CEPHALOPODA. 



545 



adopts different species as they happen to fall in 

 his way. And further, that the different species 

 of Argonauta, as the A. Argo, A. tuberculata, 

 and A.hians, have each different species of Ocy- 

 thoe. We may add that the light fragile tex- 

 ture of the Argonauta shell, like that of Ca- 

 rinaria, bespeaks a floating oceanic species, 

 and not a Mollusk that creeps at the bottom, 

 and therefore the probability is less that its real 

 inhabitant should have escaped the notice of 

 the Naturalist, supposing the Cephalopod to 

 be a parasite. 



In the posthumous volume of Poll's great 

 work on the Sicilian Testacea, it is stated that 

 that naturalist watched the daily development 

 of the ova of an Ocythoe contained in an Ar- 

 gonaut shell, and that, by means of the micro- 

 scope, he detected the rudiment of the shell 

 in the embryo : the completion of the experi- 

 ment was, however, accidentally interrupted ; 

 and the figure which the editor Delia Chiaje 

 has published of the ovum, which it was 

 hoped would have determined the question, 

 seems to shew the yolk appended to the embryo 

 instead of the shell. 



Mr. Gray,* on the other hand, has recently 

 stated that the nucleus of the Argonaut shell, 

 or that part which, from analogy, must have 

 been formed in the egg, is too large to have 

 been formed in the egg of the Ocythoe. The 

 arguments drawn from the microscopical exa- 

 mination of the ova of the Ocythoe before the 

 commencement of the development of the 

 embryo, are obviously inconclusive; since, 

 whatever the subsequent products of the egg 

 might be, at this period only the granular 

 and oily particles of the vitelline nidus could 

 be expected to be seen. 



With respect to another argument against 

 the legitimate title of the Ocythoe' to the shell, 

 founded on the supposed uniform occurrence 

 of a deposition of eggs in the same shell, we 

 can adduce three exceptions in which the 

 Argonaut shell was exclusively occupied by 

 the Cephalopod ; these specimens were taken 

 along with several others, by Captain P. P. 

 King, R.N., from the stomach of a Dolphin, 

 caught upwards of six hundred leagues from 

 land, and were kindly presented to us by that 

 gentleman. In these examples, as in others, 

 we were struck with the exact correspondence 

 between the size of the shells and that of their 

 inhabitants, every trifling difference in the 

 bulk of the latter being accompanied with 

 proportional differences in the shells which 

 they occupied. The consideration of all these 

 circumstances has prevented a satisfactory con- 

 clusion being formed with respect to this long- 

 agitated and nicely-balanced question, and we 

 are compelled to repeat after the Stagy rite, nspl 

 >e ywia-totq nal o-uvav^ntrioas TOU oyrfdnov axptflus (*iv 

 OVTTCU Ztrfen.-\ Observation of the development 

 of the Ocythoe until the period when it is ex- 

 cluded from the egg, would decide the point. 



* See Proceedings of the Zoological Society, 

 September, 1834. 



t " But as touching the generation and growth of 

 the shell nothing is as jiet exactly determined." 

 Hist. Anim. lib. ix. 



But this must be done satisfactorily, and with 

 the requisite knowledge, care, and good faith 

 on the part of the observer. 



Before, however, quitting this subject, we 

 will mention one example of a naked Ce- 

 phalopod, nearly allied to Ocythoe, having 

 manifested a parasitic propensity similar to 

 that which is laid to the charge of that genus. 

 A medical gentleman, (Dr. Moffat, of the 

 Hon. East India Company's Ship, Flora,) who 

 had collected objects in Natural History in 

 the East Indies, amongst other specimens 

 brought home an Octopus, which was caught in 

 the Madras roads in his presence, by means 

 of a baited hook and line, and, when drawn 

 out of the water, was found to have its ven- 

 tricose body firmly imbedded in a ghee-bowl, 

 (one of the small round pots in which the fluid 

 butteris brought on board ship,) which had been 

 thrown overboard. The Doctor disengaged the 

 Cephalopod from the bowl before placing it in 

 spirits, and when we related to him the interest 

 which the fact possessed in consequence of the 

 problematic nature of the Argonaut shell, of 

 which he was not before aware, he regretted 

 much that he had not preserved the Octopus 

 in the singular domicile which it had chosen. 

 Another instance of the parasitic appropriation 

 of a dwelling-place by a Poulp is related by 

 M. Desjardins, in the Report of the Natural 

 History Society of the Mauritius ; he found an 

 Octopus Arenarius in the shell of a Dolium. 



The parasitic occupation of shells by the 

 Octopi for the purpose of depositing the ova in 

 them was not unknown to Aristotle. K2 

 anorinrn o /UEV woXuTrovc EK ray &aXa/xa; Jj ilj xtpa/utoy 

 TJ a - xx xo~xov o/uo:ov, &c. " And the Polypus 

 oviposits in cavities or in shells, or some such 

 hollow places."* 



To return to the shells of the Dibranchiate 

 Cephalopods ; these, then, with the doubtful 

 exception of the Ocythoe', are always internal, 

 and either camerated and siphoniferous, or 

 laminated and more or less rudimental, 

 and concealed within the substance of the 

 mantle. 



In Octopus and Eledone the traces exist in 

 the form of two small amber- coloured styli- 

 form bodies, lodged loosely in capsules, (im- 

 bedded in the sides of the mantle,) and ex- 

 tending downwards from the insertion of the 

 shell muscles, close to the base of the bran- 

 chiae. When the capsules are laid open, the 

 styles frequently fall out in pieces, being of a 

 friable texture. In the Octopus the styles are 

 straight and elliptical ; in Eledone they are 

 largest at their upper extremities, and become 

 filiform as they pass in a curved direction 

 downwards. 



In all the Decapoda in which the shell is 

 rudimental, it is represented by a single piece 

 lodged in the middle line of the dorsal region 

 of the mantle. It is of a horny texture in all 

 the genera except the Sepia, and has generally 

 more or less the form of a feather, as in the 

 Calamary (Jig. 228), or of a straight three- 

 edged sword. 



* Hist. Anim. v. c. 16. 



