ZOOLOGICAL POSITION AND STRUCTURE 3 1 
collectively forming the haunch-bone, or sacrum ; and 
the series is completed by the twenty caudal 
vertebrae of the tail. In the bison, on the other hand, 
the number of dorsal vertebrae is increased to fourteen, 
with a reduction in the number of lumbars to five ; 
so that the number of dorso-lumbar, or trunk, vertebrae 
is nineteen throughout the genus, as it is in the 
Artiodactyla generally. The number of vertebrae in 
the tail varies, however, from fifteen to eighteen or 
twenty, according to the species. 
It should be added that in all the members of the 
BovidcE the upper tusks, or canine teeth, are wanting, 
although they are retained in the deer. Further, the 
lateral metacarpals in the fore-limb and the corre- 
sponding metatarsals in the hind-limb have com- 
pletely disappeared, so that the toe-bones have no 
bony supports. In the deer tribe, on the other hand, 
either the upper or lower ends of the metacarpals 
persist, the latter condition being shown in the 
woodcut on page 11. Large tusks, or canines, are 
present in the upper jaw of the males ; and the 
cheek-teeth have low crowns, so that the bases of 
the hollows between the four columns are visible even 
in the unworn condition. 
In the days when the aurochs, in company with 
the bison, roamed the great forests of Europe, 
members of the ox tribe were distributed over tem- 
perate and tropical regions of all the continents of 
the world, with the exception of South America and 
Australia. North America has, however, only the 
American bison (together with several more or less 
nearly allied extinct species or races) ; while in the 
highlands of central Asia the group is represented 
solely by the yak, and in Africa by one of the two 
