'Besson-forme horn' (?). Nominal pitch: F|/|E♭|/|D.

https://images.is.ed.ac.uk/luna/servlet/iiif/UoEart~2~2~81793~185995/full/,150/0/default.jpghttps://images.is.ed.ac.uk/luna/servlet/iiif/UoEart~2~2~81794~185994/full/,150/0/default.jpg