Let us now consider the different groups of birds. Living birds were formerly divided into two sub-classes--(1) _Ratitae_ (Lat., _ratis_, a raft), and (2) _Carinatae_ (Lat., _carina_, a keel). The first is the small group of flightless, running birds, made up of five living birds, all inhabiting southern lands. These are the Emu and Cassowary of Australia, the Ostrich of South Africa, the Rhea or South American Ostrich, and the Kiwi or Apteryx of New Zealand. Taken together with other evidence, all pointing in the same way, these birds have led scientists to think of a great southern land mass connecting the southern lands, for the Emu did not fly here, nor did the Rhea fly to South America, but they must have reached their present home by a land-bridge not necessarily complete at any one time. As these birds do not fly, they have no big wing-muscles, and so do not need the ridge of bone down the breast. Thus they belong to the sub-class, the members of which have a raft-like breast bone. The other living birds were placed in the sub-class the members of which have a keel on the breast bone for the attachment of the wing-muscles. Recently, however, Pycraft, a leading ornithologist, has proposed to base the division into sub-classes on the characters of the bones of the palate instead of those of the breast-bone. Thus, he places the sixth family of birds--the Tinamous, of South America--with the ratite birds, to form his primitive group--_Palaeognathae_ ("old jaw"), while the members of the old sub-class _Carinatae_, minus the Tinamous, constitute his second division, the _Neognathae_ ("new jaw"). Mr. Gregory Mathews, the first part of whose projected great work on Australian Birds has just come to hand, has followed Dr. Bowdler Sharpe in accepting this classification, so we must follow too, as Mathews' work will probably be our standard for years to come. The large number of Australian birds belonging to this second sub-class is now divided into 20 orders, which with the Emu order, make a total of 21 orders of birds represented in Australia. Now, let us consider the birds in each order. The best-known member of the first Australian order is the Emu, a bird well known to all, though, unfortunately, becoming very rare, so that few persons in the settled districts now enjoy the privilege of seeing an Emu in a wild state. ==== [Page 12] [Illustration: [1] [2] [3] [4] [5]] CLASS.--AVES.--BIRDS. Sub-Class I.--Palaeognathae. Ratitae and Tinamidae. F. 1. _Rheidae_, Rhea, 3 sp. Nl. F. 2. _Struthionidae_, Ostrich, 4 sp.--4(3)E., 1(0)P. (S. Palestine). ORDER I.--CASUARIIFORMES. F. 3. DROMAEIDAE (1), EMU, 1 sp. A. 1 1 =1 Emu=, _Dromaius novae-hollandiae_, A. Stat. r. plains 78 See diagram, second largest living bird; f., smaller. Fruits, grass. F. 4. CASUARIIDAE (1), CASSOWARY, 17 sp. A. F. 5. _Apterygidae_, Apteryx, Kiwi, 6 sp. A. (N.Z.).