Illustrated Glossary of Malacological and Conchological Terms

An Illustrated and Cross-Referenced Glossary of Malacological and Conchological Terms
by Paul S. Mikkelsen

All Terms in the Glossary
1718 terms were found.

Term

Definition

ABALONE		A member of the gastropod family Haliotidae (e.g., Haliotis spp.). The interior of Abalone shells exhibit a NACREOUS layer known as MOTHER OF PEARL.

ABAPICAL		Away from the APEX; opposite of ADAPICAL; see also: APICAL.

ABAXIAL		Away from the AXIS; opposite of ADAXIAL; see also: AXIAL.

ABERRANT		Abnormal; of freak shape or coloration.

ABORAL		Situated away from the mouth; see also: ORAL.

ABUTTING		Touching; contiguous; adjacent; see also: NAUTILOCONIC.

ABYSS ABYSSAL		Ocean depths from 2,000 to 6,000 meters, See also: HADAL, PELAGIC.

ACCESSORY BORING ORGAN (= ABO; A.B.O.)		[need definition]. Term coined by Mel Carriker.

ACCESSORY MUSCLE		Any muscle other than ADDUCTOR and PALLIAL muscles, with scar of attachment to shell (convenient noncommittal term when referring to scars of muscles of uncertain origin).

ACCESSORY PLATE		A secondary CALCAREOUS structure formed in some bivalves (e.g., the Pholadidae) to protect the soft parts; see also: HYPOPLAX; MESOPLAX; METAPLAX; PROTOPLAX; SIPHONOPLAX.

ACCESSORY VALVE		See: ACCESSORY PLATE.

ACETABULUM		The cup-shaped portion of a SUCKER of a CEPHALOPOD arm or TENTACLE.

ACHIRAL		A non-CHIRAL object; = AMPHICHIRAL.

ACLINE		Perpendicular to HINGE AXIS or almost so (applied to HINGE TEETH or, in some genera, to direction of elongation of body of shell; = ORTHOCLINE.

ACTINODONT		Descriptive of a bivalve shell having a HINGE with teeth that radiate outward from the UMBOS; with teeth radiating from BEAK, outer ones more or less elongate (applied to certain bivalves of early origin).

ACULEATE		Having sharp SPINES; see also: SPINOUS.

ACUMINATE		Tapering to a slender point; see also: ATTENUATED.

ACUTE		Sharply angled, pointed or edged; e.g., a spire with an angle of less than 90 degrees.

ADAPICAL		Toward the APEX; opposite of ABAPICAL; see also: APICAL.

ADAXIAL		Toward the AXIS; opposite of ABAXIAL; see also: AXIAL.

ADDUCTOR MUSCLE		One of two muscles connecting bivalve shells, tending to draw them together; these muscles leave diagnostic impressions on the inner surface of the valves; see also: ADDUCTOR SCAR; DIMYARIAN; MONOMYARIAN.

ADDUCTOR SCAR		See: ADDUCTOR MUSCLE SCAR.

ADHERENT		Closely ATTACHED.

ADNATE		Barely attached. A term sometimes applied to shells of the bivalve family Unionidae, which are joined together by rigid CALCAREOUS material rather than a flexible LIGAMENT.

ADPRESSED		[need definition]; see also: IMPRESSED; CHANNELED; SUTURE, ADPRESSED.

ADULT		Fully grown; sexually mature; see also: JUVENILE.

ADULT WHORLS		All whorls of a GASTROPOD shell beyond those of the nucleus, or PROTOCONCH; = TELEOCONCH; see also: NUCLEAR WHORL; PROTOCONCH.

AESTHETES		Sensory epidermal PAPILLAE in the Gastropoda and Polyplacophora; small ones are called MICRAESTHETES, while larger ones are MEGALAESTHETES, and may form eyes with a simple lens.

AESTIVATION verb: AESTIVATE		To pass the summer or dry periods in an inactive state (common for some land snails, which may create an EPIPHRAGM to seal the APERTURE of the shell to conserve moisture); see also: HIBERNATE.

ALATE		Winged; having alae; = AURICLE; see also: BIALATE; DIFFUSE; DILATED; PINNATE.

ALBINISTIC		Tending toward being an ALBINO; nearly all white; see also: MELANISTIC.

ALBINO		All white in shell and soft parts; often, without having seen the ANIMAL, the white shell is called an albino; see also: ALBINISTIC.

ALIVINCULAR		Type of bivalve LIGAMENT not elongated in longitudinal direction nor necessarily situated entirely posterior to beaks, but located between CARDINAL AREAS (where present) of respective valves, with lamellar layer both anterior and posterior to fibrous layer; example: Ostrea; see also: DUPLIVINCULAR; MULTIVINCULAR; PARIVINCULAR.

ALLOMORPHISM		A term used erroneously by some authors for XENOMORPHISM.

AMBISEXUAL		Producing both eggs and sperm side by side; see also: HERMAPHRODITE; MONECIOUS.

AMMONITE		Members of an extinct group of CEPHALOPODS in the subclass Ammonoidea. See also: BELEMNITE.

AMMONOTELIC		[need definition]; see also: URICOTELIC.

AMPHICHIRAL		See: ACHIRAL.

AMPHIDETIC		Extending on both anterior and posterior sides of the BEAK; said of the ligamentary area in certain bivalve shells, e.g., Arca.

ANACHOMATA		Small tubercles or ridgelets on periphery of inner surface of right valve of bivalves; see also: CATACHOMATA; CHOMATA (sing. CHOMA).

ANAL		Pertaining to or near the anus or posterior opening of the alimentary canal.

ANAL CANAL		= POSTERIOR CANAL; = ANAL SULCUS. See illustration: Composite Gastropod.

ANAL FASCIOLE		A band on the outer lip generated by a sinus, notch, or slit, close to the suture and anal opening of a gastropod aperture; see also: SELENIZONE; SLIT BAND.

ANAL NOTCH		A break in the circumference of the aperature over the spot where the outgoing current leaves the mantle cavity on the right; i.e., a notch in the outer lip where it joins the body whorl (present in mesogastropods, especially in the Turridae [the "TURRID NOTCH"]). See illustration: Composite Gastropod.

ANAL SINUS		[need definition]. See illustration: Composite Gastropod.

ANAL SIPHON		A tube exiting at the posterior end of the gastropod aperture, through which solid waste matter is voided; in the Typhinae (Muricidae), the anal siphon is housed in a shelly tube.

ANAL SULCUS		A groove in the posterior portion of the aperture that accommodates the ANAL SIPHON; = POSTERIOR CANAL; = ANAL CANAL.

ANASPID		A Opisthobranch gastropod which belongs to the suborder Anaspidea, which is an older name for the Aplysiomorpha (SEA HARES, e.g. Aplysia spp.); the term is from the Greek meaning "without a shield" and refers to the lack of a head shield such as is common to the CEPHALASPID gastropods.

ANGULATE		Tabulate, as distinct from CONVEX; said of the whorl profile; formed with corners; angled.

ANGULATION		The edge along which two surfaces meet at an angle.

ANIMAL		The fleshy, or soft part of a MOLLUSC; see also: CONCH.

ANISOMYARIAN		The condition, in bivalve molluscs, of having adductor muscle scars of unequal size, with the posterior one usually being the larger of the two; see also: MONOMYARIAN; DIMYARIAN; HETEROMYARIAN.

ANNULATE		Bearing more or less concentric rings, as on the inner surface of a gastropod operculum; see: OPERCULUM, ANNULATE.

ANNULUS		One of several concentric rings.

ANODONT		Lacking hinge teeth (in bivalves); = EDENTULOUS.

ANOMPHALOUS		Lacking an UMBILICUS; see also: OMPHALOUS.

ANTERIOR		Toward the end at or from which the head, in gastropods, or the FOOT in bivalves, tends to emerge; opposite of POSTERIOR; see also: PROSOGYRATE.

ANTERIOR CANAL		The SIPHONAL CANAL; a tubular or trough-like extension of the anterior end of the gastropod aperture, enclosing the INHALANT SIPHON; = CAUDAL CANAL; see also: POSTERIOR CANAL.

ANTERODORSAL		Being both forward and upward; toward the front and upper regions.

ANTEROLATERAL		Forward, towards the ANTERIOR and also toward the side or LATERAL.

ANTEROVENTRAL		Being both forward and downward; toward the front and lower regions; see also: POSTEROVENTRAL.

ANTEROVENTRAL MARGIN		In bivalves, the anterior end of the valve margin opposite the hinge; See also: POSTEROVENTRAL MARGIN;

APERTURAL		Pertaining to the APERTURE.

APERTURAL LIP		The most recently formed margin of the aperture; = PERISTOME; see also: HOLOSTOMATE; SIPHONOSTOMATE; see also: INNER APERTURAL LIP; OUTER APERTURAL LIP.

APERTURAL LIP, INNER		[need definition]. See illustration: Composite Gastropod. See also: APERTURAL LIP; OUTER APERTURAL LIP

APERTURAL LIP, OUTER		[need definition]. See illustration: Composite Gastropod. See also: APERTURAL LIP; INNER APERTURAL LIP.

APERTURAL TOOTH		Shelly protuberances in the APERTURE or opening in the shell of a gastropod.

APERTURE		The major opening of a GASTROPOD shell, through which the animal protrudes. See illustration: Composite Gastropod. See also: PERISTOME; HOLOSTOMATE; MOUTH; SIPHONOSTOMATE.

APEX (pl. APICES)		The first-formed end of a gastropod shell, generally more or less pointed; the tip of the PROTOCONCH or NUCLEAR WHORLS; opposite of BASE; see also: APICAL.

APICAL		Pertaining to the APEX; see also: ABAPICAL; ADAPICAL.

APICAL PLUG		A CALCAREOUS plate at the spire-end of the tubular shells of the Caecidae (Gastropoda); see also: MUCRO.

APLACOPHORAN		A member of the class Aplacophora, a group of molluscs made up of the subclasses Neomeniomorpha (=Solenogastres) and Chaetodermomorpha (=Caudofoveata). See the WHOI website for details.

APOMORPHY		A derived or specialized character. See also: PLESIOMORPHY; SYNAPOMORPHY.>. See the Paleos website for greater detail.

APOPHYSIS (1) (pl. APOPHYSES)		In bivalves: A projecting peg-like or finger-like structure, functioning as a support for a muscle, e.g., that serving for attachment of pedal muscle in the Pholadidae or adductor muscle in some RUDISTS; = MYOPHORE. See also: APOPHYSIS (2).

APOPHYSIS (2) (pl. APOPHYSES)		In CHITONS, the articulating plate on valves II to VII of a chiton shell. See also: APOPHYSIS (1).

APPRESSED		Pressed against or lying flat against another surface; having the WHORLS overlapping; see also: ADHERENT.

AQUACULTURE		The farming of organisms or plants in a water (AQUATIC) environment. The term is often used in reference to both freshwater and marine environments, but MARICULTURE is a better term for referring to marine environments.

AQUATIC		Pertaining to or living in the water; sometimes restrictively used to refer to fresh water only (as opposed to OCEANIC; MARINE); see also: FLUVIATILE; FRESH WATER; ESTUARINE; FLUVIATILE.

ARAGONITE		One crystalline form of CALCIUM CARBONATE, CaCO3 most evident in mollusks as NACRE or MOTHER OF PEARL; see also: CALCITE; VATERITE.

ARBOREAL		Pertaining to or living entirely in the trees; see also: TERRESTRIAL

ARCHEOGASTROPOD		[need definition].

ARCHIBENTHIC		Ocean depths from 800 to 1,000 meters; See also: BENTHIC; HADAL

ARCUATE		Arched or CURVED.

ARGONAUT		The common name for Argonauta argo (and others of that genus), a CEPHALOPOD mollusc that lives a PELAGIC existence in the tropics and subtropics. The female produces an egg case called the PAPER NAUTILUS. See: Mangold (1922-2003), Katharina M., Michael Vecchione, and Richard E. Young. 2010. Argonautidae Tryon, 1879. Argonauta Linnaeus 1758. Paper Nautilus. Version 03 February 2010. Photo: Argonauta argo Linne, 1758

ARK SHELL		A member of the BIVALVE family Arcidae. See the website: iEspana for examples of Arc Shells.

ARM		In squid, all but the 4th pair (TENTACLES) of 5 pair of appendages surrounding the mouth.

ARROW-HEADS		A common name by which fossils of the genus Belennites are known.

ARTICOID TYPE		Type of HETERODONT dentition in bivalves, intermediate between LUCINOID and CORBICULOID types; formerly termed: CYPRINOID TYPE.

ARTICULAMENTUM		Inner layer of a CHITON shell; the inner, usually hard, semi-porcelaneous shell layer, generally projecting past the TEGMENTUM on the sides and front of the valves to form the INSERTION PLATES and the sutural laminae.

ARTICULATED		Jointed; applied to parts of a shell which are fitted or jointed into each other (e.g., the valves of CHITONS, the OPERCULUM and shell of nerites).

ASCOGLOSSAN		[need definition]. Newer, preferred term for the old term: Sacoglossan. They have a UNISERIATE RADULA from which old teeth fall from the RADULA RIBBON into an ASCUS SAC. See also: SEA SLUG; NUDIBRANCH. Photo: Elysia chlorotica (Gould, 1870)

ASCUS SAC		The pouch-like container in ASCOGLOSSANS (previously called Sacoglossans) which stores old, used RADULA TEETH.

ASPELLOID		[need definition].

ASTHENODONT		Hinge often essentially mactrid, but usually degenerate or OBSOLETE, owing to modifications due to the burrowing habit.

ATTACHED		Refers to shell which are connected to the substrate in some way, perhaps by a byssus (e.g., Mytilus spp.) or by calcareous secretions (e.g., Chama spp. or Spondylus spp.); see: FREE; ATTACHED BIVALVE; RADICATED; REPENT; VALVE, INFERIOR; VALVE, LOWER; ADHERENT; REPENT; PLEUROTHETIC.

ATTENUATED		Becoming thin and fine; see: ACUMINATE; LIGULATE.

AUCTT. (AUCT.) (= AUCTORUM)		"Of authors;" when several authors erroneously identify and publish a name that does not apply to the original description, it is referred to (for example) as Conus crocatus of authors, OR: Conus crocatus Auctt. It means this cone is not true Conus crocatus Lamarck, 1810, but rather what authors have thought was crocatus; see also: TESTE.

AUGER		Common name for a SNAIL in the family Terebridae.

AURICLE		An anterior or posterior projection along the hinge line of a bivalve shell, commonly separated from body of shell by a notch or sinus; = HINGE EAR. See illustration: Composite Bivalve. See also: ALATE; BIALATE; SUBMARGIN.

