This was a reasonably common style in the 30s, as luibargi says. Could be a Continental-Eastman Recomar (which were manufactured in Stuttgart), a Porst/Hapo, the Bona mentioned above, or probably a half dozen other cameras that were very similar. If I had to guess, I'd say it's probably a Porst - perhaps the Spezialmodell T.

http://www.kamera-geschichte.de/file...5x9_1930_d.htm

Google says Walter Tabot was a camera dealer in Berlin in the early 1900s, which jives with my understanding of labeling cameras in Germany at the time.