THE LIFE OF MAMMALS 
The simplest condition is seen in the giraffe, each of whose paired horns 
is a straight, bony outgrowth, the os cornu, originally separate from the 
skull, but becoming permanently fused with it early in life, and is covered 
with wholly unmodified furry skin. In deer there is the same os cornu 
which may here be branched, and never becomes fused with the skull, but 
on the contrary is shed and renewed annually, and is covered with a skin 
modified into ‘velvet,’ which decays and drops off as soon as the horn 
core (antler) is perfected. Between these two falls possibly the extinct 
Sivatherium and certainly falls the modern pronghorn. This is an 
isolated case, but connects the giraffe and deer with the Bovide, or proper 
‘hollow-horned’ ruminants (Cavicornia). In this family the males of every 
species, and in most cases the females also, possess upon the top of the skull 
protuberances of bone into which air cells often extend from the frontal 
sinuses. These are called ‘horn cores,’ and form the support of the cor- 
neous sheaths that cover and often extend far beyond them. They are 
not present at birth for obvious reasons, but begin to grow immediately 
afterwards. The horn sheaths grow with them, and continue even after 
they have reached normal size to push out at the base as fast as they wear 
away at the tip. Their form and position on the head is characteristic of 
each group: round and lateral in the oxen; slender, retrocurved or twisted, 
and somewhat compressed or sharply keeled in most antelopes; heavy, 
cross-ridged, triangular in section and often spiral in the sheep and goats, 
and so on.” ” 
The oxen are the most typical as well as important of the 
leading ruminant family Bovide, and differ from the other 
genera by their stouter build and by the fact that their horns 
stand out from the sides of the skull, and are simply curved 
and smooth. No wild oxen inhabit South America, Madagas- 
car, or Australasia. 
The foremost species, now extinct as a wild animal but per- 
fectly traceable, is the original wild ox of Europe, the source 
of our farm cattle. It was much larger than any 
existing breed, and bore immense horns, several of 
which, following the custom of the primitive Germans, were 
mounted in silver standards and long kept in European cities 
as ceremonial drinking horns. One of these, preserved almost 
to the nineteenth century at Zabern, near Strassburg, would 
238 
Aurochs. 
