The phrase σχῆμα κεὐρυπρωκτίαν presents a crux of textual transmission and comic morphology. The first word σχῆμα (form/appearance) is standard, but κεὐρυπρωκτίαν is a hapax legomenon (or near-hapax) in this specific orthography. The form is a compound of εὐρύς (wide) and πρῶκτος (rump/anus), a grotesque physical description typical of Aristophanic caricature. However, the prefix κε- is highly irregular; it likely represents a corruption of the particle καί (and) due to the following vowel, or a dialectal/colloquial intensifier, though some editors have conjectured the text should read simply εὐρυπρωκτίαν or a related form like εὐρυπρωκτῆς. The syntactic construction functions as an accusative of exclamation or description directed at a character (likely Philocleon), where the adjective is nominalized. The combination of the abstract noun σχῆμα with the obscene, compound adjective creates a jarring comic effect, highlighting the absurdity of the character's physical transformation or behavior.