Mangilia semicarinata Pilsbry, 1904 (original combination) Guraleus semicarinatus is a species of sea snail, a marine gastropod mollusk in the family Mangeliidae.

The sculpture consists of many slightly oblique and arcuate longitudinal riblets about as wide as their intervals, and sixteen in number on the body whorl.

These are crossed by spaced spiral threads, about 18 from the shoulder down on the body whorl, a little widened where they pass over the riblets.

The aperture is narrow, Both.lips are slightly arcuate; blunt at the ends, smooth within.

The anal sinus is rather deep and rounded, the varix curving back of it.