σαί τ᾽ εἴσ᾽ ἄῤ. The Chorus have known all along that Oed. had married Iocasta, and also that he was the father of the girls (cp. 170, 322); but they are supposed to learn now for the first time that Iocasta was their mother. In the earlier versions of the Oedipus-myth (as in the ) Iocasta bears no issue to Oed.; his children are borne by a second wife, Euryganeia. The Attic poets seem first to have changed this (see Introd. to p. xv). The Chorus would say: "Thine, then, they are by a double tie, at once as children and...as sisters?" but Oed. takes out of their mouths the second name which they shrink from uttering, and utters it himself with terrible emphasis.

κοιναί, by the same mother: cp. 261 n.: so 1 κοινὸν αὐτάδελφον … κάρα.

πατρὸς with ἀδελφεαί only.