Adula H. Adams and A. Adams, 1857. Type species (M): Mytilus soleniformis d'Orbigny, 1842. Recent, western South America. Shell elongate, cylindrical. Periostracum thick, dark. Sculpture absent or of irregular wrinkles. Hinge plate thick, edentate or with small dysodont tubercles. There is some doubt as to which species should be assigned to this genus. Adula has been placed as a subgenus of Botula Mörch, 1853, but it is sufficiently distinct to warrant separation. The generic name may be derived from the Latin adulor, to admire; the gender is feminine. Most species are rock borers, excavating deep, narrow shafts, the entrance protected by a mass of agglutinated detritus. The genus is recorded as early as the Miocene. Literature: Dall (1916a), Lamy (1924).