422 PROF. OWEN ON THE ARGONAUT. 



two lobes of the mantle of the cowry. These facts are described as the re- 

 sult of actual observation ; but Madame Power, entertaining the common 

 belief of the action and use of the velated arms in the sailing of the cepha- 

 lopod, enters into considerations respecting their proportional strength in 

 relation to that hypothetical office. The subsequent observations of M. 

 Rang have fully confirmed the accuracy of Madame Power's description 

 of the relative position of the so-called sails of the argonaut to the shell ; 

 and he has published some beautiful figures illustrative of this fact. 1 



" Thirdly, M. Rang confirms the discovery of Madame Power as to the 

 faculty possessed by the cephalopod of reproducing its shell, but he was 

 unable to preserve his captive argonaut sufficiently long to witness the com- 

 plete deposition of calcareous matter in the new substance by which the 

 argonaut had repaired the fracture purposely made in its shell. 



" There are other observations in the original memoir of Madame Power, 

 as, e.g. with respect to the flexibility and elasticity of the living shell of the 

 argonaut ; the great extensibility and pump-like action of the siphon in lo- 

 comotion ; the use of the velated arms in retaining the shell firmly upon 

 the cephalopod ; the great voracity of the argonaut ; the constantly fatal 

 results of depriving it of its shell ; all of which statements are of great in- 

 terest and novelty in the history of this problematical mollusc, and some of 

 which likewise receive confirmation in the memoir of M. Sander Rang. 



" Notwithstanding, however, that so many additional facts had been thus 

 brought to bear on the relations subsisting between the argonaut-shell and 

 its occupant, Mr. Owen observed that the leading malacologists who advo- 

 cated the parasitic theory, had reiterated their conviction of its truth ; and 

 even M. Rang, though evidently biassed by what he had observed in favour 

 of the opposite view, yields so much to the authority of M. de Blainville, 

 as to declare himself in a state of the most complete uncertainty on the 

 subject ; — ' Nous nous trouvons en ce moment dans le plus complete incer- 

 titude.' — Loc. cit. 



" In this state of the question a collection of specimens of the argonauts, 

 such as Madame Power had submitted to the examination of the Zoologi- 

 cal Society, was of the greatest importance, if impartially and logically con- 

 sidered with reference to the points at issue ; and Mr. Owen stated, that 

 having studied this collection with much caTe, he should, in the first place, 

 restrict himself to such observations and arguments as would naturally flow 

 from an examination of the specimens themselves, apart from any history 

 or statement with which they had been accompanied when first placed in 

 his hands by Madame Power. 



" The collection of argonauts, — cephalopods and shells, — preserved in 

 spirits, included twenty specimens, at different periods of growth, the small- 

 est having a shell weighing not more than one grain and a half, the re- 

 mainder increasing, by small gradations, to the common-sized mature in- 

 dividual. 



" Mr. Owen's first attention was directed to the relative position of the 

 cephalopod to its shell. In every case it corresponded to that which obtains 

 in the pearly nautilus, the siphon and ventral surface of the cephalopod being 

 placed next the broad keel forming the external wall of the shell, the dorsal 

 surface of the body next the involuted spire or internal wall. In most of these 

 specimens the velated arms, which are nearest the involuted spire, were re- 

 tracted; but in some of the larger examples they had been admirably pre- 

 served in a fully-expanded and flexible state, and in their natural position 

 as envelopes of the shell. 



See No. 2 of the Sup. Plates to Mag. Nat. Hist— Ed. 



