"Russian bassoon" is wrong due to a phonetic mistake. This kind of instrument should be
called "Prussian bass horn" (upright serpent), because it was used very currently at the Prussian army from the end of the 18th century. This one in particular was made in LYON by luthier JEANTET in 1823-27. It has a painted dragon head bell, in the same way as the "buccins" (from the family of the slide trombones). There are also examples with a normal shaped bell.
It was purchased in 2013 to the instrument collector André Bissonnet, in the Paris area. It's made in maple wood and brass, with six finger holes and three keys, and it can be disassembled in four parts plus the crook and the mouthpiece. The instrument is tuned in C (or in D, according to the ancient 390hz tuning, as you can see in the following finger chart), and the fingerings are very similar to the serpent, because it's the next evolutionary step from the military serpent, with an upright shape making easier the utilization at the parades, even riding horses! It has a sweet and projected sound, and the fact of having one is a privilege, because these instruments usually are not played, only showed in the museums like curious objects.