Spergo sibogae

The 9 remaining whorls are moderately convex, slightly excavated below the conspicuous but shallow suture.

The sculpture consists of remote, oblique, axial ribs, conspicuous in the upper whorls, fainter lower on, disappearing on the back of the body whorl.

They form tubercles below the excavation, which in the upper whorls bear short plicae, just below the suture.

The peristome is damaged according to the fine growth-lines, with a very shallow sinus above, then regularly arched.

The columellar margin is concave above, then nearly straight, at last slightly directed to the left, covered with a layer of enamel, which is thin above, stronger below.