nautilus

Any of several cephalopod mollusks of the family Nautilidae of the Indian and Pacific Oceans, especially Nautilus pompilius, having numerous slender tentacles and an external coiled pearly shell divided into air-filled chambers.

The paper nautilus.

The Argonauta argo, or any other cephalopod believed to sail by means of the expanded tentacular arms.

A genus of tetrabranchiate cephalopoda, type of the Nautilacea or Nautilidæ, to which very different limits have been assigned.

A Portuguese man-of-war. See Physalia.

A form of diving-bell which requires no suspension, sinking and rising by the agency of condensed air.

The only existing genus of tetrabranchiate cephalopods. About four species are found living in the tropical Pacific, but many other species are found fossil. The shell is spiral, symmetrical, and chambered, or divided into several cavities by simple curved partitions, which are traversed and connected together by a continuous and nearly central tube or siphuncle. See tetrabranchiata.

The argonaut; — also called paper nautilus. See Argonauta, and Paper nautilus, under Paper.

A variety of diving bell, the lateral as well as vertical motions of which are controlled, by the occupants.

A marine mollusc, of the family Nautilidae native to the Pacific Ocean and Indian Ocean, which has tentacles and a spiral shell with a series of air-filled chambers, of which Nautilus is the type genus.