Procrustes, containing nearly 300 species, is almost wholly confined to this region, and would alone serve to distinguish it zoologically from all other parts of the globe. {43} Having given so full an exposition of the facts which determine the extent and boundaries of the Palaearctic region, there is less need of entering into much detail as regards the other regions of the Eastern Hemisphere; their boundaries being easily defined, while their forms of animal life are well marked and strongly contrasted. _Definition and Characteristic Groups of the Ethiopian Region._--The Ethiopian region consists of all tropical and south Africa, to which are appended the large island of Madagascar and the Mascarene Islands to the east and north of it, though these differ materially from the continent, and will have to be discussed in a separate chapter. For the present, then, we will take Africa south of the tropic of Cancer, and consider how far its animals are distinct from those of the Palaearctic region. Taking first the mammalia, we find the following remarkable animals at once separating it from the Palaearctic and every other region. The gorilla and chimpanzee, the baboons, numerous lemurs, the spotted hyaena, the aard-wolf and hyaena-dog, zebras, the hippopotamus, giraffe, and more than seventy peculiar antelopes. Here we have a wonderful collection of large and peculiar quadrupeds, but the Ethiopian region is also characterised by the absence of others which are not only abundant in the Palaearctic region but in many tropical regions as well. The most remarkable of these deficiencies are the bears the deer and the wild oxen, all of which abound in the tropical parts of Asia while bears and deer extend into both North and South America. Besides the large and conspicuous animals mentioned above, Africa possesses a number of completely isolated groups; such are the potamogale, a curious otter-like water-shrew, discovered by Du Chaillu in West Africa, so distinct as to constitute a new family, Potamogalidae; the goldenmoles, also forming a peculiar family, Chrysochloridae; as do the elephant-shrews, Macroscelididae; the singular aard-varks, or earth-pigs, forming a peculiar family of Edentata called Orycteropodidae; while there are numerous peculiar genera of monkeys, swine, civets, and rodents.