Lenoir began his studies at Rochefort-sur-Mer visiting Paris at the age of twenty to train at the Ecole des Beaux-Arts. He debuted at the Salon of 1890 and continued to exhibit there throughout his lifetime, receiving distinctions in 1892, 1896 and 1900 that culminated with his being elected to the Legion d'honneur in 1903.
Lenoir's paintings were praised for their high degree of finish, harmonious color and superb draftsmanship. A contemporary of William-Adolphe Bouguereau with whom he may have studied at the Ecole des Beaux-Arts, Lenoir also drew inspiration from Classical sources. In A dance by the sea he evokes the Greco-Roman era through the meticulous depiction of the two-stemmed diaucle flute, the tunic of the musician and the pose of the nymph which derives from antique statuary.