Skeeterbd,
The style of engraving on your Jannsen is known as Corombelle. This from my engraving glossary: A style of decorative engraving usually found on high quality Belgian shotguns that is attributed to Belgian born engraver Hyppolite Corombelle (1871-1943). The Corombelle style of engraving incorporates a background fine English scroll over which is superimposed bouquets of flowers, ribbons and festoons. Hyppolite Corombelle was the father of the late Lyson Corombelle (1894-1971) who was a highly respected gun engraver in her own right. He was also the founder of an engraving school in Bologna, Italy where he lived until his death.
Depending on the vintage of your gun, It may have actually been engraved by one of the Corombelles. I have seen that style engraved on quite a few guns including my Garbi 200 and yours is exceptionally well executed.
