60 M. SANDER RANG 



valion we have made ; it evidently tends to restore this poulp 

 to the normal state of the other cephalopods, from which it 

 has been so strangely separated ; — it destroys the fabulous 

 notions of the navigation of the argonaut ; — it explains why it 

 is necessary that this poulp should have two palmated arms 

 to retain its shell ; — and finally, it overturns the argument 

 drawn from the divergence of opinions as to the manner in 

 which the poulp swims on the surface of the water, and on 

 which was founded the statement that the parasitic inhabit- 

 ant of the argonaut was not always a poulp with palmated 

 arms, or else that it did not always place itself in the same 

 relation to the shell. 



Locomotive Faculty of the Poulp of the Argonaut at the 

 hottom of the Sea. — The observation we have just made, and 

 the description we gave at the commencement of this memoir 

 of the manner in which the poulp of the argonaut crawls along 

 the bottom of the sea, constitute a fact which is quite new, 

 and which seems not to have been previously observed. It is 

 nevertheless but just to state that it had already been pointed 

 out ; for Rumphius long ago said that this mollusc walked at 

 the bottom of the sea by the aid of its arms, and with the keel 

 of its shell uppermost. AVe then merely give a more detailed 

 confirmation of his observation. It naturally follows from 

 what we have said on this subject, that these poulps do not 

 always carry themselves with their ventral part beneath, but 

 fi*equently also with it above. 



This observation weakens still more the opinion of those 

 naturalists who suppose that the palmated arms are turned to 

 the side of the anterior part of the shell, and of those who 

 think that the mollusc places itself indifferently either one 

 way or the other ; and draw fi:om thence an argument for its 

 non-parasitism. And finally, it also restores the poulp to a 

 more normal state than that which had been assigned to it. 



Will not this peculiar mode of reptation at the bottom of 

 the sea explain why the poulp in question, supposing it to be 

 the real constructor of the shell, should preserve a space at 

 the end, instead of filling the forsaken part with a solid de- 

 posit, like the Magilus, or forming partitions there, like 

 the Nautilus ? May it not be for the puipose of preserving 

 a reservoir of air, in order to facilitate its rapid and vertical 

 ascent to the surface of the water ? Rumphius, who was a 

 close observer, as we have just shown, seems to confirm this 

 idea, when, in referring to this mollusc, he remarks that it 

 also re-ascends in a reversed position ; that is, with its head 

 below and the keel of its shell above. In fact, is it not evi- 

 dently for the purpose of retaining the air compressed by it 



