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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.

E

EAR
See AURICLE.
EDENTATE
Without HINGE TEETH, also called edentulous.
EDENTULOUS
See EDENTATE.
ELEUTHERORHABDIC
Gill type charcterized by filaments connected by interlocking cilia projecting from CILIATED DISKS; this term does not preclude the existence of tissue junctions in the same gill; see also FILIBRANCH, PSEUDOLAMELLIBRANCH. Ridewood (1903) defined a group Eleutherorhabda based on this character, equivalent to Pelseneer's (1891) group Filibranchia.
ENDOBYSSATE
INFAUNAL with BYSSUS attached to particles or objects below the surface; see also EPIBYSSATE.
ENTIRE
ENTIRE fig.Occurring without interruption (break or embayment), usually referring to the PALLIAL LINE, also called simple or integrepalliate (figure: Codakia orbicularis).
EPIBYSSATE
EPIFAUNAL with BYSSUS attached to solid substrata; see also ENDOBYSSATE.
EPIFAUNAL
Living on top of the sediment, i.e., unburied; also called epibenthic; see also INFAUNAL.
EQUILATERAL
EQUILATERAL fig.Having the UMBO at the center of the dorsal midline of the valve (figure: Tucetona pectinata).
EQUIVALVE
EQUIVALVE fig.Having valves that are equal in shape and size (figure: Periglypta listeri).
ESCUTCHEON
ESCUTCHEON fig.An oval or spindle-shaped impressed area, often clearly demarcated and of differing sculpture, along the posterodorsal margin of a bivalve (figure: Periglypta listeri).
EULAMELLIBRANCH
EULAMELLIBRANCH fig. no. 1EULAMELLIBRANCH fig. no. 2Gill type characterized by a series of narrow elongated filaments that are interconnected laterally only by tissue junctions (so that the interfilamental spaces are divided into a series of OSTIA or fenestrae), and with or without interlamellar junctions; see also SYNAPTORHABDIC; occurring in such families as Limidae and heterodont Carditoida (Crassatellidae, Astartidae, Carditidae, Condylocardiidae), Anomalodesmata (Pandoridae, Lyonsiidae, Periplomatidae, Thraciidae, Verticordiidae), and Veneroida (Lucinidae, Ungulinidae, some Thyasiridae, Chamidae, Lasaeidae, Hiatellidae, Gastrochaenidae, Trapezidae, Sportellidae, Corbiculidae, Cardiidae, Veneridae, Tellinidae, Donacidae, Psammobiidae, Semelidae, Solecurtidae, Pharidae, Mactridae, Dreissenidae, Myidae, Corbulidae, Pholadidae, Teredinidae).
EXCURRENT APERTURE or SIPHON
EXCURRENT APERTURE or SIPHON fig.Aperture or siphon that controls water outflow from the MANTLE CAVITY; also known as anal, cloacal, or exhalent (figure: Mercenaria mercenaria) aperture/siphon.
EXHALENT APERTURE OR SIPHON
See EXCURRENT APERTURE OR SIPHON.
EXTERNAL LIGAMENT
EXTERNAL LIGAMENT fig.Type of dorsal LIGAMENT which attaches to the dorsally exposed surface (or only slightly sunken on the hinge plate) of the two valves (figure: Scissula similis).
EYE
EYE fig.Organ of photoreception, existing in a range of structural types (e.g., with or without lens, simple or compound, open-cup-like or closed, etc.) within Bivalvia; (1) CEPHALIC or "true" EYES are innervated by the cerebral ganglion and occur on one or both of the anteriormost gill filaments (also called ctenidial eyes; therefore probably do not function in photoreception); (2) PALLIAL EYES are innervated by the visceral ganglia, occur on the MANTLE margin or siphon tips (see figure), and function in photoreception; also called ocellus, photoreceptor (figure: Argopecten gibbus).