es must be understood. (See also p. 583.)

The bones of the fetlock and foot constitute the skeleton on which the
other structures are built and comprise the lower end of the cannon bone
(the metacarpus in the fore leg, the metatarsus in the hind leg), the
two sesamoids, the large pastern or os suffraginis, the small pastern or
coronet, the small sesamoid or navicular bone, and the coffin bone or os
pedis. (Plate XXXIV, fig. 3.)

The cannon bone extends from the knee or hock to the fetlock, is
cylindrical in shape, and stands nearly or quite perpendicular.

The sesamoids occur in pairs, are small, shaped like a three-faced
pyramid, and are set behind the fetlock joint, at the upper end of the
large pastern, with the base of the pyramid down.

The large pastern is a very compact bone, set in an oblique direction
downward and forward, and extends from the cannon bone to the coronet.

The coronet is a short, cube-shaped bone, set between the large pastern
and coffin bone, in the same oblique direction.

The navicular bone is short, flattened above and below, and is attached
to the coffin bone behind.

The coffin bone forms the end of the foot and is shaped like the horny
box in which it is inclosed.

All these bones are covered on the surfaces which go to make up the
joints with a cartilage of incrustation, while the portions between are
covered with a fibrous membrane called the periosteum.

The joints of the legs are of especial importance, since any
interference with their function very largely impairs the value of the
animal for most purposes. As the joints of the foot and ankle are at the
point of greatest concussion they are the ones most subject to injury
and disease.

There are three of these joints--the fetlock, pastern, and coffin. They
are made by the union of two or more bones, held together by ligaments
of fibrous tissue, and are lubricated by a thick, viscid fluid, called
synovia, which is secreted by a special membrane inclosing the joints.

The fetlock joint is made by the union of the lower end of the cannon
and the upper end of the large pastern bones, supplemented by the two
sesamoids, so placed behind the upper end of the pastern that the joint
is capable of a very extensive motion. These bones are held together by
ligaments, only one of which--the suspensory--demands special mention.

The suspensory ligament of the fetlock starts from the knee, extends
down behind the cannon, lying behind