THE ARTIFICIAL SKELETON. 309 
double—one set, the superior, being continuous throughout the whole 
length of the animal from the head to the root of the tail, and containing 
the nervous system ; while the other lying below, but closely connected 
to them, is interrupted in certain localities, being found to exist chiefly in 
three regions :—Ist, where it forms the jaws and bone of the tongue ; 
2d, where, by means of the ribs and sternum, it constitutes the thorax and 
its appendages, the anterior extremities ; and, 3dly, where, in the shape of the 
pelvic arch, it protects the organs of generation, and, through the posterio1 
extremities prolonged from it, assists in locomotion. The superior of 
these arches, from containing the brain, and its prolongation, the spinal 
cord, is called the neural arch. ‘The inferior is termed the hemal arch 
(aia, blood), because it protects the heart and its large blood-vessels as 
the latter pass from the thorax towards the head and posterior extremities. 
In all the vertebrata the neural arch consists of one continuous cavity, 
defended from end to end by bony plates, strongly jomed together ; and 
in some of the lower forms (lizards) the hemal arch is nearly as complete, 
these animals having cervical ribs ; while the dugong and some others are 
furnished with ribs in their tails. Consequently, it is fair to consider the 
whole skeleton in the superior forms of the animal kingdom as composed 
of two series of arched plates, firmly united together, but still allowing 
more or less motion, and serving to protect the centres of the nervous and 
sanguineous systems, from which they have received their names. 
THE ARTIFICIAL SKELETON. 
THE BONES of the Horse, as of the other mammalia, may be preserved 
with their natural ligamentous attachments connecting them in a dry 
state, in which condition the skeleton is called a natural one. It is 
usual, however, to macerate them so long that all the soft parts readily 
separate, leaving the bones without any of the ligaments or cartilages 
which are firmly fixed to them during life. They are then put together 
by wires, &c., the cartilages being represented by leather and cork. In 
this way it often happens that the proportions are not exactly preserved, 
and, on reference to an articulated skeleton in any museum, the inex- 
perienced eye may be greatly misled. Thus it is very common to repre- 
sent the thorax in the artificial skeleton as much shallower than it is in 
nature, where its lower margin is on the average about midway between 
the top of the withers and the ground. Again, in the fresh state, the 
intervertebral fibro-cartilage is in some parts of the spine of considerable 
thickness ; and if the proper substance is not artificially supplied, the 
skeleton will be too short, or if too thick a material is added it will be 
too long. In the engraving of the skeleton occupying the opposite page, 
which is drawn from the skeleton in the Museum of the Veterinary 
College of London, the spine is correctly represented, but the thorax is 
tvo shallow, and the scapula, together with the whole fore extremity, is 
placed too far forward. 
NUMBER OF BONES COMPOSING THE SKELETON. 
THE SKELETON is composed of two hundred and forty-seven separate 
bones, which are united by joints to form the spine, thorax, pelvis, tail, 
and fore and hind extremities. The spine is finished anteriorly by the 
head, which is divided into the cranium and face, and contains the teeth. 
