Incorporating birefringence the Brillouin scattering kinematics of off-axis pure transverse (T1), quasi-transverse (T2), and quasi-longitudinal (L) phonons in hexagonal crystals has been derived in the case where the optic axis lies in the scattering plane. Numerical results are given for CdS. For T1 four possible diffraction geometries are found in a certain region of phonon frequencies and off-axis angles. Outside this region two scattering configurations are obtained. The directional dependence of the anisotropic collinear diffraction is discussed. It is shown that no lower cut-off frequency occurs for the T1-mode.