FWIW, I think that is a Jacob Rupertus pistol. If so, the barrel should be marked "RUPERTUS PAT'D PISTOL MFG. CO. PHILADELPHIA".
From Flayderman: Made c. 1870-1880 in 4 rimfire calibers, .22 (an estimated 500), .32 (1000), .38 (1000) and (reportedly) .41, they are pretty rare, but not very valuable, going for around $600 in good condition. Yours appears to have been much handled and polished, with the corners rounded and the markings nearly removed, so value would probably be in the $200-250 range.
Jim