τὴν μὲν … μετιοῦσαν: 'her (i.e. Medea) the heroes beheld going from her chamber to the chamber of her sister in quest of her.' The passage is a harsh anacoluthon: the verb which should govern τὴν μετιοῦσαν, such as τέτμον or ἐνόησαν, is omitted after the parenthesis (250-52), and a fresh constr. begins in 253. For similar anacolutha v. 4. 435-42, 852.