12 M. SANDER RANG 



which he himself draws from it decides this question ; for it 

 is very certain, that since the function of the membranes of 

 the large arms consists in seizing the shell, by enveloping it 

 from the re-entering part of the keel, to its further extremity, 

 the animal must be constantly turned, so that this arrange- 

 ment can take place, that is to say, it must have its dorsal 

 part towards the spire. 



The partisans of parasitism place great stress upon an an- 

 ecdote, which in fact would be very fit to decide the question, 

 if it constituted an accurately made and precise observation, 

 or even one worthy of confidence. We refer to the mollusc 

 of which Rafinesque has made the genus Ocythoe. We 

 know not if we are right, but it appears to us, that natural- 

 ists, who have in some instances very just pretensions to 

 having based their opinion upon scientific principles, de- 

 ceive themselves in this instance, and take hold of a fact of 

 no value, as we are about to show. The history of the genus 

 Ocythoe is as follows. — 



A traveller, studying natural history in the Sicilian seas, 

 found among other curious things, a cephalopod, of which 

 this is the description, quoted, and no doubt verbatim, by 

 M. de Blainville. " Tentacular appendages to the number of 

 eight ; the two upper ones winged within ; with interior 

 suckers; pedunculated; joined by the lateral wing; without 

 any membrane at their base." If, as we cannot doubt, such 

 is the description furnished by this naturalist, truly those who 

 back themselves upon this clause to sustain their opinion are 

 very fortunate, for never besides, according to what we know 

 of the other poulps he has described, has this observer taken 

 such great pains in describing a mollusc ; he does not speak 

 of any shell ; so that fact has been seized upon to show that 

 the mollusc is the poulp of the argonaut, walking freely in 

 the open sea, and without its testaceous covering, as if the 

 author usually took the pains to describe all that he sees in 

 a mollusc — thus the parasitism is demonstrated ! 



To all this may we not make the following objections ? — 

 1st. — It is not proved from this that the mollusc was 

 without a shell, though Rafinesque says nothing of one. 



2nd. — It is not further proved, that in case the animal was, 

 as we are willing to believe, without a shell, the shell had 

 not been lost a few minutes before the capture of the animal : 

 it is necessary, in order to reap advantage from this anecdote, 

 that we should be well acquainted with all its details. 



3rd. — The astonishing descriptions of five or six poulps 

 met with by the same traveller, and that taken from his Ocy- 

 thoe, which are the only things that we have the honour of 



