Key points are not available for this paper at this time.
A classification of clusters of galaxies based on the relative contrast of the brightest member galaxy is described. Clusters containing a supergiant D galaxy define Type I; at the other extreme (Type III) are clusters which contain no members significantly brighter than the general bright population. A list of seventy-six clusters classified according to the present system is included.
Bautz et al. (1970) studied this question.