venter [paleont] . (a) The outer and convex part of the shell of a curved or coiled cephalopod or gastropod, or the peripheral wall of a cephalopod whorl comprising the part of the shell radially farthest from the protoconch; the underside of a nautiloid and of its conch, distinguished generally by the hyponomic sinus and often by a conchal furrow (TIP, 1964, pt. K, p.59). (b) The median region of the shell of a productid brachiopod, situated between the valve surfaces on either side of the median sector of the shell (TIP, 1965, pt. H, p.155). (c) The belly region or the lower part of the carapace of an ostracode. Cf: dorsum [paleont].