400 Report of a Notice respecting 



of the case advocated by M. Rang, deduced from the cer- 

 tain and incontestable fact of the position of the Octopod 

 with long pal mated arms in the shell of the Argonaut, and 

 from the manner in which it advances along a resisting surface, 

 it will suffice, perhaps, to observe, that it is no less certain, 

 from the observations of one of us, that the Poulp, with one 

 row of suckers*, so common in the Mediterranean (and, pro- 

 bably, all the other common species of Octopods), walk, not 

 in this way, but with the back upwards, and the stomach, or 

 tube, below. 



We have observed this in a great number of specimens 

 caught in the nets of a tartane, belonging to the port of Buch, 

 at the entrance of the Pool of Berre, in the Mediterranean 

 Sea. Being thrown, with a number of other live creatures, 

 upon the bridge, they moved very nimbly in all directions, a 

 little after the manner of crabs, at the same time elevating 

 their backs so that the tube might not touch the ground ; that 

 is to say, raising the point of junction of the head and trunk, 

 crawling backward upon the lower surface of the mantle, or 

 sack, and forwards with the. help of the four arms on each 

 side, the upper ones before, and the lower ones behind, a little 

 like the Ophiurae. Our draughtsman (M. Prestre), who accom- 

 panied us, had the same opportunity of seeing and sketching it. 



Now as, from this double observation, it appears to me 

 allowable to admit that the manner of creeping observed in 

 the Octopod of the Argonaut ought to be looked upon as 

 the anomaly, and that of the animal at liberty as the normal 

 state, we see that the curious fact related by M. Rang, of the 

 pal mated arms embracing the shell, furnish a new proof that 

 this animal does not belong to it, and that it is parasitic there. 

 In effect, the other conchyliferous Molluscahave no need thus 

 to hold their shell when they creep or swim, since an organic 

 union exists between them : they crawl or swim, without 

 troubling themselves about it. It could not be thus with the 

 Ocythbe, or Octopod with palmated arms. As the animal 

 does not adhere in any organic manner to its shell, which no 

 one can dispute, and as its body even bears no resemblance 

 to it in shape, the opening of the shell being much larger than 

 its lower surface, so that it would be with difficulty held there 

 mechanically, a voluntary means of fixing the shell round itself 

 was very necessary to the mollusc; and the animal employs for 

 this purpose its long and spreading arms, as the Cancer Pa- 

 o-urus (Bernard l'Hermite) shows a particular adaptation, in a 

 pair of claws converted into hooks, to the columella of the 

 shell which serves it for a dwelling. 



* Octopus vulgaris Cuv. — Ed. 



