Sir Richard C. Jebb, Commentary on Sophocles: Electra

ἐν τούτοισι. Nauck pronounces “ἐν” ‘impossible,’ and writes ἐπὶ (‘in addition to’). There would be force in this objection, if the poet were enumerating the competitors as drawn up in line. But we cannot assume that the order of mention here is identical with the order fixed by lot for the start (709 f.); indeed, the chances would have been against the two “Λίβυες” being next each other. The Homeric narrative of the chariot-race illustrates this; for the order in which the five competitors are first enumerated ( Il. 23. 288—350) differs from that in which they are afterwards placed by lot for the start (ib. 352—357). Therefore “ἐν τούτοισι” may well mean, ‘among these,’— the competitors being here imagined as a group.

Θεσσαλὰς … ἵππους. Thessaly owed its fame as a horse-breeding country to (1) its level plains, the best in Greece for that purpose; and (2) the reliance of the wealthy oligarchies upon cavalry (cp. Arist. Pol. 4. 3. 3). An oracle ap. schol. Il. 2. 761 recommends “ἵππον Θεσσαλικὴν Λακεδαιμονίαν τε γυναῖκα”. Helen, says Theocritus, is an ornament to her company, such as “ἢ κάπῳ κυπάρισσος, ἢ ἅρματι Θεσσαλὸς ἵππος” (Idyll. 18. 30). Lucan 6. 396 “Primus ab aequorea percussis cuspide saxis | Thessalicus sonipes, bellis feralibus omen, | Exsiluit.” The Thessalian cavalry was reputed “ἀρίστη τῶν ἐν Ἕλλησι” ( Her. 7. 196). Thessalian skill in riding and driving was proverbial (Plat. Hipp. ma. 284 A: Isocr. or. 15. § 298).