(Πρώταρχος), an engraver of precious stones, whose name occurs on a very beautiful gem in the Florentine Museum, which represents Eros charming a lion with the harp. Formerly the artist's name was misread Πλώταρχος. (Gal. di Firenz. Gemm. 2.1; Müller, Archäol. d. Kunst, § 391, n. 4.)
[P.S]A Dictionary of Greek and Roman biography and mythology
Smith, William
A Dictionary of Greek and Roman biography and mythology. William Smith, LLD, ed. 1890