Argonauta

CIDE DICTIONARY

Argonauta, n. 

 A genus of Cephalopoda. The shell is called paper nautilus or paper sailor.  [1913 Webster]
" The animal has much resemblance to an Octopus. It has eight arms, two of which are expanded at the end and clasp the shell, but are never elevated in the air for sails as was formerly supposed. The creature swims beneath the surface by means of a jet of water, like other cephalopods. The male has no shell, and is much smaller than the female. See Hectocotylus."  [1913 Webster]