122 



bearings with the relations of other Molhscans and their shells, he 

 ■was more and more inclined to believe that the animal foimd in the 

 shell of Argonauta was a parasite. He gave the following reasons 

 for tliis belief. 



" 1. Theanimalhasnoneofthoseijeculiaritiesof organization for the 

 deposition, formation, and growth of the shell, nor even the muscles 

 for attaching it to the shell, which are found in all other shell- 

 bearing MoUuscans ; instead of which it agrees in form, colour, and 

 structure with the naked Mollusca, especially the nalied Cephalo- 

 pods. 



" 2. The shell, although it agrees in every respect with the shells 

 of other MoUuscans in structure, formation, and gi-owth, is evidently 

 not moulded on the body of the animal usually found in it, as other 

 shells are; but exactly agrees in every point (except in the form of 

 the spire), with the shell of Carinaria, which coincided -with the other 

 MoUuscans in all these respects. 



"3. The body of the animal does not appear to have the power of 

 secreting calcareous matter, for it does not, like all the MoUusca 

 which have that power, secrete either a solid deposit or distinct sapta 

 to adapt the cavity of the shell to the increase of the body, nor does 

 it cover over with calcareous matter any sand or other extraneous 

 bodies which may have accidentally intruded themselves between the 

 mantle and the shell, but leaves the sand, which is often found mixed 

 with the eggs, free, without taking any means to prevent it from 

 irritating the skin. 



" 4. The young shell of the just hatched animal which forms 

 the apex of the shell at all periods of its growth, is much larger 

 (ten times) than the eggs contained in the upper part of the cavity of 

 the Argonaut. 



Mr. Gray further stated, that he does not think that any inference 

 can be drawn in favour of the opinion that the Ocythoe forms the 

 shell, from either of the three arguments which have been produced 

 in favour of that hypothesis, which he then examined in detaU. 



"5. He believes that Poli must have been misled when he thought 

 that he had discovered the animal in the e^^ of an Ocythoe covered 

 with the " rudiment of a shell," because all the MoUuscans which 

 he has seen in the egg (Cephalopods as well as others) were covered 

 with a well- developed shell, even before all the organs were deve- 

 loped, and the figure which Poli gives of the rudiment does not 

 agree with the nucleus found on the apex of the shell of the Argo- 

 nauts. Unfortunately, none of the eggs of the Ocythoes that have 

 been examined by other observers have been enough developed to 

 show the foetal animal. 



" 6. The different species of Argonauta are said to be inhabited by 

 different species of Ocythoe; but allowing this to be the case, it 

 only proves that each of these genera have local species : the same 

 may be observed with respect to the Hermit Crabs, without proving 

 anything in favour of their being the framers of the shell they live 

 in. 



" 7. That though some specimens of Ocythoe presers'ed in their 



