Mayer & Riem
Looks like the Germans made quite a few of these "top venting" pieces. Here are pics of a working Perfecta, tube fed, semi-auto, 6mm blank firing pistol. I auctioned it a while back, I think it fetched about $70. Some info here:
http://www.carl-walther.de/englisch/chronik/
"The sale of the firm to the UMAREX group of companies in 1993 signalized the beginning of a new era in the history of Walther. To be exact, one has to say that the origins of the UMAREX company are also closely related with Walther. In 1937 Walther Riem, a managing executive of Walther at Zella-Mehlis, was given the permission by the management to manufacture a blank-firing pistol which he had designed himself - it was the Perfecta, the best-known weapon of its kind. The Perfecta pistol lead to the foundation of the firm of Mayer & Riem in Arnsberg, from which, after some years, the UMAREX-company evolved, which at first was a marketing company."
The pistol is not really semi-auto, technically, it's just a repeater. The blanks are loaded into the tubular magazine (you can see the domed follower) which is inserted into the grip. Pulling the trigger manually feeds, fires, and ejects the spent blank. Gas is exhausted through the circular vent atop the slide. Subsequent shots eject the blank through the rectangular port behind the vent.
I'd assume the "MaRie" mark on the grip is a conjunction of the firm names Mayer & Riem.
