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The glossary provided here is largely based on “Seashells of Southern Florida: Bivalves,” by Paula M. Mikkelsen & Rüdiger Bieler, Princeton University Press. Production of this glossary was funded in part by the National Science Foundation’s Partnerships in Enhancing Expertise in Taxonomy [PEET] Program, NSF-DEB-9978119, “Bivalves - Research, Training, Electronic Dissemination of Data” (1999-2008) to Bieler and Mikkelsen.

D

DEHISCENT
Splitting, referring here to PERIOSTRACUM that is not adherent.
DEMIBRANCH
See CTENIDIUM.
DEPOSIT-FEEDING
Feeding type of some bivalves during which organic particles are harvested (by either the SIPHONS or PALP PROBOSCIDES) from the surface or near-surface sediments; see also SUSPENSION-FEEDING.
DESMODONT
HINGE type characterized by very reduced or absent teeth, in some cases replaced by accessory ridges along the valve margins, occurring in such families as Gastrochaenidae and Myidae.
DIAPHRAGM
Ridge separating shell and siphonal chambers in the burrow or IGLOO of Gastrochaenidae; also called a SEPTUM.
DIGESTIVE GLAND
Highly branched organ surrounding the stomach within the visceral mass, into which edible food particles pass (through ducts from the stomach) and where digestion occurs; often darkly colored in living specimens, visible as a dark spot through the gills or a thin shell; in earlier literature, often called liver, midgut gland, or hepatopancreas.
DIMYARIAN
DIMYARIAN fig.Having both anterior and posterior ADDUCTOR MUSCLES (figure: Mercenaria mercenaria).
DIOECIOUS
See GONOCHORISTIC.
DIRECT DEVELOPMENT
Larval development type characterized by lack of a free-swimming stage (VELIGER) that can be absent entirely or passed entirely within an egg capsule or brooding chamber.
DIVARICATING
DIVARICATING fig.Branching, usually in reference to external radial sculpture (figure: Ctenoides sanctipauli).
DORSAL
The HINGE side of a bivalve, opposite of ventral.
DORSAL LIGAMENT
See LIGAMENT.
DUPLIVINCULAR
DUPLIVINCULAR fig.Type of dorsal LIGAMENT that is AMPHIDETIC or OPISTHODETIC in position, and has alternating lamellar and fibrous layers, repeated as a series of parallel or oblique bands, giving the appearance of a series of nested chevrons; occurring in such families as Arcidae, Noetiidae (modified), and Glycymerididae.
DYSODONT
DYSODONT fig.HINGE type featuring small simple denticles close to the UMBONES, characteristic of some members of Mytilidae (figure: Brachidontes exustus).