Your spoons were made by Jules Boivin, maker of small tableware in Paris at 15, rue des Quatre-Fils. He registered his mark on 20 January 1862, erased on 1 February 1881. Jules Boivin was the successor of Nicolas Vautrin, a ring maker.
Jules Boivin was succeeded in turn by his son, Victor Boivin in 1881, and then the company became Boivin Fils in 1897. This family firm won medals at the Universal Expositions of 1867 and 1889, where in 1889 its work was damned with faint praise by the jury, which found the pieces to be of doubtful taste, aimed to please the export market. This criticism certainly doesn’t apply to your spoons!
Hope this helps.
See Arminjon, v.2, no. 02337, p.220,
and David Allan, Le couvert et la coutellerie de table française du XIXe siècle, p.293.