  Despite much work, the connection between dwarf elliptical galaxies (dEs) and
dwarf irregulars (dIs) remains unclear. Recently, we found that the surface
brightness profiles (SBPs) of dIs in the near-infrared can be well fitted with
a hyperbolic secant (sech) function. From sech fits, a tight relationship was
derived between the absolute magnitude, central surface brightness, and 21cm
line widths, which amounts to a fundamental plane for dIs. Here we examine how
closely dEs fit into the dI fundamental plane using published data for 22 dEs
in the Virgo cluster and the Local Group. Over a 9 mag interval in absolute
magnitude the dEs fall in the plane defined by the dIs. The outstanding overlap
suggests more than a casual relationship between the two classes.
