ally drawn
downwards and forwards, the space which we now see between the shield
and the ring (pl. V, 10) would get smaller and smaller, until at last it
quite disappeared; and the distance between the front of the shield (pl.
V, 1) and the highest part of the back of the ring (pl. V, 4) would be
increased.

I may observe here that authorities differ as to whether the shield
moves upon the ring, or the ring upon the shield, and that some
maintain the one is drawn down while the other is tipped upward. It
is sufficient for our purpose, however, that a movement as upon a
hinge takes place, whereby, as explained just now, the distance
between the front of the shield and the highest part of the back of
the ring is increased.

3rd. =The Lid= (pl. V, 11) is an elastic cartilage which serves to close
the voicebox in the act of swallowing, in order to protect it against
any intruding foreign substances. The food we take has to pass over it,
and it sometimes happens, when the lid has not been pulled down tight
enough, that a particle of food enters the voicebox, in which case we
say it has "gone the wrong way," and there is then no peace until the
intruder has been got rid of, generally by a violent fit of coughing.

The lid, it is true, is not the only means of protection which the
voicebox possesses. Professor C. J. Eberth, for instance, mentions
(Archiv fuer pathol: Anatomie, vol. lxiii., p. 135, Berlin, 1868)
the case of a woman who, upon dissection, was found to be entirely
without the free upper part of the lid, which could alone cover the
voicebox. She had never experienced any difficulty in swallowing,
and it is therefore clear that with her the closing of some of the
parts immediately below was sufficient to prevent the food from
getting into the voicebox. But "the exception proves the rule," and
in spite of this and other similar cases, the fact remains that the
lid is obviously the first and most natural protector of the
voicebox.

4th and 5th. We have thus far become acquainted with three cartilages
out of the five. Let us now remove one plate of the shield, as though
cutting it off with a knife (pl. VII, 1 and 2), in order that we may
look inside and see the remaining two cartilages which have hitherto
been hidden by it. These are--

=The Pyramids= (pl. VII, 1 and 2), so called because of their shape. Their
bases are