Part 13

AMPHIDESMA. Lam. (from [Greek: Amphô], ampho, ambo, [Greek: Desmos], desmos, ligamentum). Fam. Mactracea, Lam.--Descr. Equivalve, oval or rounded, sub-equilateral, sometimes rather gaping at the sides, with slight posterior fold; hinge with one or two cardinal teeth in each valve, and two elongated lateral teeth, distinct in one valve, nearly obsolete in the other; ligament short, separated from the cartilage, which is elongated and couched obliquely in an excavation of the hinge.--Obs. In most bivalve shells, the cartilage and ligament are united in one mass, or placed close to each other; the contrary in this case gives rise to the name, which signifies double ligament. This circumstance distinguishes the genus Amphidesma from Tellina, which in other respects it greatly resembles. From Lutraria it may be known by its distinct lateral teeth, and also by its valves being nearly close all round, while the Lutrariæ gape anteriorly. The species do not appear to be numerous, no fossil species are known. A. Reticulatum, fig. 85. West India Islands, Brazil, Coast of Pacific, &c.

AMPHIPEPLEA. Nilson. The type of this proposed genus is LIMNEA glutinosa, Auct. Gray's edition of Turton, page 243, plate 9. fig. 103. The shell is polished and the inner lip expanded.

AMPHISTEGINA. D'Orb. A genus of microscopic Foraminifera.

AMPLEXUS. J. Sowerby. A. Corralloides, fig. 463. A singularly formed fossil, described as nearly cylindrical, divided into chambers by numerous transverse septa, which embrace each other with reflected margins. It occurs in the Dublin limestone, and resembles a coral or madrepore.

AMPLEXUS. A generic name proposed by Captain Brown for HELIX pulchella, Drap. 112, tab. 107-134. Zurama, Leach.

AMPULLARIA. Auct. (Ampulla, a rounded vessel). Fam. "Peristomiens," Lam. Ellipsostomata, Bl.--Descr. Spiral, globular, sometimes discoidal, frequently umbilicated, covered with a rounded, horny epidermis; spire short; whorls rapidly enlarging; aperture elliptical, rounded anteriorly; peristome nearly or quite entire, thickened and slightly reflected; operculum, testaceous, annular, with a subcentral nucleus.--Obs. This genus of fresh-water shells of which a few fossil species occur, is easily distinguished from other genera, by obvious characters, particularly by a thick, horny, greenish-brown epidermis, and the rotundity in form. One species, the A. Cornu-arietis which forms the type of Lamarck's genus Planorbis, requires notice on account of its flatness, but may be known by the aperture which in the Ampullaria is longer than wide, and in Planorbis the contrary. Lanistes, Montf. is described from a reversed species of Ampullaria. The Ampullaria is vulgarly called the Idol Shell, and is said to be held in great veneration by the South American Savages. The animal has a large bag, opening beneath, placed on the side of the respiratory cavity. It is supposed that the animal has the power of filling this bag with water, and that it is thus enabled to live a long time out of water. They have been brought as far as from Egypt to Paris alive, packed in saw-dust. Ex. fig. 318. East and West Indies, North Africa, South America, &c.

AMPULLARINA ----? A genus formed for the reception of AMPULLARIA avellana. Fig. 538. From Australia.

AMPULLINA ----? Part of the genus HELICINA, Auct.

ANALOGOUS. A term applied to certain species of fossil shells, which present a certain degree of resemblance to recent species; but which are not sufficiently similar to warrant the use of the term 'identical,' or any other implying that they are of the same species.

ANASTOMA or ANOSTOMA. Fischer. (from [Greek: Ana], ana, backwards; [Greek: Stoma], stoma, mouth) Fam. Colimacea, Lamark. A genus of land shells so named from the singular circumstance of the last whorl taking a sudden turn and reflecting the aperture upwards, so as to present it on the same plane with the spire; so that the animal walks with the spire of the shell downwards resting on the foot. In other respects, the two species of which this genus is composed, resemble other Helices; and belong to De Ferrusac's division "Helicodonta." Tomogerus is De Montfort's name for this genus. A. depressum is represented in the plates figs. 271, 272. The nearest approach to this genus will be found in the fossil shell named Strophostoma, by Deshayes, which, however, has no teeth in the aperture and is provided with an operculum like Cyclostoma. South America.

ANATIFER. Brug. ANATIFA, Lam. This name, which signifies Duckbearing, has been given to the shells commonly called Barnacles, on account of an absurd notion entertained among the ancients, that they inclose the young of the Barnacle duck, in an embryo state. The beautiful bunch of jointed arms, the ciliæ of which serve the purpose of agitating the water, so as to draw in food by the current, were supposed to be the feathers of the future bird. For a description of these shells, see PENTELASMIS; and fig. 34.

