Molluscs

have no viscera, but they have what is called a
mytis, and on it a vessel containing a thick black juice; in the sepia
or cuttle-fish this vessel is the largest, and this juice is most
abundant. All molluscs, when frightened, discharge such a juice, but
the discharge is most copious in the cuttle-fish. The mytis, then,
is situated under the mouth, and the oesophagus runs through it; and
down below at the point to which the gut extends is the vesicle of the
black juice, and the animal has the vesicle and the gut enveloped in
one and the same membrane, and by the same membrane, same orifice
discharges both the black juice and the residuum. The animals have
also certain hair-like or furry growths in their bodies.