BISON PRISCUS. 515 
slender proportions, compared with those of the Ox, which 
distinguish the fossils. There are fourteen pairs of ribs. 
The skull shows the same expanse, convexity, and short- 
ness of the frontal region, and the same angle between 
this and the occipital region, as does the fossil skull of the 
Bison priscus; the horn-cores have the same advanced 
origin, and the same direction : these, however, are rela- 
tively shorter than in most of the fossil skulls, and the 
general size of the existing Aurochs is less than that of 
the ancient or fossil specimens. Admitting with Cuvier, 
that such characters are neither constant nor proper for 
the distinction of species, we may recognise in the con- 
fined sphere of existence to which the Aurochs has been 
progressively reduced, precisely the conditions calculated 
to produce a general loss of size and strength, and a special 
diminution of the weapons of offence and defence. I can- 
not perceive, therefore, any adequate ground for aban- 
doning the conclusion to which I had arrived from a study 
of the less perfect materials available to that end, before 
the arrival of the entire skeleton of the Lithuanian Au- 
rochs, viz.—that this species was contemporary with the 
Mammoth, the Tichorhine Rhinoceros, and other extinct 
Mammals of the pliocene period. 
Fig. 212. 
Side view of cranium of Bos longifrons, Bog, Ireland. 
