  We investigated the in-plane anisotropy on the resistivity and thermopower of
the Bi_2Sr_2CaCu_2O_{8+\delta} (Bi-2212) and Bi-Sr-Co-O (BiCo) single crystals.
In Bi-2212, the b-axis resistivity is higher than the a-axis resistivity, and
is expressed as a sum of the a-axis resistivity and an additional residual
resistivity. A downward deviation due to pseudogap is observed below a
characteristic temperature T^*, which is isotropic in the form of conductivity.
These results suggest that the modulation structure along the b-axis works as
an anisotropic scattering center, but does not affect the pseudogap formation.
On the other hand, the anisotropy of the resistivity and the thermopower in
Pb-doped BiCo is substantial, probably owing to the misfit structure between
the hexagonal CoO_2 layer and the rock salt Bi_2O_2 layer. However, the
anisotropy in the resistivity in Pb-free BiCo is very small, suggesting that
the in-plane anisotropy is averaged by the modulation structure, whose
direction is tilted by 45 deg from the a- and b-axes.
