The Dauphin was the title given the eldest son (crown prince or heir presumptive) of the King of France between 1349, when the County of Dauphine, in southeast, France was sold by treaty to the King of France - and the abdication of Charles X in 1830. It was the French equivalent of the Prince of Wales. The name derives from the coat of arms – containing a dolphin (Fr. dauphin) - of the original counts of the region.