Amastra elongata is an extinct species of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the family Amastridae.
The shell is sinistral and sharply turreted, adorned with numerous well-defined longitudinal striae and covered by a brown epidermis. It consists of seven rounded whorls, with a deep and simple suture.
The aperture is ovate, and the columella bears a distinct plication. The outer lip is simple and unadorned. .
This species was endemic to Hawai, occurring on Oahu.