  A recent publication based on ALEPH $\mathrm{e}^+\mathrm{e}^-$ data taken
near the Z resonance reports an excess, near 30 GeV, in the di-muon mass
spectrum for events containing b quarks. In this paper we measure the di-muon
mass spectrum for L3 data with a bottom tag, recorded in the years 1994 and
1995 at the LEP collider at CERN, and compare it to Monte Carlo predictions.
