INTRODUCTION Hardly any group of birds is of a greater interest to the zoogeographer and to the student of evolution and speciation than the family of the Zosteropidae. It was with the fact in mind that no conclusions as regards these fields of investigation could be drawn without the reliable base of a good classification that Stresemann (1931) 1) undertook a revision of the IndoAustralian members of the family. Stresemann's revision is a pioneer work that will long remain the base for any further work in the group. Since 1931, however, 45 further names have been given in the Indo-Australian group of the Zosteropidae, adding two valid species and about 25 valid races to the number already known. Though several partial revisions have greatly elucidated some obscure points in our knowledge in recent years (Mack, 1932; Mayr, 1933; Bartels Jr., 1937; Stresemann, 1939; Mayr, 1944), no comprehensive paper has appeared since 1931. Moreover, Stresemann's was only a first attempt at classification, being barely more than a check-list of species and races. Now the time seems ripe for giving a full account of every described form, including its life-history, and with particular reference to the great gaps still existing in our knowledge of even the commonest forms. Originally I intended to revise the family as a whole, but at an early stage of the investigations it appeared that Mr. Moreau was reviewing the African group of species. As a consequence, the present work is confined to the non-African members of the family, hence, it covers the same geographic area as Stresemann's paper.