The first two lines of Mesom. 12 Heitsch, an enigmatic description of the Sphinx, are usually emended for metrical reasons. This paper proposes that these verses may not need correction as they could hide a metaliterary pun. If we preserve the text, the ionic metre contrasts with the anapaestic rhythm of the following lines, and consequently corresponds to the “spurious foot” (νόθον ἴχνος, v. 2) of the Sphinx herself. This wordplay based on the double meaning (anatomical and metrical) of words concerning feet can be fruitfully compared to analougus poetic games in other Greek poems (above all Simias’ Egg).