In all cases the head comes after the feet, in the middle of the
feet that are called arms or feelers. There is here situated a
mouth, and two teeth in the mouth; and above these two large eyes, and
betwixt the eyes a small cartilage enclosing a small brain; and within
the mouth it has a minute organ of a fleshy nature, and this it uses
as a tongue, for no other tongue does it possess. Next after this,
on the outside, is what looks like a sac; the flesh of which it is
made is divisible, not in long straight strips, but in annular flakes;
and all molluscs have a cuticle around this flesh. Next after or at
the back of the mouth comes a long and narrow oesophagus, and close
after that a crop or craw, large and spherical, like that of a bird;
then comes the stomach, like the fourth stomach in ruminants; and
the shape of it resembles the spiral convolution in the trumpet-shell;
from the stomach there goes back again, in the direction of the mouth,
thin gut, and the gut is thicker than the oesophagus. (See diagram.)