  We show that limit varieties of monoids recently discovered by Gusev, Zhang
and Luo and their subvarieties are generated by monoids of the form $M_\tau(W)$
for certain congruences $\tau$ on the free monoid. The construction $M_\tau(W)$
is a generalization of widely used Dilworth-Perkins construction. Using this
construction, we find explicit generators for Gusev limit varieties and give a
short reproof to the fact that Zhang-Luo limit variety is non-finitely based.
