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.