Thomas & Henin, their mark registered 4 Oct 1861 at 9 rue des Enfants Rouge (later 77 rue des Archives) and cancelled 16 Aug 1865. Thus, your spoons can be dated quite narrowly to 1861-1865.
The principals, Jacques Hippolyte Thomas & Jean Louis Henin, had actually been partners since 1855 when they jointly acquired the workshop of Jean Baptiste Veyrier-Montagneres (1808-1889). The firm had thence been called Thomas fils aine & Cie., and used Thomas' mark registered since 1845, "HT" with the same device, a rosebud and star (which Thomas himself had acquired from his predecessor, Eugene Theodore Gillot).
Jacques Hippolyte Thomas
Born: 5 Jan 1814, Paris, son of Pierre Eugène Charles Pascal Thomas & Augustine Françoise Perrin
Married: 24 Feb 1842, Paris, to Henriette Charriere
Died: 17 Jul 1893, Paris
Jean Louis Henin
Born: 7 Jan 1815, Courbevoie, Seine [now Hauts-de-Seine], son of Francois Henin & Catherine Henriette Jeru
Married: 21 Oct 1837, Courbevoie, to Elisabeth Belsure
Died: 12 Feb 1905, Montreuil-sous-Bois, Seine [now Seine-St.-Denis]
Thomas retired in 1865 and Henin was joined by his elder brother, Louis-Hippolyte Henin (1807-1889) to become Henin Freres, later the famous Henin & Cie.