FranÃ§ois-Auguste Boyer-Callot, who registered this mark in 1865. He was the successor to EusÃ¨be Callot (working 1845-1865), and his company was still in business until at least the end of the 19th century as SociÃ©tÃ© Boyer-Callot. (The device is actually a crowned chalice.)
A set of ice cream spoons in this exact (unnamed) pattern by Boyer-Collet is illustrated on page 110 of David Allen's French Silver Cutlery of the XIX Century. It's a beautiful book, and a must have for any collector of 19th century French flatware.
Hope this helps!