The same gradation is marked in the animal kingdom. The most characteristic feature of the arctic fauna is its dull uniformity. The species are few in number, their forms are regular, and their tints are dusky as the northern heavens. The most conspicuous animals are the reindeer, the white bear, and the various seals; but the most important are the whales, which rank lowest of all the mammals. The preponderance of marine animals clearly indicates an inferior development. The faunas of the temperate regions are much more varied than in the Arctic Zone. Instead of consisting mainly of aquatic tribes, we have a considerable number of terrestrial animals of graceful form, animated appearance, and varied coloring, though less brilliant than those found in tropical regions. It is in the tropics that animal life attains its highest development. The boundless variety of species, the richness of the colors, the diversity of forms, the size and strength of the great pachyderms that people the forests and rivers, the fleetness and vigor of the ferocious denizens of the jungle and the plain, all attest that this is the privileged zone. And here only are found the quadrumanæ, which stand at the head of the animal kingdom. Such, then, is clearly the law of the physical world. "Nature goes on adding perfection to perfection from the polar regions to the Temperate Zone, and from the Temperate Zone to the region of the greatest heat." Animal life increases in strength and development; the types are improved; intelligence enlarges; the form approaches nearer the human figure; the ourang-outang occasionally stands erect; and the presence of the mastoid and styloid processes, the development of the heel-bone, and the form of the pelvis, together with the shape of the ears and a higher frontal development, give the gorilla a startling resemblance to man. Following, then, the ascending series (especially if man be regarded as the lineal descendant of the anthropomorphic apes), we might reasonably suppose that here would be found the proper home and habitat of man, and that the tropical man would be the highest type of humanity, and, physically speaking, the most beautiful of the species. But this, as every one knows, is not the case. While all the types of plants and of animals go on increasing in perfection from the polar to the equatorial regions in proportion to the increase of temperature, "man presents to our view his purest, his most perfect type at the very centre of the temperate continents, at the centre of Asia-Europe, in the region of Iran, of Armenia, and of the Caucasus;, and, departing from this geographical centre in the three grand directions of the lands, the types gradually lose the beauty of their forms in proportion to their distance, even to the extreme points of the southern continents, where we find the most deformed and [physically] degenerated races, and the lowest in the scale of humanity."[391]