Glossary of Morphological and Anatomical Terms

caecum - Papillose outgrowth of mantle occupying a puncta and connecting with periostracum either by a brush as in articulated brachiopods or by fibrillar strands as in cranioids.Fig.31.
calcareocorneous - See chitinophosphatic.
calcariform - Falciform crura said to be distinguishable by dorsally directed process at distal end of each crus.
callist - See pedicle callist.
callus - Any excessive thickening of shell located on valve floor.Fig.352.
camarophorium - Spoon-shaped, adductor-bearing platform in stenoscismatoid dorsal valve supported by median septum.Fig.367.
camerate - Acrotretoid shell fabric of discrete apatitic lamellae connected by perpendicular walls forming polygonal chambers.Fig.241.
campagiform - Growth stage of loop of certain terebratulides marked by proportionally large funnel-shaped ascending elements without lateral lacunae.
campagiform hood - Large, commonly funnel-shaped structure without lateral lacunae, with descending branches attached to median septum by transverse processes.
canal - Fine perforation of organophosphatic shell not penetrating primary layer and partly occupied by secreting plasmalemma (and exuded bodies) of outer epithelium.Fig.261.
canaliform - Variant of raduliform type, folded longitudinally in form of dorsally facing channel or gutter.
capilla - Very fine radial ridge on outer surface of shell.
capsular muscles - Longitudinal fibers in connective tissue of pedicle of articulated brachiopods; may be attached to floor of ventral valve.
cardinal angle - Angle between hinge line and posterolateral margins of shell.
cardinal area - Posterior sector of valve of articulated brachiopods exclusive of delthyrium or notothyrium (may be interarea planarea, or palintrope).Fig.285.
cardinal buttress - Vertical plate or ridge supporting cardinal socket in some trimerelloids dividing cavity beneath beak into two umbonal chambers.Fig.375.
cardinal crests - Paired ridges originating near apex of notothyrium below chilidium and flanking cardinal process of chonetidines (equivalent to the chilidial crests of some authors).Fig.361.
cardinal extension - Thecideidine cardinal process.
cardinal extremities - Lateral terminations of posterior margin.Fig.283.
cardinal facet - See cardinal socket.
cardinal flanges - Variably disposed posteroventral extensions of inner socket ridges or cardinal plate protruding into ventral umbo in some taxa becoming thickened and serrated ventrally to accommodate diductor muscle bases.Fig.359.
cardinal margin - Curved posterior margin of shell, homologous with hinge line of strophic shells but not coincident with hinge axis.Fig.285.
cardinal muscle scar - Posterolaterally placed muscle scars in acrotretoids and obolellides.Fig.378.
cardinal pit - Depression between inner socket ridges accommodating cardinal process and diductor muscle bases as in some rhynchonellides.Fig.349.
cardinal plate - Plate extending across posterior end of dorsal valve consisting laterally of outer hinge plates and medially of either conjunct inner hinge plates or single plate commonly perforated posteriorly by dorsal foramen.Fig.331,Fig.362.
cardinal process - Blade or variably shaped boss of secondary shell situated medially in posterior end of dorsal valve and serving for separation or attachment of paired diductor muscles.Fig.357,Fig.358,Fig.359,Fig.360,Fig.361,Fig.362,Fig.363,Fig.364.
cardinal process buttress plates - Two vertical converging, parallel or diverging plates extending anteriorly from cardinal process to enclose space and, in some productidines, uniting with breviseptum.
cardinal process cowl - Proximal cover directed umbonally on triplesioid cardinal process.
cardinal process hood - See cardinal process cowl.
cardinal process lobes - Projections forming all or part of cardinal process and bearing muscle bases or myophore.Fig.357,Fig.360.
cardinal process pit - Pit at internal base of cardinal process in some plectambonitoids, chonetoids, and productoids.
cardinal process shaft - Ridge-or stalklike proximal part of cardinal process.Fig.360.
cardinal ridge - Thickened ridge confined to hinge lines of some productidines, aiding in articulation of shell.Fig.326.
cardinal socket - Transverse depression on posterior margin of trimerelloid ventral valve that receives plate or tooth of dorsal valve.Fig.375.
cardinalia - Structures of secondary shell in posteromedian region of dorsal valve associated with articulation support of lophophore and muscle attachment; include, for example, cardinal process socket ridges crural bases and their accessory plates.Fig.329,Fig.330,Fig.331,Fig.359.
carina - Major angular elevation of valve surface, externally convex in transverse profile and radial in disposition.
carinate - Opposite folding characterized by incipient lateral carinae but without median sulci.Fig.288.
catacline - See inclination of cardinal area or of pseudointerarea.Fig.285.
cella - Any chamber contained between floor of valve and elevated muscle-bearing platform best known as inverted V-shaped chamber beneath shoe-lifter process.Fig.356.
central muscles - Anteriorly or medially placed pair of muscles in lingulides, originating on ventral valve and passing anterodorsally to dorsal valve.Fig.346_1.
centronellid stage - See unisulcate.
centronelliform - Simple lanceolate loop suspended free of valve floor, commonly bearing vertical median plate in addition to echmidium.
cheniothyrid stage - See lobate stage.
chilidial crests - See cardinal crests.
chilidial plates - Pair of posterior platelike extensions of notothyrial walls, commonly forming lateral boundaries of cardinal process.
chilidium - Crescentic plate covering apex of notothyrium commonly convex externally and extending for variable distances ventrally over proximal end of cardinal process and chilidial plates when present.Fig.319,Fig.357,Fig.361.
chilidonophorid - Short loop with converging but not fused crural processes, and transverse band not well differentiated from descending branches.
