ON THE ARGONAUT. 531 



cavity of eggs, and appearing as if placed there to prevent 

 the water from rushing into this cavity, and opposing a re- 

 sistance there : — do not all these things appear exactly adapt- 

 ed for a locomotion which should be effected with quickness 

 and facility ? In truth, it must be allowed, that whatever be 

 the fabricator of the shell, it is very appropriate to the wants 

 of the mollusc which to this day we have never ceased to find 

 in it. 



We thought we perceived in its movements in open water 

 that the poulp of the argonaut had its back uppermost, and 

 consequently the tube below ; it is true however that we have 

 not constantly seen it so : and this last circumstance we have 

 been able to observe with much more certainty in specimens 

 of poulps whose arms had been deprived of their membranes. x 



Our poulp being fatigued with the useless efforts which it 

 had made in the narrow space where it was confined, and 

 perhaps hurt by the shocks it had sustained against the side 

 of the basin, allowed itself to fall to the bottom, and half 

 contracted itself in order to take some repose ; after which it 

 exhibited to us another spectacle which we were far from ex- 

 pecting. Fixing some of the air-holes of its free arms upon 

 the bottom of the basin, it erected itself upon its head, spread- 

 ing out its disc and carrying the shell straight above it, and 

 in the normal position of the shells of the gasteropods ; then 

 beginning to crawl, it presented the appearance of a pectini- 

 branchiate mollusc, as we have said in our note to the Aca- 

 demy of Sciences, without wishing to deduce from it any other 

 relation of agreement than that of a general disposition in the 

 posture and employment of some of its organs. Half drawn 

 back into its shell, this mollusc appeared to crawl upon its 

 disc, the palmatures 2 of which were a little raised to follow 

 the movements of its arms. The body was hid in the shell; 

 the siphon placed in the anterior part of it, was turned for- 

 wards ; those of its arms which were at liberty were very 

 much protruded, and twisting round, two before and two on 

 each side, like so many appendages or tentacles ; and finally, 

 the base of the two large arms seemed to prolong backwards 

 the locomotive surface, then rising along the keel they again 



1 If it he really the fact that the side on which the siphon is placed is 

 ventral, this manner in which the poulp generally swims, namely, with the 

 back upwards, would be an anomaly amongst the pelagian molluscs, all of 

 which swim with the ventral side upwards. 



2 It will perhaps excite surprise to hear us talk of palmatures in these 

 poulps, since they have hitherto been unnoticed. They nevertheless exist, 

 though it is often difficult to see them in specimens preserved in spirits of 

 wine. 



