376 



nected by the secretion of the lining membrane of the long 

 tortuous oviducts. The ova (of which the specimen showed great 

 numbers, occupying a considerable portion of the shell,) are of 

 an oval form, of the size of mustard-seed, connected in clusters 

 by long filaments entangled together. According to Von Siebold 

 {op. cit.) the shell is formed while the embryo, after its escape 

 from the e.^g, is still persistent in the spawn inside the shell of 

 its parent. Eggs have been found in very small shells, so that 

 the power of reproduction must be very early developed. As to 

 the position of the animal in the shell, which the advocates of 

 parasitism maintain is not constant, Madame Power {op. cit.), 

 from the examination of great numbers, says that the " relative 

 position of the animal to its shell is always the same ; when 

 retracted, the visceral sac is lodged in the spine, the membranous 

 arms to the right and left, the other six arms placed beneath the 

 body in the middle ; the mouth in the centre of the large aper- 

 ture, the eyes being visible on the right and left through the 

 sub-transparent shell ; the siphon (funnel) resting on the open 

 part of the keel, about two lines from its extremity ; " this was 

 the position of the specimen exhibited. According to Mr. Rang, 

 when the Argonaut rises to the surface, it does so with the keel 

 of the shell upwards, turning it downwards when it floats on the 

 water ; the shell being very light, it probably rises to the sur- 

 face by means of its funnel and arms, in the manner of the other 

 Octopods ; when frightened, by retracting its six arms within 

 the shell, and with the jmlmated ones embracing it outside, it can 

 readily sink to the bottom, without any air-chamber such as is 

 found in the Nautilus. 



Lamark, Leach, Rafinesque, De Blainville, Broderip, Sowerby, 

 Gray, and others, think the animal of the Argonaut is a para- 

 site, the shell being formed by an inferior Heteropodous Mollusk, 

 allied to Atlanta and Carinaria — and for the following reasons : 

 there is no attachment by muscular or any other texture of the 

 animal to its shell ; it may voluntarily quit it, and in this con- 

 dition was described by Rafinesque as the genus Ocytho'e ; it is 

 not found in any regular position in the shell. These objections 

 are answered by the facts in the case of Serpula, above men- 

 tioned; and, from Madame Power's numerous observations, it is 

 evident that the position of the animal in the vast majority of 



