MOST AUTHORS have classified the butterflyfishes and angelfishes as two subfamilies Chaetodontinae and Pomacanthinae, of the family Chaetodontidae (Woods and Schultz in Schultz et al 1953, Greenwood et al 1966 and Böhlke and Chaplin 1968). Ahl (1923): Weber and de Beaufort (1936), and Marshall (1964) included subfamilies, as Scatophaginae, Drepaninae, etc., within the Chaetodontidae along with Chaetodontinae and .Pomacanthinae, which are presently consIdered as families. Smith (1953, 1955) and Munro (1955, 1967) preferred to use family Chaetodontidae and family Pomacanthidae. None of the above authors gave sufficient supporting evidence to justify their use of a particular classification.
Fraser-Brunner (1945) recognized some of the distinguishing characteristics of the angelfishes (frontal bones forming a concavity between the orbits, the presence of a strong spine at the angle of the preoperculum, the absence of the pelvic axillary process, the distal portions of the ribs normally formed, and a forward ventral expansion of the first interhaemal bone) but continued to use subfamily Pomacanthinae and subfamily Chaetodontinae.
A few workers dealing with certain aspects of the anatomy of fishes have mentioned particular differences between the two groups. Some of them, such as Cockerell (1915, 1916) and Freihofer (1963), were of the opinion that the differences might be enough to warrant full family distinction.
On the basis of the following anatomical and life history differences the two subfamilies should be considered as separate and distinct families.
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