  We give a classification of heavy Majorana neutrino mass matrices with up to
three texture zeroes, assuming the Dirac masses of the neutrinos to be of the
same form as the ones of the up-quarks in the five texture zero solutions for
the quark matrices. This is the case for many unified and partially unified
models. We find that it is possible to have solutions which account for the
solar and atmospheric neutrino problems as well as the COBE observations
simultaneously, and we motivate the existence of such solutions from
symmetries.
