( 55 ) 



C. Shells exterior; no I chambered. 



6. Argon auta. (1) 



Ditto. Two of the tentacula 



with a membranous en- 

 largement. 



(1) The animal uses its shell as a boat, and when the sea is calm it is seen navi- 

 gating on the surface, employing six of its tentacula as oars, and raising two, which, 

 from the considerable membranous enlargement, serve as sails. PI. 15, fig. 1. If 

 the waves are agitated, or any danger appears, the Argonaut draws its tentacula or 

 arms within the shell, concentrates itself, and sinks to the bottom. The ancients 

 were acquainted with this singular animal and its manoeuvre ; it is their Nautilus 

 and Pompilus.— Plin. IX, cap. 29. Blainville and Dr. Leach consider the animal 

 found in the A. argo (PI. 15, fig. 2) to be parasitical, and allied to the Octopus, 

 under the name of Ocythoe. 



