Animal of the Argonaut. 529 



the specimens in my possession that the real constructor of 

 the Argonaut was fully capable of subsequently secreting 

 true shell, if circumstances rendered it necessary. In the 

 course of the discussion which followed, Mr. Owen intro- 

 duced a very fair argument to show that I attributed more 

 weight to the above facts than they were really entitled to, 

 inasmuch as neither Mrs. Power nor Captain Rang had given 

 the slightest intimation of the particular region of the shell 

 from which they removed the portions spoken of; a circum- 

 stance of most material importance with reference to any in- 

 ference which might be drawn from their experiments, since 

 the Ocythoe might not have the power of applying the secret- 

 ing portion of its mantle to apertures in the body of its shell, 

 although it might readily repair breaches taking place in the 

 margin. In relation to this view of the case, Mr. Owen re- 

 ferred to some experiments instituted by Mr. Bell upon the 

 common garden snail, published in the first volume of the 

 Zoological Journal, and which no apology is necessary for 

 introducing here. They are appended in a note to an abridged 

 translation of M. Gaspard's Memoir on the Physiology of Helix 

 pomatia, originally published in Majendie's Journal de Phy- 

 siologies torn. ii. p. 295. 



"Although it would appear, from some circumstances, such 

 as the filling up of the apex of the shell, that other parts are 

 occasionally capable of producing a calcareous secretion, yet 

 there is no doubt that the edge or collar of the mantle is the 

 organ which ordinarily performs this function. I have at 

 different times cracked the shell, removed small portions, and 

 drilled holes through it, at different parts; and I have found 

 that, if the injury were within the reach of the edge of the 

 mantle, it was always drawn up to repair it. I will par- 

 ticularise one only of these experiments to show the manner 

 in which this is done. I drilled a hole in the shell of Helix 

 pomatia in the last whorl but one, thinking that it could not 

 draw the edge of the mantle high enough to repair it in the 

 usual way ; however, it effected this immediately by pro- 

 truding the foot to make room for the mantle being drawn 

 high up into the shell ; and as soon as the edge came in con- 

 tact with the injured part, it was passed repeatedly over the 

 hole, leaving a layer of calcareous matter each time, until it 

 became opaque ; and, in a day or two, on examining it, I 

 found the newly formed part apparently as strong as the rest 

 of the shell. Another curious circumstance connected with 

 this subject is, that in the species of snails with coloured 

 bands (H. nemoralis, for instance) there are the same number 

 of bands on the mantle as in the shell, which are brown and 

 transparent; and these, probably, contain comparatively little 



