  Let S be the variety of irreducible sextics with six cusps as singularities.
Let W be one of irreducible components of W. Denoting by M_4 the space of
moduli of smooth curves of genus 4, the moduli map of W is the rational map
from W to M_4 sending the general point of W, corresponding to a plane curve D,
to the point of M_4 parametrizing the normalization curve of D. The number of
moduli of W is, by definition the dimension of the image of W with respect to
the moduli map. We know that this number is at most equal to seven. In this
paper we prove that both irreducible components of S have number of moduli
exactly equal to seven.
