forms,' says Agassiz, are found by the side of the most grotesque, decked with every combination of brilliant colouring. 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 temperate 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 continents cannot depend simply upon any influence of the climate of the tropics; if it were 80, 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, &c.-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 demarcation.

The powers of locomotion possessed by different animals have not-as we might have supposedany apparent influence on the extent of country over which they range. On the contrary, animals whose locomotive powers are extremely small, as, for example, the common oyster, have a far greater range than some of our fleet animals, such as the

moose.

'The nature of their food has an important bearing upon the grouping of animals, and upon the extent of their distribution. Carnivorous animals are generally less confined in their range than herbivorous ones, because their food is almost every where to be found. The herbivora, on the other hand, are restricted to the more limited regions corresponding to the different zones of vegetation.' Similarly, birds of prey, like the eagle and vulture, have a much wider range than the granivorous and gallinaceous birds; but even the birds that wander furthest, have their definite limits; for example, the condor of the Cordilleras, although, from the extreme heights at which he is often seen, he cannot fear a low temperature, is never found in the temperate region of the United States.

A very influential factor is the distribution of aquatic animals in the depths of water. The late Professor Forbes distinctly shewed that we may recognise distinct faunas in zones of different depth, just as we mark different zones of animal and vegetable life in ascending lofty mountains. The zoophytes, molluscs, and even fishes, found near the shore in shallow water, usually differ very materially from those living at the depth of 20 or 30 feet; and these, again, are different from those which are met with at a greater depth. The extreme depth at which animal life, in its lower forins, ceases to exist, is unknown; late researches of Dr Wallich and Alphonse Milne Edwards shew, however, from the evidence of deep-sea soundings, and of pieces of telegraph wire raised from great depths, that the region of animal life extends bathymetrically (to use Professor Forbes's word) further than was anticipated.

Before concluding these general remarks, we must observe that occasionally one or more animals are found in one very limited spot, and nowhere else; as,

for example, the chamois and the ibex upon the Alps. (On this point, the reader should consult Darwin's Journal of Researches, &c., in which it is shewn that the Galapagos Archipelago, consisting of a small group of islands situated under the equator, and between 500 and 600 miles westward of the coast of America, not only contain numerous animals and plants that are found in no other part of the world, but that many of the species are exclusively confined to a single island.)

All the faunas of the globe may be divided into three great groups, corresponding to the three great climatal divisions-viz., the Arctic or Glacial, the Temperate, and the Tropical Faunas, while the two last-named faunas may be again divided into several zoological provinces. Each of these primary divisions demands a separate notice.

ARCTIC FAUNA.-The limits of this fauna are easily fixed, as we include within them all animals living beyond the line where forests cease, and are succeeded by vast arid plains, known as barren lands, or tundras. Though the air-breathing species are not numerous here, the large number of individuals compensates for this deficiency, and among the marine animals we find an astonishing profusion and variety of forms. The larger mammals which inhabit this zone are the white bear, the walrus, numerous species of seal, the reindeer, the musk-ox, the narwal, the cachalot, and whales in abundance. Among the smaller species, we may mention the white fox, the polar hare, and the lemming. Some marine eagles and a few wading birds are found; but the aquatic birds of the family of Palmipedes (the web-footed birds), such as the gannets, cormorants, penguins, petrels, ducks, geese, mergansers, and gulls, abound in almost incredible profusion. No reptile is known in this zone. Fishes are very numerous, and the rivers especially swarm with a variety of species of the salmon family. The Articulata are represented by numerous marine worms, and by minute crustaceans of the orders Isopoda and Amphipoda; insects are rare, and of inferior types (only six species of insects were observed in Melville Island during Parry's residence of eleven months there). Only the lowest forms of mollusca are found, viz., Tunicata and Acephala, with a few Gasteropoda, and still fewer Cephalopoda. The Radiata are represented by numerous jelly-fishes (especially the beröe), by several star-fishes and echini, and by very few polypes.

With this fauna is associated a peculiar race of men, known in America under the name of Esquimaux (q. v.), and in the Old World under the names of Laps, Samoyedes, and Tchuktsches. This race,' says Agassiz, 'differs alike from the Indians of North America, from the whites of Europe, and the Mongols of Asia, to whom they are adjacent. The uniformity of their characters along the whole range of the arctic seas, forms one of the most striking resemblances which these people exhibit to the fauna with which they are so closely connected.'

