Glossary of Morphological and Anatomical Terms

imbricate - Strong, regular, overlapping growth lamellae.
impunctate - Shell lacking punctae, pseudopunctae, or canals of any kind.
inclination of cardinal area or of pseudointerarea - Commonly used terms to describe the condition of either valve based on convention of viewing specimen in lateral profile with beaks to left and dorsal valve uppermost, referring cardinal area to its position within one of four quadrants defined by commissure plane and plane normal to it and symmetry plane, touching base of cardinal areas; Cardinal area lying on continuation of commissure plane is orthocline Moving clockwise, cardinal area in first quadrant (top left) is weakly to strongly anacline in second quadrant (top right) weakly to strongly hypercline Moving counterclockwise from orthocline position, cardinal area lying in bottom left quadrant is weakly to strongly apsacline at 90° to orthocline it is catacline and continuing counterclockwise into bottom right quadrant cardinal area is weakly to strongly procline.Fig.285.
inclined beak - See beak angle.
incurved beak - See beak angle.
inequidistribute - Vascula genitalia of dorsal mantle saccate and contributing little to canal circulation.Fig.380.
inner carbonate layer - See secondary layer.
inner hinge plates - Pair of subhorizontal or concave plates in cardinalia located medially of crural bases and fused laterally with them.Fig.330,Fig.331.
inner plates - Pair of subvertical plates in cardinalia of some pentameroids lying on ventral side of base of brachial process and fused dorsally with it; homologue of outer hinge plates.
inner socket ridge - Ridge of secondary shell commonly overhanging dental socket and forming its inner or anterior margin.Fig.329,Fig.330,Fig.331.
interarea - Posterior sector of shell with growing edge at hinge line also, more commonly used for any plane or curved surface lying between beak and posterior margin of valve and bisected by delthyrium or notothyrium.Fig.285.
intercalary lamellae - See accessory lamellae.
intercalation - Costella arising by insertion between costae or costellae, not by bifurcation of existing costa or costella.Fig.297.
intercamarophorial plate - Short, low median septum on posterior midline of camarophorium in stenoscismatoids, extending to underside of hingeplate but independent of median septum duplex.Fig.367.
interconnecting bands - See connecting bands.
intercostal sulci - See interspace.
internal oblique muscles - Pair of muscles in someinarticulated brachiopods originating on ventral valve between anterior adductors and passing posterolaterally to insertions on dorsal valve locatedanterolaterally of posterior adductor muscles.Fig.374.
interridge - Median external ridge in pedicle pseudointerarea of some acrotretoids.
interspace - Flat or externally concave sectors of shellbetween adjacent costae or costellae.Fig.298,Fig.300.
intertext - See alternate folding.
intertrough - Median, narrowly triangular furrow dividing pseudointerarea of ventral valve of someacrotretoids.Fig.286.
intraplicate - See plicosulcate.
intraseptal lamella - Sheet of prismatic calcite of varying persistency found in median septum of spondylium duplex.Fig.351_2b.
inverted stage - See sulcate.
ismeniform - See diploform.