A while back, William Annis introduced me to the Oxyrhynchus Papyri project, and I was digging around on the site yesterday. It linked off to a parent site, which contained yet more Oxyrhynchus papyri. In that part of the site was a page called "A Millenium of Documents", (
http://www.csad.ox.ac.uk/POxy/VExhibiti ... ame_hi.htm), and that in turn, three lines from the top, has a picture of a Latin letter (Syneros to ...