Anomalous Electron Pair and Muon Pair Events Produced in Electron Positron Annihilation.

We have observed events where an electron and a positron annihilate to form electron pairs or muon pairs and in which there are no other detected particles and there is substantial missing energy; and which cannot be explained by conventional electromagnetic interactions. We show that these events can be explained as the decay products from the pair production of a new charged lepton, the Tau, of mass 1.9 GeV/c('2). Some properties of these events are presented.