Argonaut.] 



MUSEUM OF ANIMATED NATURE. 



183 



bability of a passive kind, or influenced only by the 

 action of the respiring currents, when expelled by 

 the funnel, through the surrounding medium; and 

 at all events it can no longer be supposed to have 

 been aided by the fabled sails and oars of the 

 argonaut." The mode of sailing with outspread 

 tentacles is described by Rumphius, who says that 

 in fine weather, alter a storm, they are seen in troops 

 thus navigating the seas, like a fleet of pigmy 

 vessels, and that as soon as they wish, they take in 

 their tentacles, upset their boat, and so return to 

 the bottom. 



We may here observe, that the tube or siphuncle 

 prolonged through the compartments of the ca- 

 merated shell of the nautilus is continued from the 

 great venous cavity or pericardium, which freely 

 communicates with the branchial cavities, and 

 which, receiving the water from these cavities, 

 can thus by its contraction transmit it through the 

 siphuncle into the chambers of the shell. These 

 chambers naturally contain air, or some gaseous 

 element, and being thus filled with a fluid more 

 buoyant tlian water, endow the animal with the 

 means of floating, notwithstanding the density of 

 the shell itself. Now, when the animal wishes to 

 sink, it forces water through the tube, thereby com- 

 pressing the air, and thus it immediately becomes 

 heavier than the surrounding medium. It would 

 appear that the retraction of the head and tentacles 

 into the shell involves the contraction of the peri- 

 cardium, and consequently the forcing of water 

 through the tube ; while the protrusion of the head 

 and tentacles, by relieving the pericardium from 

 pressure, permits it to expand, when the air of the 

 chambers necessarily drives back the water, and 

 the buoyancy of the animal returns accordingly. 

 Surely no comments are needed to enforce upon 

 the mind a perception of the beauty and fitness of 

 such a contrivance, a contrivance which enables 

 the pearly nautilus to float on the surfiiee of the 

 deep, luxuriating in the light and warmth of the 

 sun ; and then in a moment, when danger threatens, 

 to sink to the bottom, and there find a harbour of 

 security. 



Fig. 2528 represents the mandibles of the nau- 

 tilus. A, mandibles of Nautilus Pompilius: a, cal- 

 careous extremity of upper mandible ; b, extended 

 internal horny laminae of the same ; c, notched 

 calcareous extremity of lower mandible ; d d, ex- 

 ternal horny laminae of the same. B, upper man- 

 dible, showing the form of the calcareous extremity, 

 and the proportions of the external and internal 

 horny laminae. C, one-half of the lower mandible, 

 showing the different proportions of the two horny 

 laminae, and the extension of the horny substance 

 at a, upon which the calcareous matter is deposited ; 

 a', the internal horny lamina ; b, the external horny 

 lamina. Nat. size. (Owen.) 



Fig. 2529 represents a series of Rhyncholite?, or 

 the fossil beaks of nautili from the oolite (Stones- 

 field), and the lias of Lyme Regis, &c. They were 

 formerly mistaken for the beaks of birds, o, side 

 view (muschelkalk of Luneville) ; b, upper view 

 (same locality) : c, upper view (lias of Lyme Regis) ; 

 ■«f, calcareous point of an under mandible, internal 

 view, from Luneville. (Buckland.) 



2530. — The Wide-mouthed Bellerophon 



{Bellerophon hiidcus). A fossil shell, which, though 

 heavier and thicker than the shell of the Argonaut, 

 in one of an allied cephalopod ; it is unilocular. 

 It occurs in the mountain-limestone ! formation ; 

 and is figured in the late Mr. Martin's ' Petrificata 

 Derbiensia,' T. x!., i. 2 (1809). The form and situ- 

 ation of the dissepiments, he says, are unknown ; 

 they have been since proved not to exist. 

 We shall now pass to the Argonaut 



253L — The Argonaut 



{Argonauta Argo). The shell ; a, shell of young. 



2532. — The Tuberculous Argon.^ut 



{Argonattta Argo). The shell j a, a, shell of young 

 in two views. 



The Argonaut or Paper Nautilus has been ever 

 regarded with interest, and conflicting in the ex- 

 treme have been the opinions respecting the tenant 

 ■of the shell, some believing that the real fabricator 

 of this beautiful structure would be ultimately 

 found to be a gasteropodous mollusk, allied to 

 Carinaria (the shell of which is very like that of 

 Argonauta), others contending that the animal 

 usually found in it, always indeed (and the fact has 

 been observed from the earliest periods), where any 

 inhabitant is taken with the shell, viz., a cephalo- 

 pod, is not only its tenant, but its fabricator, and 

 therefore not a usurper. 