AURICULAR CRURA (sing. CRUS)		Blunt internal ridges, swelling out distally as low tubercles, marking lower border of auricles in some Pectinidae.

AURICULAR SULCUS		External furrow at junction of AURICLE (of bivalves) with body of shell. See illustration: Composite Bivalve.

AURICULATE		Having ears or ear-like appendages, e.g., the shells of the Pectinidae, or some ascoglossan rhinophores (Stiliger spp.); those shells having but one ear are UNIAURICULATE, while those with two ears are BIAURICULATE; see also: BIALATE.

AURIFORM		Shaped like a human ear; used in describing the rhinophores of Hermaea spp.; see also: AURICULATE; HALIOTOID.

AUSTRAL		Pertaining to the south (i.e., southern hemisphere); southern.

AUTOPHAGY		Eating part of itself.

AUTOTOMY		Voluntary separation of a part of the body; self amputation (usually initiated to avoid predation).

AVICULIFORM		[need definition].

AXIAL		Pertaining to or more or less parallel to the axis of coiling in a gastropod shell; see also: ABAXIAL; ADAXIAL; SPIRAL.

AXIAL SCULPTURE		SCULPTURE running parallel to the axis of the gastropod shell; see also: CONCENTRIC SCULPTURE.

AXIS		The center around which the WHORL of a gastropod shell coil. See illustration: Composite Gastropod. See also: COLUMELLA.

BANDING		A color marking in continuous stripes; see also: FASCIATE. Photo: Melampus coffeus (Linne, 1758)

BASAL		Pertaining to the base or bottom.

BASAL FASCIOLE		A special band on the base of a shell formed by a series of more or less curved growth lines that define the SIPHONAL SINUS (canal).

BASAL FOLD		A fold (PLICA) near the anterior end of the columella and above the SIPHONAL CANAL; see also: COLUMELLAR FOLD.

BASAL MARGIN		Edge of shell opposite hinge, in bivalves; = VENTRAL MARGIN.

BASAL TOOTH		Calcareous deposit on the base of the apertural lip.

BASE		In coiled gastropods, the area below the periphery of the body whorl, excluding the aperture; opposite of APEX; in uncoiled or limpet-like gastropods, the apertural rim; also used, less precisely, for the flattened apertural side of cowries (Cypraeidae). In bivalves, the basal margin opposite the upper or hinge margin.

BATHYAL		Living on the bottom, but in depths exceeding 3,000 meters; see also: BENTHAL or BENTHIC.

BATHYPELAGIC		Living in fairly deep water, but not on the sea bottom; the PELAGIC animals which live below a depth of 150-200 meters.

BEACHWORN		Referring to the quality of a shell as being of poor color and texture due to having been ERODED, as an empty dead shell, occurring on and being deteriorated by beach conditions.

BEADED		Sculptured in such a way as to resemble beads or strings of beads. See illustration: Composite Gastropod. See also: MONILIFORM. Photo by Marlo F. Krisberg; Cerithium lutosum Menke, 1828.

BEAK (1)		In bivalves, the earliest part formed, = UMBO; any part which is drawn out like a beak or ROSTRATED. See illustration: Composite Bivalve. See: Bivalve terminology, Anatomy of bivalves by Marlo Krisberg.

BEAK (2)		In cephalopods, the CHITINOUS plates of the mouth, which resemble the beak of a parrot. See the excellent "Cephalopod Glossary" by Richard E. Young, Michael Vecchione, and Katharina M. Mangold.

BEAN COWRIE		Common name for Trivia spp.

BELEMNITE		Members of an extinct group of CEPHALOPODS in the subclass Belemnoidea. See also: AMMONITE.

BELOPTERA		The bony support of a species of CUTTLEFISH, partly resembling Sepia; see also: CUTTLEBONE

BENTHAL		See: BENTHIC; = BENTHONIC.

BENTHIC		Living on the bottom or in the bottom sediments; see also: BATHYAL; ARCHIBENTHIC, PELAGIC.

BENTHONIC		= BENTHAL.

BIALATE		With 2 wings or AURICLES, in bivalves (e.g., Pectinidae); see also: BIAURUCULATE.

BIANGULATE		Having two angles.

BIAURICULATE		Having two AURICLES; see also: BIALATE.

BICOLORED		Composed of two different colors; see also: MULTICOLORED; VARIEGATED.

BICONIC		Composed of two conical shapes, base to base; diamond-shaped and having the spire about the same size and shape as the body whorl, in gastropods; CONICAL. See other gastropod shapes.

BIFID		Divided into two parts, often by a GROOVE; applied especially to the hinge teeth in bivalves; see also: BIFURCATE; BISECTED.

BIFURCATE		Forked, or double pronged; divided into two parts by a groove or cleft; = BIFID; BISECTED.

BILOBATE		Having two LOBES; see also: LOBATE; TRILOBATE.

BINARY NOMENCLATURE = BINOMIAL NOMENCLATURE		The use of BINOMEN, that is a GENUS and SPECIES name combination to name and refer to a SPECIES; see also: ICZN; NONBINOMIAL.

BINOMEN (adj: BINOMIAL)		The combination of a GENUS and SPECIES name, conforming to the principles of binary nomenclature; the full generic and specific name of a species, e.g., Strombus gigas. Together, these names comprise the SCIENTIFIC NAME of a species; see also: COMMON NAME.

BIPARTITE		Divided into two parts; see also: TRIPARTITE.

BIPECTINATE		Having two comb-like margins; branched like a feather; see also: PECTINATE; MONOPECTINATE.

BIRAMOSE (=BIRAMOUS)		Having two projecting parts or branches. See also: Having projecting parts or branches. See also: RAMOSE; TRIRAMOSE.

BIROSTRATE		Having two ROSTRUMS.

BISECTED		Divided into two parts; see also: BIFID; BIFURCATE.

BITTERSWEET		A COMMON NAME referring to a member of the bivalve genus Glycymeris.

BIVALVE		Typically, a mollusc in the class Bivalvia, with two shelly valves, such as an oyster or scallop; = CLAM. Additionally, other bivalved molluscs exist such as the Paleozoic ROSTROCONCHS, and the Recent bivalved gastropods of the family Juliidae; other phyla, such as the Brachiopoda, are not strictly referred to as "bivalves"; see: LAMELLIBRANCH; see also: UNIVALVE.

BIVALVE, ATTACHED		Bivalves which have cemented themselves to a substrate, e.g., species in genera such as Crassostrea, Ostrea, Spondylus, Chama, Mytilus; see also: ATTACHED; BORING BIVALVES; CEMENTATION; INFERIOR VALVE.

BIVALVE, BORING		Bivalves with dissolve their substrate (rock or wood), forming burrows into which they exist and grow, e.g. SHIPWORMS, Teredo spp.; see also: ATTACHED BIVALVE.

BIVALVE, BROODING		A bivalve which undergoes internal fertilization, and sheds its young as miniature adults (commonly) or sometimes as larvae (less commonly) after having brooded or incubated them within the MANTLE CAVITY of the parent, e.g. Bornia spp., Parastarte spp., Lyonsia spp.

BIVALVED GASTROPOD		A GASTROPOD (e.g., Julia spp. [Ascoglossa: Juliidae]) with two VALVES, like a clam.

BLADE		An erect, flattened sculptural element perpendicular (or nearly so) to the shell surface; the broadened, distal portion of a PALLET.

BOARS TUSK		Common name applied to SCAPHOPOD shells of the genus Dentalium, due to their similar appearance to a boars tusk; = ELEPHANTS TUSK or, generally, TUSK SHELL.

BODY		In a gastropod shell, the body whorl exclusive of the shoulder and the siphonal canal. In bivalves, the entire shell, with the exception of WINGS or AURICLES; = DISK. In all molluscs, the ANIMAL, or soft tissue.

BODY WHORL		The most recently formed WHORL of a gastropod shell, usually enclosing most of the animal's body. See illustration of Composite Gastropod.

BOREAL		Pertaining to the north (i.e., northern hemisphere; northern). See also: BOREAL PROVINCE; CIRCUMBOREAL.

BORER		A general term applied to species of molluscs which bore into rocks (some Pholadidae) or wood (Teredo spp.); = TEREBRATING SHELLS.

BOURRELET		Either of two portions of bivalve ligamental area flanking RESILIFER on its anterior and posterior sides, each comprises growth track and seat of the lamellar LIGAMENT. The posterior bourrelet is flattish in all oysters except the Exogyrinae, in which it is a narrow, sharp-crested spiral ridge on the left valve and a corresponding GROOVE on the RIGHT VALVE.

BRANCH (pl. BRANCHIAE)		The gills; see: GILL for list of the various type of taxonomic groupings.

BRANCHIAL PLUME		[need definition]. In nudibranchs… See illustration: Composite Nudibranch.

BRANCHITELLUM (pl. BRANCHITELLA)		Point on posteroventral margin of OYSTERS nearest to palliobranchial fusion, commonly forming conspicuously projected posteroventral tip on left valve, especially in sickle-shaped oysters; aboral end of gills points towards it.

BREATHING PORE		Opening in the MANTLE or mantle edge of SLUGS for passage of air (or often water in aquatic species) into the air sac or lung cavity; see also: PNEUMOSTOME.

BREVICONE		[need definition]; see also: CYRTOCONE; ORTHOCONE.

BRISTLE		A stiff, fine projection. In CHITONS, the GIRDLE may be adorned with bristles. See illustration: Composite Chiton.

BROODER		Term applied to a bivalve or gastropod which retains the young within the parental shell, and liberates them as miniature forms of the adult, or as larvae, but not as fertilized or unfertilized eggs; see also: BIVALVE, BROODING; DEVELOPMENT, DIRECT.

BUBBLE FLOAT, BUBBLE RAFT		A mass of bubbles (left image) generated by planktonic snails to keep them at the surface, maintaining accessibility to their prey (e.g., Portuguese Man of War, Physalia; the By The Wind Sailor, Vellella; or the Blue Buttons, Porpita. Also, Janthina creates a bubble raft (right, dual image) to support its EGGS. Left Photo: Janthina pallida (Thompson, 1840) Two Right Photos: Janthina sp. upperside and underside of its EGG MASS.

BUBBLE SHELL		A CEPHALASPID OPISTHOBRANCH mollusk. Examples are those species in the genera Bulla and Acteocina.

BUCCAL		Pertaining to the organs of the mouth area. In a gastropod, pertaining especially to the bulging, flexible tissue mass that supports the radula. In cephalopods, the rounded orifice containing the mouth and surrounded by tissue (the buccal membrane) at the base of the arms.

BUCCAL MASS		[need definition].

BUCCAL PUMP		The organ, in the nudibranch family Goniodorididae, which sucks only the juices of its food, the polyzoa and ascidians.

BUCCINOID		Having the shape of shells of the gastropod family Buccinidae. See other gastropod shapes.

BULBOUS		Bulging or globular.

BULLA		The form of a young COWRY (aka Cowrie), before it forms its final whorls and generates APERTURAL TEETH.

BULLOID		Bubble-shaped; in the shape of a shell of the genus Bulla. See also: BUBBLE SHELL. See other gastropod shapes.

BUTTRESS		A shell-strengthening structure, e.g., a complete or partial supporting ridge. In bivalves, an internal projection from wall of shell, supporting hinge plate or chondrophore; see also: CLAVICLE.

BYNE'S DISEASE		A reaction of shells to acid vapors in the air, resulting in a white powdery residue on the shells. Oak wood is one source of such vapors. One thing to remember about Bynes Disease is that the cause has two components. The development of the condition requires (1) a material capable of releasing acid vapors, and (2) sufficient moisture to allow those acid vapors to form. Some woods, such as oak have the capacity to release such vapors, in the presence of moisture. If you cannot keep your cabinets in an area free of high humidity, you should be careful about the wood they are made from. But if you have a good dry place to keep the collection, then the type of wood in the cabinets is far less problematic. Good ventilation is a plus, but it is not the deciding factor. If you have an acid-producing wood in a moist environment, then Bynes can occur, even with good ventilation (though probably more slowly than with poor ventilation). If you have the collection is a low humidity environment, then Bynes should not occur, even if the ventilation is poor. It is a good idea to control humidity regardless of what kind of cabinets you have, since high humidity tends to favor other problems as well, especially fungal growth. (Per: Paul Monfils, Conch-L listserve May 21, 2001).

BYSSAL		Pertaining to the BYSSUS.

BYSSAL FORAMEN		Opening in the right valve in Anomiidae for passage of calcified byssus; see also: BYSSAL GAPE; BYSSAL NOTCH; BYSSAL SINUS.

BYSSAL GAPE		Opening between margins of a bivalve shell for passage of the BYSSUS; see also: BYSSAL FORAMEN; BYSSAL NOTCH; BYSSAL SINUS.

BYSSAL NOTCH		Indentation below anterior auricle of right valve in many Pectinacea for passage of the byssus or protrusion of the foot. See illustration: Composite Bivalve. See also: BYSSAL FORAMEN; BYSSAL GAPE; BYSSAL SINUS. See: Bivalve terminology, Anatomy of bivalves by Marlo Krisberg.

BYSSAL PLUG		[need definition]

BYSSAL SINUS		Embayment of margin below anterior auricle of left valve in many Pectinacea, corresponding to byssal notch of right valve but usually shallower; see also: BYSSAL FORAMEN; BYSSAL GAPE; BYSSAL NOTCH.

BYSSAL THREAD		See: BYSSUS.

BYSSATE		Having a BYSSUS; = BYSSIFEROUS.

BYSSIFEROUS		Having a BYSSUS; = BYSSATE.

BYSSUS (=BYSSUS THREAD; =BYSSAL THREAD)		A clump of thread-like, CHITINOUS (usually) filaments secreted by the foot of a MUSSEL or other bivalve which serves to anchor it to the substrate; the byssus of the Anomiidae is CALCAREOUS. See illustration: Composite Bivalve. See also: RADICATED.

CAECUM		A blind pouch or cavity open at one end; see examples in the family Caecidae. See also: MUCRO.

CALCAREOUS		Composed mostly of, or impregnated with, CALCIUM CARBONATE (lime), three forms of which commonly occur in molluscs: ARAGONITE, CALCITE, and VATERITE; see also: CORNEOUS.

CALCITE		A common crystalline form of natural CALCIUM CARBONATE, CaCO3, that is the basic constituent of seashells (as well as limestone, marble, and chalk); see also: ARAGONITE; VATERITE.

