
of the damaged condition of the specimen in this region, this point 
cannot be accurately determined; in the ox this articulation is very 
long. 
Parietals. 
The parietals differ in but few points from the corresponding 
portion of Bison americanus. The parietal eminences are broader 
and more swollen than in this species, and the swelling invades the 
frontals somewhat anteriorly. The notch found at the superior 
portion of the temporal fossa and formed by the anterior wing and 
the inferior periotic portion of the parietals, is more acute than in 
Bison americanus. In the ox the anterior wings are more vertically 
placed than in the two species of bison mentioned. In the ox 
