Craig, it's an Infallible Single Selective trigger , not uncommonly found on guns after the turn of the century. I believe Lancaster Arms [or similar] offered them and there was even an office in Suhl. Can't say for sure on the gun itself. Could it be the Facile Princeps design of Greener, sometimes seen made in Germany. I do not see any Anson Deeley cocking lugs.

http://www.bakercollectors.com/