Alcadia affinis is a species of an operculate land snail, terrestrial gastropod mollusk in the family Helicinidae.
(Original description in Latin) This species is similar to Alcadia solitaria <small>(C. B. Adams, 1845)</small>, but the shell is not convex, but arranged in a conical spiral. The outer lip is reflexed, angled below and not split.
This species occurs on Jamaica.