Founded in 1881 in Saint Etienne by a gentleman named Regis Darne, this company manufactures double-barrelled rifles and shotguns. What makes them unique among dozens of other European hunting arms manufacturers is the rather unusual sliding breech and tilt lever locking mechanism of their guns.
Unlike other double-barreled designs, barrels of this action are fixed in the receiver. In order to open the action, you need to raise the lever behind the breech and pull the breech block backward. The advantages of this action are probably the higher accuracy and more consistent patterns due to fixed barrels. The fixed barrel design should also ensure consistency of the patterns over the years of use.
Here is a video (in French) showing how this action works:
I wonder if this action can be made magazine fed with two rounds resting in a magazine below the action. Perhaps this sounds like a heresy for the fans of this brand, but it could make the action even more interesting. I assume at least with smaller gauges such layout is possible.
Interesting fact: Darne was contracted to manufacture Lewis aircraft machine guns. From 1915 to the end of the WW1, they made 3,266 machine guns. During the interwar period (from 1918 to mid-1930s) they manufactured about 11,000 Lewis machine guns.
The top image is by losgi.com, other images are from the manufacturer’s website.