Amastra is a genus of small air-breathing land snails, terrestrial pulmonate gastropod mollusks in the family Amastridae.

[1] Like many Hawaiian land snails, species in this genus have adapted to a specific ecological niche and have evolved in relative isolation.

Many of the species in this genus have become extinct in recent times or have become critically endangered through habitat loss or predation.

The columella features a spiral lamella that penetrates about half a whorl, and is present at all stages of growth observed.

The jaw is vertically striate, and the teeth are arranged in nearly straight transverse rows, exhibiting the typical quadrate form.