κάτεχεν: see on 2.699. A euphemism for death. “They were dead and buried.”
The epith. seems out of place here, but is used only in this connection. — Acc. to this story, both Dioscuri (“Διὸς κοῦροι
”) were dead. The later form of the story made Castor mortal, but Polydeuces immortal; but after the death of Castor, Zeus granted the prayer of Polydeuces that both brothers should be together alternately in heaven and in Hades. cf. Od. 11.299
ff. In post-Homeric times, they became the patron saints of sailors.