Note: The head of the animal bears numerous simple tapered
arms, or tentacles, arranged in groups, but not
furnished with suckers. The siphon, unlike, that of
ordinary cephalopods, is not a closed tube, and is not
used as a locomotive organ, but merely serves to
conduct water to and from the gill cavity, which
contains two pairs of gills. The animal occupies only
the outer chamber of the shell; the others are filled
with gas. It creeps over the bottom of the sea, not
coming to the surface to swim or sail, as was formerly
imagined.
2. The argonaut; -- also called {paper nautilus}. See
{Argonauta}, and {Paper nautilus}, under {Paper}.
3. A variety of diving bell, the lateral as well as vertical
motions of which are controlled, by the occupants.