What is Actio Families Erciscundae?

Legal Definition
An action for the partition of an inheritance. Inst. 4, 6, 20; Id. 4, 17, 4. Called, by Bracton and Fleta, a mixed action, and classed among actions arising ex quasi contractu. Bract, fol. 100b; Id. fols. 448b, 444; Fleta, lib. 2, c. 60, § 1.
-- Black's Law Dictionary