On the basis of a sample of Virgo cluster galaxies in a larger set of heterogeneous literature data, it is shown that ellipticals, early-type dwarfs, and bulges of S0s and of spirals form two distinct families in the plane of the effective parameters, R(e) and mu(e). The 'ordinary' family is composed of all galaxies fainter than MB of about -19.3. Their effective parameters range over a wide interval for the same total luminosity: R(e) varies by at least 0.7 dex and mu(e) by 3.5 mag. The 'bright' family is composed of the brightest cluster members and the host galaxies of QSOs. Their effective radii extend up to about 300 kpc, and are directly related to the effective surface brightness: mu(e) of about 3 log R(e)+constant. It is suggested that the objects belonging to this family have undergone merging phenomena.