The 48-inch Sky Survey plates are ideally suited to the classification of the forms of the brighter galaxies; the uniform quality of the plates makes feasible the use of somewhat finer subdivisions than in the case of Paper I. In many cases, much more detail is visible on photographs made with the great reflectors; however, the uniformity of contrast and resolution on the Sky Survey negatives permits intercomparison of different galaxies to be made with high precision.
As a result of this, certain minor modifications were made in the system of Paper I; these are:
In cases where the same galaxy has been classified in Paper I and the present paper, the later type is to be preferred.
A catalogue of 642 galaxies is given in Table I. The types were determined on the blue plates of the Palomar Sky Survey, except in the case of one field where the blue plate was not available. The galaxies classified on the red plate are noted in the remarks to the table. The latter are referred to by an asterisk following the NGC number.
A few galaxies inadvertently omitted from the survey were classified on the glass copies of the Sky Atlas at the Lick Observatory; in addition, one system was classified from the paper print at the Yerkes Observatory.