Memoires de la Societe (VHist. Nat. de Paris. 535 



list of distinguished naturalists ; and it is still maintained by Dr. 

 Leach, on the evidence of the unfortunate Crunch, by Sir Everard 

 Home, and especiallybyM.de Blainville. On the other side, names 

 of equally high authority might be advanced. In our own times 

 MM. Bosc, Lamarck, and Cuvier, who in the earlier part of their 

 zoological career had advocated the Uoctrine of the parasitic na- 

 ture of the animal in question, have been converted to the oppo- 

 site opinion, and have avowed their belief that the shell and the 

 animal are mutually connected ah ovo, the former being entirely 

 constructed by the latter. This is also the opinion of M. de 

 Ferussac, who supports it by several facts observed in a small 

 specimen recently sent to him in spirits, by M. Risso of Nice. 



In this specimen the shell was completely filled by the Cepha- 

 lopode, which was octopodous, and corresponded with the des- 

 cription usually given of the animal found in the jlrgGnunta 

 Argo. When thus retracted within the shell four of its arms were 

 found to be bent down upon its back within the enlarged keel, in 

 such a manner, as to apply the suckers with which they are 

 furnished, against the internal surface of the keel. The remain- 

 ing four arms were folded, in the opposite direction, into the spi- 

 ral cavity of the shell, which they iilled ; the intermediate pair, 

 or the palmate arms destined to support the eggs, occupyirg the 

 middle, and forming a mass, over which were folded the extre- 

 mities of the outer pair, these latter resting, through the greater 

 part of their extent, upon the sides of the body. On breaking 

 the shell, the mantle was found to correspond precisely with its 

 internal surface, presenting a repetition of the sulci, of the broad 

 and flat keel, and of the tubercles which are disposed along its 

 sides. 



This exact accordance of the form of the animal with that of 

 the shell, and its complete adaptation, when retracted, to the 

 different parts of its habitation, are the only facts adduced from 

 observation by the Baron de Ferussac in support of his opinion. 

 His explanation of the probable arrangement and uses of the arms 

 in floating, it is unnecessary to advert to, it being entirely founded 

 on theory. The remainder of his paper consists of arguments drawn 

 from the facts, that no other animal has been at any time found in the 