TEMPERATE FAUNAS.-To the glacial zone, which encloses a single fauna, succeeds the temperate zone, included between the isothermes (or lines of equal mean temperature) of 32° and 74°, characterised by its pine-forests, its maples, its walnuts, and its fruittrees, and inhabited by the terrestrial bear, the wolf, the fox, the weasel, the marten, the otter, the lynx, the horse and ass, the boar, numerous genera and species of deer, goats, sheep, oxen, hares, squirrels, rats, &c.; and southwards by a few representatives of the tropical zone. Considering the whole range of the temperate zone from east to west, Agassiz divides it, in accordance with the prevailing physical features, into-1st, the Asiatic realm, embracing Mantchuria, Japan, China,

Mongolia, and passing through Turkestan into, 2d, the European realm, which includes Iran, Asia Minor, Mesopotamia, Northern Arabia and Barbary, as well as Europe properly so called; the western parts of Asia and the northern parts of Africa being intimately connected by their geological structure with the southern part of Europe; and 3d, the North American realm, which extends as far south as the table-land of Mexico.

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The temperate zone is not characterised, like the arctic, by one and the same fauna. Not only are the animals different in the eastern and western hemispheres, but there are differences in the various regions of the same hemisphere as we before remarked, the species resemble, but are not identical with one another. Thus, in Europe, we have the brown bear; in North America, the black bear; and in Asia, the bear of Tibet; the common stag or red deer of Europe is represented in North America by the Canadian stag or wapiti and the American deer, and in Eastern Asia by the musk-deer; the North American buffalo is represented in Europe by the wild aurochs of Lithuania, and in Mongolia by the yak; and numerous other examples might readily be given.

The marked changes of temperature between the different seasons occasion migrations of animals more in this zone than any other, and this point must not be overlooked by the naturalist in determining the fauna of a locality within it. Many of the birds of Northern Europe and America, in their instinctive search for a warmer winter climate, proceed as far southward as the shores of the Mediterranean and of the Gulf of Mexico. See MIGRATIONS OF ANIMALS.

Amongst the most characteristic of the animals of the Asiatic realm, we may mention the bear of Tibet, the musk-deer, the tzeiran (Antilope gutturosa), the Mongolian goat, the argali, the yak, the Bactrian or double-hunched camel, the wild horse, the wild ass, and another equine species, the dtschigetai (Equus hemionus). The nations of men inhabiting these realms all belong to the so-called Mongolian race.

That the European is a distinct zoological realm, seems to be established, says Agassiz, by the range of its mammalia, and by the limits of the migrations of its birds, as well as by the physical features of its whole extent. Thus we find its deer or stag, its bear, its hare, its squirrel, its wolf and wild cat, its fox and jackal, its otter, its weasel and marten, its badger, its bear, its mole, its hedgehogs, its bats, &c. Like the eastern realm, the European world may be subdivided into a number of distinct faunas, characterised each by a variety of peculiar animals. In Western Asia, we find, for instance, the common camel instead of the Bactrian; whilst Mount Sinai, Mounts Taurus and Caucasus, have goats and wild sheep which differ as much from those of Asia as from those of Greece, the Alps, the Atlas, or of Egypt.' There is no reason for our referring, as many writers have done, our chief domesticated animals to an Asiatic origin. A wild horse, different in species from the Asiatic breeds, once inhabited Spain and Germany, and a wild bull existed over the whole range of Central Europe. The domesticated cat, whether we trace it to Felis maniculata of Egypt or to Felis catus (the wild cat) of Central Europe, belongs to this realm; and whatever theory be adopted regarding the origin of the dog, the European realm forms its natural range. The merino sheep is still represented in the wild state by the mouflon of Sardinia, and formerly ranged over all the mountains in Spain. The hog is descended from the common boar, still found wild over most of the temperate zone of the Old World. Ducks, geese, and pigeons have their wild representatives in

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Europe. The common fowl and the turkey are, on the other hand, not indigenous, the former being of East Asiatic, and the latter of American origin. The reader will observe that the European zoological realm is circumscribed within exactly the same limits as the so-called white race of man.

