the peg, _e_, of the axis.

THE RIBS, also twenty-four in number, are arranged in pairs on each side
of the chest. At the back, they are all attached to the spine. In front,
the upper seven pairs are tied by cartilages to the breastbone (sternum);
three are fastened to each other and to the cartilage above, and two, the
floating ribs, are loose.

The natural form of the chest is that of a cone diminishing upward. But,
owing to the tightness of the clothing commonly worn, the reverse is often
the case. The long, slender ribs give lightness, [Footnote: If the chest
wall were in one bone thick enough to resist a blow, it would be unwieldy
and heavy As it is, the separate bones bound by cartilages yield
gradually, and diffuse the force among them all, and so are rarely
broken.] the arched form confers strength, and the cartilages impart
elasticity,--properties essential to the protection of the delicate organs
within, and to freedom of motion in respiration. (See note, p. 80.)

FIG. 9.

[Illustration: _The Pelvis._ a, _the sacrum;_ b, b, _the right
and the left innominatum._]

THE HIP BONES, called by anatomists the innominata, or nameless bones,
form an irregular basin styled the _pelvis_ (_pelvis_, a basin).
In the upper part, is the foot of the spinal column--a wedge-shaped bone
termed the _sacrum_ [Footnote: So called because it was anciently
offered in sacrifice.] (sacred), firmly planted here between the
widespreading and solid bones of the pelvis, like the keystone to an arch,
and giving a steady support to the heavy burden above.