geological period, remains of marsupials, some insectivorous, as Spalacotherium and Triconodon, others with teeth like the peculiar premolars in the Australian genus Hypsiprymnus, have been found in the upper oolite of the Isle of Purbeck*. In the lower oolite at Stonesfield, Oxfordshire, marsupial remains have been found having their nearest living representatives in the Australian genera Myrmecobius and Dasyurus.

Thus, it would seem, that the deeper we penetrate the earth, or, in other words, the further we recede in time, the more completely are we absolved from the present laws of geographical distribution. In comparing the mammalian fossils found in British pleistocene and pliocene beds, we have often to travel to Asia or Africa for their homologues. In the miocene and eocene strata some fossils occur which compel us to go to America for the nearest representatives. To match the mammalian remains from the English oolitic formations, we must bring species from the Antipodes.

These are truly most suggestive facts, unrecognized until science looked abroad upon the world. If the present laws of geographical distribution depend, in an important degree, upon the present configuration and position of continents and islands, what a total change in the geographical character of the earth's surface must have taken place since the 'Stonesfield slate' was deposited in what now forms the county of Oxfordshire !

These and the like considerations from the modifications of geographical distribution of particular forms or groups of animals warn us how inadequate must be the phenomena connected with the present distribution of land and sea to guide to the determination of the primary ontological divisions of the earth's surface. Some of the latest contributions to this most interesting branch of Natural History have been the result of endeavours to determine whether, and how many, distinct creations of plants and animals have taken place. But, I would submit, that the discovery of two portions of the globe, of which the respective Faunæ and Floræ are different, by no means affords the requisite basis for concluding as to distinct acts of creation.

Such conclusion is associated, perhaps unconsciously, with the idea of the historical date of creative acts: it presupposes that the portion of the globe so investigated by the botanist and zoologist has been a separate and primitive creation, that its geographical limits and features are still in the main what they were when the creative fiat went forth.

But Geology has demonstrated that such is by no means the case with respect to the portions of dry land now termed continents and islands. The incalculable vistas of time past into which the same science has thrown light are also shown to have been periods during which the relative positions of land and sea have been ever changing.

Already the directions, and to a certain extent the forms of the submerged tracts that once joined what now are islands to continents, and which once united now separate or nearly disjoined continents by broad tracts of conti* These fossils are due to the researches of Messrs. Brodie and Beckles.

nuity, begin to be laid down in geological maps, addressing to the eye such successive and gradually progressive alterations of the earth's surface.

These phenomena shake our confidence in the conclusion that the Apteryx of New Zealand and the Red-grouse of England were distinct creations in and for those islands respectively. Always, also, it may be well to bear in mind that by the word 'creation,' the zoologist means 'a process he knows not what.' Science has not yet ascertained the secondary causes that operated when "the earth brought forth grass and herb yielding seed after its kind," and when "the waters brought forth abundantly the moving creature that hath life." And supposing both the fact and the whole process of the so-called 'spontaneous generation' of a fruit-bearing tree, or of a fish, were scientifically demonstrated, we should still retain as strongly the idea, which is the chief of the 'mode' or 'group of ideas' we call 'creation,' viz. that the process was ordained by and had originated from an all-wise and powerful First Cause of all things.

When, therefore, the present peculiar relation of the Red-grouse (Tetrao scoticus) to Britian and Ireland-and I cite it as one of a large class of instances in Geographical Zoology-is enumerated by the zoologist as evidence of a distinct creation of the bird in and for such islands, he chiefly expresses that he knows not how the Red-grouse came to be there, and there exclusively; signifying also, by this mode of expressing such ignorance, his belief that both the bird and the islands owed their origin to a great first Creative Cause.

And this analysis of the real meaning of the phrase 'distinct creation' has led me to suggest whether, in aiming to define the primary zoological provinces of the globe, we may not be trenching upon a province of knowledge beyond our present capacities; at least in the judgment of Lord Bacon, commenting upon man's efforts to pierce into the dead beginnings of things.'

This at least is certain, that, being aware of former operations requiring to be well understood before we can draw conclusions as to other facts related to the unknown operations, one writes to no purpose in affirming conclusions without such preliminary knowledge.

Thus, the changing level of the land part of the earth's crust, throughout geological time, leads to the recognition of the present shape and size of continents and islands as being recent and temporary.

