1 -I 



NAUTILIDJE. 



NAUTILID^E. 



ton 



and u iU locomotive apparatus is confined to the brad, the received 

 denomination of the clue remains undisturbed by iU admission. The 

 inferior or ventral pair of labial proceaM* I consider u analogous to 

 the superseded pedunculated anna of the CutUe-Piah and Calamary, 

 which also come off more internally than the shorter arms, and are 

 approximated or united at their bases on the ventral aspect of the 

 mouth. The other pair in A r a/i'/tu appear to result from a higher 

 degree of organiaation of the part analogous to the external lip in the 

 preceding genera. The curtailed digitations are however but feeble 

 repreaentativea of the elongated and cotyligerous arms of the Poulp, 

 or Cuttle-fish ; and the retractile tentacle*, pedicellate eyes, and flat- 

 tened disc, which, according to the testimony of Rumphius, is applied 

 to the ground in the progressive motions of the animal, attest an 

 obvious tendency towards the Gatttropoda. And while tracing these 

 examples of affinity with the different and heretofore widely-spread 

 groups of Molliuca, between which this remarkable form, I apprehend, 

 is osculant, there may also be perceived in the whole of this singular 

 but at the same time regular and symmetrical arrangement of the 

 palpigeroua organs about the mouth, an analogical relation to the 

 higher Ammiota." 



Before Professor Owen enters upon the Muscular System, which is 

 described carefully and in detail, he notices what he aptly terms the 

 internal skeleton or frame-work from which its principal masses take 

 their origin. Like that of the Dibranchiate Cephalopoda, this skeleton, 

 according to Professor Owen, is cartilaginous, yields readily to the 

 knife, and in texture and semitransparency closely resembles the 

 cartilage which constitutes the skeleton of the Skate. In .SY/.i.i, Tie 

 observes, this cartilaginous part completely encircles the oesophagus, 

 and on the dorsal aspect of that tube is dilated into a large cavity, 

 which contains the brain; but in Xaiitilut the circle is incomplete 

 behind, and the brain is protected only by its membranous sheath. 



Digestive System. The jaws are two, endowed with a vertical 

 motion, and in form resembling a parrot's bill reversed, the upper 

 mandible being encased in the lower when they are closed. Posteriorly 

 they are adapted to a muscular basis, to which they owe their 

 motions. "Thus far," continues Professor Owen, "they resemble 

 the mandibles of the Dibranchiate Cephalopoda; but they are not 

 composed entirely of horny matter, nor are they uniformly of a 

 brown or black colour, their extremities being of a dense calcareous 

 nature, and of a bluish-white colour ; they are also less pointed at 

 the end, and the oval margins of the lower mandible are notched and 

 dentated." They are larger in proportion than in the Cuttle-Fish. 

 Professor Owen proceeds to state that the calcareous extremities of 

 both mandibles are of a hardness apparently adequate to break 

 through the most dense crustaceous coverings, or even shells of a 

 moderate thickness. The extremity of the upper mandible is sharp- 

 pointed, and solid to the extent of five lines from the extremity ; 

 but in the lower one the calcareous matter is deposited on both 

 sides of a thin layer of the black horny substance, and thus a combi- 

 nation of tough with dense matter U obtained, which much diminishes 

 the liability to fracture. This mandible is also more hooked than 

 the upper one, but U more obtuse at the end. " It seems," observes 

 Professor Owen, "from its dentated margin, evidently intended to 

 break through bard substances, whilst the sharp edges of the beak of 

 the cuttle-fish better adapt it for cutting and lacerating the soft 

 bodies of fish." In the particulars here stated the mandibles of 

 AWi/Ki differ, as Professor Owen remarks, from those of every other 

 known species of recent Cephalopoda, The circular lip which sur- 

 rounds the jaws is much deeper thnn in the Cuttle-Fish, and the jaws 

 are provided with four retractor muscles, and one for protrusion. 

 The tongue is Urge, and supported by an oblong horny substance. 

 The fleshy substance is produced anteriorly, and forms three caruncles, 

 which are very soft in texture, and beset by numerous papilla;, 

 having all the characters of a perfect organ of taste. The anterior 

 extremity of the horny substance is embraced by a pair of retractor 

 muscles, which arise from the posterior margin of the lower mandible, 

 and four delicate retractor or depressor muscles are inserted into the 

 anterior or terminal caruncle. Behind the caruncles the dorsum of 

 the tongue is encased with a thin layer of horny matter, from which 

 rise four longitudinal rows of slender recurved prickles between one 

 and two lines in length, the same in number as the labial tentacles, 

 namely, 12. There is an analogous structure in the Cephalopoda and 

 in many of the Utuferopoda. " The necessity of such a structure," 

