(Κερόεσσα), a daughter of Zeus by Io, and born on the spot where Byzantium was afterwards built. She was brought up by a nymph of the place, and afterwards became the mother of Byzas. (Steph. Byz. s. v. Βυζάντιον.) From this story it must be inferred, that Argos had some share in founding the colony of Byzantium, which is otherwise called a colony of Megara. (Müller, Dor. 1.6.9.)
[L.S]A Dictionary of Greek and Roman biography and mythology
Smith, William
A Dictionary of Greek and Roman biography and mythology. William Smith, LLD, ed. 1890