From the 16th century on the editors of Pomponius Mela's workDe chorographia have corrected thermodon of the MSS for hermus in I. 89, thinking thermodon to be a mistake. However, it is not very probable that the copyist would have made a word half as long again. This makes the author suppose that the original text had a hydronym consisting of hermus + an unknown word. He thinks that the unknown word might have been ostium «mouth (of the river)» and that originally the text read as hermi ostium amnis (the mouth of the river Hermus). A similar construction was used in Mela's work when he described the river of Tagus: tagi ostium amnis (Ш. 8). The similarity does not seem to be coincidental, for, as the author shows, by the time when De chorographia was written, Roman literature had developed a topos putting the Tagus (Spain) and the Hermus (Asia Minor) side by side as two chief auriferous rivers of the West and the East.