1838.] 



Zoological Sociely of London, 



263 



action, sometimes assuming a dome shape, at others segments of circles 

 or straight lines. — London and Edinburgh Philosophical Magazine, and 

 Journal of Science, No. 65. 



Zoological Society of London. 



November 22, 1836.— Mr. Gray exhibited a specimen of Argonaut 

 with an Ocythoe from the Cape of Good Hope, and stated that 

 as the subject had been brought forward at the last meeting, he 

 was induced to remark that every time he considered it, and compar- 

 ed it under its various bearings with the relations of other Mollusca?is 

 and their shells, he was more and more inclined to believe that 

 the animal found in the shell of Argonauta was a parasite. He gave 

 the following reasons for this belief. 



" 1. The animal has none of those peculiarities of organization for 

 the deposition, formation, and growth of the shell, nor even the mus- 

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

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

 structure with the naked Mollusca, especially the naked Cephalopods. 



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

 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 calcarious 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 calcarious 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. 



