Two racing runners. They are likely to be competing in either the standion event, which was a sprint 600 feet long, or the diaulos, which was twice that length. the runners are flanked by either judges or spectators.
Related to the Dolphin Group. Probably Euboean rather than Attic.
The Perseus Project. http://www.perseus.tufts.edu/hopper/artifactBrowser?object=Vase&field=Collection&value=University+Museum%2C+University+of+Pennsylvania.
White, Donald J., Keith R. DeVries, David G. Romano, Irene B. Romano, and Yelena Stolyarik. The Ancient Greek World:The Rodney S. Young Gallery. Philadelphia: University of Pennsylvania Museum of Archaeology and Anthropology, 1995. See: p. 27
Beazley, John D. Paralipomena: Additions to Attic Black-Figure Vase-Painters and Attic Red-Figure Vase-Painters (Second Edition). Oxford: Clarendon Press, 1971. See: p. 200, no. 3
