  Quantitative structural analysis of the galaxies present in the Hawaiian Deep
Fields SSA13 and SSA22 is reported. The structural parameters of the galaxies
have been obtained automatically by fitting a two-component model (Sersic
r^{1/n} bulge and exponential disc) to the surface brightness of the galaxies.
The galaxies were classified on the basis of the bulge-to-total luminosity
ratio (B/T). The magnitude selection criteria and the reliability of our method
have been checked by using Monte Carlo simulations. A complete sample of
objects up to redshift 0.8 has been achieved. Spheroidal objects (E/S0)
represent ~33% and spirals ~41% of the total number of galaxies, while mergers
and unclassified objects represent ~26%. We have computed the comoving space
density of the different kinds of objects. In an Einstein-de Sitter universe a
decrease in the comoving density of E/S0 galaxies is observed as redshift
increases (a ~30% less at z=0.8), while for spiral galaxies a relatively quiet
evolution is reported. The framework of hierarchical clustering evolution
models of galaxies seems to be the most appropriate to explain our results.
