Zoological Society. 127 



of other Molluscans in structure, formation, and growth, 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 

 Molluscans 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 Mollusca 

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

 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 detail. 



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

 that he had discovered the animal in the egg of an Ocythoe covered 

 with the ' rudiment of a shell,' because all the Molluscans 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 preserved in their 

 shells are marked with cross grooves resembling the grooves on the 

 shell, yet these grooves are only formed by the pressure of the dead 

 animal against the shell ; for the specimens of the animal which are 

 found out of the shell, or which are taken out of the shell while re- 

 cent, are always destitute of these grooves, or of the compressed 

 form of the cavity of the shell. That some specimens which he 

 had received from the Cape (of which that now on the table was 

 one), which had been packed on their sides, had the upper side 

 of the animal smooth and rounded, and the lower flat, and curved 

 like the shell on which it was pressed by its own weight ; while a 

 specimen which he had received from the Mediterranean packed 



