Castor and Pollux in Fausset's Bible Dictionary

The Dioscuri or two mythical sons of the chief idol of Rome and Greece, Jupiter. The tutelary gods of sailors, identified with the phosphoric lights which play about masts and sails. The constellation Gemini, "the Twins." At Cyrene in the region of Africa, adjoining Alexandria, they were especially worshipped. This accords with the Alexandrian vessel that Paul sailed in (Acts 28:11), having as the figure head or painting on the bow these deities, as they may be seen on coins of Rhegium (where the ship touched); two youths on horseback, with conical caps, and stars above their heads.