  We present a new 408 MHz survey (B3.1) carried out with the ''Croce del
Nord'' radiotelescope in Bologna. The survey coordinates limits are $-2^\circ
00^\prime$ to $+2^\circ 15^\prime$ in Dec. and 21h to 24h, 00h to 17h in R.A.,
equivalent to 0.388 sr. The B3.1 is complete to 0.15 Jy but many sources down
to 0.1 Jy are included. Our aim was to select a new and complete sample of
Ultra Steep Spectrum (USS) radio sources, as they proved to be good candidates
to find high-z radiogalaxies and their surrounding protoclusters. The
observations and the reduction procedure are described and the observational
errors are discussed. A cross-identification with the NVSS survey was performed
to obtain the spectral index $\alpha_{408}^{1400}$ and radio size of the
sources. We found no evidence of a change of the spectral index distribution as
radio flux decreases. The B3.1 USS sample contains 185 sources down to 0.1 Jy
and it is about one order of magnitude deeper in flux with respect to the 4C
USS sample. For 146 B3.1 USS sources no optical counterpart was found on the
POSS-I sky survey. A cross-correlation with the FIRST survey gave maps for a
subset of 50 USS sources, and their optical ID search was also made on the
POSS-II, resulting in 39 empty fields
