This palm-squeezer type pistol was designed by Catello Tribuzio (sometimes spelled Trabuzio) of Turin around 1890. It is a very simple design, including a clever dual purpose ejector that also acts as the sear for firing. This example has a 7.65mm bore, although sometimes these are described as 8mm - whether there were two versions or simply a repeated error in documentation (since there is no ammunition available and I doubt one of these has actually been fired in at least 50 years) is not clear.