Lewis & Short

1. Vulturnus (Volt-), i, m., a river in Campania, the mod. Volturno, Liv. 8, 11; Verg. A. 7, 729 al.
Hence, Vulturnus (Volt-), a, um, adj., of or belonging to the Vulturnus, Vulturnian: vada, Sil. 12, 521: amnis, Plin. 36, 26, 66, § 194: oppidum, id. 3, 5, 9, § 61.