  We report new B-band CCD surface photometry on a sample of 76 disk galaxies
brighter than B_T = 14.5 mag in the Uppsala General Catalogue of Galaxies,
which are confined within a volume located in the outer part of the Local
Supercluster. With our earlier published I-band CCD and high S/N-ratio 21cm HI
data (Lu et al. 1993), this paper completes our optical surface photometry
campaign on this galaxy sample. As an application of this data set, the B-band
photometry is used here to illustrate two selection effects which have been
somewhat overlooked in the literature, but which may be important in deriving
the distribution function of disk central surface brightness (CSB) of disk
galaxies from a diameter or/and flux limited sample: a Malmquist-type bias
against disk galaxies with small disk scale lengths (DSL) at a given CSB; and a
disk inclination dependent selection effect that may, for example, bias toward
inclined disks near the threshold of a diameter limited selection if disks are
not completely opaque in optical. Taking into consideration these selection
effects, we present a method of constructing a volume sampling function and a
way to interpret the derived distribution function of CSB and DSL. Application
of this method to our galaxy sample implies that if galaxy disks are optically
thin, CSB and DSL may well be correlated in the sense that, up to an
inclination-corrected limiting CSB of about 24.5 mag per square arcsec that is
adequately probed by our galaxy sample, the DSL distribution of galaxies with a
lower CSB may have a longer tail toward large values unless the distribution of
disk galaxies as a function of CSB rises rapidly toward faint values.