The American realm contains many animals not found in Europe or Asia, amongst which we may mention the opossum; several species of insec tivora, as, for example, the shrew-mole (Scalop aquaticus) and the star-nosed mole (Condylar cristata), several species of rodents (especially the musk-rat), the Canadian elk, &c., in the northen portion; and the prairie-wolf, the fox-squirrel, &c. in the southern portion of the fauna. Amonst other types characteristic of this zone must reckoned the snapping-turtle among the tortoises the Menobranchus and Menopoma among the sh manders; and the rattlesnake among the serpents; and the Lepidosteus and the Amia, important res sentatives of two almost extinct families, among fishes.

The faunas of the southern temperate region de from one another more than those of the corresp ing northern region. Each of the three contineti peninsulas jutting out southerly into the represents, in some sense, a separate world i animals of South America beyond the tropic Capricorn are in all respects different from those s the southern extremity of Africa. The hy wild boars, and rhinoceroses of the Cape of ba Hope have no analogies on the American conta and the difference is equally great between s birds, reptiles, fishes, insects, and molluses Holland, with its marsupial mammals, with w are associated insects and molluscs no less furnishes a fauna still more peculiar, and wi has no similarity to those of any of the adja countries. In the seas of that continent, the curious shark, with paved teeth and spin the back (Cestracion Philippi), the only representative of a family so numerous in f zoological ages.'

TROPICAL FAUNAS are distinguished in continents by the immense variety of animais they contain, and in many cases by the bril their colour. Not only are all the principal: of animals represented, but genera, spate, individuals occur in abundant profusion tropical is the region of the apes and monkeys 1 seem to be naturally associated with the us tion of the palms, which furnish to a great the food of the monkeys on both contin herbivorous bats, of the great pachyderma the elephant, the hippopotamus, and the tap of the whole family of edentata. Here, to largest of the cats, the lion and the tiger. A birds, the parrots and toucans are ess tropical; amongst the reptiles, the largest crocodiles, and tortoises belong to this also do the most gorgeous insects. fauna is also superior in beauty, size, and to those of other regions. The tropical each continent furnishes new and pecular Sometimes whole types are restricted to tinent, as the sloths, the toucans, and the b birds to America; the gibbons, the re the royal tiger, and numerous peculiar 5 Asia; and the giraffe and hippopotamus & while sometimes animals of the same gro different characteristics on different Thus, for example, the American monkeys and widely separated nostrils, thirty-six generally a long prehensile tail; while the of the Old World have their nostrils chos only thirty-two teeth, and non-prehensie b

The

The island of Madagascar has its peculiar fauna. A large number of species of quadrumana, cheiroptera, insectivora, &c., are found only in this island; and of 112 species of birds that have been described, 65, or more than half, are found nowhere else. We have already referred to the still more exclusive fauna of the Galapagos Islands, which has been specially studied by Darwin.

From a general survey of such facts as we have given in a very condensed form in the preceding columns, Agassiz draws the following conclusions: 1. Each grand division of the globe has animals which are either wholly or for the most part peculiar

to it.

2. The diversity of faunas is not in proportion to the distance that separates them. Very similar faunas are found at great distances apart, while very different faunas are found at comparatively short distances.

3. There is a direct relation between the richness of a fauna and the climate, and likewise between the fauna and the flora; the limit of the former being oftentimes determined, so far as terrestrial animals are concerned, by the extent of the latter. 4. The distribution of animals cannot (any more than their organisation) be the effect of external influences, but is the realisation of a wisely designed plan, by which each species of animal was originally created at the place and for the place which it inhabits. The only way to account philosophically for the distribution of animals as we now find them, is to regard them as autochthonoi-that is to say, as originating on the soil where they exist. There is not a single fact in favour of, indeed, all scientific observations are in direct opposition to the view, that the whole animal world was created in one single centre.

