Wikipedia
Leptoxis
Leptoxis is a genus of freshwater snails with a gill and an operculum, aquatic gastropod mollusks in the family Pleuroceridae.
Species within this genus inhabit rocky fast-flowing parts of unpolluted and unimpounded mid-sized rivers in the American mid South and the southern Midwest. Species in the subgenus Mudalia inhabit rivers and creeks in the Atlantic drainage.