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. The animal makes a consequent use of 

 it, and in calm weather 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 spires 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 were well acquainted with this singular animal 



and its manoeuvres. It is their Nautilus and their Pompilus, 



Pliny, IX, c. xxix. 



Several species are known, closely resembling each other both 



in the animal and the shell, which were united by Linnaeus under 



the name of Argonauta argo t or the Paper Nautilus^. 



BELLEROPHON, Montf. 



Certain fossil shells, so called, the animal of which is supposed to 

 have been analogous to the Argonauts. They are spirally and sym- 

 metrically convoluted, without seyta, but thick, and not fluted ; the 

 last whorl proportionably shorter ||. 



LOLIGO, Lam. 



The Calmars have an ensiform lamina of horn in the back in lieu 

 of a shell j the sac has two fins, and besides the eight feet promis- 

 cuously loaded with litle cups on short pedicles, the head is furnished 

 with two much longer arms, provided with cups near the end only, 

 which is widened. 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 others have formed the animal into 

 the genus OCYTHOE. 



f All that has been stated to the contrary, even in modern times, is founded upon 

 report and conjecture. 



; Poli, test. Ncapol., Ill, p. 10. See, also, Flrussac, Mem. de la Soc. d'Hist. 

 Nat., II, p. 160, and Ranzani, Mem. di Stor. Nat. dec., 1, p. 85. 



Arg. argo, Favanne, VII, A, 2, A, 3 ; Arg. haustrvm, Delw., ib., A, 5 ; A. 

 tuberculata, Shaw, Nat. Misc., 995 :A. naricula, Solander, Fav., VII, A, 7;^. 

 Wow, Sol., Fav., VII., A, 6 -,A. Cranchii, Leach, Phil. Trans.. 1817. 



|| Bellorophon tasulites, Montf., Conch. Syst., I. p. 51. See, also, Defrance, 

 Ann. des Sc. Nat., I, p. 264. 



