430 PROF. OWEN ON THE ARGONAUT. 



" 'As to the seventh statement, its value will be manifest, when the ac- 

 count given by Mr. Cranch, on which it is founded, is carefully analysed 

 and considered. Mr. Cranch's observations, as quoted by Dr. Leach, amount 

 simply to this: — 'When the cephalopod (Argonauta hians, Solander, or 

 Ocythoe Cranchii, Leach) was adhering, with the vela retracted, to the side 

 of the vessel of sea-water in which it was placed, the shell could be remov- 

 ed ; ' in other words, there was no muscular adhesion. ' In this state of 

 captivity some of the cephalopods lost the power of retaining hold of the 

 shell ; one which had thus left its shell lived several hours, and showed no 

 desire to return.' 



" 'Now had the Ocythoe been a parasite, — supposing that it had ever be- 

 fore obtained its shell by placing its body in one ready-made, — and had it 

 been in the habit of repeating this act during its whole period of growth, 

 as it must have done to produce the concordance in size which the obser- 

 vations of Poli, Prevost, Madame Power, and myself, establish as a general 

 fact ; — then the probability would have been greater that the cephalopod 

 would have returned to, and so manoeuvred as to regain possession of, its 

 shell : the observation of such a fact would have told as strongly for the 

 parasitic theory as the phenomena witnessed by Mr. Cranch testify, in my 

 opinion, against it. I have repeated Mr. Cranch's experiment with a true 

 parasite, — the common hermit-crab of our coasts ; and I would invite any 

 naturalist to remove a parasitic Pagurus from its shell, and place it, with the 

 empty shell, in a basin of sea-water, and see whether the parasite will manifest 

 no desire to return his body into its accustomed hiding place. In my experi- 

 ments, the Pagurus lost no time in regaining possession of its shell. As 

 Mr. Cranch's argonaut survived four hours without showing the least dispo- 

 sition to return to its shell, instead of concluding therefrom that it had stol- 

 en it, I infer that such a mode of acquiring a shell was totally foreign to 

 its instincts and economy, 



" ' Madame Power states that the constant result of depriving the argo- 

 naut of its shell, is a gradual loss of vital power* and ultimate death within 

 a few hours at furthest. The experiment of M. Sander Rang was followed 

 by the same result. 



'"With respect to the eighth statement, I must say that the weakness of 

 the side of the question advocated by M. de Blainville is clearly betrayed 

 by the dubious notice of the Ocythoe by M. Rafinesque having been pressed 

 into the service of the parasitic theory in the disguise of an established fact. 

 M. Rang 1 informs us, that the entire description of the much talked-of 

 Ocythoe, as given by its discoverer, is as follows: — 'Appendices tentacu- 

 laires au nombre de huit, les deux superieures ailes interieurement, a su- 

 ^oirs interieurs, pedoncles, reunis par l'aile laterale, sans aucune membrane 

 a leur base.' And amongst other just observations on the inadequacy of 

 this meager indication, to the support of the theory that the cephalopod of 

 the argonaut naturally existed without its shell, and was identical with the 

 Ocythoe of Rafinesque, M. Rang adds that the description of the Ocythoe 

 above cited is equally applicable to any of the species of Octopus to which 

 M. Ferussac has applied the term i VSliferes. i 



" ' I now come to the consideration of the arguments for the parasitism of 

 the cephalopod of the argonaut, founded by M. de Blainville on undoubt- 

 ed or admissible facts. The first of these arguments reposes on the often- 

 repeated statement of the absence of any organ for muscular adhesion in 

 the cephalopod of the argonaut. I confess, that when I discovered the ce- 

 phalopod of the Nautilus to be fixed to its shell by two strong muscles, and 



1 Guerin's Magazin, p. 31, 



