PORTUNUS or PORTUMNUS
the protecting genius of harbours among the Romans. He was invoked to grant a happy return from a voyage. Hence a temple was erected to him at the port of the Tiber, from whence the road descended to the port of Ostia. At his temple an annual festival, the Portunalia, was celebrated on the 17th of August.
He was represented with a key in his hand, portus as well as porta signifying a place which can be closed. At the time when the Romans became familiar with Greek mythology, Portnnus was identified with the Greek Palaemon.