  We present CCD images of a sample of 39 HII galaxies taken at the Danish
1.54m telescope on La Silla. The images are used to analyse the morphology of
these emission line dwarfs, and the structural properties of the knots of star
formation and of the underlying galaxy. The sizes of the starbursts are
measured. We propose a morphological classification based on the presence or
absence of signs of tails, extensions, or distorted outer isophotes. This
criterion segregates the objects into two broad morphological types with
different physical properties: the more disturbed and extended (type I) HII
galaxies having larger luminosities and velocity dispersions than the more
compact and regular (type II) objects. The relative position of HII galaxies
and of a sample of dwarf elliptical galaxies in the [R -- sigma] diagram
support the hypothesis of a possible evolutionary link between the two types of
galaxy.
