as tr o - ph / 9 71 12 27 19 N ov 1 99 7

We construct a spectral classiication scheme for the galaxies of the Las Campanas Redshift Survey (LCRS) based on a principal component analysis of the measured galaxy spectra. We interpret the physical signiicance of the spectral classes and conclude that they are sensitive to morphological type and the amount of active star formation. In this rst analysis of the LCRS to include spectral types, we nd that the general luminosity function for the survey, expressed as a weighted sum of type-speciic luminosity functions, exhibits a broad shoulder centered on an absolute magnitude of M ?20 in the R-band, a signiicant deviation from the Schechter parameterization. At fainter magnitudes, the slope of this luminosity function rises steadily; at M = ?17:5 it has a value of ?1:1, steeper than predicted in a type-independent analysis. The luminosity functions of the individual spectral types show a smooth steepening of the faint-end slope from +0:5 for early types to ?1:9 for late types. We also nd that for a given spectral type the luminosity function can depend on environment. Speciically, the faint-end slope in the case of early-type galaxies steepens signiicantly with increasing local density. These results, coupled with the known density-dependence of the relative populations of galaxy types, may explain the discrepancy between the luminosity functions of the LCRS galaxies and other redshift catalogs such as the Century Survey (Geller et al. 1997). Furthermore, these results have interesting implications for theories of galaxy formation, for they suggest that galaxies of a given type are, on average, fainter when they are located in high-density regions of the Universe.