130 KANSAS UNIVERSITY QUARTERLY. 
quite deeply concave and the lambdoid crest is overhanging, the 
occiput, a character not found in Bos. The ex-occipital element is 
strongly convex just above the condyles. The condyles are more 
obliquely set than in Bison americanus, and although the animal was 
much larger in every respect, yet the size of the foramen magnum 
is proportionally less than in the recent bison. The inter-condyloid 
notch is also proportionally broader in the recent form, the articu- 
lar portions are regularly convex, the superior and inferior portions 
of each condyle insensibly grading into each other without being 
separated by the sharp ridge found at this point in Bos ¢aurus. 
The basilar portion is more horizontally situated, and does not 
have the rugose knob-like projections just anterior to the condyles, ' 
so prominently marked as in Bison americanus. The par-occipital 
processes are firmly co-ossified with the mastoid portion of the 
periotic, are proportionally more slender and directed more inward 
than in either of recent forms mentioned above, and the, external 
border is not so sharp as in Los taurus. 
Skull of Bison antiquus, front view. 
Sphenoid. 
The basi-sphenoid is shorter and more tapering than the basi- 
occipital; from the point of junction with this bone it is directed 
forward, but not so sharply upward as in Bison americanus. The 
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