CALCIUM CARBONATE = CaCO3		The mineral, CaCO3, which makes up molluscan shells, occurring in different forms such as ARAGONITE, CALCITE, and VATERITE. See also: see also: PRISMATIC LAYER; PORCELANEOUS LAYER; PRISMATIC LAYER.

CALLOSITY		see: CALLUS.

CALLOUS		Coated with a smooth enamel-like layer (INDUCTURA).

CALLUM		Shell material filling a gape between valves in certain bivalves. Secondary CALCAREOUS structure present in some Pholadidae, forming anterior extension of shell proper and closing PEDAL GAPE in adult. Example: the MESOPLAX in Martesia striata (Linne, 1758).

CAMEO		A low relief carving into the surface of an object, such as a mollusc shell. Shells of the genus Cassis are often used for such art.

CANAL		In gastropods, a narrow notch or semitubular extension of the aperture, usually enclosing a siphon; see also: CANALICULATE; SIPHONAL CANAL.

CANALICULATE		Having a distinct groove or canal.

CANCELLATE		Having sculptural lines that intersect at right angles; = DECUSSATE; RETICULATE. See illustration: Composite Gastropod and Composite Bivalve. See also: TESSELLATE. Photo: Chione cancellata (Linne, 1767)

CANTED		Slanted or sloped in relation to an adjoining structure; nonperpendicular.

CAPACIOUS		Large, roomy, spacious; said of the aperture or shell body of gastropods.

CAPSA (pl. CAPSAE)		[need definition]

CAP-SHAPED		Broadly conical, as in the shell of LIMPETS; see also: CANTED; PATELLATE; PATELLIFORM. See other gastropod shapes.

CAPTACULA		The cluster of feeding appendages of SCAPHOPODS. See illustration at UCMP.

CARDINAL AREA		In bivalves, situated more or less in the central part of the hinge area, immediately below the BEAKS. Flat or slightly concave, commonly triangular surface extending between beak and hinge margin in many bivalves, and partly or wholly occupied by LIGAMENT.

CARDINAL AXIS		Imaginary straight line along which 2 valves of shell are hinged; = HINGE AXIS.

CARDINAL COSTA		Ridge or rib demarcating cardinal area from outer surface of shell.

CARDINAL CRURA (sing. CRUS)		Narrow lamelliform teeth radiating from apex of LIGAMENT PIT in the Pectinacea.

CARDINAL MARGIN		The edge of a BIVALVE shell on which the HINGE TEETH are located.

CARDINAL PIT		[need definition]

CARDINAL PLATFORM		Shelly internal plate bearing hinge teeth, situated below beak and adjacent parts of dorsal margins and lying in plane parallel to that of commissure; = HINGE PLATE.

CARDINAL TOOTH		The main or largest teeth (usually) in a bivalve HINGE, located just below the UMBONES. See illustration: Composite Bivalve. See also: TOOTH, LATERAL.

CARDO		[need definition]; (see: Popov, 1980).

CARINA (pl. CARINAE)		A keel-like part; a prominent knife-edged ridge; = KEEL. See illustration: Composite Gastropod. See also: WHORL, CARINATE; WHORL, BICARINATE.

CARINATE		Having a CARINA, especially at the periphery of a WHORL; = KEELED.

CARNIVOROUS		Feeding on animal matter; see also: HERBIVOROUS; OMNIVOROUS; DETRITIVOROUS.

CARRIER SHELL		A SNAIL of the family Xenophoridae. These snails attach objects to the periphery of their whorls, thereby "carrying" them.

CARTILAGE		An old term used for the INTERNAL LIGAMENT in bivalves. The substrate on which a radula sits.

CARTILAGINOUS		Having a flexible or HORNY texture, as contrasted with SHELLY or CALCAREOUS.

CAST		The mould from a FOSSIL shell, composed of matter which entered the shell in a soft state and has subsequently hardened, the shell eroded away, and the hardened material left to represent the internal form of the shell. See also ENDOCAST.

CATACHOMATA		pits in the left valve of bivalves for reception of ANACHOMATA; see also: CHOMATA (sing., CHOMA).

CAUDAL CANAL		The elongated, hollow process which terminates the aperture anteriorly, in some gastropod shells (e.g., Murex spp.); = ANTERIOR CANAL; = SIPHONAL CANAL.

CAUDAL PIT		A conspicuous depression in the posterior dorsum of the foot of some snails which contains mucous glands.

CAUDATE		With narrow, tail-like extremity.

CEMENT BODY		Gland near the top of a SPERMATOPHORE containing a glue-like fluid.

CEMENTATION		Permanent fixation to the substrate in sessile molluscs, especially bivalves. See also: ATTACHED.

CENTRAL		At the center; see also: SUBCENTRAL.

CEPHALASPID		An OPISTHOBRANCH gastropod mollusc which possesses a "head shield"; examples include those in the genera Bulla and Acteocina. = BUBBLE SHELL. See also: ANASPID.

CEPHALOPOD		A member of the molluscan class Cephalopoda (once referred to, by Pliny, as Mollia), which is characterized by muscular tentacles attached directly to their head. They have a beaked mouth and their eyes are well developed. This term pertains to SQUID, OCTOPUS, CHAMBERED NAUTILUS, CUTTLEFISH and the extinct AMMONITES and BELEMNITES; see also: TEUTHOLOGIST; TEUTHOLOGY. See the excellent "Cephalopod Glossary" by Richard E. Young, Michael Vecchione, and Katharina M. Mangold.

CEPHALOTOXIN		A toxin produced by the posterior salivary glands of CEPHALOPODS, used by OCTOPUS to paralyze crabs. See: Ghiretti, F. 1959. Cephalotoxin: the crab-paralysing agent of the posterior salivary glands of cephalopods. Nature 183:1192-1193 (25 April 1959).

CERAS (pl. CERATA)		On of the slender, club-shaped or horn-shaped dorsal appendages in the NUDIBRANCHIA and ASCOGLOSSA, which either lie separately or in several rows or may be clustered together in tufts and palmate bunched; they contain blood from the HAEMOCOEL and are invaded also by tubular branches of the digestive gland which, as evolution proceeds, becomes deployed on On of the slender, club-shaped or horn-shaped dorsal appendages in the Nudibranchia and Ascoglossa, which either lie separately or in several rows or may be clustered together in tufts and palmate bunched; they contain blood from the haemocoel and are invaded also by tubular branches of the digestive gland which, as evolution proceeds, becomes deployed on the dorsal surface; see also: CLADOHEPATIC; HOLOHEPATIC. See illustration: Composite Nudibranch.

CERATUS		A hornlike structure; a large spur; see also: LABIAL TOOTH.

CF (CONFER)		Sometimes put in front of a species name to mean that the species being identified is close to, but not exactly, a certain species; it also implies that you know for sure that it is not that species mentioned, but merely close to it, e.g., Conus cf. crocatus Lamarck, 1810; (a "?" prior to a specie indicate that the correct name is possibly the one mentioned).

CHAETODERM		[need definition].

CHALAZA		An EGG capsule; (see: Franz, 1971:177). See also: NIDAMENTAL GLAND.

CHAMBERED		Having an essentially discontinuous cavity, usually separated by diaphragms or septa, as in the chambers of the CHAMBERED NAUTILUS (chambers also occur in some species of Spondylus and several turrited gastropods); see also: CONCAMERATIONS.

CHAMBERED NAUTILUS		[need definition]. A CEPHALOPOD… ; see also: CONCAMERATIONS; PHRAGMOCONE; SIPHUNCLE.

CHANNEL		A deep groove; see also: FLUTED.

CHANNELED		Sculptured with deep grooved; having a groove; see also: FLUTED; STRIATE.

CHARACTER, ADAPTIVE		Those characters which are immediate modifications for a particular mode of life; see also: CHARACTER, PROGRESSIVE; CHARACTER, CONSERVATIVE.

CHARACTER, CONSERVATIVE		Those characters that persist unchanged over long periods. It is these characters that are most useful in showing real affinities of one group toward another; see also: CHARACTER, ADAPTIVE; CHARACTER, PROGRESSIVE.

CHARACTER, PROGRESSIVE		Those characters which usually show a definite trend of advance, often running parallel through several unrelated groups; see also: CHARACTER, ADAPTIVE; CHARACTER, CONSERVATIVE.

CHERRYSTONE		The midsized QUOHOG clam, Mercenaria mercenaria. See also: LITTLENECK.

CHEVRON (GROOVE)		V-shaped furrow on cardinal area in some Arctacea and early Pectinacea, for insertion of the LIGAMENT.

CHIASTONEURY		The condition in the GASTROPOD visceral nerve loop being twisted into a figure-8, during TORSION.

CHINK		A long, narrow cleft, especially in the umbilical area.

CHIRAL		An object having the property of CHIRALITY.

CHIRALITY		An asymmetry property important in several branches of science. An object or a system is called CHIRAL if it differs from its mirror image, and its mirror image cannot superimpose on the original object. A chiral object and its mirror image are called ENANTIOMORPHS (Greek opposite forms) or, when referring to molecules, enantiomers. A non-chiral object is called ACHIRAL (sometimes also AMPHICHIRAL) and can be superimposed on its mirror image. Used in the context of Busycon and the SINISTRAL and DEXTRAL forms.

CHITIN		The general name for a group of HORNY, proteinaceous substances, one of which (CONCHIOLIN) is found in PROTOCONCHS, RADULAE, etc.

CHITINOUS		Chitin-like; composed of CHITIN; see also: HORNY.

CHITON		Common name for members of the molluscan class POLYPLACOPHORA, commonly called COAT OF MAIL SHELLS. Photo: Acanthopleura granulata (Gmelin, 1791) A glossary of chiton terms is also available on the Gallery of Chitons website.

CHOMATA		Collective term for ANACHOMATA, which are small tubercles or ridgelets on periphery of inner surface of right valve of bivalves, and CATACHOMATA, which are pits in the left valve for reception of anachomata; both generally restricted to vicinity of the hinge, but may encircle whole valve.

CHONDROPHORE		A pit or spoon-like shelf in the hinge of a bivalve, such as Mactra, and into which fits a CHITINOUS cushion or RESILIUM.. See illustration: Composite Bivalve. See also: LIGAMENT PIT; RESILIFER.

CHRESONYMY		A SYNONYMY that includes misuses of names as well as true synonyms (i.e., most "synonymies").

CHROMATOPHORE		Tiny, elastic, transparent cell fringed with pigment, and responsible for display of coloration; common in CEPHALOPODS.

CICATRIX		Old term for the scar, on the interior of a shell, due to a muscle attachment; see also: MUSCLE SCAR.

CILIA		Minute hairs; see also: MUCOCILIARY FEEDING.

CILIATED		Having minute hairs (or CILIA); see also: MUCOCILIARY FEEDING.

CINEREOUS		Grayish or ash-colored.

CINGULUM (pl. CINGULA)		A band or girdle, e.g., a band of color or raised sculpture.

CIRCUMBOREAL		Distributed around the world, in the northern BOREAL region. See also: PROVINCE.

CLADISTICS		[need definition]. See also: CLADOGRAM. See the Paleos website.

CLADOGRAM		[need definition]. See also: CLADISTICS.

CLADOHEPATIC		Having the "liver" or digestive gland broken up and dispersed throughout the body and often into club-shaped CERATA or fleshy fingers on the DORSUM of OPISTHOBRANCHS. This condition originated independently in various groups and can be used only for identification and not classification; see also: CERATA; HOLOHEPATIC.

CLAM		Common term for a BIVALVE. See also some common names for various types of clams: COQUINA; DATE MUSSEL; GIANT CLAM; MUSSEL; OYSTER; PIDDOCK; QUAHOG; RAZOR CLAM; SHIPWORM.

CLANDESTINE EVOLUTION		see: EVOLUTION, CLANDESTINE.

CLASSIFICATION		[need definition]; see also: TAXONOMY; SYSTEMATICS.

CLATHRATE		Having intersecting sculptural elements forming a broad lattice.

CLAUSILIUM (=CLAUSIUM)		A CALCAREOUS, loose "sliding door" in the Clausiliidae (Pulmonata) which fits into the grooves of the COLUMELLA, serving as a door. When not prevented by counteracting pressure, the clausilium springs forward on its elastic LIGAMENT and encloses the animal into its shell.

CLAUSIUM		see: CLAUSILIUM.

CLAVATE		Having one extremity of a shell attenuated and the other suddenly VENTRICOSE or GLOBULAR.

CLAVICLE		Shelly buttress supporting a CHONDROPHORE in some genera.

CLEIDOIC		A type of egg which is not impermeable to water (the cytoplasm of the egg is adapted to tolerate a considerable water loss, rather than the shell to prevent it).

CLOSED		In bivalves, having the valves meet tightly along the entire margin; see also: GAPE; GAPING.

CLOSURE SEAM		A line of junction; a line, groove, or ridge formed by or between abutting edges.

CLUB		In squid, the expanded area (generally bearing large suckers) on the distal end of the tentacle.

CLUB-SHAPED		In a GASTROPOD shell, having a compact, rounded body and a long SIPHONAL CANAL.

COALESCED		Fused or merged together.

COAT OF MAIL (SHELL)		Common name applied to CHITONS (the molluscan class Polyplacophora), due to their resemblance to jointed armour.

COCHLEATE		Being hollow and oval, like a spoon, e.g., the LIGAMENT PIT of Mya spp.

COELOCONOID		Slightly concave; see also: CYRTOCONOID. See other gastropod shapes.

COELOM		[need definition].

COGNATE		Of, or proceeding from, the same stock; allied; of the same or similar nature, as in the case of closely related forms or species on both sides of the Central American isthmus.

COILING		In gastropods, the wrapping of one WHORL around a previous whorl; see also: LOGARITHMIC SPIRAL; LOOSELY COILED; TIGHTLY COILED.

COLL.		An abbreviation for the latin, Collegit, meaning: Collected by. However, this abbreviation is also interpreted as: In the collection of. Because of this ambiguity, the use of LEG. is preferred over COLL.

COLLABRAL		Parallel or nearly so. See also: COLLABRAL LINES.

COLLABRAL LINES		A series of similar, adjacent lines. See also: GROWTH LINE.

COLLAR		A raised rim bordering a suture. In cephalopods, the free edge of the mantle in squids, etc., at the "neck."

COLUMELLA		A pillar surrounding the AXIS around which the shell is coiled, formed by the inner surface of the WHORL; the wall opposite the outer APERTURAL LIP. See illustration: Composite Gastropod. See also: AXIS; PILLAR.

COLUMELLA, STRAIGHT		[need definition].

COLUMELLA, TRUNCATE		[need definition].

COLUMELLAR		Pertaining to the COLUMELLA.