And still further : — With respect to the form and 

 habits of this cephalopod, the tenant of the shell, 

 the most extravagant ideas have prevailed. Mont- 

 gomery, in his ' Pelican Island,' thus describes it, 

 in accordance with the accounts promulgated by 

 Jiaturalists : — > 



*' Liijht as a flake of foam upon tlie wind. 

 Keel upwards, from the deep emerired a shell, 

 .Shap'd like the moon ere half her orb is filled. 

 Frausjht with yoiin^ life, itri),'hted as it rose, 

 And moved at will alons; the yielding water. 

 The native pilot of this little bark 

 Put out H tier of oars on either side. 

 Spread to the wafting breeze a two-fold sail, 

 And mounted up and glided down tlie ()illo\v 

 In happy freedom, pleased to feel the air, 

 And wander in the luxury of li^ht." 



Since the days of Aristotle, the history of the 

 argonaut has been enveloped in a tissue of mis- 

 conceptions and difficulties. The argonaut has 

 been a centre round which theories and speculations 

 and poetry have revolved, but upon which the scru- 

 tiny of rigid and persevering research seemed never 

 to be brought to bear. It is indeed only recently 

 that the cloud of doubts and errors which hung 

 around this tenant of the sea has been dissipated ; 

 and it is principally to the observations and ex- 

 periments of Madame Jeannette Power, a French 

 lady residing in Sicily, that the true nature and 

 history of the argonaut, so abundant in the Medi- 

 terranean, have been cleared up. The results of 

 her researches, with collections of specimens in 

 illustration of them, have been transmitted by her 

 to the different scientific societies of England, 

 France, and Italy ; and Professor Owen and M. 

 Rang have contributed their labours in the eluci- 

 dation of many points of difficulty and interest. 



By way of condensing the matter, it may be 

 stated, in the first place, that naturalists have 

 doubted as to the claim of the cephalopod to the shell 

 it is found, and ever has been found, to inhabit, 

 and arguments have been adduced to prove, that, 

 like the hermit crab (Pagurus), it had usurped the 

 shell of another, either during the life, or after the 

 death of its lawful proprietor, — a proprietor which 

 ever remained to be discovered. M. Blainville in 

 France, and many zoologists of rank in this country, 

 adopted this opinion. In the second place, it has 

 been an established opinion that the velated dorsal 

 arms were used as sails to catch the breeze, and that 

 as it floated over the tranquil waters of the sea, or 

 the rippling waves, it was thus wafted onwards. 



Now, with reference to the lawful occupation 

 of the shell, it is incontestably proved that the 

 cephalopod in question is the maker of it, and con- 

 sequently not a usurper of another's right. Speci- 

 mens in every stage of growth, from young indivi- 

 duals whose shell weighed only a grain and a half up 

 to those of the ordinary size, have been sent to 

 England, and accurately examined by Professor 

 Owen, to whose observations we shall presently 

 allude. Again, it was found by Madame Power (the 

 fact has been subsequently corroborated), that the 

 shell of the argonaut, while investing the living 

 animal, is not hard as it appears in cabinets, but of 

 a yielding and flexible consistence, with a degree of 

 elasticity, which the mechanism of respiration and 

 locomotion of the animal requires ; it is, moreover, 

 diaphanous or permeable to light. It was also 

 proved that while in the egg, the young argonaut, 

 though otherwise in a high stage of development, 

 had neither the membranous velated arms, nor any 

 rudiment of shell ; but that both these arms and the 

 shell became developed at a certain period after 

 exclusion, viz., about the tenth or twelfth day. 



Another discovery was, that when the shell was 

 fractured, or portions were removed, it was repaired 

 (from the outside) with similar materials to that of 

 the rest of the shell ; and that, moreover, the shell 

 was really moulded on the body of the animal, to 

 the form of which it is beautifully adapted, that 

 the relative position of the animal with respect to 

 the shell was invariably the same, and that if re- 

 moved from the shell the animal speedily died. 

 These facts were ably commented upon by Pro- 

 fessor Owen, who in February, 1839, exhibited at 

 a meeting of the Zool. Soc. specimens of the animal 

 in question and its shell, of all sizes, shells fractured 

 and repaired, and eggs in every stage of develop- 

 ment, and who ably confuted the views of M. 

 Blainville. 



