Next Contents Previous


In an abstract of the present classification (Bautz and Morgan 1970), an additional Type IV was described. This type has been omitted here, since its discriminant (spirals as brightest members of clusters of galaxies) differs in nature from that used for the other types (degree of contrast of brightest member of cluster).

We are greatly indebted to Dr. G. O. Abell for several discussions, for unpublished information, and for preprints of two of his papers. One of us (W. W. M.) wishes to acknowledge support by a grant from the National Science Foundation.