COLUMELLAR CALLUS		A smooth, shelly layer extending over the COLUMELLAR area, secreted by the mantle; see also: PARIETAL CALLUS.

COLUMELLAR FOLD		A raised ridge on the COLUMELLA that follows the helical growth pattern of a gastropod shell.; see also: FUNICLE.

COLUMELLAR LIP		The part of the inner lip, of a gastropod shell, nearest to the axis of coiling, and comprising the visible part of the COLUMELLA.

COLUMELLAR PLAIT		[need definition]. See illustration: Composite Gastropod.

COLUMELLAR PLICAE		[need definition]. See illustration: Composite Gastropod.

COLUMELLAR TOOTH		A sharply raised projection, emanating from the COLUMELLA and protruding into the APERTURE of a GASTROPOD. See illustration: Composite Gastropod.

COLUMELLAR WALL		Surface of the COLUMELLA.

COMMARGINAL		[need definition].

COMMARGINAL RIB		[need definition]; see also: OVERRIDE.

COMMENSAL		The association of one species with a different species in which one or more is benefitted, and others are not harmed. See also: PARASITE.

COMMISSURE		Line of junction of 2 VALVES of a BIVALVE.

COMMON NAME		See: VERNACULAR NAME; see also: SCIENTIFIC NAME.

COMPLANATE		Flattened; level; unsculptured; see: COMPRESSED.

COMPRESSED		Flattened, typically laterally (opposite of DEPRESSED); having reduced thickness or height; see: COMPLANATE.

CONCAMERATIONS		A series of chambers joining each other, as in Nautilus spp.; see: CHAMBERED; PHRAGMOCONE.

CONCAVE		Hollowed and curved or rounded; opposite of convex; see also: COELOCONOID; CYRTOCONOID.

CONCAVITY		The quality or state of being CONCAVE; a concave point.

CONCENTRIC		Having a common center, as circles. In gastropod shells, said of structures roughly parallel to growth lines (referred to as LONGITUDINAL by some authors); see also: ANNULATE; TRANSVERSE. The term COMMARGINAL is preferred by some modern authors. See also: ECCENTRIC.

CONCENTRIC LINE		See: GROWTH LINE. See illustration: Composite Bivalve.

CONCENTRIC SCULPTURE		[need definition]; see also: AXIAL SCULPTURE.

CONCH		A COMMON NAME referring to a member of the gastropod family Strombidae. Also, and generally, a seashell; see also: ANIMAL. People that study seashells (conchs) are CONCHOLOGISTS. Note: Although the "Florida Horse Conch" (Triplofusus giganteus (Keiner, 1840)) is so named, it is a misnomer and is more properly called a "Horse Whelk," as it is in the whelk family: Fasciolariidae.

CONCH PEARL		A PEARL, often pink in color, produced by the Queen Conch, Strombus gigas.

CONCHIOLIN		A HORNY, proteinaceous material that makes up the periostracum of a shell and also forms the organic matrix for calcareous parts of the shell; often termed CHITIN; see also: PRISMATIC LAYER; CALCITE; ARAGONITE; VATERITE.

CONCH-L LISTSERV		A "List" on a LISTSERV supported by the University of Georgia. Members subscribe to "the list" to facilitate an easy exchange of emails via "posting" one email to "the list" which is distributed by the Listserve to all subscribers of the list to which the initial email was sent. Interested individuals may subscribe here. Past posts to this List are available at the CONCH-L archives. See also: MOLLUSCAlist. U. Georgia listserve "home" page: http://www.listserv.uga.edu/ Join or leave CONCH-L: http://www.listserv.uga.edu/cgi-bin/wa?SUBED1=conch-l&A=1 CONCH-L archives: http://www.listserv.uga.edu/archives/conch-l.html Help, Manuals: http://www.listserv.uga.edu/docs.html List of U. Georgia listservs: http://www.listserv.uga.edu/archives/

CONCHOLOGIST		A specialist in the study of molluscan shells (CONCHS). A group organized to share such interests is the CONCHOLOGISTS OF AMERICA (COA). See also: MALACOLOGIST; TEUTHOLOGIST.

CONCHOLOGISTS OF AMERICA (COA)		A group organized to share interests in CONCHOLOGY and which describes itself on the COA website as a "society for shell enthusiasts from all walks of life, at all levels of interest." This organization publishes American Conchologist. See also: SHELL CLUB.

CONCHOLOGY		The study of molluscan shells (CONCHS). See also: CONCHOLOGIST; CONCHOLOGISTS OF AMERICA; MALACOLOGY; TEUTHOLOGY; CONCHOMETRY.

CONCHOMETRY		[need definition]. See references: Boycott, A.E. 1928. Conchometry. Proc. Malac. Soc. London 18:8-31. Parodiz, J.J. 1951a. Me´todos de conquiliometry #305;´a. Physis 20(58): 241–248. Parodiz, J.J. 1973e. Gastropod conchometry. Pittsburgh Shell Club Bulletin 8: 14–16.

CONDYLE		An enlarged and prominent end of a RIDGE, serving as a pivot.

CONE SHELL		Common name applied to a SNAIL of the genus Conus. See also: CONOTOXIN. Also, see: The Conus Biodiversity Website.

CONFLUENT		Coming together; merging; see also: COALESCED.

CONGENER		A species belonging to the same genus as the species used as a point of reference; see also: CONSPECIFIC.

CONGENERIC		Belonging to the same genus as the species used as a point of reference; see also: CONGENER.

CONICAL		Cone-shaped; tapering; see also: BICONIC; CONICAL; CYLINDRICAL. See other gastropod shapes.

CONMARGINAL		Preferred term by some modern authors for structure with direction coinciding with that of growth lined; = CONCENTRIC, in bivalves.

CONOTOXIN		A neurotoxin produced by the venom gland of GASTROPODS of the genus Conus; often referred to as CONE SHELL venom.

CONSPECIFIC		Of the same species as an organism used as a point of reference; see also: CONGENER; CONGENERIC.

CONSTRICTED		Marked by a more or less abrupt narrowing; waist-like; pinched.

CONSTRICTION		A narrowed area.

CONTIGUOUS		Touching each other, as in the WHORLS of some gastropods in which the whorls rest upon or touch each other; see: DISCONTIGUOUS; DISCONTINUOUS; DISTAL; PROXIMAL.

CONTINUOUS		Uninterrupted; intact from one point to another; see: CONTIGUOUS; DISCONTINUOUS; HOLOSTOMATE; SIMPLE.

CONTRACTED		Drawn together; reduced in extent; shrunken.

CONTRACTILE		Capable of reducing length by shortening and thickening; see also INVERSIBLE.

CONVEX		Curved or rounded; bulging outward; opposite of CONCAVE; see also: CYRTOCONOID.

CONVEXITY		Degree of inflation.

CONVOLUTE		Having the body whorl of the shell expand abruptly so as to wrap around and conceal all the older, subsequent whorls. See also: INVOLUTE. See other gastropod shapes.

COPULATORY ORGAN		Usually a penis or other organ used by the male to insert sperm into the female; see also: VERGE.

COQUINA CLAM		Common name for CLAMS of the genus Donax.

CORBICULOID TYPE		Heterodont dentition (in bivalves) with 3 cardinal teeth in each valve, middle one of right valve occupying median posterior position below BEAKS; formerly termed CYRENOID TYPE.

CORBULIFORM		Shaped like the shells of the bivalve genus Corbula.

CORD		A thickened round-topped transverse (i.e., spiral) or axial sculptural element.

CORDATE		Shaped like a heart; often applied to shells such as Cardium, Cardita, and Venus; see also: SEMICORDATE.

CORDED		Sculptured with cords.

CORDIFORM		Heart shaped, as in the bivalve Corculum cardissa.

CORNEOUS (=CORNEUS)		HORNY in texture and composition; see also: CALCAREOUS.

CORONA		A crown-like structure; see also: CORONATE.

CORONATE		Crown-like; having a CORONA; encircled by a row of spines or prominent nodes, especially at the shoulder of the last whorl in gastropods.

CORRODED		Worn away (usually with age), as in the UMBONES of some bivalves or spires of some gastropods; see: DECOLLATE; OBSOLETE.

CORRUGATE		Folded or ridged on the surface; broadly or heavily sculptured with FOLDS.

CORSELET		A differentiated (by sculpture) POSTERIOR area of a BIVALVE.

COSTA (pl. COSTAE)		A round-topped sculptural element, stronger than a cord, usually formed by periodic thickening of the outer lip in gastropods. Moderately broad and prominent elevation of surface of shell, directed radially or otherwise; see also: COSTELLA.

COSTATE		Having rib-like AXIAL sculptural elements. See illustration: Composite Gastropod and Composite Bivalve.

COSTELLA		Rather narrow linear elevation of surface of shell; formerly: COSTULE; see also: COSTA.

COSTULATION		A pattern of sculpture in small RIDGES.

COSTULE		Old term for COSTELLA.

COWL		A hood; a fold-like structure extending over the front or outward like a hood.

COWRY (= COWRIE)		Common name applied to gastropods in the family Cypraeidae. See also: BULLA.

CRABBED		A gastropod shell, usually in poor condition, formerly used as a home for a hermit crab (Crustacea: Paguridae). The columella may have a U-shaped worn area.

CRENATE		Having a regularly notched or scalloped edge; see also: CRENULATE.

CRENULATE (pl. CRENULATIONS)		Same as CRENATE, but implying smaller or finer divisions. See illustration: Composite Bivalve. See also: DENTICULATION

CRENULE		Small notches or beads.

CREST		The apex of a peak or ridge; the top of a sculptural element.

CRISPATE		Irregularly curled; roughened into small frets, waves, or folds.

CROSSED-LAMELLAR		Type of shell structure comprised of primary and secondary LAMELLAE, the latter inclined in alternate directions in successive primary lamellae.

CRUMPLED		Creased or pressed into wrinkles or folds.

CRURAL		Pertaining to CRURA.

CRUS (pl. CRURA)		Pairs of diverging ridges on the hinge of some bivalves, resembling teeth.

CRYPTODONT		Lacking HINGE TEETH (applied to certain groups of early origin only); see also: EDENTULOUS; EDENTATE; ANODONT.

CRYSTALINE STYLE		[need definition]. In bivalves...

CTENIDIUM (pl. CTENIDIA)		The respiratory organ in the Mollusca; a GILL which has been modified for food-gathering in the BIVALVIA; see also: DIBRANCH; EULAMELLIBRANCH; FILIBRANCH; LAMELLIBRANCH; PROTOBRANCH; PSEUDOLAMELLIBRANCH; SEPTIBRANCH; TECTIBRANCH; TETRABRANCH.

CTENODONT		[need definition]; see also: PSEUDOCTENODONT; PSEUDOTAXODONT.

CTENOLIUM		Comb-like row of small teeth on the lower side of BYSSAL NOTCH in some Pectinacea. See: Bivalve terminology, Anatomy of bivalves by Marlo Krisberg.

CUNEIFORM		Wedge-shaped.

CURVED		Arched or gently bent; = ARCUATE.

CUSP		A prominence or point, especially on a RADULAR TOOTH or a DENTICLE on the shell.

CUSPIDOBLAST		One of the cells in a CAECUM or pouch at the posterior of the RADULA which secrete the radular teeth.

CUTICULAR SHIELD		In Aplacophorans…

CUTTLEBONE CUTTLEFISH BONE		The internal shell of the CUTTLEFISH (Cephalopoda), Sepia officinalis. See also: BELOPTERA.

CUTTLEFISH		[need definition]. A CEPHALOPOD… See also: BELOPTERA.

CYATHIFORM		Cup-shaped (as in the "cup" of "cup and saucer" limpets, the Calyptraeidae).

CYCLODONT		BIVALVE DENTITION with HINGE TEETH curving out from below HINGE MARGIN, HINGE PLATE being small or absent.

CYLINDRICAL		Like a cylinder; applied to shells with sides which are nearly parallel, with the extremities either rounded, flat or conical. See also: CONICAL. See other gastropod shapes.

CYPRAEIFORM		A shape exemplified by the gastropod genus Cypraea. See other gastropod shapes.

CYPRINOID TYPE		Same as ARTICOID TYPE.

CYRENOID TYPE		Old name for CORBICULOID TYPE.

CYRTOCONE		In cephalopods, laterally compressed, curved shells; see also: BREVICONE; ORTHOCONE.

CYRTOCONOID		Slightly convex. See also: COELOCONOID. See other gastropod shapes.

DART SAC		A muscular caecum developed from the vagina in which is produced a fine, pointed, calcareous shaft, the TELUM AMORIS, or "love dart;" see also: SARCOBELUM.

DATE MUSSEL		Common name applied to CLAMS of the genus Lithophaga.

DEAD SHELL		Term applied by collectors to a shell which did not have a live animal in it when collected; see: LIVE SHELL.

DECK (1)		A small sheet of SHELLY substance in the UMBONAL region of a valve; see also: DECK (2).

DECK (2)		The diaphragm of slipper shells (Crepidula spp.); see also: DECK (1).

DECOLLATE		Cut off; TRUNCATED, e.g., the top several whorls of the spire (as in Truncatella spp.); typically, the loss of this portion of the shell is by design, rather than wear or corrosion; see: CORRODED.

DECORTICATED		Missing the NACRE and/or true coloration.

DECURRENT		Extending downward; see also: DEFLEXED.

DECUSSATE		Having intersecting sculptural elements, not necessarily at right angles; RETICULATE. See illustration: Composite Gastropod and Composite Bivalve. See also: CANCELLATE; LATTICED.

DEFLEXED		Bent sharply backward or downward; see also: DECURRENT; RECURVED; REFLEXED.

DEHISCENT		Capable of falling off very easily; often used in reference to the PERIOSTRACUM; see also: EXFOLIATE.

DELIMITING		Bounding; fixing a limit.

DELTOID		Triangular, TRIGONAL.

DEMARCATION LINE		In bivalves, an imaginary line on the surface of valve originating at the BEAK and marking locus of points on successive positions of margin where transverse growth component has had maximum effect; forms dorsoventral profile when VALVE is viewed from one end; see also: CORSELET; DIAGONAL RIDGE; ESCUTCHEON RIDGE.

DEMIBRANCH		One of the paired lamellibranch gills. The longitudinal half of a feather-shaped gill; see also: DIBRANCH; TETRABRANCH.

DENTAL FORMULA		See: RADULA FORMULA.

DENTATE		Toothed; having HINGE TEETH; having a toothed margin; see also: DENTICULATE; TRIDENTATE.

DENTICLE		A small, tooth-like projection.

