VENTRAL. (_Venter_, the belly.) The margin of a bivalve shell opposite the hinge. The under valve in Brachiopodous bivalves is the ventral valve. The ventral surface of an univalve spiral shell is that which faces the observer when the aperture is placed towards him. The ventral part of the whorls of symmetrical convolute shells, is the inner part, that which is nearest to the spire. VENTRAL SIPHON. In symmetrical convolute univalves, is one placed near the inner edge of the whorls. VENTRICOSE. (_Ventricosus._) Swelled, rounded out, (_bombé Fr._) as Harpa ventricosa, fig. 419. VENUS. Auct. (_Goddess of Beauty._) _Fam._ Marine Conchacea, Lam. Conchacea, Bl.--_Descr._ Equivalve, inequilateral, sub-globose, sub-ovate, transverse, externally rugose, striated, ribbed, cancellated or smooth; margins entire, simple, close; hinge with three more or less distinct cardinal teeth, diverging from the umbones in each valve; muscular impressions two, lateral, distant; palleal impressions sinuated posteriorly; ligament external.--_Obs._ This extensive genus, including some bivalves of splendour and beauty, justifying the name given to it, may be known from Cytherea by the absence of a lateral tooth, which is found near the cardinal teeth in the latter. Artemis is distinguished not only by its beautiful form, but by the deep angular sinus in the palleal impression. Fig. 119, 119 a. Found mostly in temperate and tropical climates. VERMETUS. Adanson. _Fam._ Scalariana, Lam. Cricostomata, Bl.--_Descr._ Spiral at the apex, irregularly twisted towards the aperture; aperture round, small.--_Obs._ This shell resembles the Serpulæ in general appearance, although it is regularly spiral near the apex. The animal is known to be a true mollusc, rather nearly allied to that of the genus Dentalium, which is also placed wrongly in the Lamarckian system. Vermetus Lumbricalis, fig. 345. Coast of Africa. VERMICULAR. (_Vermicularis._) Worm-shaped, tubular, serpentine. _Ex._ Vermilia triquetra, fig. 7. VERMICULARIA. Lam. VERMETUS, Adanson; afterwards VERMETUS, Lam. VERMILIA. Lam. A genus composed of species of Serpula, which are attached by the whole length of the shell, no part being free. Vermilia triquetra, fig. 7. VERTEBRALINA. D'Orb. A genus of microscopic Foraminifera. VERTEX. Apex. VERTIGO. Müll. _Fam._ Colimacea, Lam.--_Descr._ Cylindrically fusiform, sinistral, hyaline; aperture marginated, sinuated, denticulated on the inner edge; peristome sub-reflected.--_Obs._ This genus of minute land shells, resembles Pupa, but is a reversed, hyaline shell. Vertigo pusilla, fig. 293. Europe. VERRUCA. Schum. CLITIA, Leach. VESICA. Sw. A sub-genus of Bulinus, Sw. p. 360.