Unable to communicate her plight to her father and sisters in any other way, boviform Io writes a message in the dust with her hoof (Met. 1.649-50):
littera pro uerbis, quam pes in puluere duxit,
corporis indicium mutati triste peregit.
Although Ovid is not explicit, commentators sometimes assume that Io writes only her name. For instance, W. S. Anderson (Ovid’s Metamorphoses, Books 1-5, Oklahoma, 1995) writes: “Ingenious Io finds a way to identify herself: by pawing in the earth the two letters of her name.” Others, including A. Barchiesi (Ovidio, Metamorfosi, Volume I, Libri I-II, Fondazione Lorenzo Valla, 2005), find a pun in her name: “Se si imagine che Io scriva il suo nome in lettere greche, si ottiene un forma adatta alle possibilità scrittorie di uno zoccolo nella sabbia: IΩ. Inaco riconosce il messaggio ed esclama ripetutamente me miserum! In effetti però il nome greco assomiglia, fatta salva la quantità della prima vocale, all’esclamazione patetica ἰώ, per cui siamo di fronte a una sorta di gioco di parole translinguistico: me miserum! traduce il messaggio di dolore che è come iscritto nel nome di Io.”
I have long wondered if there another joke involved. A cow who can write either IO or IΩ in the dust does not seem all that impressive: no name could be easier, both in the number of characters and the simplicity of their shapes, and therefore none could be more likely to occur fortuitously in a cow’s hoofprints. Of course, IΩ would be even easier for a mare, who prints Ω whenever she takes a step in soft ground, and either mare or cow makes something like an I whenever she drags her hoof, but an O is simple enough. In short, I would be far more impressed by a cow, or horse, that could write IPHIGENIA or CLYTAEMNESTRA or ALPHESIBOEA in the dust, in either Greek or Latin letters. Unfortunately, although Ovid does not seem the sort to miss a likely joke, or to keep it to himself when he finds one, I can find no evidence in the text that he is joking here about the unimpressiveness of the portent he describes. I may of course have been influenced myself by Anderson’s “two letters of her name”, and the phrasing suggests that the same (modern, if not ancient) joke may have occurred to him, though he does not spell it out.