are classed by some naturalists as species, and by others as sub-species. It is preferable to place them in the former category, as no intermediate forms are certainly known. But in Papua, besides typical Echidna, the family is also represented by its larger brother, Proechidna, with a single well-known species (Proechidna bruijni) and perhaps another species not yet certainly distinguished.

The second family of Monotremes embraces only the excessively anomalous aquatic and fossorial form commonly known as the Duck-bill (Ornithorhynchus anatinus). The Duck-bill occurs in Northern Queensland, and spreads southwards thence into New South Wales, Victoria, and South Australia. It is likewise found in Tasmania, but so far as we know has never yet been obtained in any part of Western Australia.

Table of the Order Monotremata, showing the distribution of the species.

1. The Order of Monotremes contains five species

referable to three genera and two families.

2. It is entirely restricted to the Australian Region.

SECTION VII.-FINAL CONCLUSIONS

Thus we see that whether we take the Mammals in Geographical or in Systematic order, we arrive at nearly the same result-namely, that the best Primary Geographical Divisions of the earth are six in number. Of these the Australian Region (Neogæa), in which the Mammalfauna is pre-eminently Marsupial, and embraces the whole Order of Monotremes, is by far the most distinct. It is, however, also easy to separate the Neotropical Region (Notogæa), with its one family of Marsupials and numerous Edentates. The remaining Regions (Arctoga), may be grouped together, but are still separable-on more slender grounds, it is true, into four divisions - the Ethiopian Region remarkable for its abundant Ungulates, the Giraffe, and the Hippopotamuses, the Oriental known by its Orangs, Gibbons, and Tapir, and the Palearctic and Nearctic, which, no doubt, present many points of similarity as regards their Mammal-faunas, but may nevertheless be properly kept apart. The Nearctic Region, as has been shown above, has been overrun by an inroad from the northern portion of the Old World, but has a strongly developed under-stratum of endemic forms mixed up with some Neotropical types, which are utterly foreign to the Palearctic Region.

INDEX