In "A classification of living and fossil genera of decapod crustaceans" De Grave and colleagues divided Majoidea into six families:[1]
The classification has since been revised, with subfamilies Epialtinae and Mithracinae being elevated to families and Hymenosomatidae being moved to its own superfamily. The family composition according to the World Register of Marine Species is as follows:[2]
There is one fossil family, Priscinachidae, represented by a single species, Priscinachus elongatus, from the Cenomanian of France.[4]