  A Higgs sextet is introduced in order to generate Dirac and Majorana neutrino
masses in the 331 model with right-handed neutrinos. As will be seen, the
present sextet introduction leads to a rich neutrino mass structure. The
smallness of neutrino masses can be achieved via, for example, a seesaw limit.
The fact that the masses of the charged leptons are not effected by their new
Yukawa couplings to the sextet is convenient for generating small neutrino
masses.