DENTICULATE		Having small, tooth-like projections; see also: DENTATE; SERRATE.

DENTICULATION		The overall pattern of DENTICLES in a given shell or specimen.

DENTITION		Gastropoda: referring to the structure of the elements of the RADULA. Bivalvia: referring to the tooth structure of the hinge; the hinge teeth and sockets, considered collectively; see also: ACTINODONT; CORBICULOID TYPE; ANODONT; CRYPTODONT; CTENODONT; CYCLODONT; CYPRENOID TYPE; DIAGENODONT; DYSODONT; HETERODONT; ISODONT; ORTHODONT; PACHYODONT; PANTODONT; PRIONODONT; PSEUDOCTENODONT; PSEUDOTAXODONT; SCHIZODONT; TAXODONT; TELEODONT; ARTICOID TYPE; HINGE; LUCINOID TYPE; VINCULUM.

DEPAUPERATE		Poorly developed.

DEPRESSED		Pressed down, typically dorso-ventrally (opposite of COMPRESSED); low in proportion to diameter.; see also: DISCOIDAL.

DEPRESSION		A hollowed area; a concavity.

DET. = DETERMINAVIT		Identified by. Example on a specimen label: Det: John Doe; or: John Doe, det. See also: LEG.

DETACHED		Separated; marked off; see also ATTACHED.

DETORSION		[need definition]. See also: TORSION.

DETRITIVOROUS		Feeding on detritus. See also: CARNIVOROUS; HERBIVOROUS; OMNIVOROUS.

DEVELOPMENT, DIRECT		Passing the entire larval stages within an egg case or within the adult; lacking a free-swimming or floating larval stage; see also: BROODER; DEVELOPMENT, PLANKTONIC.

DEVELOPMENT, PLANKTONIC		Having a free-swimming or floating larval stage; see also: DEVELOPMENT, DIRECT; LECITHOTROPHIC; PLANKTOTROPHIC, PLANKTON.

DEVOLUTE		[need definition]; see also: LOOSELY COILED.

DEXTRAL		Turning clock-wise or to the right, or "right-handed" in gastropods; the direction of coiling in which, with the shell held upright (apex at the top), the aperture is at the right; and in which, with the shell viewed from above the apex, the coiling proceeds from the apex in clockwise direction; = RIGHT HANDED.; opposite of SINISTRAL; See also: CHIRALITY; HETEROSTROPHY; ULTRADEXTRAL. See other gastropod shapes.

DIAGENODONT		Bivalve DENTITION with differentiated CARDINAL and LATERAL TEETH located on HINGE PLATE, laterals not exceeding 2 or cardinals 3 in either valve; example: Astarte spp.; see also: TELEODONT.

DIAGNOSIS		A short, comparative description of a SPECIES.

DIAGNOSTIC		Central to identification; especially characteristic; reflecting critical comparative scrutiny.

DIAGONAL RIDGE		In bivalves, a ridge running from the UMBO toward posteroventral part of VALVE; see also: CORSELET; DEMARCATION LINE.

DIAMETER		The greatest width of a snail shell at right angles to the shell axis. See illustration: Composite Gastropod. See also: WIDTH; WRS.

DIAPHANOUS		Clear, or TRANSPARENT; see also: PELLUCID; OPAQUE.

DIAPHRAGM		The septa which divide the chambers of MULTILOCULAR and other shells. Also, the DECK of SLIPPER SHELLS.

DIBRANCH		Possessing two gills (CTENIDIA); the name applied to all living cephalopods, except Nautilus, which is a TETRABRANCH; see also: EULAMELLIBRANCH; FILIBRANCH; LAMELLIBRANCH; PROTOBRANCH; PSEUDOLAMELLIBRANCH; SEPTIBRANCH; TECTIBRANCH.

DIFFUSE		Spread out; applied to the APERTURE of a gastropod shell which is widened into a flat surface; = ALATE; = DILATED.

DIGESTIVE GLAND		[need definition].

DIGITATE		In a finger-like fashion; having finger-like processes.

DIGITATION		A finger-like part; a pattern of finger-like parts.

DILATED		Expanded or spread; = ALATE; = DIFFUSE.

DIMORPHISM		Having two forms, e.g., differing forms for different sexes = sexual dimorphism; see also: POLYMORPHISM.

DIMYARIAN		The condition in bivalve molluscs of having two ADDUCTOR MUSCLES, the anterior and posterior; see also: ANISOMYARIAN; HETEROMYARIAN; MONOMYARIAN.

DIOECIOUS		Having the male and female sexes separate; see also: AMBISEXUAL; HERMAPHRODITE; MONECIOUS; PROTANDRY.

DIOTOCARDIAN		Having a heart with two auricles. See also: MONOTOCARDIAN.

DIRECT DEVELOPMENT		See: DEVELOPMENT, DIRECT.

DIRECTIVE SPIRAL		Spiral curve formed by DIRECTIVE RIB within its own plane.

DISC		The VALVES of bivalves; in Pectinacea, the whole of the valve, excluding the AURICLES; see also: FLANK.

DISCOIDAL		Round and flat, like a disk.; see also: DEPRESSED; LENTICULAR; PLANISPIRAL; SEMIDISCOIDAL. See other gastropod shapes.

DISCONTIGUOUS		Not touching each other, as in the whorls of some gastropods in which the whorls are separated and do not rest upon or touch each other; see: CONTIGUOUS; CONTINUOUS; WHORL, DISJUNCT; GYROCONIC.

DISCONTINUOUS		Interrupted; not continuing intact from one point to another; see: CONTINUOUS.

DISSOCONCH		The postlarval shell of bivalves (and scaphopods?). See illustration: Composite Bivalve. See also: MESOCONCH; NEPIOCONCH; PRODISSOCONCH.

DISTAL		Situated away from the base or point of attachment; = DISTANT; opposite of PROXIMAL; see also: CONTIGUOUS.

DISTANT		See: DISTAL; see also: REMOTE<.a>.

DIVARICATE		Having the sculpture composed of pairs of rather widely divergent COSTAE or threads, as in the genus Divalinga. See illustration: Composite Bivalve. See also: LATTICED; SCISSULATE; TRANSVERSE. Photo: Divalinga quadrisulcata (d'Orbigny, 1846)

DOCOGLOSSATE		Having a radula in which the RACHIDIAN TOOTH is small or absent, and there are 3 LATERAL TEETH with hard, black tips, flanked by 3 smaller, unpigmented MARGINALS on each side; = STEREOGLOSSATE; examples in the Patellacea: Acmaeidae, Lepetidae, Patellidae; RADULAR FORMULA: 3+D+2+R+2+D+3 or 3+D+2+0+2+D+3 (where R = RACHIDIAN, D = DOMINANT DENTICLE).

DONACIFORM		A form of TRIGONAL shape exemplified by the BIVALVE genus Donax. See other bivalve shapes.

DORATOPSIS		The LARVAL stage of the CEPHALOPOD family Chiroteuthidae.

DORSAL		Of, pertaining to, or situated on the back or upper surface; in bivalves, at or toward the HINGE; see also: VENTRAL.

DORSUM		The DORSAL surface of a shell or animal. The "back" of a gastropod shell, opposite the APERTURAL side.

DOUBTFUL NAME		See: NOMEN DUBIUM.

DRAP MARIN		The French naturalist term for periostracum.

DRUPE		Common name applied to gastropod shells of the genus Drupa.

DUPLIVINCULAR		The type of bivalve LIGAMENT with lamellar component repeated as a series of bands, each with its 2 edges inserted in narrow grooves in cardinal areas of respective valves; example: Arca; see also: ALIVINCULAR; PARIVINCULAR; MULTIVINCULAR.

DWARF		Of less than usual or normal size for a given stage of development.

DYMANTIC		Referring to a response to fear or disturbance, characterized by changes in coloration (in the cephalopoda) and appearance.

DYSODONT		In bivalves, a HINGE with small, weak teeth close to BEAKS (as in some Mytilacea).

EAR		See: HINGE EAR; WING.

EAVES		In CHITONS, the portions of the TEGMENTUM just over the points where the INSERTION PLATE and sutural laminae push from under it.

ECCENTRIC		Not having the same center; not CONCENTRIC; deviating from the center, as in an elliptical orbit. In the gastropod shell, not following the GROWTH LINES.

ECHINOSPIRA		A type of VELIGER, in the Lamellariidae, Cypraeidae (Eratoinae) and Capulidae [all Gastropoda], in which the young definitive shell is covered by a much larger secondary shell, the SCAPHOCONCHA, which has practically no weight and assists in floatation during the long swimming life of a larva.; see: LARVA.

ECOLOGIC FORM		A morphological condition brought about by the influence of the environment, such as long SPINES in quiet waters; also called: ECOTYPE or ECOPHENOTYPE. See also: FORM or FORMA

ECOMORPH		One whose morhology is determined by the ecology; = ECOPHENOTYPE.

ECOPHENOTYPE		An organism whose visual characteristics (PHENOTYPE) have been influenced by the environment. Example: a shell having longer spines due to growing in calm waters vs. having short or no spines due to life in fast-flowing waters. See also: ECOMORPH; ECOPHENOTYPIC VARIATION; FORM; GENOTYPE.

ECOPHENOTYPIC VARIATION		Variation caused by environmental conditions. Such variability has been use by SPLITTERS to distinguish one "species" from another. See also: ECOLOGIC FORM; ECOPHENOTYPE.

ECOTYPE		See: ECOLOGIC FORM; ECOPHENOTYPE.

ECTOPARASITE		Living PARASITICALLY on the outside of another organism; for example, the Pyramidellidae.

EDENTATE		Toothless; same as ANODONT, in bivalves.

EDENTULATE		Toothless; EDENTATE; EDENTULOUS.

EDENTULOUS		Toothless; EDENTATE; EDENTULATE..

EGG		A female gamete or reproductive body; an ovum. See also: CHALAZA; EGG MASS; EGG CAPSULE.

EGG CAPSULE		See: CHALAZA.

EGG MASS		A cluster of EGGS, sometimes deposited by an individual, but sometimes by multiple individuals contributing to a single mass (e.g., some Muricids). For a PELAGIC example, see: BUBBLE FLOAT. Photo: Murex pomum Gmelin, 1791

ELEPHANTS TUSK		Common name applied to SCAPHOPOD shells of the genus Dentalium, due to their similar appearance to an elephants tusk; = BOARS TUSK or, generally, TUSK SHELL.

ELEVATED		ERECT; raised; said of prolonged sculptural elements and other structures; see also: DEPRESSED.

ELLIPTICAL		Like an ellipse or flattend oval; see also: ELONGATE ELLIPTICAL. See other bivalve shapes

ELONGATE		Lengthened; extended in one dimension. Illustration: Solen sp. See also: ENSIFORM; LINGUIFORM. See other bivalve shapes. Photo: Tagelus divisus (Spengler, 1794)

ELONGATE ELLIPTICAL		A basically ELLIPTICAL shape that has been elongated; like a flattened oval. See other bivalve shapes.

EMARGINATE		Notched at the MARGIN.

EMBAYMENT		An indentation; a bay. Sometimes used referring to the PALLIAL SINUS in bivalves.

EMBRYONIC WHORL		A single WHORL of the NUCLEUS or PROTOCONCH; the earliest portion of the LARVAL SHELL.

ENANTIOMORPH		[need definition].

ENCRUSTED		Covered with foreign matter derived from living organisms.

ENDEMIC		Confined to a particular geographic area; native; see also: INDIGENOUS.

ENDOCAST		A FOSSIL formation created by material entering the interior of a shell hardening; the exterior shell material then degrades and dissolves away with the outside of the CAST taking on the interior shape of the shell.

ENSIFORM		An ELONGATE bivalve shape, like an Ensis; with outline resembling a curved sword. See other bivalve shapes.

ENTIRE		Continuous; having no breaks; said of the margin (PERISTOME) of a shell aperture; see also: HOLOSTOMATE.

EPIDERMIS		Skin of the soft part (= "ANIMAL") of a mollusk; see also: PERIOSTRACUM.

EPIPHRAGM		A temporary apertural seal of dried mucous constructed prior to AESTIVATION to prevent loss of moisture; found in the higher PULMONATE gastropods, such as Helicidae. The epiphragm may become very thick and even calcified, as in the Achatinidae.

EPIPODIUM		A fringe, like a false MANTLE, around the base of the gastropod foot, which bears delicate tentacles that come in contact with the substratum and are probably both chemosensory and tactile.

EQUILATERAL		In bivalves, having the anterior and posterior ends of equal size; see also: EQUIVALVE; INEQUILATERAL; SUBEQUILATERAL.

EQUIVALVE		In bivalves, having each VALVE equal in size and shape; see also: EQUILATERAL; INEQUIVALVE. See other bivalve shapes.

ERECT		Upthrust or upright; see also: ELEVATED.

ERODED		Worn away; see also: BEACHWORN.

ESCARGOT		Common name for SNAILS, typically of the genus Helix (often H. pomatia, but also H. aspersa and H. lucorum), which are an epicurean delicacy cooked in a garlic and butter sauce and served as an appetizer.

ESCUTCHEON		In bivalves, a long, somewhat depressed area on the dorsal surface just posterior to the BEAKS. See illustration: Composite Bivalve. See also: LUNULE. See: Bivalve terminology, Anatomy of bivalves by Marlo Krisberg.

ESCUTCHEON RIDGE		Ridge extending posteriorly from beak in each valve (of bivalves) and forming border of ESCUTCHEON; see also: DEMARCATION LINE.

ESOPHAGUS		The tubular portion of the digestive tract that leads from the PHARYNX to the stomach.

ESTUARINE		Pertaining to or living in salt water which is measurably diluted with fresh water (to decrease the salinity below oceanic levels: 35 parts per thousand); see also: AQUATIC; FRESH WATER; MARINE; OCEANIC.

EULAMELLIBRANCH		A type of bivalve CTENIDIUM or gill in which [need definition]; see also: DIBRANCH; EULAMELLIBRANCH; FILIBRANCH; LAMELLIBRANCH; PROTOBRANCH; PSEUDOLAMELLIBRANCH; SEPTIBRANCH; TECTIBRANCH; TETRABRANCH.

EUPYRENIC		The numerous, small, normal type of SPERM; see also: OLIGOPYRENIC.

EUTHYNEUROUS		Having straight visceral nerve loops (as in some gastropods); see also: STREPTONEUROUS.

EVANESCENT		Transient; ephemeral; barely discernable.

EVOLUTE		[need definition]; see also: DEVOLUTE.

EVOLUTION		[need definition]; see also: EVOLUTION, CLANDESTINE; EVOLUTION, PROGRAMME.

