We have conducted bivariate and multivariate statistical analysis of data measuring the integrated luminosity, shape, and potential depth of the Einstein sample of early-type galaxies (presented by Fabbiano et al. 1992). We find significant correlations between the X-ray properties and the axial ratios (a/b) of our sample, such that the roundest systems tend to have the highest L_X_ and L_X_/L_B_. The most radio-loud objects are also the roundest. We confirm the assertion of Bender et al. (1989) that galaxies with high L_X_ are boxy (have negative a_4_). Both a/b and a_4_ are correlated with L_B_, but not with IRAS 12 micron and 100 micron luminosities. There are strong correlations between L_X_, Mg_2_ and σ_v_ in the sense that those systems with the deepest potential wells have the highest L_X_ and Mg_2_. Thus the depth of the potential well appears to govern both the ability to retain an ISM at the present epoch and to retain the enriched ejecta of early star formation bursts. Both L_X_/L_B_ and L_6_ (the 6 cm radio luminosity) show threshold effects with σ_v_ exhibiting sharp increases at log (σ_v_)~ 2.2. Finally, there is clearly an interrelationship between the various stellar and structural parameters: The scatter in the bivariate relationships between the shape parameters (a/b and a_4_) and the depth parameter (σ_v_) is a function of abundance in the sense that, for a given a_4_ or a/b, the systems with the highest σ_v_ also have the highest Mg_2_. Furthermore, for a constant σ_v_ disky galaxies tend to have higher Mg_2_ than boxy ones. Alternatively, for a given abundance, boxy ellipticals tend to be more massive than disky ellipticals. One possibility is that early-type galaxies of a given mass, originating from mergers (boxy ellipticals), have lower abundances than "primordial" (disky) early-type galaxies. Another is that disky inner isophotes are due not to primordial dissipational collapse, but to either the self-gravitating inner disks of captured spirals or the dissipational collapse of new disk structures from the premerger ISM. The high measured nuclear Mg_2_ values would thus be due to enrichment from secondary bursts of star formation triggered by the merging event.
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Eskridge et al. (1995) studied this question.