New Zealand avifauna by recognising endemic genera to include the older elements. Latterly, the opposite process, synthesis of related forms into wide genera to emphasize relationships, has resulted in the dropping of many names long current. Both these attitudes to systematics have made important contributions, and if both sets of conclusions can be crystallised in the nomenclature, so much the better. Subgenera have traditional sanction in zoological nomenclature, and, though avoided by some contemporary workers, are used by James Lee Peters in his Checklist of the Birds of the World, which is likely to remain a standard work for some considerable time. Their citation is desirable in the full formal name of a bird, wherever the name is to be used as a basis for phylogenetic or zoogeographic discussion—i.e., in faunal lists generally, though not necessarily in field guides, in life history studies, or on specimen labels. The nomenclature here adopted is an attempt to indicate both the affinities and distinctness of the New Zealand robins: it is unlikely to appeal to all other students, some of whom will prefer to retain Miro as a full genus, others of whom may drop the name altogether and list the robins as Petroica. Such variations merely emphasize the subjective nature of supraspecific categories. The most important innovation in the present paper is the attempt to indicate in the nomenclature the diverse affinities of the two black forms, Petroica macrocephala dannefaerdi Roths, and Petroica (Miro) traversi Buller. Affinities: With one exception, the structural characters that distinguish the species grouped as Miro are all found, chiefly to a lesser degree, in one or more of the forms of Petroica s.str. The exception is the emarginate or cut away 7th primary, a feature not seen at all in Petroica s.str. This is directly connected with the rounder wing of Miro. (Ticehurst, 1938). Primitive characters of Petroica, present in Miro, are the general plumage pattern, the small, white frontal spot, yellow soles of feet, streaked fledgling plumage, slightly graduated tail, and persistent alar bar. The specialised characters of Miro, large size, loss of tail pattern, reduction of alar bar, loss of sexual dimorphism (through adoption of retarded plumage by males) and the structural characters, are all approached in one or other species of Petroica (s.str.). The species of Miro, can indeed be regarded as a branch of Petroica which have undergone some of the same changes, but to a greater degree, during lengthy isolation in New Zealand, as have species and subspecies of Petroica which have colonised islands at more recent dates. This topic is elaborated in another section. Petroica (Miro) australis (Sparrm.) New Zealand Robins. Characters: Large races of the subgenuus Miro with cream, pale yellow, or whitish breasts and dusky dorsal colouration; frontal spot present; wing with reduced alar bar; primary formula 2 = 8/9,* Rarely 2 = 9/10 (usually 5>6 = 4>3>7>8>2>9 >10); first primary 52–57% of second; tarsus long, 37–42% of wing. Soft parts: tarsi mauvish horn; soles of feet lemon yellow: rictal membrane and interior of mouth yellow; iris very dark brown (Mamakn).