Huxley.° Some of the " regions " have now to be called subregions, e.g.
(A) Austrogaea, the Australian region in the wider sense,with the Papuan, Australian and New Zealand subregions, including also Polynesia.
The boundaries of the subregions are not well defined.
Both subregions possess, besides others, the following characteristic birds: Ratitae, viz.
So large a portion of the Ethiopian subregion lies between the tropics that no surprise need be expressed at the richness of its fauna relatively to that of the last two subregions we have considered.
Naturally no line whatever can be drawn between the Oriental and the Palaearctic subregions, and many otherwise essentially Indo-Malayan families extend far into the Australian realm, far across Wallace's line, whilst the reverse takes place to a much more moderate extent.