  Searches for unstable neutral and charged heavy leptons, N and L+-, and for
excited states of neutral and charged leptons, nu*, e*, mu*, and tau*, have
been performed in e+e- collisions using data collected by the OPAL detector at
LEP. The data analysed correspond to an integrated luminosity of about 58pb-1
at a centre-of-mass energy of 183GeV, and about 10pb-1 each at 161GeV and
172GeV. No evidence for new particles was found. Lower limits on the masses of
unstable heavy and excited leptons are derived. From the analysis of
charged-current, neutral-current, and photonic decays of singly produced
excited leptons, upper limits are determined for the ratio of the coupling to
the compositeness scale, f/Lambda, for masses up to the kinematic limit. For
excited leptons, the limits are established independently of the relative
values of the coupling constants f and f'.
