Terebratula
in zoölogy and palæontology, the type genus of Terebratulidæ. Shell smooth, convex; beak truncated and perforated; foramen circular; deltidium of two pieces frequently blended; loop very short, simple, attached by its crura to the hingeplate. Animal attached by a pedicle; brachial disk trilobed, center lobe elongated and spirally convoluted. Terebratula proper has three recent species, from the Mediterranean, Vigo Bay, and the Falkland Islands; fossil, 120, from the Devonian onward. Subgenera: Terebratulina, Waldheimia, Meganteris, and Rensselæria, the latter from the Silurian to the Devonian.