German Selenus bone set, 4.4" kings; early to mid 1800s?

A delicate bone German Selenus ("tulip") chess set, possibly from early to mid 1800s based on comparison to sets I have seen in other collections. That any of these sets survive is a wonder, as this one arrived to me with several pieces in pieces!

Nice old fitted box, as pictured. The top of the box is inscribed with the owner's name - a Dr Claus W Jungeblut. Dr Jungeblut (1897-1976) was born in Minnesota, USA, but educated at the University of Bern, where he obtained his M.D. in 1921. He was a bacteriologist at the New York State Department of Health, an associate professor at Standford University (1927-1929), and Professor of bacteriology at Columbia University (1929-1962). He conducted some of the first experiments on vitamin C therapy for polio, although Albert Sabin (who developed the polio vaccine) was unable to replicate Jungeblut's results. Whether Claus picked the set up when studying in Europe, or whether it belonged to his mother or father (Gertrude and Nicholas) is unknown.