  We study the DC transport of finite graphene samples with random gap. Using
Dirac fermions to describe the low-energy physics near the Dirac point, we
employ a generalized Drude form for the conductivity. The latter is constant
for a vanishing average gap but always decreases with increasing sample size
for a nonzero average gap. The asymptotic conductivity of the infinite sample
is either nonzero if the average gap is smaller than a critical value or zero
otherwise. Our results are in agreement with recent numerical calculations of
Bardarson et al..