Now, with respect to the velated dorsal arms, 

 though Madame Power fell into the common error 

 of supposing that they were used as sails, yet she 

 describes them as "being placed next the invo- 

 luted spire of the shell, over which they are bent, 

 and expanded forwards, so as to cover and conceal 

 the whole of the shell, and from which they are 

 occasionally retracted in the living argonaut." 

 During subsequent experiments she ascertained that 

 these expanded organs are the actual producers of 

 the shell, that to them it owes its original formation, 

 and its preparation when injured ; and she justly 

 compares these membranous expansions to the 

 two lobes of the mantle of the cowry, reflected 

 over its shell, and which they produce. "These 

 facts," observes Professor Owen, " are the results of 

 actual observation ; and the subsequent observa- 

 tions of M. Rang have fully confirmed the accuracy 

 of Madame Power's description of the relative posi- 

 tion of the so-called sails of the argonaut to the 



shell ; and he has published some beautiful figures 

 illustrative of this fact." 



Among other points noticed by Madame Power, 

 in her memoir, was the great extensibility combined 

 with the forcible pump-like action of the siphon, 

 which emerges ficm the anterior edge of the mar- 

 ginal opening of the shell, the dorsal surface of the 

 animal's body being always next the involuted spire, 

 or internal wall. 



"The proof," says Professor Owen, "that the 

 velated arms possess, like the expansions of the 

 mantle of the Cypraea, a calcifying power, was 

 aftbrded by the third series of specimens on the 

 table of the Society. These consisted of six shells 

 of the argonaut, from which Madame Power had 

 removed pieces of shell while the argonauts were 

 in life and vigour, in her marine vivarium. One of 

 the shells had been removed from the animal ten 

 minutes after the fracture ; another argonaut had 

 lived in the cage two months after being subjected 

 to the experiments : the remaining specimens ex- 

 hibited intervening periods between the removal 

 of a portion of the shell and its reparation. The 

 fractured shell first described had the breach re- 

 paired by a thin transparent membranous film : the 

 piece removed was taken from the middle of the 

 keel. In a second specimen calcareous matter 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 irregularity 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 cha- 

 racteristic of the repairing substance, but the tran- 

 sition of this substance into the material of the 

 shell, subsequently added in the ordinary progress 

 of growth, was so gradual, in the resumption in 

 the repairing material of the ordinary clearness 

 and striated structure of the shell, that it was im- 

 possible 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 re- 

 acted precisely like the ordinary shell with nitric 

 acid. 



Mr. Owen then observed, that the specimens 

 submitted to the meeting by Madame Power pos- 

 sessed in themselves the means of confirming 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 had been repaired should have 

 been deposited 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 calcifying organs." 



For abundant details on the structure of the 

 argonaut, we refer to the 'Proceeds. Zool. Soc' 

 for February, 1839 ; to which we have previously 

 alluded. 



The following interesting account of th'e living 

 animal and of its actions is from the paper by M. 

 Ransr : — 



"The poulp, with its shell lying motionless at 

 the bottom of the vase in which we had placed it, 

 struck us at once by the brilliancy of its hues and 

 their richness ; which our sketch is far from con- 

 veying. It appeared little more than a shapeless 

 mass, but it was a mass of silver with a cloud of 

 spots of the most beautiful rose colour, and a fine 

 dotting of the same, which heightened its beauty. 

 A long semicircular band of ultra-marine blue, 

 which melted away insensibly, was very decidedly 

 marked at one of its extremities, that is, of the keel. 

 The shell was nowhere visible, but with a little 

 attention we could easily recognise its general form, 

 and we could even distinguish some grooves on its 

 surface as well as the tubercles of the keel. A 

 i large membrane covered all ; and this membrane 

 I was the expanded velation of the arms, which so 

 \ peculiarly characterize the poulp of the argonaut. 

 i The animal was so entirely shut up in its abode, 

 that the head and the base of the arms only were a 

 very little raised above the edges of the opening of 

 the shell. On each side of the head a small space 

 was left free, allowing the eyes of the mollusk some 

 scope of vision around, and their sharp and fixed 

 gaze appeared to announce that the animal was 

 watching attentively all that passed around it. The 

 slender arms were folded back from their base, and 

 inserted very deeply round the body of the poulp, 

 I in such a manner as to fill in part the empty spaces 

 ! which the head must naturally leave in the much 

 1 larger opening of the shell. Of these six arms, the 

 ! two lower ones descended on each side the whole 

 length of the keel, leaving a space between them 



