Dauphin of France

The Dauphin was the heir apparent to the throne of France from 1350–1791, and from 1824–1830. 
History.
Guy VIII, Count of Vienne, had a dolphin on his coat of arms and had been nicknamed "le Dauphin" (French for "dolphin"). The title of Dauphin of Viennois descended in his family until 1349, when Humbert II sold his signeurie, called the Dauphiné, to King Philippe VI on condition that the heir of France assumed the title of "le Dauphin" and govern this territory. The Dauphin retained the title only. The estates belonged to the crown. On the death of the Dauphin, his eldest son inherits the title. If there is no son, his oldest brother succeeds him. If the king does not have a son the title does not go to anyone. It is never given to a brother of the king. The wife of the Dauphin was known as the "Dauphine". The first French Dauphin was Charles V. The title is roughly equivalent to the English title "Prince of Wales". The Dauphin was entitled to the use of the style of Royal Highness but this was only ever used in written form.
The title of "Dauphin of Auvergne" was used by the Count of Clermont.