The headword is the demotikon, here in the accusative case, of the Attic deme Phegous (phi 261), on which see generally J.S. Traill, Demos and Trittys (Toronto 1986) 126 (superseding The Political Organization of Attica (Princeton 1975) 38); D. Whitehead, The Demes of Attica (Princeton 1975) index s.v.
[1] So the nonsensical transmitted text, with "Frogs," *batra/xwn. In fact there was a single victim, an informer whose name (or nickname) was *ba/traxos, "Frog." See Lysias fr. 61 Sauppe (now 68b Carey OCT), correct in the Suda's source here, Harpokration s.v.