Originally he was an Italic god paired with Salacia, possibly the goddess of the salt water. At an early date (399 BC) he was identified with Poseidon, when the Sibylline books ordered a lectisternium in his honour (Livy v. 13).In earlier times it was the god Portunes or Fortunus who was thanked for naval victories, but Neptune supplanted him in this role by at least the first century BC, when Sextus Pompeius called himself "son of Neptune".Neptune was associated as well with fresh water, as opposed to Oceanus, god of the world-Ocean .Like Poseidon, Neptune was also worshipped by the Romans as a god of horses, under the name Neptune Equester, patron of horse-racing