For excellent information on French silver standard marks please see the forum’s World Marks pages:
http://www.925-1000.com/Ffrench_marks.html
The maker is Pierre Défontaine, mark PD, symbol a boar’s head (tête de sanglier). Défontaine was a flatware maker working in Paris at 2 rue des Trois-Canettes, then at 31 rue Marmousets beginning in 1813. He first registered a mark in 1708-99, then in 1807. No end date is given, but he was mentioned in the Almanach Azur until 1820.
See Arminjon, v. I, no. 02906, p. 288.