Alcadia major is a species of an operculate land snail, terrestrial gastropod mollusk in the family Helicinidae.
(Original description) The shell is depressed ovate and nearly globular, with a smooth, brownish surface. The spire is convex and has a purplish hue on the upper part, while the front is rather convex and pale. The peristome is thickened, white, and reflected, featuring a slight blunt notch near the columellar angle. The inner lip is thickened, convex, and pale.
This species occurs on Jamaica.