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Show 312 MOLLUSCA. SEPIA, Lam. The Sepire, properly so called, have the two long arms of a Lolj. go, and a fleshy fin extending along the whole length of each side of the sac. The shell is oval, thick, convex, and composed of nume· rous and parallel calcareous lamin::e, united by thousands of little hollow columns, running perpendicularly from one to the other, This structure rendering it friable, causes it to be employed for po· lishing various kinds of work; it is also given to birds in aviaries, for the purpose of whetting their beaks. The ink-pouch of the Sepi::e is detached from the liver and situ. ated more deeply in the abdomen. The glands of the oviducts are enormous. The eggs are produced attached to each other in branch· ing clusters resembling those of grapes, and are commonly termed sea .. grapes. The species most commonly found in the seas of Europe, Sepia officinalis, L.; Rondel., 498, Seb., III, iii, attains the length of a foot and more. Its skin is smooth, whitish, aod dotted with red. The Indian Ocean produces another, Sepia tube1·culata, Lam. Soc. d'Hist. Nat., 4to, pl. i, f. 1(1). NAuTILus, Lin. In this genus Linnreus united all spiral, symmetrical and chambered shells, that is to say such as are divided by septa into several cavi· ties; their inhabitants he supposed to be Cephalopoda. One of them, in fact, belongs to a Cephalopode that strongly resembles a Sepia, but it has shorter arms-it forms the genus, SPIRULA, Lam. In the hind part of the body, which is that of a Sepia, is an inte· rior shell, which, although very different from the bone of that ani· mal as to figure, differs but little in its formation. A correct idea of the latter may be obtained by imagining the successive laminre, instead of remaining parallel and approximated, to be concave to· wards the body, more distant, increasing but little in breadth, and (1) Small bodies, armed with a spine, are frequently found among Fossils-they are the extremities of the bones of Sepia:. They constitute the genus BEtor· TEn~ Deshayes. See my note on this subject, Ann. des Sc. Nat. Il, xx, 1, 2. There are some other-but petrified-Fossil!!, which appear to be closely alli~~ to the above bones. They are the RYNcuoLl'l'liES of M. Faure Biguet. Sec Gal · lardot, Ann. des Sc. Nat., II, 485, and pl. :uii, and of Orbigny, lb., pl. vi. UEPIIALOPODA. 313 forming an angle between them, thus producing an elongated cone, spirally convoluted in one plane and divided transversely into chambers. Such is the shell of the Spirula, which has additional characters consisting of a single hollow co] umn that occupies the internal side of each chamber, continuing its tube with those of the other chambers to the very extremity of the shell-this column is termed the siphon. The turns of the spire do not come into contact. But a single species, Nautilus spirula, L.; List., sso, 2, is known. The NAUTILUS, propel'ly so called, Has a she11 which differs from the Spirula in the sudden crossing of the lamin::e, and in the last turns of the spire, which not only touch the preceding ones but envelope them. The siphon occupies the centre of each septum. N. pompilius, L.; List. 551, the most common species; it is very large, formed internally of a beautiful nacre, and covered externally with a white crust varied with fawn-coloured bands or streaks. The animal, according to Rumph, is partly contained within the last cell, has the sac, eyes, parrot-beak, and funnel of the other Cephalopoda; but its mouth, instead of having their large feet and arms, is surrounded by several circles of numerous small tentacula without cups. A ligament arising from the back traverses the whole siphon and fastens it there(l). It is also probable that the epidermis is extended over the outside of the shell, though we may presume it is very thin over the parts that are coloured. Individuals are sometimes founcl,-Naut. pompilius, ~' Gmel.; List., 552; AMMONIE, Montf., 74, in which the last whorl does not envelope and conceal the others, but where all of them, though in contact, are exposed, a circumstance which approximates them to the Ammonites; they so closely resemble the common species, however, in all the rest of the shell, that it is scarcely possible to believe them to be any thing more than a variety of it. Fossil Nautili are found of a large or moderate size, ~nd (1) The figure of Rumphius is absolutely unintelligible, and it is somewhat astonishing, that, of the many naturalists who have visited the Indian Ocean, not one has ever examined or collected this curious animal, which belongs to so commona shell. VoL. 11.-2 P \ |