1 Introduction

The use of the Baldwin et al. (1981) or Veilleux & Osterbrock (1987) diagnostic diagrams generally yields an immediate classification of the nuclear emission-line clouds; "transition objects'' exist however, which cannot be classified unambiguously from their line ratios (Heckman et al. 1983; Keel 1984; Veilleux & Osterbrock 1987; Ho et al. 1993a). When observed with sufficient spectral resolution, such objects show different profiles for the permitted and forbidden lines (Heckman et al. 1981; Busko & Steiner 1990; Véron et al. 1981a,b; Véron-Cetty & Véron 1985, 1986b).

In a previous paper (Véron et al. 1997, hereafter Paper I), we presented high-dispersion (66 Åmm^-1) spectroscopic observations of 15 "transition objects'' selected for having an ambiguous location on the Veilleux & Osterbrock (1987) diagnostic diagrams, and showed that most of them are in fact "composite". This was done by modelling the $\rm H\alpha$, [N II]$\lambda\lambda$6548, 6583 and/or $\rm H\beta$, [O III]$\lambda\lambda$4959, 5007 emission lines with Gaussian profiles, allowing for the contribution of several components; best fits showed these components to have different line strengths and widths, as the result of the lines being produced in regions that are kinematically and spatially distinct, usually a Seyfert 2 or Liner cloud and a H II region.

We have found in the literature 88 emission-line galaxies located north of $\delta \sim$ -20$^\circ$, with z < 0.100 and B < 17.0, for which the published line ratios gave indication of a "transition'' spectrum, constituting an unbiased sample of such objects. Here we report results for 53 of these galaxies, including seven already observed in Paper I, bringing up to 61 the total number of observed objects, or 70% of our unbiased sample of galaxies with a "transition'' spectrum.