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The coffin bone or third digit is peculiar in the horse. Both in structure 
and economy there isa close analogy between this bone in the horse and 
the double form of the same bone in the ox; but the resemblance is only 
partial, each bone being fitted for the special purpose for which it is wanted. 
The cloven-footed animal moves with astonishing security over granite rocks, 
where the horse is less adapted to venture. This fact is shown also in the 
different kinds of goat and deer, and in a lesser degree in the ox. All 
cloven-footed animals are endowed with wonderful security of foothold, but 
they lack the elasticity needed to carry weight, as well as the graceful movement 
of the horse, with his ample security of footing over hill and dale. In such 
places the noble creature finds sustenance for life, and, here his special 
powers of speed and endurance are required. The coffin bone has much of 
the form of the hoof in its exterior aspect, and when the lateral cartilage, 
with the other structures attached to it, is seen in connection the whole 
structure is similar in its outward form to that of the hoof (Gamgee). On 
reference to the accompanying picture of the coffin bone, it is seen to 
resemble in its leading features the external form of the hoof, one chief 
difference being found to consist in the former being fully a fourth shorter than 
the inner cavity of the latter. When, however, this wonderfully- 
constructed bone, of which we append a drawing, is furnished with the 
cartilages, ligaments, tendons, and all the other important structures, of 
which it constitutes the centre, it assumes the form and becomes the 
counterpart of the hoof. 
The horse’s hoof is not only to be regarded as a covering for the 
protection of the sensitive structures from injury. The hoof has its specially 
assigned place in the whole economy of the foot, and each separate 
component part must be looked upon as an essential constituent of the 
whole organisation. The hoof forms an integral part of the foot, and those 
animals that lack it, though amply protected as they are, cannot sustain 
weight and undergo the same fatigue on the same spots, as those which 
possess it. Of all creatures gifted with the hoof, the horse is the superior 
(Gamgee). ; 
The inner face of the hoof presents over its entire extent white parallel 
leaves, which dovetail with the prolongations or laminze of sensitive vascular 
tissues. The hoof has three parts—the wall, the sole, and the frog ; and 
the horn composing these parts differs in composition, That of the wall-is 