For further details on this subject, we may refer to the various works of Agassiz, of which we have made free use in the compilation of this article; to Vogt's Zoologische Briefe, vol. ii.; Mrs Somerville's Physical Geography, vol. ii.; Maury's La Terre et Homme; Klöden's Handbuch der Physischen Geographie; and especially to Schmarda's great work on the subject, entitled Die Geographische Verbreitung der Thiere.

GEOGRAPHICAL DISTRIBUTION OF PLANTS, also called GEOGRAPHICAL BOTANY, and PHYTOGEOGRAPHY, is that branch of botany which treats of the geographic distribution of plants, and connects botany with physical geography. A knowledge of facts belonging to it has been gradually accumulating ever since the science of botany began to be studied, but its importance was little understood until very recent times. Humboldt may be said to have elevated it to the rank which it now holds as a distinct branch of science. It was

indeed impossible for botany to be studied without attention being arrested by the great diversity of the productions of different countries, and even of those not very dissimilar in climate. But it was long ere important generalisations were attempted; and a large accumulation of particular facts was in the first place necessary. Even to this day, the deficiency of information concerning the botany of wide regions is painfully felt.

Every climate has plants particularly adapted to it. The plants of the tropics will not grow in frigid, nor generally even in temperate regions; as little will aretic or subarctic plants endure the heat of the torrid zone. And as the climate changes with the elevation above the level of the sea, the mountains of tropical countries have a flora analogous to that of the temperate, and even of the frigid zones. The vegetation of every place bears a relation to its mean annual temperature. But owing to the

peculiarities of different plants, it bears also important relations to the mean temperatures of the summer and winter months; and thus great diversities are found not only in the indigenous vegetation of countries very similar in their mean annual temperature, but even in their suitableness for plants which may be introduced into them by man. Nor is temperature the only thing of importance in the relations of climate to vegetation. Moisture must be ranked next to it. Some plants flourish only in a dry, and some only in a humid atmosphere. The flora of the very dry regions of Africa and of Australia is almost as notably different from that of moist countries in similar latitudes, as that of the temperate from that of the torrid zone. Nor is the difference merely in the species of plants produced, but in the whole character of the vegetation, which very much consists either of succulent plants with thick epidermis, or of plants with hard and dry foliage.

Much depends also on soil. Sandy soils have their peculiar vegetation; peat is also favourable to the growth of many plants which are seldom or never to be found in any other soil. The chemical constitution of soils determines to some extent the character of their flora; and therefore certain plants are almost exclusively to be found in districts where certain rocks prevail, and a relation is established between botany and geology. Limestone districts, for example, have a flora differing to a certain extent from other districts even of the same vicinity. Some British plants are almost entirely limited to the chalk districts. The other physical qualities of the soil are not unimportant. Light soils are suitable to plants with fine roots divided into many delicate fibrils, as heaths, which will scarcely grow in stiff clay.

Sometimes

Some groups of plants are almost entirely limited to peculiar situations, as the Algae and other smaller groups of aquatic plants. Some are exclusively tropical; others are only found in the colder parts of the world; and if any of the group occur within the tropics, it is on mountains of considerable elevation. But besides all this, and apart from all obvious differences of climate, soil, &c., some groups of plants, and these often containing many species, are only or chiefly found in certain parts of the world. Thus the Cactacea are exclusively American; whilst of the numerous species of Heath (Erica), not one is indigenous to America, although many other plants of the Heath family (Erice) are so. the plants which chiefly abound in one part of the world seem to be replaced by other but similar species, sometimes by those of another group, in another part of the world, with similar physical characteristics. Thus Mesembryacea and Crassulacea seem in some countries to occupy the place of the American Cactaceae, whilst the black-fruited Crowberry (Empetrum) of the northern parts of the world finds a representative in a red-fruited species, extremely similar, in the southern parts of South America. Of many groups which chiefly belong to certain climates or certain parts of the world, there are yet species which wander, as it were, into very different climates or remote parts of the world; these species being often, however, unknown where the other species of the group abound. Thus the common periwinkle is a northern wanderer of a family mostly tropical. Some groups are common to parts of the world widely remote, and their prevalence is characteristic of these parts, as Rhododendrons and Magnoliacea of North America and of the mountainous districts of the East Indies, although the American and the Asiatic species are not the same. Some species are believed to exist only within a very narrow range; others are very widely

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