  Monte Carlo simulations were performed in order to determine the excess
number of clusters b and the average density of clusters n_c for the
two-dimensional "Swiss cheese" continuum percolation model on a planar L x L
system and on the surface of a sphere. The excess number of clusters for the L
x L system was confirmed to be a universal quantity with a value b = 0.8841 as
previously predicted and verified only for lattice percolation. The excess
number of clusters on the surface of a sphere was found to have the value b =
1.215(1) for discs with the same coverage as the flat critical system. Finally,
the average critical density of clusters was calculated for continuum systems
n_c = 0.0408(1).
