  The superconductor-insulator transition in ultrathin films of amorphous Bi
was tuned by an applied magnetic field. A finite size scaling analysis has been
carried out to determine the critical exponent product vz=0.7 for five films of
different thicknesses and normal state resistances. This result differs from
the exponents found in previous experiments on InOx and MoGe films. We discuss
several possible reasons for this disagreement.
