Genotype: Gegania (Tubena) viola n. sp. Awamoan, Lower Miocene, N.Z.

Shell conic, umbilicate, thin. Protoconch paucispiral, smooth, tilted about 30° from horizontal and with an immersed nucleus; plainly defined by its sinused aperture from short neanic stage which is slightly swollen, develops two keels, and is itself clearly defined from juvenile axially sculptured stage. Spire whorls with two chief keels, a third weaker one soon developing above, and a fourth, still weaker, below. Fine axials which nodulate spirals extend from suture to suture but do not cross base. Umbilicus open, of moderate size, bordered by two cords. Aperture effuse, projecting anteriorly; inner lip gently reflexed.

Tubena differs from Gegania pinguis, also from Tuba striata Lea, in being umbilicate, and in having better developed axial sculpture. The sculpture, indeed, resembles that of Mathildona Iredale, 1929, type M. euglypta Ired. but this shell, besides being imperforate, has a more deviated protoconch and also the shape of Mathilda. Jeffreys did not give an enlarged figure of the protoconch of Gegania and the apex of the shell as portrayed is not unlike that of Tubena; but he described it as “globular and intorted,” again as “bulbous, introverted,” terms that do not well suit Tubena. Cossmann (1895, p. 17, fig. 27) has figured the protoconch of Tuba striata Lea, and this is still more unlike.

Gegania (Tubena) viola n.sp. Plate 26, fig. 14; plate 27, fig. 30.

Shell of moderate size, spire one and a half times height of aperture. Protoconch of little more than one, almost planorbid, tilted whorl, not increasing much in diameter from a fairly large, immersed nucleus. Sculpture: Spire whorls sub-convex, with two distant primary spiral cords, the lower somewhat stronger. The wide inter-