144 MAMMALS

Another noteworthy antelope is the chousingha,
Tetraceros quadricornis, the only living ruminant
with four horns. Yet another that must not be
passed unmentioned is the gnu, or wildebeest, with
horns of much the same structure as those of the
cattle, and in other respects representative of the last
batch of antelopes.

The giraffe has the same dental formula as a sheep,
the typical ruminant formula of 0033 over 3133, and
would probably be classed with the Boude if it were
not for perhaps the most insignificant thing about him,
namely, his three ‘horns.’ Two of these prominences
are really bones which at birth are separate from the
skull but unite with it later on. They are covered
with skin and not horn, and to a certain extent are
one step further on the road from those of the prong-
buck to those of the deer. The third ‘horn’ is a
protuberance on the front of the skull forming a
triangle with the other two. The extinct giraffes had
these bony processes, which are also traceable in allied
fossil genera such as sivatherium, which was the
biggest ruminant that, as far as we yet know, has
walked the face of this earth. In short, the giraffe is
not one by himself, but the last representative of an
old and numerous and lofty family. Like all the big
‘animals, he is fast disappearing. There are a few left
in the Kalahari desert and in the north of the Soudan ;
if any person will bring one alive, in sound health and
condition, to Regent’s Park, he will receive 1,000/.

The deer are unknown in Africa south of the
Sahara, where the antelopes take their place. They
may be regarded in a general way as ruminants that