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Aperture - opening at the front
end of gastropod shell and a tusk shell.
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Apex - starting point of shell
growth, the 'top' of a gastropod spire.
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Apophysis - a projecting spur
inside a bivalve shell below the umbo, the site of a muscle
attachment.
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Axis - an imaginary line around
which the whorls revolve, drawn from the anterior to the apex
of gastropods.
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Bivalve - a mollusc with s shell
formed of two pieces.
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Body whorl - the
largest section of a gastropod, this encolses the soft parts.
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Byssus - a bunch of silky threads
anchoring some bivalves to solid object.
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Calcareous - made of calcium
carbonate, chalky.
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Callus - a thick or thin layer of
shelly substance, smooth and glossy, usually transparent.
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Canal - a channel at the top or
bottom of the aperture to accommodate the siphon of a
gastropod.
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Cancellation - a sculptured area
of lines crossing others at right angles, in a lattice-like effect; also
referred to as reticulation.
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Cardinal tooth -
projection on the hinge plate below the umbo.
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Chiton - a mollusc with a foot, a
head bearing tentacles and eight shelly plates held together by a girdle.
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Columella - the spirally-twisting
pillar surrounding the axis of a gastropods.
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Concentric- following the
direction of growth lines, mostly in bivalves.
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Ear - an extension of the
hinge region of a bivalve shell, as in scallops.
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Escutcheon - a depression found
behind the umbones of a bivalves shell, often compassing an
extenal ligament.
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Family - a unit comprising of two
or more closely related species belonging to one genus or two
or more genera, subordinate to a superfamily.
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Fluted - scalloped or arched.
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Foot - the fleshy sole that a
gastropod creeps or glides upon, or by which it adheres.
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Gastropod - any of various
mollusks of the class Gastropoda, such as the snail, slug, cowrie, or
limpet, characteristically having a single, usually coiled shell or no shell at
all, a ventral muscular foot for locomotion, and eyes and feelers
located on a distinct head.
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Genus (Genera)
- a unit comprising one or more species, subordinate to a family.
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Girdle - the muscular ribbon
surrounding and binding together a chiton's shelly plates.
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Globose - rounded or almost
spherical.
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Granulose - tending to be
inflated, like a ball.
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Growth line - a
fine or coarse, raised line defining a temporary pause in the growth of the
shell. Otherwise knowth as ridge.
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Hinge - inner edge of the
valve of a bivalve shell, usually joined by a ligament to
the opposite valve and usually bearing teeth that interlock
with teeth in that valve.
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Impressed - indented or sunken, a
term usually applied to the suture.
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Incised - finely scratched.
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Incurved - turned inwards.
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Keel - a raised, often sharp
ridge.
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Ligament - the elastic, corneous
structure joining the valves of a bivalves.
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Lip - the inside or outside edge
of the aperture of a gastropod shell.
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Lunule - a heart shaped depression
in front of the umbones of a bivalves shell.
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Mantle - a fleshy lobe which
secretes the mollusc's shell and lines the inside of the shell wall.
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Margin - the shell edge.
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Mollusc (Mollusks) - A soft body,
legless, invertebrate animal which usually secretes a calcareous shell.
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Mother-of-pearl - a shelly layer
or the inner lining of a shell, displaying a pearly surface.
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Muscle scar - the
impression inside the valve of a bivalve shell made by a
muscle holding the valves together.
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Nympth - the narrow ledge, on the
hinge behind the umbo, to which the external ligament
is attached.
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Obsolete - ceasing to exist, no
longer present.
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Operculum - grown on the foot
of many species of gastropod, this is an oval or rounded
structure which seals the aperture when the animal withdraws into its
shell.
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Ornament - raised or depressed
features on the shell surface.
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Ovate - oval; egg-shaped.
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Pallial line - an impressed line
inside the valve of a bivalve shell parallel to the margin,
which marks the position of the mantle edge.
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Parietal area/wall - occasionally
referred to as the inner lip, this is the area in gastropods that lies
opposite the outer lip and above the columella.
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Radial - ray-like
ornamentation or sculpturing, diverging from the umbones of
bivalves; the direction of the raised or depressed ornamental
feature of a bivalves, running form the umbo towards the
edge of the valve.
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Range - the total distribution of
a species.
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Recurved - curving upwards or
downwards.
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Rib - a continuuous elevation of
the shell surface.
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Ridges - see growth lines.
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Scale - raised, sharp edged,
ornamental feature, sometimes fluted.
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Serrated - edge of a shell that
exhibits a series of grooves or points.
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Shelf - a thin plate obsuring the
aperture of some species of gastropod shells.
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Shell tube -
hollow tube occupied by most gastropods, all tusk shells and few bivalves.
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Shoulder - the angulation of a
whorl at or just below the suture.
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Sinuous - greatly waved.
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Siphon - a rectractable fleshy
tube of gastropods and bivalves, used for various purposes,
including feeding and the explusion of waste.
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Siphonal canal -
otherwise known as notch; the tube or gutter at the front end of the
aperture, to hold the front siphon of a gastropod.
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Slit - a shallowor deep cut in the
shell margin of some gastropods and in the umbones of
some bivalves.
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Species - a group of beings
sharing virtually identical characteristics; it is subordinate to and contained
within a genus.
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Spine - a blunt or sharp
projection, often found in murex.
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Spiral - on gastopod
shells and tusk shells, going in a transverse direction.
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Spire - the coiled part of a
gastropod shell apart from the body whorl.
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Stria (striae) -
fine raised or grooved line on the surface of a shell, sometimes an indication
of growth stage.
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Suture - the junction of two
whorls, it is often depressed or indented.
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tooth (teeth) -
pointed or blunt structure(s) inside the outer or inner lip of a
gastropod shells, and on the hinges of bivalves shells.
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Umbilicus - the lower open
axis around which the whorls of a gastropods are coiled.
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Umbo (Umbones) -
the earliest-formed part of a bivalve shell's valve.
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Valve - one piece of a bivalve
shell or of a chiton.
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Whorl - one complete turn of the
tube of a gastropod shell about its imaginary axis.
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