GEOGRAPHICAL DISTRIBUTION OF ANIMALS. Each great geographical or climatal region of the globe is occupied by some species of animals not found elsewhere. Thus, the ornithorhynchus belongs exclusively to Australia; the sloth, to America; the hippo potamus and camelopard, to Africa; and the reindeer and walrus to the arctic regions; and each of these animals, when left in its natural freedom, dwells within certain limits, to which it always tends to return, if removed by accident or design. A group of ani mals inhabiting any particular region, and embracing all its species, both aquatic and terrestrial, is called its FAr.N.A (q.v.), just as the collective plants of a country are termed its FLORA. There is a close and obvious connection between the fauna of any-place and its temperature, although countries with similar climates are not always inhabited by similar animals; and the soil and vegetation are likewise important factors in determin ing the characters of any special fauna.
The influence of climate is well seen in the distribution of animals in the arctic regions. The same animals inhabit the northern polar regions of Europe, Asia, and America. Thus, for example, the polar bear, whales, seals, and numerous birds, are common to the northern regions of these three continents. In the temperate regions, on the other hand, the types remain the same, but they are represented by different species, still, however, retain the same general features. These general resemblances often led our early American colonists erroneously to apply the names of European. species to the similar, but not identical animals of the New World. Similar differences occur in distant regions of the same continent, within the same parallel of latitude. Thus, as prof. Agassiz has remarked, the animals of Oregon and of California are not the same as those of New England; and the difference, in some respects, is even greater than between the animals of New England and Europe; and similarly, the animals of temperate Asia differ more from those of Europe, with which they are continuous, than they do from those of America, from which they are separated by a large surface of ocean.
Under the torrid zone, we not only find animals different from those occurring in temperate regions, but we likewise meet with a fauna which presents the greatest variety amongst the individuals which constitute it. "The most gracefully propor tioned forms," says Agassiz, are found by the side of the most grotesque, decked with every combination of brilliant coloring. At the same time, the contrast between the animals of different continents, is more marked; and in many respects, the animals of the different tropical faunas differ not less from each other than from those of the tem perate or frozen zones; thus, the fauna of Brazil varies as much from that of Central Africa as from that of the Southern United States. This diversity in different conti nents cannot depend simply upon any influence of the climate of the tropics; if it were so, uniformity ought to be restored in proportion as we recede from the tropics towards the antarctic temperate region. But instead of this, the differences continue to increase —so much so, that no faunas are more in contrast than those of cape Horn, the cape of Good Hope, and New Holland, Hence, other influences must be in operation besides those of climate, etc.—influences of a higher order, which are involved in a general plan, and intimately associated with the development of life on the surface of the earth." If space permitted, we might point out the influence of the natural features of the earth's surface in limiting and separating faunas. A mountain chain or a desert may act as effectually as the depths of ocean in separating one fauna from another. When no such obstacles exist,. one fauna gradually merges into another, without any definite line of denaarkation.
The powers of locomotion possessed by different animals have not—as we might have supposed—any apparent influence on the extent of country over which they range. On the contrary, animals wlum locomotive powers are extremely sinall, as, for example, the common oyster, have a far greater range than some of our fleet animals, such as the MOM.