EVOLUTION, CLANDESTINE		The development of many structures by the larvae for its own needs, as distinct from the morphology of the adult; as such, larvae are not always reliable guides to PHYLOGENY; see also: ONTOGENY.

EVOLUTION, PROGRAMME		Having several independent groups running through a series of broadly similar changes.

EX		From; example: Ex Doe, MS. = from Doe's manuscript or unpublished work; ex pisces = from the stomach (usually) of a fish.

EXCAVATED		Strongly depressed; hollowed out.

EXCERTED		Prominently extended or elongated; = EXSERTED.

EXCURRENT		Forming a passage for current of water expelled from within the MANTLE CAVITY; applied to mantle opening or siphon; = EXHALENT; see also: HYPONOME.

EXFOLIATE		To come off in layers or scales. See also: DEHISCENT.

EXHALANT SIPHON		[need definition]; see also: HYPONOME; INHALANT SIPHON.

EXHALENT		Same as: EXCURRENT.

EXOGASTRIC		In CEPHALOPODS, having the hyponomic sinus on the convex side.

EXOGYRATE		Shaped like the shell of Exogyra, that is, with the left valve (of bivalves) strongly convex and its dorsal part coiled in posterior direction, with right valve flat and spirally coiled.

EXPANDED		Enlarged; swollen; distended; see also: COMPRESSED.

EXSERTED		See: EXCERTED.

EXTANT		Living; typically referring to a SPECIES or taxonomic group of species; opposite of EXTINCT.

EXTERNAL		On the outside; see: INTERNAL.

EXTINCT		No longer continuing to exist, typically referring to a SPECIES or a taxonomic group of species; opposite of EXTANT.

EXTRA-BRANCHIAL APPENDAGE		[need definition]. In NUDIBRANCHS… See illustration: Composite Nudibranch.

EXTRAPALLIAL FLUID		That fluid between MANTLE and the PERIOSTRACUM, which is rich in CaCO3 in solution, which precipitates out, forming the shell.

EYE STALK		The extensible and retractable (sometimes INVERSIBLE) pedestal which terminates with the eye of many gastropods. See also: TENTACLE.

FAIR		Term used in shell trade to designate the quality of a shell as having either major breaks or poor coloration; see also: GRADING SYSTEM.

FALCIFORM		Sickle-shaped.

FAN SHAPED		A CLAM (bivalve) shape exemplified by the bivalve genus Atrina. See other bivalve shapes. Photo: Atrina rigida (Lightfoot, 1786)

FASCIATE		Banded or striped. See also: BANDING.

FASCICLE		Small bunch (of ribs); see also: FASCICULATED.

FASCICULATED		Arranged in small bunches; see also: FASCICLE.

FASCICULATED		Having a little bunch of hairs or BRISTLE against each end of each VALVE (as in some species of the genus Chiton).

FASCIOLE		A spiral band generated by a notch, bordered by successive lamellar growth striae of a canal (either anterior or posterior) in gastropods; see also: SIPHONAL FASCIOLE.

FATHOM		A measure of water depth, equal to six feet.

FAUNA		The animal life living in a given region or during a specified period of time.

FENESTRATE		Having depressed, rectangular, pit-like "windows."

FERRUGINEOUS		Of an iron rust color.

FIDE		Trusting to; on the word of; often used to document the designation of a SYNONYM.

FILIBRANCH		A type of bivalve CTENIDIUM or gill in which [need definition]. The Mytilacea, Pteriacea, Pectinacea, and Anomiacea have filibranch CTENIDIA. See also: DIBRANCH; EULAMELLIBRANCH; LAMELLIBRANCH; PROTOBRANCH; PSEUDOLAMELLIBRANCH; SEPTIBRANCH; TECTIBRANCH; TETRABRANCH.

FIMBRIA (pl. FIMBRIAE)		A border or fringe; see also: FIMBRIATE; FIMBRIATION.

FIMBRIATE (=FIMBRICATED)		Fringed; bordered by fine, frilly sculptural elements; = FIMBRICATED; see also: FIMBRIA; FRILLED; LACINIATE.

FIMBRIATION		A fringe; see also: FIMBRIA.

FINE		A term used in the shell trade to designate the quality of a shell as having minor breaks or scars; see also: GRADING SYSTEM.

FINE+		A term used in the shell trade to designate the quality of a shell as very slightly irregular. See also: GRADING SYSTEM.

FISSURE		A slit or cut. See also: GROOVE.

FLABELLIFORM		Fan-shaped.

FLAGELLUM		A tubular outgrowth of the PENIS in which the SPERMATOPHORE is secreted by the male duct.

FLAMULATION		See: FLAMULE.

FLAMULE		A small, flame-shaped spot of color; = FLAMULATION; see also: FULGURATE. Photo: Astyris lunata (Say, 1826)

FLANGE		A rib or flattened ridge lending strength and reinforcing the juncture of two shell structures.

FLANK		Median part of surface of valve (of a bivalve), limited posteriorly by posterior ridge where present; see also: DISC.

FLARING		Opening or spreading outward rapidly, said especially of the outer APERTURAL LIP.

FLATTENED		Level; even.

FLEXICLAUDENT		A type of OPERCULUM that flexes upon retraction. See also: RIGICLAUDENT. See the 1998 article by Checa and Jiménez-Jiménez: Constructional morphology, origin, and evolution of the gastropod operculum..

FLEXUOUS		Having windings or bendings (e.g., the posterior twist of Macoma spp.); see also: HAMIFORM; RECURVED.

FLEXURE		A bending or angulation.

FLUTED		Grooved; decorated with flutes or CHANNELS.

FLUVIATILE		Living in or belonging to rivers or streams; see also: AQUATIC.

FOLD		A spirally wound ridge on the COLUMELLAR WALL of the gastropod shell.; see also: COLUMELLAR FOLD; PLAIT; PLICAE; RUGA.

FOLIACEOUS		Resembling foliage; furnished with or made up of foliations or leaflike small plates; = FOLIATE; FOLIOSE.

FOLIATE		See: FOLIACEOUS.

FOLIATION		A single leaflike structure; see also: FROND; FOLIACEOUS.

FOLIOSE		See: FOLIACEOUS.

FOOT		A muscular organ of locomotion, projecting anteriorly through the aperture of shelled GASTROPODS (often for crawling); see also: LANMGUIR TROTH. In BIVALVES, a organ lying anteroventrally between the VALVES of many bivalves (often for digging). In SCAPHOPODS, an anterior organ also used for digging; See illustration at UCMP.

FORAMEN		A round hole or fissure; usually applied to the hole in the LOWER VALVE of Anomia spp. which exists for passage of the BYSSAL PLUG. Photo: Anomia simplex Orbigny, 1842

FORM or FORMA		A minor genetic variant, color phase, aberration, or variation due to diet or environment (e.g., an ECOLOGIC FORM); see also: ECOPHENOTYPE; ECOPHENOTYPIC VARIATION; ECOTYPE; VARIETY.

FORNICATED		Arched or vaulted (e.g., exfoliations on the COSTAE of Tridacna spp.)

FOSSA		A ditch-like or trench-like depression; see also: FURROW; SCROBICULATE; SULCATE.

FOSSETTE		A pit-like resilifer for the attachment of the internal ligament; a socket, as for cardinal tooth in bivalves; see also: CHONDROPHORE; RESILIFER.

FOSSIL		The remains of an animal (or plant) from past ages; see also: CAST; TAPHONOMY.

FOSSULA		A shallow linear depression on the inner LIP of some cypraeid gastropods.

FRAGILE		Tender, easily broken; delicate.

FREAK		A malformed shell; see also: GRADING SYSTEM.

FREE		Refers to a shell which is not ATTACHED (e.g., to substrate); see also: VALVE, FREE.

FREE EDGE		The outer margin or OUTER APERTURAL LIP of a gastropod shell.

FREE VALVE		In attached bivalves, the valve which is not attached to the substrate; = UPPER VALVE.

FRESH WATER		Rererring to those which inhabit rivers and streams (= FLUVIATILE), ponds and lakes; see: ESTUARINE; MARINE.

FRILL		See: EPIPODIUM. For an example illustration see images of a live ABALONE.

FRILLED or FRILLY		Having a wrinkled, fluted, or crumpled edging of laminae, flanges, or blade-like varices; see also: FIMBRIATE.

FRINGED		Having an edging or trimming of projecting ends of sculptural elements; twisted or PLAITED at the margin.

FROND		A FOLIACEOUS, leaf-like extension of a sculptural element, as on a vertical spine; see also: FOLIATION.

FRONDOSE		Resembling a much divided leaf, like a palm leaf; see also: FOLIATION.

FRONT		The surface of a shell on which the aperture appears.

FULGURATE		Like a flash of lightning; said of coloration patterns; see also: FLAMMULE.

FUNICLE		A ridge of callus spiraling into the UMBILICUS in the naticid gastropods; see also: COLUMELLAR FOLD.

FUNICULAR		Pertaining to a cord, shaped like a small cord or band.

FUNNEL		In CEPHALOPODS, the tube on the ventral side of the body used to expel water from the mantle cavity. See also: MULLERS ORGAN. See illustration of composite squid by Young, Vecchione, and Mangold.

FUNNEL PLATES		Transverse LAMINAE in wall of radiolitid lower valve, inclined downward and funnel-wise toward axis and combining with radial laminae to produce cellular structure.

FUNNEL-SHAPED		See: INFUNDIBULIFORM.

FURROW		A narrow channel, GROOVE, or wrinkle; see also: SCROBICULATE; SULCATE.

FUSED		United or bound together; merged into a single structure or surface.

FUSIFORM		Spindle-shaped; biconic, i.e., swelling in the central part and tapering at the extremities. See other gastropod shapes.

FUSION		Something formed by merging; the process of merging.

FUSION LAYER		Part of LIGAMENT secreted where the MANTLE edges are united dorsally by secondary FUSION (i.e., anteriorly and posteriorly to mantle isthmus).

FUSOID		See: FUSIFORM.

GAPE		A narrow opening remaining between the VALVES of a bivalve when the ADDUCTOR MUSCLE have closed the shell.

GAPING		Not closing tightly; in bivalves, having the VALVES not meet, so as to leave a hole or GAPE; see: CLOSED.

GARSTANG'S THEORY		[need definition]; see also: TORSION.

GASTRIC SHIELD		A flange of protective cuticle of the stomach wall on which the head of the rotating STYLE bears upon or is partly surrounded by.

GASTROPOD		A UNIVALVE, a SNAIL, a member of the class Gastropoda; see also: CONCH, PERIWINKLE, etc.

GASTROVERM		Common name for a member of the molluscan class Monoplacophora; limpet-shaped, segmented, snail-like molluscs living in very deep water. Living genera include Laevipilina, Monoplacophorus, Neopilina, and Vema.

GEM		A term used to designate the quality of a shell as perfect... no flaws whatsoever; see also: GRADING SYSTEM.

GENITAL OPENING		See: GENITAL PORE.

GENITAL PORE		[need definition]; = GENITAL OPENING; See labelled photo on www.jaxshells.org/eraj1.htm

GENOTYPE		The genetic makup of an organism. The genetic makeup of an organism can distinguish one species from another, as well as document lineage. See also: PHENOTYPE.

GENUS (pl. GENERA)		[need definition]

GENUS NOVUM (abbrev: GEN. NOV.)		A new GENUS; Used in publication the first time (and first time only!) that a new genus is presented; see also: SPECIES NOVUM.

GEODUCK		[need definition]. Pronounced GOO-ee-duck See: Discovery Channel's episode of "Dirty Jobs" that featured Geoduck farming. Photo: Panopea sp.

GERONTIC		Showing the characteristics of old age, and/or abnormally extreme size.

GIANT CLAM		A CLAM of family Tridacnidae, genus Tridacna.

GIANT SQUID		SQUID, often of extremely large size, typically members of the CEPHALOPOD genera Architeuthis and Ommastrephes. Photo: Ommastrephes caroli (with a meter stick in the photo, for reference)

GIBBOSE (or GIBBOUS)		Swollen.

GILL		A BRANCH; the respiratory organ in the mollusc; see also: CTENIDIUM; PLICATIDIUM; TETRABRANCH; DIBRANCH; PROTOBRANCH; FILIBRANCH; PSEUDOLAMELLIBRANCH; EULAMELLIBRANCH; SEPTIBRANCH; TECTIBRANCH.

GILL RETRACTOR MUSCLE		Muscle present in a few bivalvia, attaching one of the GILLS to the shell.

GIRDLE		A flexible, leathery, muscular integument holding the CHITON valves in place, often ornamented with BRISTLES, SCALES, SPICULES, GRANULES or hairy processes. See illustration: Composite Chiton.

GIZZARD PLATES		[need definition].

GLABROUS		Smooth.

GLADIUS		The "PEN" or internal remnant of a shell, in some CEPHALOPODS, e.g. SQUID. See the detailed web page on gladius terminology, from the excellent "Cephalopod Glossary" by Richard E. Young, Michael Vecchione, and Katharina M. Mangold.

GLAND		A body organ producing one or more specific chemical substances.

GLASS SCALLOP		Common Name for CLAMS (bivalves) of the family Propeamussiidae; See also: SCALLOP. See Henk Dijkstra's website on Scallops.

GLAZED		Having a shiny surface or shiny deposit; see also: MARGARITACEOUS; NACREOUS.

GLOBOSE		Roughly spherical in form; rounded; see also: GLOBULAR; NERITIFORM. See other gastropod shapes.

GLOBULAR		Globe-shaped or sphere-shaped, like a ball; see also: GLOBOSE.

GLOCHIDIUM (pl. GLOCHIDIA)		The LARVAE of freshwater Unionacean bivalves. As a dispersal mechanism, this larva temporarily attaches itself to the gills of fish.

GONAD		The sex gland in which the sperm or eggs are formed.

GOOD		A term used to designate the quality of a shell as deficient in one character, as color, otherwise "FINE;" see also: GRADING SYSTEM.

GRADING SYSTEM		Degrees of condition of specimens, usually employed by shell dealers. GEM: perfect FINE+: very slightly irregular FINE: minor breaks or scars GOOD: deficient in one character FAIR: with either major break or poor color POOR: badly beachworn; having major breaks See also: FREAK; MICRO; MINIATURE.

GRANULATED		Having a rough surface of grain-like elevations; see also: GRANULOSE.

GRANULE		A pustular surface sculpture. In CHITONS, these may adorn the GIRDLE. See illustration: Composite Chiton. See also: PUSTULE.

GRANULOSE		Grainy or finely pustulose; covered with granules; see also: GRANULATED.

