2. M.Mettus, was sent by Caesar at the opening of the Gallic war, in B. C. 58, as legatus to Ariovistus, king of the German league, and was detained prisoner by him, but subsequently rescued by Caesar. (Caes. Gal. 1.47, 53.) The annexed coin, which bears the legend M. Mettius, and has on the obverse the head of Caesar, probably refers to this Mettius.
[W.B.D]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