Gap Sequences and Moduli in Genus 4.
Genus 3 normal coverings of the Riemann sphere branched over 4 points.
In this paper we study the 5 families of genus 3 compact Riemann surfaces which are normal coverings of the Riemann sphere branched over 4 points from very different aspects: their moduli spaces, the uniform Belyi functions that factorize through the quotient by the automorphism groups and the Weierstrass points of the non hyperelliptic families.