ARGONAUTA. 



more than the Oeythoe itself. We think, moreover, that 

 our opinion respecting the nature of the animal belonging 

 to this Genus obtains some support from a passage in a 

 paper " On the animal of Argonauta/' by Mr. Broderip, 

 in the Zoological Journal^ vol. IV., p. 65, which we take 

 the liberty of transcribing. " I have sometimes thought 

 I could observe traces of muscular impression in the in- 

 side of the involuted termination of the chamber of the 

 shell, such, for instance, as might be caused by the inser- 

 tion of parts similar to those inserted in the shell of Cari- 

 naria.'^ And in confirmation of the opinion advanced above 

 that the Oeythoe, so usually found in the shell of the 

 Argonaut, does not really belong to it, I am happy to be 

 permitted, by Mr. Broderip, to state that he is more and 

 more fully convinced that it is only a parasite, and that he 

 has not arrived at this conviction without the most mature 

 consideration of all the facts that have come to his know- 

 ledge. We sincerely wish that those who have opportu- 

 nities would use every endeavour, by deep sea trawling 

 in those situations where the Argonauts with the Oeythoe 

 abound, to discover the real animal of which the Argo- 

 naut constitutes an essential part, most probably for the 

 defence of important viscera. 



The Argonaut is only known in a recent state, al- 

 though several fossil Ammonites approach so nearly to it 

 in general form, that some inexperienced Geologists have 

 taken them for Argonauts : there are several very distinct 

 species of the Genus, and of the Argo several remarkable 

 varieties, which have by some been regarded as distinct 

 species. 



In general form the Argonaut, when placed in a cer- 

 tain position, having its aperture nearly horizontal, 

 may be compared to a little ship; it consists of a single 

 valve, which is never attached, and very thin and 

 generally ribbed or tubercular all over ; it is somewhat 

 spiral, the spiral part being involute; the aperture is 

 very large and lanceolate in form: the back or keel 

 part is formed of two rows of sharpish tubercles, between 

 which there is a narrow flat space. 



