These "X" style chairs are variations on the design of armchairs known as Savonarola chairs. Whereas the latter have the X and the folding mechanism running from side to side, these chairs, without arms, have the X and folding mechanism from front to back. They are narrower in the seat and back than the armchair design but still display intricate carving and scrollwork on the rail which forms the top piece of the back.
Reference
Ader-Tajan, Collection Bruno Perrier Haute Epoque (Catalog for Sale at Auction on April 6, 1992 at the Hôtel Drouot, Paris); Boccador, Jacqueline, Le Mobilier Français du Moyen Age à la Renaissance, Editions d'Art Monelle Hayot (Saint-Just-en-Chaussée, 1988)
Uses
These chairs complement any other Renaissance or Medieval items in a room.