Schema Alcmanĭcum（σχῆμα Ἀλκμανικόν). A name given to the use of a verb in the plural (or dual) number with a noun in the singular when there follows another noun to which the verb has also reference—e. g. in Homer ( Il. v. 774):
ἡ?χι ῥοὰς Σιμόεις συμβάλλετον ἠδὲ Σκάμανδρος. So also Od. xi. 513; Il. xx. 138.The grammarians say that the construction was frequent in the poems of Alcman, whence the name.