They are divided into five sub-families, based on the difference in the structure of the segments of the body, absence or presence of a sting, and a few other minor characters. The leading specialists differ somewhat in the sequence of these groups; I follow Forel in placing the _Ponerinae_ at the head of the family; and for a good classification and definition of the genera would refer my readers to Emery’s paper in the “Annales de la Societe Entomologique de Belgique,” Vol. xl., 1896. All our species described before 1858 are listed in Smith’s British Museum “Catalogue of the Formicidae,” where he described a number of new species: Lowne described a number of new species collected in the neighbourhood of Sydney in the Entomologist, Vol. ii., 1865: Mayr in several papers, chief of which are “Myrmecologische Studien,” “Neue Formiciden,” and “Die Australischen Formiciden” added many up to 1876. Emery, Forel, and others have since added to the list; and in Dalla Torre’s great “Catalogue of the Hymenoptera,” published in 1893, all species described up to that date are recorded. I have lately (1905) published a list of Australian species (Miscellaneous Publications No. 889, Dep. Agr. N.S.W.), including all Forel and others have added to our fauna, in which nearly 400 species are recorded, without counting the large number of races and varieties into which some of them are divided. From my own researches I think a great many more will be found when they are systematically collected in the tropical scrubs and the dry districts in the interior, which as yet have hardly been touched. * * * * *