NGC 151. - This galaxy has several points of similarity to NGC 2532 and should probably be classified as an SBb(r). There is a thin nearly complete bright ring and narrow bright arms. In both galaxies the bright blue arms define the spiral pattern better than the dust, which is very difficult to detect when the arms are so thin. The HII regions define the arms fairly well; however, two of the regions brighter in H appear to be interarm objects immersed in the darkest of the dust lanes (these lie to the north of the inner ring). Note the asymmetry of the two arms - the one to the east is relatively regular; the one to the west appears as several fragments rich in HII regions, similar to the appearance of M81.
The velocity of NGC 151 is not in de Vaucouleurs's catalog, but it is assumed to be about 4000 km s-1 because the HII regions appear on the 6650 photograph rather than the 6563 one. If this velocity is correct, the system must be similar in size to NGC 3646 but of a lower luminosity class.