His father Antoine Louis Valentin (born 1784) was a master carpenter working mostly in ebony.
Jean-Marie was assisted by his brother Antoine, as was often the case, and the pulpit was indeed signed "Valentin Frères, Architectes et sculpteurs".
For this work he received a prize in 1888 from the "Salon des Artistes français" where it was shown before installation in the cathedral.
The altar includes a bronze reliquary by Placide Poussièlgue-Rusand and a small terra cotta figure of a hermit by an unknown artist.
Ten years later Valentin produced a similar composition in stone for the Église Sainte-Croix de Saint-Servan (Saint-Malo).
These include the memorial to Abbé Huchet in Saint Malo cathedral, to Aubrée in Vitré, to Fouré in La Guerche de Bretagne and to Meslé at the base of the tower of Notre Dame in Rennes.
He also executed two memorials to Monseigneur Brossay Saint Marc, one in Bourg des Comptes and the other in Rennes cathedral.
For the Basilique Notre-Dame-de-l'Assomption de La Guerche-de-Bretagne, Valentin executed the memorial to Abbé Fourré.
For the Caen Église de Notre Dame, Valentin executed the memorial to the Vénérable Jean Eudes.
Valentin depicts a kneeling Eudes at the feet of the Holy Virgin who holds the Infant Jesus in her arms.
For the Église Notre Dame en Saint-Melaine in Rennes, Valentin executed a memorial to Curé Joseph Meslé in 1873.
In the Métropole Saint-Pierre Rennes work, the cardinal is depicted on his knees, his hands clasped together in prayer.
Those in the nave depicted a "Mère des Douleurs", an "Ecce Homo", John the Evangelist, Francis de Sales, saintes Cecilia and Barbe, and saints Étienne and Godefroy, whilst those in the choir included Aaron and Melchisédech.
For this church in Dinard Valentin created the main altar with a bas-relief depicting Jesus giving communion to his apostles.
For the same church Valentin created the pulpit decorated with three large statues, several statuettes and bas-reliefs.
He is clothed in his great white cloak, his shoulders are covered with his chaperone whilst his head resting on a piece of rock supported by two angels.
The sculpture was shown at the 1888 salon de la société des Artistes Français before being placed in the cathedral.