are limited only to standing on the ground, there are only two
digits on each foot, and only a single one is to be found in the
_solipedes_ (the horse, the ass).

"Moreover, among these herbivorous animals, and especially among the
ruminants, it has been found that from the circumstances of the
desert countries they inhabit they are incessantly exposed to be
the prey of carnivorous animals, and find safety only in precipitous
flight. Necessity has forced them to run swiftly; and from the habit
they have thus acquired their body has become slenderer and their
limbs much more delicate: we see examples in the antelopes, the
gazelles, etc.

"Other dangers in our climate to which are continually exposed the
deer, the roebuck, the fallow-deer, of perishing from the chase made
by man, have reduced them to the same necessity, restrained them to
similar habits, and have given rise to the same results.

"The ruminating animals only using their legs as supports, and not
having strong jaws, which are only exercised in cutting and browsing
on grass, can only fight by striking with the head, by directing
against each other the _vertex_ of this part.

"In their moments of anger, which are frequent, especially among the
males, their internal feelings, by their efforts, more strongly urge
the fluids toward this part of their head, and it there secretes the
corneous matter in some, and osseous matter mixed with corneous
matter in others, which gives origin to solid protuberances; hence
the origin of horns and antlers, with which most of these animals
have the head armed.

"As regards habits, it is curious to observe the results in the
special form and height of the giraffe (_camelopardalis_); we know
that this animal, the tallest of mammals, inhabits the interior of
Africa, and that it lives in localities where the earth, almost
always arid and destitute of herbage, obliges it to browse on the
foliage of trees, and to make continual efforts to reach it. It has
resulted from this habit, maintained for a long period in all the
individuals of its race, that its forelegs have become longer than
the hinder ones, and that its neck is so elongated that the
giraffe, without standing on its hind legs, raises its head and
reaches six meters in height (almost twenty feet).

"Among the birds, the ostriches, deprived of the power of flight,
and raised on very long legs