Phorcus lineatus, common name the lined top shell, is a species of sea snail, a marine gastropod mollusk in the family Trochidae, the top snails.

It is dull grayish, densely marked all over with very numerous fine flexuous or zigzag braided purplish-black lines.

The columella is short, obtusely subdentate near the base, spreading at the insertion into a heavy callous, which covers the umbilicus.

This species is similar to Phorcus turbinatus in form, but usually has the outlines of the spire more convex.

The columella projection or tooth is nearer the base than in the Phorcus turbinatus, and the diverse color patterns will serve to further distinguish the two species.