Glossary of Morphological and Anatomical Terms
schizolophe - Lophophore indented anteromedially to define pair of brachia each bearing row of paired tentacles, at least distally.Fig.112,Fig.113,Fig.114.
schizolophus - See schizolophe.
secondary layer - Shell deposited by a layer of outer epithelium within the circumferential lobes of the mantle and consisting of fibers or laminae ensheathed in interconnecting membranes.Fig.5,Fig.222.
secondary pseudointerea - Flat, undivided pseudointerarea lacking flexure lines and developing after origin of pedicle foramen in some lingulides.
secondary sockets - Pair of small depressions immediately posterodorsal of cardinal process lobes receiving secondary teeth.
secondary teeth - Pair of dorsally directed projections from ventral process fitting into secondary sockets of strophodontid dorsal valve.
see frill - .
septal pillar - High, brachial septum anterior to cardinalia formed early in development ofterebratelloid loop.
septal plates - Various parts of cardinalia.
septalial plates - Crural plates forming floor of septalium and united with earlier formed part of median septum.
septalium - Troughlike structure of dorsal valve between crural bases consisting of crural plates (or homologues) fused medially and usually supported by median septum but may be unsupported or sessile; does not carry adductor muscles.Fig.330_4.
septiform - Crura having form of septa that descend directly from brachial side of hinge plates to floor of dorsal valve.
septum - Relatively long, narrow elevation of secondary shell, commonly bladelike; indicated within underlying floor of valve by persistent high, narrow deflections of shell fabric originating near primary layer.Fig.354.
sessile cruralium - Cruralium united with floor of dorsal valve without intervention of supporting median septum.
sessile spondylium - Spondylium united with floor of ventral valve without intervention of supporting medium septum.
shaft - See cardinal process shaft.
shell mosaic - See mosaic.
shell space - Cavity enclosed by conjoined valves.
shoe-lifter process - Arched platform of secondary shell attached posteriorly and laterally to floor of either valve but sharply elevated and free medially; in ventral valve, bearing part of ventral muscle field and lying between or supporting dental plates in dorsal valve bisected by median septum.Fig.356.
short loop - See loop.
sinus - Major undulation of commissure with crest directed ventrally, commonly but not invariably associated with ventral fold and dorsal sulcus also used irrespective of commissure as a synonym of sulcus.
siphonothyrid - Pedicle foramen continued internally as tube made up of exaggerated pedicle collar.
socket line - Posterior side of triangular slot in internal molds of orthide brachiopods produced by brachiophore base (and fulcral plates if present) and bounding impression of socket.
socket plate - See fulcral plate.
socket plates - Pair of plates supporting inner socket ridges attached to cardinal process and resting on floor of dorsal valve of orthotetoids and some orthoids; also pair of plates defining sockets of atrypid dorsal valve confined by inner socket ridges medially and normally supported by thickened shell deposit.Fig.332.
socket ridges - Linear elevations of secondary shell extending laterally from cardinal process and bounding anteromedian margin of dental sockets.
socket valve - See dorsal valve.
some authors - .
spine apertures - Internal opening of spine bases.
spine ridge - Ridgelike radial trace of prostrate spine on shell exterior.
spinuliform - Variant of raduliform type, but with crura laterally compressed.
spiralia - Pair of spirally coiled lamellae composed of secondary shell and supporting lophophore.Fig.333,Fig.336.
spiriferid stage - Long, straight posterior margin.
spirolophe - Lophophore in which brachia are spirally coiled and bear single row of paired tentacles.Fig.113.
splanchnocoele - See body cavity.
spondylial cavity - Space enclosed by posterior part of spondylium and purported to be bounded by spondylial lining.
spondylial lining - Thin prismatic layer of tertiary shell forming more or less continuous veneer on dorsal surface of pentameroid spondylium and entire deltidial cover.
spondylium - Trough-shaped or spoonlike apparatus composed of dental plates in various stages of coalescence, usually with median septum accommodating ventral muscle field.Fig.354.
spondylium discretum - Muscle-bearing chamber formed by slight convergence of dental plates that are attached separately to floor of valve.
spondylium duplex - Spondylium formed by convergence of dental plates and supported by variably developed median septum arising from floor of ventral valve.Fig.351_2.
spondylium pseudotriplex - See spondylium triplex.
spondylium simplex - Spondylium formed by convergence and growth of dental plates and supported by variably developed simple ventral median septum or ridge.Fig.351_1.
spondylium triplex - Spondylium supported by median septum and two lateral septa as in Polytoechia.Fig.353.
spondyloid - Basal inner surfaces of dental plates thickened and coalesced to simulate spondylium.
squama - Small arc of posterolateral margin of dorsal valve especially of rhynchonellides, overlapping complementary arc (glotta) of ventral margin.
stegidium - Convex plate or series of imbricate concentric plates closing gap between delthyrial plate and spiriferide dorsal valve consisting of series of concentric layers deposited by outer epithelium associated with atrophying pedicle migrating dorsally.Fig.320.
straight beak - See beak angle.
strainer spines - See endospines.
strangulate - See lobate.
striae - Fine grooves or incisions.
suberect - See beak angle.
suberect spines - Spines inclined to shell surface at angles between 45° to 75°.
subhypothyrid - Foramen occupying apex of delthyrium as in atrypids.
submarginal ridge - Thickening of either valve anterolaterally bordering corpus cavity.
submegathyrid - Posterior margin approximately straight and slightly less than maximum width of shell.
subperipheral rim - Elevation of secondary shell concentric to and within margin of valve.
subplectolophous - See plectolophe.
subterebratulid - Posterior margin considerably less than maximum width of shell but not strongly curved.
sulcate - See unisulcate.
sulciplicate - Form of alternate folding with dorsal valve bearing median fold indented by shallow median sulcus.Fig.289.
supporting septum - Median septum attached to floor of thecideoid ventral valve and supporting concave plates of hemispondylium.
supra-apical foramen - Pedicle foramen initially located in ventral umbo away from apex of delthyrium.Fig.319_2.
symbolothyrid - Pedicle opening shared by both valves.
symphytium - Deltidial plates fused dorsally or anteriorly from pedicle foramen and retaining only weak median line of junction.Fig.317.
syndeltarium - See deltidial cover.
syrinx - Tube of secondary shell medially located on ventral side of delthyrial plate and split along its ventroanterior surface.Fig.355.
