CEPHALOPODA. 
11 
broad membrane. The two cartilaginous granules of the common 
Octopus are wanted, but these mollusca are always found in a very 
thin shell, symmetrically fluted and spirally convoluted, the last whorl 
of which is so large, that it bears some resemblance to a galley of 
which the spine is the poop. Tlie animal makes a consequent iise'of 
it, and in calm Aveather whole fleets of them may be observed navi- 
gating the surface of the ocean, employing six of their tentacula as 
oars, and elevating the two membranous ones by way of a sail. If 
the sea becomes rough, or they perceive any danger, the Argonaut 
withdraws all its arms, concentrates itself in its shell, and descends to 
the bottom. The body of the animal does not penetrate to the 
bottom of the sinres of the shell, and it appears that it does not 
adhere to it, at least, there is no muscular attachment, a circumstance 
which has induced some authors to believe, that its residence there 
is that of a parasite* * * § , like the Pagurus Bernhardus, for instance. 
As it is always found in the same shell, however, and as no other animal 
is ever seen theref , although it is very common and so formed as to 
show itself frequently on the surface, and as the germ of it is visible 
even in the ovum of the Argonaut;]:, this opinion must be considered 
as highly problematical, to say nothing more of it. 
The ancients Avere Avell acquainted Avith this singular animal 
and its manoeuvres. It is their Nautilus and their Pompilus, 
Pliny, IX, c. xxix. 
Several species are kiioAvn, closely resembling each other both 
in the animal and the shell, Avhich Avere united by Linnseus under 
the name of Argonauta argo, or the Paper Nautilus^. 
Bellerophon, Montf. 
Certain fossil shells, so called, the animal of Avhich is supposed to 
have been analogous to the Argonauts. They are spirally and sym- 
metrically convoluted, Avithout seyta, but thick, and not fluted ; the 
last Avhorl proportionably shorter]]. 
Loligo, Lam. 
The Calmars haA'^e an ensiform lamina of horn in the back in lieu 
of a shell ; the sac has tAA'o fins, and besides the eight feet promis- 
cuously loaded Avith litle cups on short pedicles, the head is furnished 
with tAVo much longer arms, provided Avith cups near the end only, 
which is Avidened. The animal uses these latter to keep itself im- 
movable, as if at anchor. The receptacle of the colouring matter is 
* It is upon this hypothesis that M. Rafin and othei's have formed the animal into 
the genus Ocythoe. 
t All that has been stated to the contrary, even in modern times, is founded upon 
report and conjecture. 
X Poll, test. Neapol., Ill, p. 10. See, also, Fcrussac, Mem. de la Soc. d’Hist. 
Nat., II, p. 160, and Ranzani, Mem. di Stor. Nat. dec., I, p. 85. 
§ Arg. argo, Favanne, VII, A, 2, A, 3 ; — Arg. haustrum, Delw., ib., A, 5 ; — A. 
tuberciilata, Shaw, Nat. Misc., 995 : — A. riucicula, Solander, Fav., VII, A, 7 ; — A. 
Mans, Sol., Fav., VII., A, 6 ; — A. CrancMi, heach, Phil. Trans.. 1817. 
II Bellorophon vasulites, Montf., Conch. Syst., I. p. 51. See, also, Defrance, 
Ann. des Sc. Nat., I, p. 264. 
