An Italian X-chair (also known by the names Dante, Dantesca, hip-joint, or Savonarola), 16th or 17th century.
 
Height 36", width 25", depth 20"
 
Condition: Structurally in good condition, with an nice old patina.  The wood with normal signs of wear, with typical worm holes (inactive).  The leather seat with wear and cracking, reinforced underneath with later fabric.  The leather back with a small tear at the top left surface, reinforced with a later piece of leather applied on the back.
 
Comparable piece:  A very similar chair is in the collection of the Metropolitan Museum of Art, pictured here, and with more photos at this link:
https://www.metmuseum.org/art/collection/search/461020