GROOVE		A distinct furrow, depression, channel, or hollow cut occurring on the surface as opposed to a thin, shallow scratch (e.g., a STRIA); see also: FISSURE; SCROBICULATE; SULCATE; SPIRAL GROOVE. Photo by Marlo F. Krisberg; Nerita fulgurans Gmelin, 1791.

GROWING EDGE		The outermost edge of the outer APERTURAL LIP of a gastropod shell, or the margin of a bivalve shell.

GROWTH LINE		A line on the shell surface indicating the position of the shell margin at an earlier stage of growth; = INCREMENTAL LINE; = CONCENTRIC LINE. See illustration: Composite Gastropod and Composite Bivalve. See also: COLLABRAL LINES.

GROWTH RUGA		Irregular wrinkle on surface of shell, of similar origin to growth line, but corresponding to more pronounced hiatus in growth; see also: RUGA.

GROWTH THREAD		Thread-like elevation of surface of shell, of similar origin to growth line.

GROWTH, EXPONENTIAL		Rapidly, but regularly increasing in size.

GRYPHAEATE		Shaped like shell of Gryphaea (Bivalvia), i.e., with left VALVE strongly CONVEX and its dorsal part incurved, and with RIGHT VALVE flat.

GUTTERED		Marked with wide, shallow GROOVES.

GYROCONIC		Having the WHORLS not in contact with each other; see also: DISCONTIGUOUS; LOOSELY COILED; NAUTILOCONIC.

HABITAT		The kind of place where an organism normally lives.

HADAL		[need definition].

HAEMOCOEL		[need definition].

HAEMOCYANIN		A copper-containing substance carried in the blood plasma of gastropods and cephalopods, which acts as the respiratory pigment; it colors the blood a faint blue. NOTE: A few gastropods have developed haemoglobin; it is not certain that any bivalve has haemocyanin, but some possess haemoglobin (most do not possess any oxygen-carrying substance, the oxygen partial pressure in the blood being that of the surrounding medium).

HAIRY		see: HIRSUTE; SETIFEROUS.

HALIOTOID		Ear-shaped, like species of Haliotis; see: AURIFORM.

HAMIFORM		Curved at the extremity; see also: FLEXUOUS; RECURVED; REFLECTED.

HEAD		The ANTERIOR end of an animal.

HEAD VALVE		The first of (typically) eight valves of a CHITON. See illustration: Composite Chiton. See also: TAIL VALVE; MEDIAN VALVE.

HEART		[need definition].

HECTOCOTYLUS (pl. HECTOCOTYLI)		A specially modified ARM of CEPHALOPODS which is used to transfer SPERMATOPHORES from the male to the female.; see also: SPADIX; TENTACLE.

HEIGHT		In bivalves: the greatest distance measured vertically, from the UMBONES to the ventral margin, i.e., dorsoventrally. In gastropods: the distance from the tip of the SPIRE to the most DISTAL point along the AXIS of the shell. See illustration: Composite Gastropod. See also: LENGTH; WIDTH; WRS.

HELICAL		Spirally coiled.

HELICIFORM		Shaped like shells of the genus Helix. See also: ESCARGOT. See other gastropod shapes.

HERBIVOROUS		Feeding on vegetable matter. See also: CARNIVOROUS; OMNIVOROUS; DETRITIVOROUS.

HERMAPHRODITE		Having both sexes in the same animal; see also: AMBISEXUAL; MONECIOUS.

HETERODONT		In certain bivalves, having the hinge differentiated into distinct cardinal and lateral areas. See illustration: Composite Bivalve. See also: ARTICOID TYPE; CORBICULOID TYPE; DENTITION; LUCINOID TYPE.

HETEROMYARIAN		The restriction of the anterior adductor muscle (in bivalves) to a small size, with the moving of the byssus and foot to the anterior (as in the Mytilidae); see also: ANISOMYARIAN; DIMYARIAN; MONOMYARIAN.

HETEROPOD		[need definition]; see also: PTEROPOD.

HETEROSTROPHIC		Having APICAL whorls coiled in a direction apparently opposite to that of succeeding WHORLS; see also: HYPERSTROPHIC.

HETEROSTROPHY		Condition of having the gastrpod PROTOCONCH coiled at 90 degrees to the POSTMETAMORPHIC whorls.

HEXAGONAL		Having six sides; see also: POLYGONAL; OCTOGONAL; QUADRATE; RHOMBOID.

HIBERNATE		To pass the winter in an inactive state; see also: AESTIVATE.

HIBERNATION		See: HIBERNATE.

HIGH SPIRED		Said of a gastropod shell which is much higher than wide; see also: LOW SPIRED. See other gastropod shapes.

HINGE		Collective term for structures of dorsal region of bivalves, consisting of the teeth and ligament, whose function is to facilitate the opening and closing of valves; see also: ACTINODONT; ANODONT; ASTHENODONT; CRYPTODONT; CTENODONT; CYCLODONT; DIAGENODONT; DYSODONT; HETERODONT; ISODONT; ORTHODONT; PANTODONT; PACHYODONT; PRIONODONT; PSEUDOCTENODONT; PSEUDOTAXODONT; SCHIZODONT; TAXODONT; TELEODONT; ...as well as: ACLINE; ARTICOID TYPE; CORBICULOID TYPE; LUCINOID TYPE; ORTHOCLINE; VINCULUM.

HINGE AXIS		Imaginary straight line along which 2 valves of a shell are hinged; = CARDINAL AXIS; see also: HINGE LINE.

HINGE EAR		In bivalves, an anterior and/or posterior expansion of the VALVE in the hinge area; = AURICLE.

HINGE LINE		In bivalves, the region along which the VALVES are attached to each other. Term applied loosely by many authors to part of bivalve shell bordering dorsal margins and occupied by or close to hinge teeth and ligament; used by some in same sense as HINGE AXIS.

HINGE MARGIN		Edge of bivalve shell that approximates most closely to hinge axis.

HINGE PLATE		In bivalves, the dorsal margin carrying the hinge teeth; = CARDINAL PLATFORM. A shelly, internal platform, bearing hinge teeth, situated below the beak and adjacent parts of dorsal margins, and lying in plane parallel to that of the commissure. See illustration: Composite Bivalve.

HINGE TOOTH		Shelly STRUCTURE in bivalves (usually on of a series) adjacent to dorsal margin and received in socket in opposite VALVE; hinge teeth serve to hold valves in position when closed.

HINGE TOOTH SOCKET		The indentation, in a bivalve shell, which accepts the protruding HINGE TOOTH when the valves are closed. See illustration: Composite Bivalve.

HINGE TOOTH		See: HINGE TOOTH.

HINGE, TRANSPOSED		Condition in which certain hinge teeth present in one valve occupy positions of teeth usually found in the other (= TRANSPOSED HINGE TOOTH). See: Van der Schalie, H. 1936. Transposed hinge teeth of North American naiades. Nautilus 49(3):79-84.

HIPPURITID		A type of RUDIST.

HIRSUTE		Covered with hairs.

HOLLOW SPINE		A stiff, sharp, sculptural structure, the interior of which is not filled with shell matter. see also: HYOTE SPINE.

HOLOHEPATIC		Having the "liver" or digestive gland compact; see also: CERATA; CLADOHEPATIC.

HOLOPLANKTON		PLANKTON which spends its entire life in the water column. See also: MEROOPLANKTON.

HOLOSTOMATE		Characterizing an aperture lip of a gastropod shell that is uninterrupted by any anterior notch or sinus; = HOLOSTOMATOUS; see also: ENTIRE; SIMPLE; SIPHONOSTOMATE (= SIPHONOSTOMATOUS).

HOLOSTOMATOUS		See: HOLOSTOMATE.

HOLOTYPE		A single specimen upon which a species is based; the only specimen unquestionably identifiable as a given species; see also: LECTOTYPE; TYPE SPECIMEN. See the publication: "Terminology of Types" by Frizzell.

HOMOMYARIAN		Bivalves having two ADDUCTOR MUSCLES equal in size or almost so; = ISOMYARIAN.

HOMONYM		Two identical names given to separate species (the latter would be termed the JUNIOR SYNONYM, the first, the SENIOR HOMONYM). See also: HOMONYM; HOMONYMY; PRIMARY HOMONYM; SECONDARY HOMONYM.

HOMONYMY		A nomenclatural situation in which two or more different species bear the same name. See also: HOMONYM; SYMONYMY.

HOOK		A SPINE tip that is bent or strongly recurved.

HORNY		[need definition]; see also: CHITINOUS.

HUMPED		Being somewhat higher in the center of the dorsum than towards the anterior or posterior (as in some Cypraea spp.).

HYALINE		Glassy and semi-transparent; see also: PELLUCID.

HYBRID		The offspring of parents of two different populations, and usually two different SPECIES.

HYOTE SPINE		Hollow, tubular, and cylindrical shell outgrowths open distally at their tips as well as on their distal flanks, arising periodically from the thin edges of shell margins of OYSTERS [the tip ends are rounded, ear-shaped openings, typically developed on Hyotissa hyotis (Linne, 1758)].

HYPERSTROPHIC		[need definition]; see: ULTRADEXTRAL; see also: HETEROSTROPHIC. See other gastropod shapes.

HYPNOMIC SINUS		In cephalopods, the notch in the shell margin for the HYPONOME or excurrent siphon.

HYPOBRANCHIAL		Situated below the gills.

HYPOBRANCHIAL GLAND		Large mucous gland beside the rectum ("hypobranchial" is a misnomer) and which consolidates particles before the leave the pallial cavity.

HYPONOME		The EXHALANT SIPHON of CEPHALOPODS.

HYPOPLAX		An accessory, ventral shell piece between the valves in some burrowing clams. Elongate, calcareous ACCESSORY PLATE extending along posterior end of ventral margin in some Pholadidae. MESOPLAX; METAPLAX; SIPHONOPLAX. Photo: Cyrtopleura costata (Linne, 1758)

HYPOSTRACUM		(1) Inner layer of shell wall, secreted by entire epithelium of MANTLE (original usage of term); (2) part of shell wall secreted at attachments of ADDUCTOR MUSCLES.

HYPOTYPE		A specimen not in the original TYPE MATERIAL of a species but known from a published illustration or description. See the publication: "Terminology of Types" by Frizzell.

I.C.Z.N. (also: ICZN)		International Commission on Zoological Nomenclature (convenes in London). Also, the International Code of Zoological Nomenclature, that is maintained by the Commission. An associated publication of interest is the Bulletin of Zoological Nomenclature. See also: ITZN.

I.T.Z.N. (also: ITZN)		The International Trust for Zoological Nomenclature states its mission as "The International Trust for Zoological Nomenclature (ITZN or “the Trust”) was established in 1947, registered in England as a non profit company limited by guarantee. ITZN acts on behalf of the Commission to raise and administer funds in accordance with the policy of the Commission and the International Union of Biological Sciences (IUBS)." [note: "the Commission" = ICZN]

IBIDEM (abbrev: IBID)		The same.

ICONOGRAPH		An illustrated systematic treatment; an illustrated MONOGRAPH.

IMBRICATE		Having overlapping scales or laminae; see also: SQUAMOUS.

IMMATURE		Not fully developed; said of shell characters that are partly or completely different from those at maturity.

IMMERSED		Sunken; said especially of APICAL whorls.

IMPERFORATE		Not open or perforated; often said of a closed UMBILICUS; see also: PERFORATE.

IMPRESSED		Indented, as in the case of a line pressed into an otherwise unscored surface; said of a shell SUTURE; see also: ADPRESSED; CHANNELED; SUTURE, IMPRESSED.

IMPRESSION		See: MUSCULAR IMPRESSION.

IN LITTERIS (abbrev: IN LITT)		Information conveyed in literature, e.g., a letter or by other correspondence; see also: PERS. COMM.

INCIPIENT		About to develop or appear; beginning to appear.

INCISED		Sculptured with sharply cut GROOVES.

INCRASSATE		Thick or thickened (e.g., the hinge of Glycimeris spp.); see also: MARGINATE.

INCREMENTAL AXIAL		In gastropods, the GROWTH LINES between lines of AXIAL ribbing.

INCREMENTAL LINE		see: GROWTH LINE.

INCURRENT		Forming passage for current of water drawn into mantle cavity from medium (applied to mantle opening or siphonal opening); = INHALANT; see also: EXCURRENT.

INCURVED		Curved inwardly toward the shell or upward and inward toward the SPIRE; see: INFLECTED.

INCUT		See: INCISED.

INDENTATION		A NOTCH or recess in the margin of an APERTURAL LIP, vertical margin, or other surface.

INDENTED		Pressed in or having dents or a series of small cavities.

INDIGENOUS		Occurring naturally in a particular region; not introduced; see also: ENDEMIC.

INDUCTURA		An unusually large and erect expansion of the inner APERTURAL LIP of a gastropod shell; a smooth, shelly layer extending from the inner side of the APERTURE; see also: CALLUS.

INEQUILATERAL		In bivalves, having the parts of the shell anterior and posterior to the beaks differing appreciably in length; see: INEQUIVALVE; SUBEQUILATERAL.

INEQUIVALVE		In bivalves, having one valve that is larger (as in the genera Anadara and Corbula) or more convex (as in the genus Pecten) than the other valve. See also: EQUIVALVE; MARGIN, DISCORDANT. See other bivalve shapes. Photo: Anadara brasiliana (Lamarck, 1819)

INFERIOR VALVE		That valve (of "attached" bivalves) which is attached to the substrate; = ATTACHED VALVE; = LOWER VALVE.

INFLATED		Swollen; typically applied to rotund shells of a thin texture; see also: TUMID; TURGID; VENTRICOSE.

INFLATION		The distance, in bivalves, between two planes parallel to the plane of commissure and touching outermost parts of two valves.

INFLECTED		Turned inwards, e.g., the outer lip of a spiral shell when it turns toward the body whorl; see: REFLECTED; INCURVED.

INFRAMARGINAL		Situated below a MARGIN.

INFUNDIBULIFORM		Funnel-shaped, as in the siphon or funnel of a CEPHALOPOD.

INHALANT		See: INCURRENT.

INHALANT SIPHON		[need definition]; see also: EXHALANT SIPHON.

INNER LIGAMENT		See: LIGAMENT, INNER.

INOPERCULATE		Lacking an OPERCULUM; see also: OPERCULATE.

INSERTAE SEDIS		Uncertain classification.

INSERTION		In gastropods, the point where the OUTER LIP meets the PARIETAL WALL.

INSERTION PLATE		Narrow marginal extensions of the ARTICULAMENTUM of the valves of CHITONS projecting into the GIRDLE.