 says Professor Owen, " becomes very apparent in the Pearly Nautilus, 

 if, as Ilumphius has asserted, it creeps with the shell uppermost; 

 ince in that case the tongue, having its position reversed, would, be 

 opposed instead of being assisted by gravitation while regulating the 

 movements of the food in the mouth. And it is worthy of remark 

 that in the Flamingo, which turns the upper mandible to the ground 

 while taking its food, the tongue is similarly armed with regularly- 

 developed recurved spines, calculated, as in the Pearly Nautilus, to 

 rake the alimentary morsels towards the fauces." [Dtcug.] Behind 

 the homy parts the tongue again becomes soft and papillose, but the 

 papilla are larger and coarser. The only traces of a salivary system 

 detected were in two broad fleshy processes projecting forward from 

 the sides of the fauces : they were papillose, and perforated in the 

 middle of their inner surfaces by a small aperture which led into a 

 glandular cavity between the folds of the mem taane, and from these 



cavities an opaque whitish substance could be expressed. In the 

 Dibranchiate Cephalopoda these glands are remarkably developed. 

 The alimentary canal, which was filled with the fragments of Crusta- 

 ceans, was everywhere connected to the parietes of the abdomen by 

 numerous filaments ; the only trace of a mesentery existed between 

 the two last portions of the intestine, which were connected together 

 by the ramifications of an artery and vein. Among the crustaceous 

 fragments, portions of branchia, claws, and palpi were distinctly 

 recognised, so as to leave no doubt that the greater part of them had 

 belonged to a Brachyurous Decapod of a hirsute character, and not a 

 swimmer. The crop, which was capacious and pyriform, was tensely 

 filled with these fragments, and Professor Owen remarks that the 

 capability of propelling such rude and angular particles through a 

 narrow canal into the gizzard without rupturing the tunics of the 

 preparatory cavity is not one of the least extraordinary examples of 

 the powers of living matter. The gizzard very much resembles that 

 of a fowl, as it does in Octoptu. A globular cavity communicates 

 with the intestine at a little distance from the pylorus, and its reception 

 of the biliary secretion renders it in some measure analogous to a 

 gall-bladder; but Professor Owen thinks that its chief use is probably 

 to pour into the commencement of the intestinal canal a fluid necessary 

 for digestion ; so that, like the laminated and spiral ccocum of the 

 higher Cephalopoda, and the pyloric appendages of fish, it is essentially 

 a simple form of pancreas. The interior of the alimentary canal, 

 which was filled with smaller fragments of crustaceous shell, pre- 

 sented a few longitudinal ruga) and slight transverse puckcrings. 

 The liver is bulky, and extends on each side of the crop from the 

 ccsophagus to the gizzard. There was no trace of structure analogous 

 to the ink-bag of the Dibranchiate Cephalopoda. 



* 



I 



\auliliu rnmpiliia. In the prone position, with the labial processes ami ten. 

 taclc*, the mandibles, and the digestive orgmni displayed. (Reduced from 1'ro- 

 fciwor Owen's figure.) 



n a, the hood, or upper pirt of the oral sheath, longitudinally divided ; b b, 

 the posterior lobes or angles of the hood; c c, the posterior concavity of the 

 hood ; rf rf, the ridge In the same ; ttr, the cat lurface* of the above parts ; 

 //, the Internal surface of the oral thesth ; f f, the external labial processes ; 

 A h, the external labial tentacle* ; i i, the internal labial processes ; * A, the 

 internal labial tentacle* : /, the olfactory lamina* ; m, m, the circular fringed 

 Up, longitudinally divided ; n, the superior mandible ; o, the inferior mandible ; 

 f, the muscular basis on which the mandibles are fixed ; g q, the lupcrlor pair 

 of mn wlen which retract the jaws ; r r, the semicircular muscle which protmdc* 

 the jaw, divided longitudinally ; i, the irmphagn* ; I, the crop ; u, the narrow 

 canal leading to r, the glr.rard ; tr, the Intestine ; >', the terminal fold of intes- 

 tine drawn out of its situation ; r, the anu ; y, th? laminated pancreatic bag ; 

 : i, the liver ; 15, a branch of the anterior aorta, which ramifies In tbe membrane 

 connecting the two portions of the terminal fold of the intestine; 19, the con. 

 tinuatlon of the posterior aorta along the doraal nspect of the crop ; 20, its 

 bifurcation at the ccaophagtu, to form a vascular circle corresponding to the 

 nervmin circle round that tube ; 21 and 22, arteries of the crop, gizzard, ic. 

 (Owen.) 



In the Museum of the Royal College of Surgeons (' Physiological 



