Berceau (barrel vault)

This type of vault has the same cross section across its entire length: an arc en plein cintre (round arch).
In the picture a barrel vault in the Saint-Pierre-et-Saint-Paul in Montceau-l'Étoile.
See also voûte en berceau (synonym).

Voûte en berceau - Wikipedia

Saint-Pierre et Saint-Paul - Montceau-l'Étoile