  Two dimensional films comprising of Bi clusters ranging in size from 25 to
100 $\mathrm{\AA}$ show an influence of the underlying matrix on normal state
resistivity and the superconducting transition temperature $T_\mathrm{c}$. This
is in contrast to crystalline Bi. Quantum size effects are observed by changing
the deposition temperature, which determines cluster size. These observations
can be attributed to superconductivity at the surface. Implications for the
requirement of a critical number of superconducting clusters before the
establishment of global phase coherence are briefly discussed.
