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The criterion used to assign objects to this Category is that the spiral arms of the galaxy depart markedly in brightness, width or shape from those usually found in symmetrical, two-armed spirals. A further criterion was that there should be no galaxies of appreciable size nearby or that the peculiarity was such that it could not be readily ascribed to such a companion. The aim was again to select a class of objects from which something could be learned about the physical nature of spiral arms, independently of companions and obvious interactions. It should be emphasized that the present Category is distinct from Category 11: Three-Armed Spirals and Multiple-Armed Spirals, and Category 12: Peculiar Disks. The latter Category deals only with spirals whose main body, not just the arm, is peculiar.

10a. E's with Faint Rings

The first two pages show E's, or galaxies with an apparently old-type stellar population, which have nevertheless very faint, circular rings around them resembling low-surface-brightness, tightly wound spiral arms. Only very deep photography would reveal such features and so there may be more examples of this type which remain undiscovered. On page 10.1, a photograph is shown of AM 0148-472 which was obtained with the 4m CTIO telescope (1421A). To decide whether these are peculiar ellipticals or disk systems (i.e., SO galaxies) will require calibrated surface photometry, but it is clear that had the limiting magnitude of this survey been brighter, many of these objects would certainly have been passed over as being normal ellipticals.