216 MOLLUSCA. 



is extremely delicate, as thin as paper, white and 

 pellucid ; its whole surface is marked by deep trans- 

 verse furrows. The animal is allied to the genus 

 Octopus, as it wants the two lengthened feet which 

 distinguish the other genera, but the two arms next 

 the back are expanded at the tips into broad fleshy 

 disks, whose use we shall presently see. It has been 

 poetically assumed, that man first learned the art 

 of navigation from the inmates of these fragile barks, 

 which may be frequently seen floating on the calm 

 surface of the Mediterranean, with the broad disked 

 arms expanded as sails, and the slender ones used 

 for rowing, or at least hanging over the side. The 

 animal, however, has no muscular attachment to its 

 beautiful shell, but has the power of forsaking it 

 at pleasure, and of resuming it; whence it was 

 long supposed that it was not the original fabri- 

 cator, but a hermit who had taken possession of an 

 empty lodging, if not a cruel pirate, who had mur- 

 dered the real inhabitant, and seized his vessel. But 

 the experiments and observations of Madame Power, 

 and M. Rang, have at length proved, to the satisfac- 

 tion of naturalists, that this shell is the natural 

 cover of the Poulpe, as well as given many interest- 

 ing notices of its powers and habits. Madame 

 Power made public her observations in 1836. Re- 

 siding at Messina, she had ample opportunities of 

 investigating the history of the Argonauts, (A. Argo^) 

 which she collected of various sizes, and enclosed 

 them in cages, which being placed in the sea, ad- 

 mitted the water between their bars. Every two or 



