Glossary of Morphological and Anatomical Terms

vallum - Wall of secondary shell surrounding body and mantle cavities in lyttoniid valves.
varix - See growth line.
vascula - antemyaria, arcuata, cardinalia cruralia, dentalia, media exteriora, media interiora, myaria ventri, spondyliaria, terminalia; Finely divided components of mantle canal.
vascula genitalia - Mantle canals of articulated brachiopods that contain gonads; may consist of vascula dentalia and vascula spondyliaria in ventral valve and vascula cruralia and vascula cardinalia if developed, in dorsal valve.Fig.379.
vascula intermyaria - Posteromedian parts of vasculamyaria, segments passing between anterior and posterior adductor scars, distal continuations of which form vascula myaria exteriora.
vascula lateralia - Laterally located pair of mantle canals developed in both valves of inarticulated brachiopods.Fig.384.
vascula media - Pair of mantle canals in either valve, medially located, projecting anteriorly from body wall.Fig.379.
vascula myaria - Simple or branched pair of mantle canals arising between anterior and posterior adductor muscle scars of dorsal valve of some articulated brachiopods.Fig.379.
vascular markings - Impressions of mantle canals on shell interior.
vascular ridges - See vascular markings.
vascular sinus - See mantle canal.
vascular trunk - Any major branch of mantle canal system.
venter - Median region of productoid shell between lateral slopes.
ventral - Direction toward ventral valve from dorsal valve.
ventral adjustor muscles - See adjustor muscles.
ventral adminicula - See adminicula.
ventral biplicate - See biplicate.
ventral dental socket - See denticular cavities.
ventral process - Median callus of secondary shell underlying pseudodeltidium and projecting dorsally to fit between lobes of cardinal process.
ventral valve - Valve through which pedicle commonly emerges, usually larger than dorsal valve and invariably containing teeth when present.Fig.283.
ventribiconvex - Both valves convex, ventral valve more strongly so than dorsal.
vertical connecting bands - See connecting bands.
vertical plate - Plate of secondary shell more or less in plane of symmetry and borne on echmidium.
vertical zone - Part of valve secreted normal to commissure plane.
vestibule - Subcylindrical prolongation of ventral valve dorsal of dorsal valve.
virgate - Straight and erect.
visceral area - Part of shell enclosing body cavity.
visceral cavity - See body cavity.
visceral disk - Part of shell posterior to origin of trails.
visceral foramen - See dorsal foramen.