42 



had been deposited at the margins of the membrane, where it was 

 attached to the old shell. In a third specimen, in which a portion 

 of the shell had been removed from the keel, about two inches 

 from the mouth of the shell, the whole breach had been repaired by 

 a calcareous layer, differing only in its greater opacity and irregu- 

 larity of form from the original shell. In the specimen longest 

 retained after the fracture, a portion had been removed from the 

 margin of the shell : here the new material next the broken edge 

 presented the opacity characteristic of the repairing substance, but 

 the transition of this substance into the material of the shell, sub- 

 sequently added in the ordinary progress of growth, was so gra- 

 dual, in the resumption in the repairing material of the ordinary 

 clearness and striated structure of the shell, that it was impossible 

 to doubt but that the reparation as well as the subsequent growth 

 had been effects of the same agent. The repaired parts of the shell 

 reacted precisely like the ordinary shell with nitric acid. 



Mr. Owen then observed, that the specimens submitted to the meet- 

 ing by Madame Power possessed in themselves the means of confirm- 

 ing or refuting her theory of the formative organs of the shell of the 

 Argonaut : for if the shell were secreted, as in gastropods, &c., by 

 the edge of the mantle covering the body, the new material by which 

 the breaches of the shell liad been repaired, should have been depo- 

 sited on the inside of the fractured edge ; but, on the contrary, it 

 was clearly obvious in two of the specimens, that the new material 

 had been laid on upon the outside of the fractured part — as it must 

 have been, supposing the vela or membranous arms to be the calci- 

 fying organs. 



Mr. Owen then recapitulated as follows, the evidence, which, in- 

 dependently of any preconceived theory or statement, could be de- 

 duced from the admirable collection of At-yonauta Argo due to the 

 lal)ours of the accomplished lady who had contri!)uted so materially 

 to the elucidation of a problem which had divided the zoological 

 world from the time of Aristotle. 



1st. The Cephalopod of the Argonaut constantly maintains the 

 same relative position in its shell. 



2nd. The young Ce])halopod manifests the same concordance 

 between the form of its body and that of the shell, and the same per- 

 fect adaptation of the one to the other, as do the young of other 

 testaceous Mollusks. 



3rd. The young Cephalopod entirely fills the cavity of its shell : 

 the fundus of the sac begins to be withdrawn from the apex of the 

 shell only when the ovarium begins to enlarge under the sexual 

 stimulus. 



4th. The shell of the Argonaut corresponds in size with that of its 

 inhabitant, whatever be the differences in the latter in that respect. 

 (" The observations of Poll, of Prevost, and myself, on a series of 

 Argotiauta rv.fa, before cited, are to the same effect.") 



5th. The shell of the Argonaut possesses all the requisite flexibi- 

 lity and elasticity which the mechanism of respiration and locomo- 

 tion in the inhabitant requires : it is also permeable to light. 



(jth. The Cephalopod inhabiting the Argonaut repairs the frac- 