ANATINA. Lam. (That which belongs to a duck.) Fam. Myaria, Lam. Pyloridea, Bl.--Descr. Thin, transparent, generally equivalve, inequilateral, transverse, marine; hinge with a spoon-shaped process in each valve, containing the cartilage.--Obs. Some species included in the genus Anatina of authors, A. striata, for instance, have not the spoon-shaped prominence, but in its place a small, testaceous, moving appendage, connected with the interior of the hinge. These are now separated, and form the genus LYONSIA. The genus Næara, Gray, is composed of Anatina longirostrum, and similar species, which have neither the bony appendage nor the spoon-shaped prominence. Mya is distinguished from Anatina, by the thickness of the shell, and also by having the prominence only in the hinge of one valve. Fig. 69. A. rostrata. The Anatinæ are found in the East Indies and South Sea Islands.

ANATINELLA. G. B. Sowerby. (Dimunition of Anatina). A genus so named from its resemblance to Anatina, from which it differs in being destitute of the internal appendage, and having no sinus in the palleal impression. One species having been brought from Ceylon, received the name of Anatinella Sibbaldii. Another has lately been found in the Philippine Islands. Fig. 70.

ANATOMUS. Montf. Tom. 2, plate 279. A microscopic shell, appearing from the figure to resemble SCISSURELLA.

ANAULAX. Brogn. ANCILLARIA, Auct.

ANCILLA. Lam. ANCILLARIA, Auct.

ANCILLARIA. Auct. ANCILLA, Lam. (A handmaid.) Fam. convolutæ, Lam. Angyostomata, Bl.--Descr. Smooth, oblong, subcylindrical. Spire short, sutures hidden by enamel. Aperture long, anteriorly emarginated and somewhat effuse. Columella tortuous, oblique, tumid, truncated.--Obs. The Ancillariæ are pretty shining shells, enveloped almost entirely by the soft parts of the animal. They resemble Oliva, from which they are distinguished by the suture of the spire being filled up with shelly enamel, nearly covering the surface. The whorls in Oliva being separated by a distinct canal. Ancillaria may be known from Terebellum by the tumid varix at the base of the columella. The well known Ivory shell, Eburna glabrata, Lam. belongs to this genus, of which a few fossil species are found in the London clay, Calcaire grossièr and green sand, Turin. The recent species are found in the Islands of the Indian Ocean and Australian Seas. A. glabrata is represented in the plates fig. 455; A. cinnamonea, fig. 456.

ANCULOSA. Say. Fam. Melaniana, Lam. Ellipsostomata, Bl. A genus proposed to include some fresh-water shells resembling those of the genus Melania, the difference between them being that the spire of Anculosa is more depressed, and the anterior of the outer lip more angulated than in Melania. On an examination of the different species, however, it will be found that this is quite unsatisfactory, as a generic distinction; because some of the species with short flattened spires, have rounded, and others angulated apertures. North America. An example of each is represented, fig. 314.

ANCYLUS. Geoffroy. Fam. Calyptracea, Lam. Otides, Bl.--Descr. Thin, obliquely conical, patelliform; apex acute, turned sidewise and backwards; aperture oval; margin simple.--Obs. Although the little fresh-water shells described under this name, resemble those of the genus Patella, the animals which produce them are nearly allied to the Lymneanæ. And, it may also be observed, that the shells themselves differ from Patella in not being quite symmetrical, having the apex turned on one side. A. fluviatilis, fig. 246. Found in Great Britain, and in Southern and Central Europe, West Indies, &c.

ANDROMEDES. Montf. VORTICIALIS, Lam. Fam. Nautilacea, Lam. A genus of microscopic Foraminifera.

ANGULATED. (Angulatus.) Having an angle, or corner, as the anterior of the aperture of Eulima, fig. 348; the posterior side of Castalia, fig. 140; the whorls of Carocolla, fig. 277.

ANGULITES. Montf. A genus composed of species of fossil NAUTILI, described by De Blainville as not umbilicated, with a dorsal keel and angular aperture. NAUTILUS triangularis Buffon.

ANGIOSTOMATA. Bl. The third family of Siphonobranchiata, Bl. described as differing little from the family of Entomostomata, but having long, narrow, straight apertures, and the columellar lips straight or nearly so. Were it not for the admission of the genus Strombus into this family, it would correspond with COLUMELLARIA and CONVOLUTÆ of Lamarck.

ANNELIDES. The ninth class of invertebrated animals, divided into three orders, namely, A. Apodes, A. Antennés, and A. Sedentaires. The last only contains families of testaceous Mollusca. The animals are vermicular, some naked, others inhabiting shelly tubes. See SEDENTARY ANNELIDES.

ANNULAR OPERCULUM is one which has the nucleus central, or nearly so, the other layers surrounding it in flattened rings. The term concentric is also applied. See Introduction.

ANNULATED. (Annus, a ring.) Composed of, or surrounded by rings, as in the case of Tubicinella, fig. 14.

ANODON. Brug. Fam. Submytilacea, Bl. Nayades, Lam. A genus composed of such species of NAYADES as are destitute of teeth on the hinge. Europe, North America, &c. An example is given in A. Cataractus, fig. 152.

ANOMALINA. D'Orb. A genus of microscopic Foraminifera.