12G 
The Evolution of the IForse. 
ancient representatives, while the horses are all inhabitants of 
the open plains, for life upon which their whole organisation is 
in the most eminent degree adapted. The length and mobility 
of the neck, the position of the eye and the ear, and the great 
development of the organ of smell, give them ample means of 
becoming aware of the approach of enemies ; while the length of 
their limbs, the angles the different segments form with each 
other, and especially the combination of firmness, stability, and 
a. 
Fig. 3. — Permanent incisor of the Horse* [See page 125.] 
lightness in the reduction of all the toes to a single one, upofi 
which the whole weight of the body and all the muscular power 
of the limb are concentrated, give them speed and endurance 
surpassing those of almost any other animal. 
If we were not so habituated to the sight of the horse as 
hardly ever to consider its structure, we should greatly marvel 
at being told of an animal so strangely constructed that it had 
but a single too on each limb, on the end of the nail of which it 
walked or galloped. Such a formation is without a parallel, 
1 From Professor Brown's pamphlet on Dentition as Indicative of the Age 
of the Animals of the Farm, published by the Society, 
