36 



were invariably placed against the outer witll or keel of the shelf^ 

 and the opposite, or dorsal surface of the body next the involuted 

 spire. 



Secondly, with reference to the relative position of the arms of the 

 Cephalopod to the shell, and the uses of the dorsal pair of arms, usually 

 called the " sails," Madame Power had described these velated arms 

 as being placed next the involuted spire of the shell, over which 

 they were bent, and expanded forwards so as to cover and conceal 

 the whole of the shell, and from which they were occasionally re- 

 tracted in the living Argonaut : she further made the important 

 discovery that these expanded membranes were the organs of the 

 original formation and subsequent reparation of the shell, and in- 

 geniously and justly compared them, in her memoir of 1836, to 

 the two lobes of the mantle of the Cowry. These facts are de- 

 scribed as the result of actual observation ; but Madame Power, 

 entertaining the common belief of the action and use of the velated 

 arms in the sailing of the Cephalopod, enters into considerations 

 respecting their proportional strength in relation to that hypothetical 

 office. The subsequent observations of M. Rang have fully con- 

 firmed 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. 



Tlurdly, 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 complete 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 locomotion ; 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 interest and novelty in 

 the history of this problematical mollusc, and some of which like- 

 wise 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 lead- 

 ing Malacologists who advocated the parasitic theory, had reiterated 

 their comaction 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 la plus complete incerti- 

 tude." Loc. cit. 



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

 Argonauts, such as Madame Power had submitted to the examina- 

 tion of the Zoological Society, was of the greatest importance, if 



