544 CEPHALOPODA. 



of repose, and the vesicles are contracted and ville* has carefully delineated for this pur- 

 invisible, the skin be slightly touched, the co- pose, the back of the Ocythoe' is next the invo- 

 loured vesicles show themselves, and in an in- luted convexity of the shell, the funnel is 

 stant, or sometimes with a more gradual mo- towards the opposite expanded concavity, but 

 tion, the colour will be accumulated like a turned out of the middle line, and separated 

 cloud or a blush upon the irritated surface. If from the parietes of the shell by the retracted 

 a portion of the skin be removed from the feet. In the figure which illustrates Brode- 

 body and immersed in sea-water, the lively rip's excellent Memoir,t the animal is repre- 

 contractions of the vesicles continue ; when sented with the funnel next the involuted crest 

 viewed in this state under the microscope by of the shell. In another specimen in the unique 

 means of transmitted light, the edges of the collection of the same Naturalist, the Cephalo- 

 vesicles are seen to be well defined, and to pass pod is retracted on a mass of ova, its arms hud- 

 in their dilatations and contractions over or died together, and its funnel projecting from 

 under one another. If the separated portion of the middle of one side of the shell ; on the op- 

 integument be placed in the dark, and exa- posite side numerous suckers are seen expand- 

 mined after a lapse of ten or fifteen minutes, ed and applied to the inner surface of the shell, 

 all motion has ceased; but the vesicles, when demonstrative of the abnormal mode of its ad- 

 re-exposed to a moderately strong light, soon, in hesion to that body. 



obedience to that stimulus, recommence their Whatever be the position in which the 

 motions. As the vibratile microscopic cilia Ocythoe' is found, the whole of the exterior 

 have been recently traced through the higher surface of its mantle is coloured as in the 

 classes of the animal kingdom, it is not an un- naked Cephalopods, which seems to indicate 

 reasonable conjecture that equally inexplicable that it lias not been permanently excluded from 

 motions of the colouring parts of the integu- light by an opake calcareous covering, such as 

 ment may also be detected in other classes the Argonauta shell must have formed if it 

 than that in which we have just described them, had been applied to the body of the Ocythoe 

 and thus a clue may be obtained towards the ab ovo. What is more remarkable, and con- 

 explanation of the influence of geographical trary to the analogy of true testacea, is, that 

 position on the prevailing colours of the animal there is little or no correspondence between the 

 kingdom. disposition of the colour of the Ocythoe and 

 Besides the colouring matter, another kind of that of the Argonaut shell. The external sur- 

 product is secreted between the corium and face of the skin of the Ocythoe' has the same 

 cuticle, viz. the shell : this presents diffe- entire epidermic covering as in the naked 

 rent degrees of development in different genera. Poulp, yet the Argonaut shell is furnished with 

 M. De Blainville in France, and Leach, a delicate epidermis in its natural state. 

 Broderip, Gray, and Sowerby, among the All Mollusks which are naturally pro- 

 able naturalists of our own country, maintain vided with external shells have them for pro- 

 that the Argonaut shell is not the product of tecting either a part or the whole of the body ; 

 a Cephalopod, but of some inferior Mollusk, and in the latter case the interior of the shell 

 allied to the Carinariae, whose shell Linnteus is always kept clear, that the animal may retire 

 indeed placed in the same genus with the to it for safety ; but this retraction into the hol- 

 Argonauta, in consequence of the close rela- low of the shell is impossible to the Ocythoe, 

 tionship subsisting between them, both in form at least in those numerous cases in which the 

 and structure. The principal grounds for this shell is found more or less filled with masses 

 opinion are the following. The Ocythoe has of ova. Other Cephalopods, with external 

 no muscular or other attachment to the Argo- shells, indubitably their own, as the Pearly 

 naut shell. When captured, and placed alive Nautilus, have adequate muscular attachments ; 

 in a vessel of sea-water, it has been seen vo- and it may reasonably be asked does the Argo- 

 luntarily to quit the shell, and in one instance naut afford a valid exception to this rule? 

 without manifesting any disposition to return Such an exception indeed it must form if 

 to it. In this state, viz. without its shell, the shell be really secreted, as the Continuator 

 it was described by Rafinesque as a new genus o f Poli asserts, by the Cephalopod inhabi- 

 of Cephalopod under the name of Ocythoe, tant ; and not only in this particular, but in 

 and De Blainville, who first recognized this every principle which has been established in 

 genus as being founded on an animal identical reference to the relations of a shell to the body 

 with the Cephalopod of the Argonaut, or the and the reciprocal influences affecting them in 

 Nautilus primus of the ancients, retained the the Molluscous classes. 



name in order to distinguish the supposed parasite The naturalists who maintain that the Ce- 

 from the shell which it had, according to this phalopod of the Argonaut and the shell are parts 

 theory, adopted. Agreeably with the absence o f one and the same animal, insist on this unde- 

 of any natural connexion between the Ocythoe niable fact, that from the time of Aristotle to the 

 and the shell in question, is the fact that this present day the Argonaut shell has never been 

 animal is not found in any constant or regular found with any other inhabitant than the 

 position in the shell. In most examples we Ocythoe; and, what is of more weight, that the 

 have found the funnel and ventral aspect of the Ocythoe has never been found in any other shell 

 body turned towards theexternal wall of theshell, than the Argonauta. Whereas the Hermit-Crab 

 as in the figure (Ji-g. 206). The Cranchian speci- 

 men figured by Mr. Sowerby was in the same * Malacologie, torn. ii. p. 1, 

 position. In the specimen which M.De Blain- t Zoological Journal, vol. iv. 



