It is a copy of the original 1894 Darne R patent gun, with what appears to be a revision to the safety in the breech block itself, rather than the rocker in the guns lower metal action rails. Typically, an unmarked gun will feature single proof, and is the very definition of a using bird gun. I can't see the bore, but, assuming they are as nice as the rest of the gun, with un-buggered screws and traces of color, think more like $750-1000.
Best,
Ted