My researches in Australia have enabled me to add four other species to the group, three possessing well-defined specific characters, and one, the distinctive markings of which are not so apparent, but which, in my opinion, is equally distinct; the specific characters of some groups of birds are, in fact, so difficult to be determined, both from the similarity of the species and the want of a knowledge of their natural habits, as to cause the naturalist no little trouble and research in properly distinguishing them; and to no group does this remark more strongly apply than to the one under consideration; the ample materials, however, at my command, and the possession of a large number of specimens, the sexes of which have all been ascertained by dissection, and the habits of which have been observed in their native localities, enables me to give as perfect an account of this curious group as any I have yet attempted. On a careful examination of the members of this genus, it will be perceived that their relationship to the _Corvidæ_, to which they have been usually assigned, is very remote, their size and colour being, in fact, the only features of resemblance; their whole structure and economy is indeed very different from those of every other bird known, except those of _Gymnorhina_ and _Cracticus_, with which genera they form a very natural group among the great family of _Laniadæ_ or Shrikes. All the species yet discovered are not only peculiar to Australia, but are strictly confined to the southern portion of that continent; their range being limited to the country comprised within the 25th and 40th degrees of south latitude; future research may, however, add both to the number of species and to the extent of their range; still their great stronghold is undoubtedly the most southern portion of the Australian continent, the islands of Bass’s Straits and Van Diemen’s Land.