chitinophosphatic - Consisting dominantly of some form of calcium phosphate and chitin (hexosamine) with various proteins.
cicatrix - Scar on ventral umbo or umbonal region, representing place of cementation of shell to substrate.
ciliform - Variant of raduliform type; flattened in plane of commissure forming direct prolongations of horizontal hinge plates, then turning parallel to plane of symmetry as slightly crescentic blades.
cinctid stage - See opposite folding.
cincture - External concentric furrow in either valve of some productoids, corresponding to internal shell deflection or thickening.
circinate - Distally coiling spirolophe.
cirri socles - See spicules.
clavicular plates - See cardinal crests.
colleplax - Triangular umbonal plate in dictyonellidines exposed externally by resorption of ventral umbo.Fig.321.
columnar - Acrotretoid shell fabric of discrete apatitic lamellae connected by microscopic perpendicular columns.Fig.240.
coma - Concentrically disposed impersistent and irregular protuberance composed of primary and secondary shell on external shell surface of some plectambonitoids.Fig.295.
commissural plane - Plane containing cardinal margin and either commissure of rectimarginate shell or points on anterior commissure midway between crests of folds in both valves.Fig.283.
commissure - Line of junction between edges or margins of valves.Fig.283.
concavoconvex - Dorsal valve concave; ventral valve convex.Fig.287.
conjunct deltidial plates - Deltidial plates in contactanterodorsally of pedicle.
connecting band - Band of terebratellide long loop connecting ascending lamellae to each other (transverse band), descending lamellae to median septum (lateral connecting band), and descending lamellae to ascending lamellae (vertical connecting band).Fig.338.
connectivum - Medially united plates extending from crural bases to cover septalium ventrally.Fig.329.
convexoconcave - Dorsal valve convex; ventral valve concave.Fig.287_2.
convexoplane - Dorsal valve convex; ventral valve plane.
corpus - Shell enclosing principal part of body cavity and mantle cavity excluding peripheral extensions of shell such as trails or flanges (see section on Productida in systematic volume Part H(R), volume 2, in preparation).
coscinidium - Reticulate extension of inner secondary shell over aperture of conicoventral valve of richthofenioids.Fig.273.
costa - First-formed radial ridge on external surface of shell most commonly originating at the junction between the brephic and neanic shell.Fig.297.
costella - Radial ridge on external surface of shell originating later than costa by bifurcation of existing costa or costella or by intercalation between earlier-formed ribs.Fig.297.
costellate - Shell radially ornamented by costae and costellae.
cowl - Anterodorsally growing shell producing conical shape of holoperipheral ventral valve of lyttoniids.
crenulations - See denticles.
crescent - Site of cardinal socket of trimerelloids.
cristae - See socket ridges.
crossed-bladed structure - Sheets of parallel aggregations of laths or blades oriented in different directions in adjacent sheets and in parts of same sheet of a laminar shell succession, for example, secondary layer of most strophomenides.Fig.251.
crown of crescent - See crescent.
crura - Paired processes extending from cardinalia or septum to give support to posterior end of lophophore distal ends may also be prolonged into primary lamellae of spire or descending lamellae of loop.Fig.329,Fig.330,Fig.331.
crural band - Ribbon of secondary shell joining crural processes ventrally.
crural bases - Parts of crura united to hinge plates or socket plates and separating inner and outer hinge plates when present.Fig.329,Fig.330,Fig.331.
crural fossette - Cavity on inner face of tooth receiving posteroventral edge of brachiophore or crural plate when valves are closed.Fig.322.
crural hooks - Hooklike ends of crura facing a matching set of curved primary lamellae of the spiralium.
crural keel - Dorsal extension of crus beyond junction with flange.
crural lobe - Strongly developed, posteroventrally elevated inner socket ridge in atrypoids and some athyroids.
crural pit - Cavity near floor of dorsal valve separating brachiophore plate and fulcral plate in some orthides.
crural plate - Plate extending from inner edge of outer hinge plate or crural base to floor of dorsal valve may fuse medially with counterpart to form septalium.
crural point - See crural process.
crural process - Pointed part of crus directed obliquely inward and ventrally.Fig.334.
crural trough - See septalium.
cruralium - Spoon-shaped structure of dorsal valve formed by dorsal union of pentameroid, ambocoeliidid, or some meristellid brachiophore plates (or homologues) and bearing adductor muscles.Fig.365.
cruralium discretum - Paired outer plates attached independently of each other to floor of pentameroid dorsal valve to enclose dorsal adductor field.
crus - See CRURA.
cryptacanthiiform - Long, reflected loop unsupported by median septum with descending lamellae anterolaterally divergent but still fused posteromedially.
cryptonelliform - Long, reflected loop unsupported in adults by median septum and having narrow transverse band.
ctenophoridium - Cardinal process with radially striated myophore not elevated on a shaft but commonly on an elevated transverse ridge.Fig.358.
cucullate - Phase of loop development with a hood on either vertical plate or septal pillar.
curvature of beak - Curvature of beak toward the opposing valve.
curvilinear - A dimension measured along the external curvature of a valve.
cuticle - Organic cover of pedicle secreted by pedicle epithelium.
cyclothyrid - See auriculate.
cynocephalous - Sharply folded dorsal valve.
cyrtomatodont - Knoblike or hook-shaped hinge teeth developed by differential secretion and resorption of secondary shell.Fig.322.1.
cyrtomorph - Chonetid hinge spines curving medially or laterally but remaining close to commissural plane.
cystose - Valves containing blisters of secondary shell.Fig.372.