  It is shown that bright cluster dwarf ellipticals follow a relation between
metallicity and apparent flattening. Rounder dwarfs tend to be more metal-rich.
The evidence is based on colour as well as spectroscopic line-strength data
from the literature. The large scatter of dEs around the mean
metallicity-luminosity relation, usually ascribed to large observational
errors, turns out to be an ellipticity effect. In the magnitude range $-14 \ga
M_B \ga -18$ the metallicity of dEs depends more strongly on ellipticity than
luminosity. A possible explanation is that galaxies with masses around $10^{9}$
$M_{\odot}$ suffered a partial blowout of metal-enriched gas along their minor
axis, rendering ellipticity a critical parameter for metallicity (De Young &
Heckman 1994).
