lemmatizing: θήλεας ἵππους
In the combination θήλεας ἵππους, the first-declension accusative plural in -as, positioned before a vowel, is scanned here as a short rather than long syllable. The attestation of such a form -ăs reflects not dialectal variation but formulaic simplification: an earlier complementary distribution of prevocalic *-ăns (which becomes -ās) and preconsonantal *-ăs is simplified, resulting in occasional instances of prevocalic -ăs.