Gaius Plinius Secundus, HN  35.114 (ca. A.D. 65):

Parva et Callicles fecit, item Calates comicis tabellis, utraque Antiphilus. Namque et Hesionam nobilem pinxit et Alexandrum ac Philippum cum Minerva, qui sunt in schola in Octaviae porticibus, et in Philiippi Libertum patrem, Alexandrum puerum, Hippolytum tauro emisso expavescentem, in Pompeia vero Cadmum et Europen.

Callicles also made small pictures, and so did Calates of subjects taken from comedy; both classes were painted by Antiphilus, who executed the famous picture of Hesione, and an Alexander and a Phillip with Athene which are now in the school in Octavia's Porticoes, and in Philippus' Portico a Father Liber or Dionysus, a Young Alexander, a Hippolytus alarmed by the Bull rushing upon him, and in Pompeius' Portico a Cadmus and Europa. (H. Rackham, trans.)