In 1166 Bertram de Verdon [grandson of this Bertram] held two knights' fees in chief. In a return of the knights of Le Mont St-Michel in 1172 there is the entry "Radulfus de Fulgeriis debet unum militem de medietate de Buillun et de Chavei et de quadam parte Olivi. Istud autem servicium debet facere pro eo Bertramnus de Verdum, filius Normanni." The places are Bouillon (Manche, arr. Avranches, cant. Granville) and Chavoy (arr. and cant. Avranches). The entry makes it highly probable that Bertram derived his name from Verdun as above. (Verdun: a fief in par. Vessey, Manche, cant. Pontorson) [The Origins of Some Anglo-Norman Families]