Scraped groove on top of foot. Graffito on floor and under foot: ΔΕ, ligatured. There are many cups of this shape from the same deposit; of the following, several carry graffiti: P 5116 Hesperia, V, 1936, ... 470-460 B.C.
Black glaze vicup with graffito ... Horizontal (normal)
Black glaze vicup with graffito ... AMS Horizontal (normal)