MATRI´NUS(Ματρῖνος), a river of Picenum, flowing into the Adriatic, now called La Piomba. Strabo describes it as flowing from the city of Adria, but it is in reality intermediate between Adria (Atri) and Angulus ( Civita S. Angelo). According to the same writer it had a town of the same name at its mouth, which served as the port of Adria. (Strab. 5. p. 241.) Ptolemy also mentions mouth of the river Matrinus next to that of the Aternus, from which it is distant about 6 miles (Ptol. 3.1.20), but he is certainly in error in assigning it to the Marrucini.
[E.H.B]