Considerable difference of opinion exists with regard to the best classification of the family, some authorities including most of the species in the typical genus Rhinoceros, while others recognize quite a number of sub-families and still more genera.
The second and third series containing only about 400 species, the Aglypha still present the appalling number of moo species, and even the grouping of this mass into three sub-families does not lighten the task of arranging the chaos, since one of these sub-families contains only one, and the other but a very few species.
This author divides the family into three sub-families: Neodrepaninae, consisting of a single genus and species peculiar to Madagascar; Nectariniinae, containing 9 genera, one of which, Cinnyris, has more than half the number of species in the whole group; and Arachnctherinae (sometimes known as "spider-hunters"), with 2 genera including I I species - all large in size and plain in hue.
Parker recognizes five genera, with about twenty species, which he combines into three sub-families: Dinornithinae with Dinornis, Anomalopteryginae with Pachyornis, Mesopteryx and Anomalopteryx, comprising the comparatively least specialized forms; and Emeinae with the genus Emeus, not to be confounded with the vernacular emeu.
Canu (1892) distinguishes eight sub-families, Longipediinae, Peltidiinae, Tachidii.nae, Amymoninae, Harpacticinae, Idyinae, Canthocamptinae (for which Canthocampinae should be read), and Nannopinae, adding Stenheliinae (Brady) without distinctive characters for it.