fraction are starburst galaxies, as suggested by their colors.

The relative elemental abundances rather than absolute ones are a valuable diagnostic of the first elemental buildup. This is because absolute abundances are affected by all the model assumptions, whereas abundance ratios generally depend only on the assumed nucleosynthesis and stellar lifetimes. The way of using the information contained in abundance ratios is to compare the observed ratios with predictions from chemical evolution models which take into account detailed stellar nucleosynthesis and lifetimes. As in the Milky Way, we hope to distinguish halo-like abundances, produced by type II SNe and characterized by enhancements of $\alpha$ elements with respect to the iron-peak elements, from disk-like abundances, produced by the cumulative effect of both type Ia and type II SNe, where the abundance ratios become progressively solar. The halo abundance pattern follows from the fact that Fe arises mostly from type Ia supernovae with some contribution from type II, while the reverse is true for Si and O. The longer lifetimes of the SNIa, which are believed to have progenitors with masses of 1-8 M$_{\odot}$, result in a delayed iron enrichment compared to the major SNII products such as $\alpha$-elements (Tinsley, 1980; Greggio 