Glossary of terms used in describing Mollusca
- Acicular Needle shaped.
- Adductor Muscles Anterior and posterior muscles that close a bivalve shell.
- Anterior Apertural or head end of a gasropod
- Anterior canal Notch or tubular extension of anterior apertural margin supporting the inhalant siphon.
- Aperture: Opening of the shell providing outlet for the head and foot. Entrance of the body whorl.
- Axial Longitudial ribs or colour bands. Parallel to the shells axis.
- Axis Imaginary line through the apex, about which the whorls are coiled. Central structure of a Gastropod shell.
- Benthic Bottom dwelling.
- Body Whorl Last whorl of a univalve/gastropod.
- Byssus Fibres secreted by foot in bivalves, used for attachment.
- Canaliculate Gutter-like or channelled. Applied to suture of some Gastropod shells.
- Cardinal In bivalves, situated more or less in the central part of the hinge area directly below the beaks.
- Carinate Angled or keeled.
- Cerata Dorsal appendages in nudibranchs.
- Chondrophore Pit containing the resilium, a chitinous pad in certain bivalves.
- Clathrate Latticed by axial and spiral ridges.
- Columella Apertural part of axis in a spiral gastropod.
- Concentric Arc-like ridges or striae following the same direction as the ventral margin of a bivalve shell or the growth lines.
- Dentate Sculptured with teeth or short ridges.
- Dextral Right hand coiled Gastropod.
- Divaricate Forked or branched. Diverging sculptural elements, often forming chevrons.
- Dorsal In gastropods, the side of the shell opposite the aperture. In bivalves, the surface or margin nearest the hinge.
- Dorsum Back of the shell, opposite the aperture in Gastropods.
- Escutcheon Depressed area behind ligament in bivalves.
- Fasciole In Gastropods, either a spiral ridge at base of pillar, or groove on shoulder area, often ending in a sinus.
- Fimbriate Fringed.
- Foramen A natural hole or perforation.
- Fusiform Spindle shaped, Gastropods with tall spire and long canal.
- Hinge Junction of two bivalve shells, usually characterised by interlocking teeth.
- Holotype A single specimen upon which a species is based.
- Labrum Outer lip in Gastropods.
- Lamellae Thin plates or sharply raised ridges.
- Lectotype A lectotype is a specimen later selected to serve as the single type specimen for species originally described from a set of syntypes. In zoology, a lectotype is a kind of name-bearing type. When a species was originally described on the basis of a name-bearing type consisting of multiple specimens, one of those may be designated as the lectotype. Having a single name-bearing type reduces the potential for confusion, especially considering that it is not uncommon for a series of syntypes to contain specimens of more than one species.
- Lirate Fine raised lines.
- Lirations Fine raised lines.
- Lunule Heart shaped depression in front of beaks in bivalves.
- Mantle Outer edge of molluscan animal that secretes shell.
- Neotype A specimen later selected to serve as the single type specimen when an original holotype has been lost or destroyed or where the original author never cited a specimen.
- Nepionic Stage following the embryonic one.
- Nodose Bearing tubercules or knobs.
- Operculum In Gastropods
- Pallial Sinus An indentation or inward bending in the pallial line on the interior of a bivalves valves. Corresponds to the position of the siphons.
- Paralectotype Any additional specimen from among a set of syntypes, after a lectotype has been designated from among them.
- Paratype Specimen or specimens from the same lot as the holotype, used in original description of species.
- Parietal Upper part of inside wall of aperture in Gastropods.
- Pelagic Swimming or drifting in the open sea.
- Periostracum Outermost horny covering of a shell
- Peristome Aperture margin of Gastropod.
- Plaits Fold on columella or pillar of Gastropods.
- Prodissoconch Embryonic shell in Bivalves, often preserved at beaks.
- Protoconch Embryonic shell in Gastropods, often preserved at apex.
- Pyriform Pear-shaped.
- Resilium Chitinous pad associated with Bivalve hinge. Causes the shell to open when adductor muscle relaxes.
- Reticulated Cross ridged, forming network pattern.
- Rhinophores Pair of club like sensory appendages in nudibranchs.
- Scalariform Loosely coiled, unwound.
- Selenizone Spiral band of crescentic growth lines, associated with marginal slit or foramen, in certain univalves.
- Sinistral Left hand coiled Gastropod, opposite of dextral.
- Sinus A curve, cleft or indentation.
- Spatula Spoon-shaped central area of the shell interior of a limpet, usually differing in colour from the rest of interior of the shell. Usually resulting from where the animal was attached to the shell.
- Spire In Gastropods: all whorls except last one (body whorl).
- Syntype A syntype is any one of two or more specimens that is listed in a species description where no holotype was designated
- Teleoconch Entire shell, other than protoconch.
- Tessellated Checkered pattern, mosaic-like squares.
- Topotype A biological specimen that is of the same species or subspecies as a type specimen and has been collected from the same location.
- Umbilicus Gap between reflected inner lip of shell aperture and the first body whorl of Gastropod.
- Umbo Early part of bivalve shell, often called the beak. Larval shell.
- Varix A ridge formed at the outer lip in some Gastropods. Left at successive growth stages in some species, and dissolved prior to new growth in other species.
- Whorl One complete spiral of a Gastropod shell.