Alaginella vercoi is a species of sea snail, a marine gastropod mollusk in the family Marginellidae, the margin snails.

(Original description) The shell is pyriform with broad shoulders, especially pronounced over the aperture, and features a prominent spire.

The aperture is narrow, widening somewhat towards the squared anterior end.

The outer lip is thick and nearly straight, bending well forward from the shoulder, and has about six denticles near the center of its length on the inner edge.

The columella is somewhat excavated, bearing four folds: the first rises with a strong upward sweep from the base, while the others are less oblique, smaller, and more widely spaced as they ascend.