The Sonoran region does not appear to us to have great claims to recognition. It shows a mingling of southern with northern forms exactly as might be expected. An Armadillo and _Didelphys_ have, as it is believed, invaded it from the Neogaeic realm; it possesses also the South American genera, _Dicotyles_, _Nasua_, {88} _Conepatus_, _Sigmodon_. On the other hand, the Sonoran genera _Antilocapra_, _Cynomys_, _Procyon_, and the Insectivora _Blarina_ and _Scapanus_, extend further north. Peculiar to this region are only six genera of Rodents, which seems an insufficient reason for raising the Sonoran province to the dignity of a region. Considered from the point of view of numbers of peculiar forms, the Thibetan subregion has more claims to distinction as a region; for confined to that area we have the genera _Nectogale_, _Aeluropus_, _Eupetaurus_, _Pantholops_, _Budorcas_; while by slightly extending its limits, a number of other peculiar forms might be added. Madagascar has distinctly more claims to regional division. Absolutely confined to it are eleven of the seventeen existing genera of Lemurs, the family Centetidae among the Insectivora, which contains seven genera, and another recently discovered and peculiar genus, _Geogale_; it has six peculiar genera of Viverridae; it has five peculiar genera of Rodents. In addition to this it is negatively characterised by the absence of the following typical African animals, Felidae, Proboscidea, Rhinocerotidae, Equidae, Monkeys, etc. It seems to be impossible to avoid allowing the rank of a region to this part of the world. In separating the Nearctic from the Palaearctic region, stress must be laid rather upon the absence of Asiatic and European forms from North America than upon the existence in the northern half of the New World of many peculiar forms. Peculiar to the Nearctic are the Goat genus _Haploceros_, the Rodents _Erethizon_, _Zapus_, and the family Haplodontidae. The Mole genus _Condylura_ is also restricted to this part of the New World. Even so it has more peculiar forms than the Sonoran. If we add to this the absence of Horses, Antelopes except _Antilocapra_, Pigs, Hyaenas, etc., there are strong grounds for retaining this division. It must be agreed, however, that it comes rather nearer to the Eurasian district than the latter does to the Oriental. The Oriental region has many characteristic animals. It has among the Anthropoid Apes the Orangs and Gibbons; of Old World Apes it has confined to its own area the genera _Semnopithecus_ and _Nasalis_. Of Lemurs there are _Loris_ and _Nycticebus_, and _Tarsius_, representing a family of that order, or even a sub-order. The Galeopithecidae are entirely Malayan. There are many Rodent, Carnivorous, and Insectivorous genera; the Rhinoceroses and the Elephant of this region differ from those of Africa. {89} _Tragulus_ concludes a sample from a very rich list of peculiar forms.