TRIPHORA, or TRISTOMA. Deshayes. A genus composed of small reversed species of CERITHIUM, Auct. which have the anterior canal closed at the anterior of the aperture, but opened at the extremity, and a small tubular opening on the upper part of the whorls, making three openings on the body whorl. This genus stands in the same relation to Cerithium as the Typhis to Murex. Fig. 375 in the old plates, and fig. in the new plates. TRIPLEX. Humph. MUREX, Linn. TRIPLODON. Spix. HYRIA, Auct. TRIPTERA. Quoy et Gaimard, CUVIERA, Fer. Described in the Voyage de la Coquille, and represented as a molluscous animal destitute of a shell. TRIQUETRA. Bl. Triangular species of VENUS Auct. TRISIS. Oken. ARCA tortuosa, Auct. TRISTOMA. Described as TRIPHORA. TRITON. Auct. _Fam._ Siphonostomata, Bl. Canalifera, Lam.--_Descr._ Oblong or oval, thick, ribbed or tuberculated, with discontinuous varices placed at irregular distances; spire prominent, mammillated; aperture round or oval, terminating anteriorly in a generally long, slightly raised canal; columellar lip granulated or denticulated; outer lip thickened, reflected, generally denticulated within; epidermis rough; operculum horny.--_Obs._ However nearly allied the Tritons may appear to be to the Murices and Ranellæ there are still to be traced in the shells of each of those genera, several constant and well marked distinctions, by which they maybe at once recognized. In the Ranellæ, the varices run in two rows along the spire; in the Murices, they form three or more rows; but in the Tritons, they do not follow each other, _i.e._ they do not occur in the same part of each volution. The large species of Triton, are sometimes used as trumpets. The Tritons are brought from the Mediterranean, Ceylon, the East and West Indies, and South Seas. Fig. 398 to 401. TRITONIDEA. Sw. A genus of "Buccininæ," Sw. thus described: "Shell bucciniform, but the basal half is narrowed, and the middle more or less ventricose; spire and aperture equal. Pillar at the base with two or three obtuse and very transverse plaits, not well defined; outer lip internally crenated and with a superior siphon; inner lip wanting, or rudimentary." This genus is the same as the one first distinguished by Mr. Gray under the name of Pollia. We do not regret the discovery made by Mr. Swainson of that name being previously occupied for a genus of Lepidopterous Insects. Fig. 415, represents Tritonidea articularis. (Pollia, Gray.) TRIVIA. Gray. A genus composed of those small species of CYPRÆA, Auct. which are characterized by small ridges on the dorsal surface, and have the anterior of the columella internally concave and ribbed. C. Pediculus. Auct. fig. 449, 450. TROCHATELLA. Sw. A sub-genus of Helicinæ, consisting of those species which are acute and trochiform.