39 



most "; so that, if the accuracy of the above observations made by- 

 Mr. Owen on two series of two distinct species of Argonaut, be 

 admitted,* "a Naturalist entertaining the parasitic theory, must 

 be compelled to suppose that the young Ocythoe, or Cephalopod, 

 is engaged in a perpetual warfare with the hypothetical Nucleo- 

 branchiate constructor of the Argonaut shell, which shell, to pro- 

 duce the correspondences above described, the young Ocythoe must 

 change two or three times a week, if not every day. And never- 

 theless, although each prolific Cephalopod of the Argonaut sends 

 into the world hundreds of little ones that must be so accommodated, 

 and although, on the parasitic hypothesis, hundreds of the hypothe- 

 tical Nucleo-branchiate constructors of the Argonaut shSll ought 

 to swarm about the port of Messina, where Madame Power obtained 

 the specimens with which she stocked her molluscous vivarium, and 

 notwithstanding that M. de Blainville has called the special atten- 

 tion of Naturalist-collectors to the hypothetical true constructor of 

 the Argonaut-shell, as a chief desideratum in Malacology ; and 

 lastljs notwithstanding this hypothetical Nucleo-branchiate mollusk 

 ought, on M. de Blainville's theory, to be nearly allied to the Allanta 

 and Carinaria, and therefore a floating Pelagic species, generally to 

 be met with on the surface of the ocean ; — yet had it still evaded 

 the observation of the numerous active collectors engaged in ex- 

 ploring the zoological riches of the Mediterranean in different parts 

 Q^ts coasts." 



It is in vain to'repeat, with reference to the non-discovery of any 

 other inhabitant of the Argonaut than the Cephalopod, ' Ce que ne 

 peut etre range au nombre des argumens, parceque ce qui n' a pas 

 eu lieu jusqu' a un moment determine, peut se montrer le moment 

 suivant;' that, 'what is a fact at the present moment, viz. the 

 non-discovery of the hypothetical true constructor of the Argonaut, 

 may be no longer a fact at the moment after.' Such an observation 

 could only possess argumentative force iii the absence of other facts 

 showing the high degree of improbability that a floating Pteropod, 

 or Heteropod, sufiiciently abundant to have supplied all the Argo- 

 nauts of the Mediterranean with their shells, could have escaped ob- 

 servation." 



Mr. Owen then proceeded to state that he had dissected every 

 specimen of Argonaut in the present collection in which the absence 

 of ova in the shell left the sex doubtful, and that they all proved to 

 be females ; this fact rendered it allowable to conjecture that the* 

 calcifying brachial membranes, and consequently the shell, might 

 be sexual characters and peculiar to the female. But, he argued, 

 " the known paucity of males as compared with females in other 

 species of Cephalopods, rendered the conjecture to a certain degree 

 problematical. Should it, however, be hereafter proved that the 



* They accord with the statement of Pt>li, and with the observations of 

 M. Prevost, founded on a suite of specimens of the Argonaut from the 

 size of one and two inches to three or four inches. These are quoted by 

 M. de Blainville in his memoir of 1837 (p- l'^)» but without the deduc- 

 tions which I have drawn from the sanu- facte. 



