5. Cylichna simplex, n. sp. Plate XXI, figs. 3, 4.
Shell small, subcylindrical, involute, imperforate, thin and glossy. The sculpture consists of exceedingly fine growth-striæ, with here and there faintly marked growth-periods; the axial
striæ are crossed by equally fine microscopic spiral lines, in places scarcely perceptible. Colour white. Spire sunken, concave, broad and deep, with a minute dome-shaped projection arising from and closing the axial perforation. Protoconch showing as a minute globular central point. Aperture as long as the shell, narrow above, expanded and slighty effuse below. Outer lip almost straight, sharp, rounded at both ends. Inner lip spread as a thin callus over the inner wall, thickening upon the columella, which is uniformly curved and has a slightly reflected rounded margin; the fold imperceptible. Altitude, 4·38 mm.; diameter, 2·21 mm.
Type in the Colonial Museum, Wellington.
Obs. A fair number of dead shells were found. In dimensions and contour this species is near to C. striata, Hutt., but the very different form of the columella at once distinguishes it.