This is the second of two patents covering the freaky design of the Marelmo derailleur. The first iteration of the design was a sliding rod system with a fixed main body, much like an early 1950s design. This second iteration mounts the sliding rod on a fancy articulating rig with a sprung pivot. It might have worked quite well - although it certainly doesn't look alluringly petite or feather-light.
Again Giorgio Marchigiano is listed as the inventor.