INSERTION TEETH		Articulating processes that unite the valves of a chiton to the GIRDLE or INSERTION PLATES.

INTEGROPALLIATE (or INTEGRIPALLIATE)		The condition in bivalves of having no PALLIAL SINUS; see also: SINOPALLIATE.

INTEGUMENT		An outer covering layer of the soft parts.

INTERBAND		Longitudinal band on surface of lower valve of radiolitid rudist, separating two bands designated as siphonal bands.

INTERCALATE		Interposed; interspersed.

INTERCOSTAL		Of or in the spaces between ribs or COSTAE.

INTERDENTUM		Shelly plate present in some Unionidae bridging space between PSEUDOCARDINAL and LATERAL TEETH.

INTERGRADE		To possess characters (as in a series of specimens) that bridge the morphological gap between one entity and another.

INTERNAL		On the inside; see: EXTERNAL.

INTERNAL CAST		See: ENDOCAST.

INTERNAL SHELL		Having the shell always inside of an animal (as is the shell of Aplysia spp.).

INTERSPACE		Space between regular sculptural features; in particular, channels between sculptural ribs; see also: INTERSTICE.

INTERSTICE		A space between structures; see: INTERSTITIAL.

INTERSTITIAL		Pertaining to or occurring in INTERSTICES.

INTERTIDAL		Located on the shore between low-tide and high-tide levels.

INTERVAL		A space or gap, in many cases between sculptural or color elements; synonymous with INTERSPACE, when applied to ornament.

INTERVARICAL		Lying between two VARICES.

INTERVARICAL SPACE		The area between one VARIX and another; a shell area indicative of active growth.

INTRITICALYX		A chalky, white, surface layer in the shells of many marine molluscan groups. Prominent in the Muricidae, where its patterns of MICROSCULPTURE are often useful in identification.

INTRORSE		Turned inward; turned toward the AXIS.

INVAGINATED		Folded back within itself; see: INVERSIBLE.

INVALID SPECIES		Names not to be used; said of an improper name (those proposed improperly) in TAXONOMY. Do not confuse with validly proposed names which have become NOMINAL SPECIES or SYNONYMS.

INVERSE		Term formerly applied to a chamid bivalve in which attachment is by left valve or a rudist in which attachment is by right valve.

INVERSIBLE		Capable of being withdrawn by being inverted (as in some gastropod tentacles) See also: CONTRACTILE; INVAGINATED.

INVOLUTE		Having the last whorl enveloping earlier ones, so that the height of the APERTURE is generally the height of the shell, as in the Bullidae; see also: CONVOLUTE. See other gastropod shapes.

IRIDESCENT		Reflecting the colors of the rainbow; see also: NACRE; MOTHER OF PEARL.

IRREGULAR		Descriptive of shells which, being attached to or embedded in other marine bodies, have no consistent form due to conforming to the shape of their attachment substrate.

IRREGULARLY COILED		Gastropod coiling in a nonuniform manner, as exemplified by the genus Distorsio; see also: LOOSELY COILED; TIGHTLY COILED; SPIRALLY COILED. See other gastropod shapes.

IRRORATE		Having minute marks of color or minute grains or specs of color, as in Littorina irrorata.

ISODONT		Descriptive of a bivalve shell that has a hinge with one pair of teeth and one pair of pits on one valve that articulate with two pits and two teeth on the other. See illustration: Composite Bivalve. See also: DENTITION.

ISOMYARIAN		Descriptive of a bivalve shell having two adductor muscle scars on the inner surface which are approximately equal in size; = HOMOMYARIAN.

ISOSTROPHIC		Gastropod COILING coiling in which [need definition]. See other gastropod shapes.

JAW		[need definition].

JUGAL SINUS		In CHITONS, the depression between the sutural laminae; = SUTURAL SINUS; see also: JUGUM.

JUGAL TRACT		In CHITONS, the surface of the TEGMENTUM adjacent to the JUGUM; see also: JUGUM.

JUGUM		A longitudinal ridge, sharp or rounded, on some intermediate CHITON valves. See illustration: Composite Chiton. See also: JUGAL SINUS; JUGAL TRACT.

JUNIOR SYNONYM		A latter name for a SPECIES with an acceptable prior name.

JUVENILE		Demonstrating the characteristics of immaturity, as in shell growth; see also: ADULT.

KEEL		A prominent, sharply raised sculptural element, most frequently spiral in orientation. See illustration: Composite Gastropod.

KEELED		Having a prominent sharp ridge; see also: CARINATE; KEEL.

KNOBBY		Bumpy or NODULOSE.

LABIAL		See: LABRAL.

LABIAL PALPS		[need definition].

LABIAL TOOTH		A CERATUS, a relatively long, spur-like or hornlike extension of the outer lip margin of a gastropod shell, projecting toward the interior of the aperture.

LABIUM (pl. LABIA)		The INNER LIP of the aperture; see also: PERISTOME.

LABRAL		Pertaining to the outer APERTURAL LIP margin (by common usage; properly: LABIAL).

LABRUM		The OUTER LIP of the aperture; see also: PERISTOME.

LACUNAE (adj. LACUNOSE)		Small gap or pits.

LAMALLA, AXIAL		[need definition]. See illustration: Composite Gastropod.

LAMELLA (pl. LAMELLAE)		A thin plate or scale, generally more or less erect; see also: LAMINA; RUFFLED; SQUAMOUS; WEBBING.

LAMELLAR LAYER		Plate-like; the thick middle layer of a shell; see also: PRISMATIC LAYER; PORCELANEOUS LAYER.

LAMELLATE		Having LAMELLAE.

LAMELLIBRANCH		Older name for any BIVALVE having platelike gills.

LAMELLOSE		Having numerous plates or scales on the surface; see also: LAMELLATE.

LAMINA (pl. LAMINAE)		A plate or scale, generally parallel to the shell surface.

LAMINAR TOOTH		[need definition]; used in describing Neaeromya (see: Abbott, 1974).

LAMINATE		Formed of thin, overlapping plates or scales.

LAMINOSE		Having many LAMINAE.

LANCEOLATE		Shaped like a lance; extended to a point at both ends.

LANGMUIR TROTH		The groove, constructed by the FOOT of gastropods floating upside down on the surface of water, which collects the surface monolayer of protein, draws it over the foot by CILIA, and is intercepted by the RADULA. This process accomplished by the freshwater Lymnaea, and tropical prosobranchs Ampullarius and Pila.

LAPPET		A fold, lobe, or small flap.

LAPSUS CALAMI (abbrev: LAPSUS)		An unintentional error in spelling.

LARVA (pl. LARVAE)		The juvenile stage, following the egg, of many forms of life; usually provides a mechanism for dispersal of the species; see also: DORATOPSIS; ECHINOSPIRA; GLOCHIDIUM; LECITHOTROPHIC; NEOTENY; PEDIVELIGER; PLANKTOTROPHIC; PROTOCONCH; RHYNCHOTEUTHIS; SPAT; TROCHOPHORE; VELIGER.

LATERAL		Situated at the side of or arising from the side of a structure (in reference to a shell, RADULAR tooth, etc.).

LATERAL HINGE SYSTEM		Hinge structures present in some PRODISSOCONCHS anterior and posterior to the PROVINCULUM.

LATERAL SECTION		More or less raised area on the TEGMENTUM of valves II to VII of a chiton shell, bounded by the posterior edge of the valve and by a line from the midpoint to the ANTEROLATERAL edge; see also: MEDIAN SECTION; POSTERIOR SECTION.

LATERAL TOOTH		In gastropods, those teeth of a RADULA which lie immediately to the side (left and right) of the RACHIDIAN or central tooth and more inward from the MARGINAL TOOH (if present). See also: RADULA FORMULA. In bivalves, those shelly protuberances on the dorsal margins of the shell, and at some distance from the UMBONES. In Bivalves, at or of the hinge area on either side of the cardinal area, well removed from the BEAKS.

LATTICED		Having crossed sculptural elements; see also: DECUSSATE; DIVARICATE.

LEADING EDGE		The side or surface of a sculptural structure nearest the line of active growth; TRAILING EDGE.

LECITHOTROPHIC		A type of egg having a large supply of yolk; the LARVA takes no food while in the plankton, and is considered to be a rather clumsy "YOLK LARVA"; see also: PLANKTOTROPHIC.

LECTOPARATYPE		[need definition]. See the publication: "Terminology of Types" by Frizzell.

LECTOTYPE		A specimen selected from primary syntypic material to serve in place of a HOLOTYPE where one either was never selected by the original author or has definitely been lost or destroyed; other specimens in the SYNTYPE lot then become LECTOPARATYPE; see also: TYPE SPECIMEN.

LEFT HANDED		Same as SINISTRAL.

LEFT VALVE (abbrev: LV)		Valve of a bivalve lying on left-hand side when shell is placed with anterior end pointing away from observer, and with commissure vertical, the hinge being uppermost; see also: RIGHT VALVE. Visit Let's Talk Seashells for how to distinguish between right and left valves.

LEG. = LEGIT		An abbreviation for the Latin word, legit, which means: Collected by. To avoid confusion, this term is preferred over COLL. which can mean: collected by, but can also mean: in the collection of. Example on a specimen label: Leg. John Doe See also: LEG.

LENGTH		The distance of a specimen, from anterior extremity to posterior extremity. See illustration: Composite Gastropod. See also: HEIGHT; WIDTH; WRS.

LENTICULAR		Shaped like a lentil or lens; having a narrowly doubly convex form, as in the aperture of certain gastropod shells; see also: DISCOIDAL; PLANISPIRAL. See other gastropod shapes.

LESSEPSIAN		Lessepsian comes from the name of Monsieur de Lesseps, the French engineer who cut the Suez Channel and refers to the phenomena of migration facilitated by humans, e.g., through the Suez Channel. "Lessepsian" does not refer only to molluscs, but also to fish, crustaceans, and all forms of marine life which have undertaken this geographic expansion, made possible only by human intervention.

LIG (pl. LIGS)		A short, common name for a tree snail of the genus Liguus; see also: LIG POLE.

LIG POLE		A long, sometimes collapsible pole with a cup attached to the distal end. This pole is used to extend one's reach up into the trees to dislodge and collect "LIGS" (tree snails of the genus Liguus) in the terminal cup.

LIGAMENT		A band of tough, brown, elastic material which unites the dorsal margins of a clam, usually posterior to the BEAKS, sometimes externally visible, rarely internal; causes the valves to open when the adductor muscles relax; see also: ALIVINCULAR; AMPHIDETIC; BOURRELET; CARTILAGE; DUPLIVINCULAR; LIGAMENT, FIBROUS; MULTIVINCULAR; PARIVINCULAR; TENSILIUM. See: Bivalve terminology, Anatomy of bivalves by Marlo Krisberg.

LIGAMENT FULCRUM		Narrow, lunate platform extending posteriorly from beak along dorsal margin and serving for attachment of ligament; = NYMPH.

LIGAMENT GROOVE		Narrow depression in CARDINAL AREA for attachment of fibers of the LIGAMENT.

LIGAMENT PIT		Relatively broad depression in cardinal area for attachment of ligament in bivalves; see also: CHONDROPHORE; COCHLEATE.

LIGAMENT RIDGE		Narrow ridge or lamina formed by projection of outer layer of shell wall into body cavity of many rudists (particularly hippuritids and radiolitids), thought to have served for attachment of ligament.

LIGAMENT STRUCTURE		Elongated space behind UMBONES apparent after erosion of LIGAMENT.

LIGAMENT, EXTERNAL		That part of the ligament visible from outside the bivalve shell, consisting of a LAMELLAR LAYER under tensional stress. See illustration: Composite Bivalve. See also: LIGAMENT, (types).

LIGAMENT, FIBROUS		See: LIGAMENT, INNER. See also: LIGAMENT, (types).

LIGAMENT, INTERNAL		(1) = RESILIUM; (2) Inner layer of ligament; = FIBROUS LIGAMENT. See also: LIGAMENT, (types).

LIGAMENT, LAMELLAR		Part of ligament characterized by lamellar structure and containing no CALCIUM CARBONATE; secreted at mantle edge and elastic to both compressional and tensional stresses. See also: LIGAMENT, (types).

LIGAMENT, PRIMARY		Part of ligament, of bivalves, representing original condition of structure, consisting of PERIOSTRACUM and lamellar and fibrous layers, but excluding secondary additions, notably FUSION LAYER. See also: LIGAMENT, (types).

LIGAMENTIFEROUS		Having or containing the LIGAMENT, e.g., the CARDINAL PIT of Mya spp.

LIGULATE		Thin, slender, like a slip or neck of any thing (e.g., the muscular impression of Lucina spp.); see: ATTENUATED.

LIMACIFORM		[need definition]; used by Abbott, 1974 (pg. 367) in description of Dendronotus.

LIMPET		A common name for saltwater and freshwater SNAILS (GASTROPODS) which have a low profile, conical (PATELLIFORM) shell.

LINE OF GROWTH		See: GROWTH LINE.

LINEAR		Resembling a line; long, often narrow, and of uniform breadth; see also: RECTILINEAR.

LINGUIFORM		Tongue-shaped. See also: ELONGATE

LIP		The margin of the aperture; the inner lip (= LABIUM) extends from the foot of the columella to the suture and consists of the columellar lip and the parietal lip. The outer lip (= LABRUM) is that part of the aperture farthest from the axis of coiling; see also: PALATAL; PERISTOME.

LIP, COLUMELLAR		The lower portion of the INNER APERTURAL LIP; see also: LIP, PARIETAL.

LIP, FLARED		[need definition]. In the Strombidae…

LIP, INNER		The portion of the apertural margin of a gastropod shell opposite the outer lip and abutting the earliest portion of the body whorl; = LABIUM; the combination of the COLUMELLAR LIP and the PARIETAL LIP.

LIP, OUTER		The outer, distal, growing or leading edge of a gastropod shell; = LABRUM; = PERISTOME. See illustration: Composite Gastropod. See also: OUTER APERTURAL LIP; PALATAL.

LIP, PARIETAL		The upper portion of the inner APERTURAL LIP, which is attached to the subsequent WHORL.

LIP, REFLECTED		[need definition].

LIRA (pl. LIRAE)		Fine linear elevation on shell surface or within OUTER LIP (Cox, 1960); this feature is often on the inner surface of the outer lip of the APERTURE; see also: STRIA.

LIRATE		Sculptured with spirally oriented RIDGES, as in the APERTURE of a shell; see also: STRIATE; VERMICULATION.

LIRATION

A fine, threadlike spiral sculptural element; see also: LIRA. </