From The Collaborative International Dictionary of English v.0.48 [gcide]:
Argonauta \Ar`go*nau"ta\, n. (Zool.)
A genus of Cephalopoda. The shell is called paper nautilus
or paper sailor.
[1913 Webster]
Note: 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]
From WordNet (r) 3.0 (2006) [wn]:
Argonauta
n 1: type genus of the family Argonautidae: paper nautilus [syn:
Argonauta, genus Argonauta]