||the first formed part of a valve, usually above the hinge.
||split in two (as in the tooth in the hinge).
||clump of horny threads spun by the foot and attached to the
||hinge tooth situated near the umbo.
||sculpturing running parallel to the growth margin of the
||a smooth, long surface on the upper margin of the valve behind
the horny ligament.
||opening or gap at either end of the closed valves.
||top interlocking margin of the valves, usually with teeth.
||hinge tooth situated before or behind the cardinal teeth and
at greater distance from the umbo.
||an external or internal horny band, usually behind the beaks,
holding the valves together or ajar.
||an arrow-shaped or heart-shaped impression on the valves just
in front of the beaks.
||an embayment or U-shaped curve in the pallial line.
||an outer layer of thin or thick chitinous material covering
the outer shell.
||sculpture or colour rays running from the beaks to the lower
margins of the valves, crossing the concentric sculpturing one of the main
shelly halves of a bivalve.
||slits allowing the enterance of water (inhalant, ventral
siphon) or its exit (exhalant, dorsal siphon).
||one of the main
shelly halves of a bivalve