We feel that there have been phenomena attending, for example, the actual flow of continuous ocean between Ireland and Newfoundland, the nature and succession of which should be known in order to enable us to comprehend the causes or conditions of the present differences between the Flora and Fauna of those islands respectively: and so of every other part of dry land now circumscribed by sea.

All affirmations as to the time, place, and kind of origin of the organisms of a so circumscribed land, in the absence of a knowledge of the causes and conditions of such circumscription, must be guess-work.

It is a part of sound knowledge to be able to recognize the subjects regarding which we have not, at present, the basis of true assertion.

On the few occasions in which I have been led to offer observations on the probable cause of the extinction of species, the chief weight has been given to those gradual changes in the conditions of a country affecting the due supply in sustenance to animals in a state of nature, I have also pointed out the characters in the animals themselves calculated to render them most obnoxious to such extirpating influences; and on one occasion * I have applied the remarks to the explanation of so many of the larger species of particular groups of animals having become extinct, whilst smaller species of equal antiquity have remained.

In proportion to its bulk is the dificulty of the contest which, as a living organized whole, the individual of such species has to maintain against the surrounding agencies that are ever tending to dissolve the vital bond and subjugate the living matter to the ordinary chemical and physical forces. Any changes, therefore, in such external agencies as a species may have been originally adapted to exist in will militate against that existence in a degree proportionate, perhaps in a geometrical ratio, to the bulk of the species. If a dry season be gradually prolonged, the large mammal will suffer from the drought sooner than the small one; if such alteration of climate affect the quantity of vegetable food, the bulky Herbivore will first feel the effects of stinted nourishment; if new enemies are introduced, the large and conspicuous quadruped or bird will fall a prey, whilst the smaller species conceal themselves and escape. Smaller animals are usually, also, more prolific than larger ones.

"The actual presence, therefore, of small species of animals in countries where larger species of the same natural families formerly exisied, is not the consequence of any gradual diminution of the size of such species, but is the result of circumstances, which may be illustrated by the fable of the 'Oak and the Reed;' the smaller and feebler animals have bent and accommodated themselves to changes which have destroyed the larger species."

Accepting this explanation of the extirpation of species as true, Mr. Wallacet has recently applied it to the extirpation of varieties; and, assuming, as is probable, that varieties do arise in a wild species, he shows how such deviations from type may either tend to the destruction of a variety, or to adapt a variety to some changes in surrounding conditions, under which it is better calculated to exist, than the type-form from which it deviated.

No doubt the type-form of any species is that which is best adapted to the conditions under which such species at the time exists; and as long as those conditions remain unchanged, so long will the type remain; all varieties departing therefrom being in the same ratio less adapted to the environing conditions of existence. But, if those conditions change, then

* On the Genus Dinornis (part iv.), Zool. Trans. vol. iv. p. 15 (February 1850). † Proceedings of the Linnean Society, August 1858, p. 57.

the variety of the species at an antecedent date and state of things will become the type-form of the species at a later date, and in an altered state of things.

Mr. Charles Darwin had previously to Mr. Wallace illustrated this principle by ingenious suppositions, of which I select the following:-" To give an imaginary example from changes in progress on an island:-let the organization of a canine animal which preyed chiefly on rabbits, but sometimes on hares, become slightly plastic; let these same changes cause the number of rabbits very slowly to decrease, and the number of hares to increase; the effect of this would be that the fox or dog would be driven to try to catch more hares: his organization, however, being slightly plastic, those individuals with the lightest forms, longest limbs, and best eyesight, let the difference be ever so small, would be slightly favoured, and would tend to live longer, and to survive during that time of the year when food was scarcest; they would also rear more young, which would tend to inherit these slight peculiarities. The less fleet ones would be rigidly destroyed. I can see no more reason to doubt that these causes in a thousand generations would produce a marked effect, and adapt the form of the fox or dog to the catching of hares instead of rabbits, than that greyhounds can be improved by selection and careful breeding *."

Observation of animals in a state of nature is required to show their degree of plasticity, or the extent to which varieties do arise: whereby grounds may be had for judging of the probability of the elastic ligaments and joint-structures of a feline foot, for example, being superinduced upon the more simple structure of the toe with the non-retractile claw, according to the principle of a succession of varieties in time†.

Observation of fossil remains is also still needed to make known the antetypes, in which varieties, analogous to the observed ones in existing species, might have occurred, so as to give rise ultimately to such extreme forms as the Giraffe for example‡.

This application of paleontology has always been felt by myself to be so important that I have never omitted a proper opportunity for impressing the results of observations showing the "more generalized structures" of extinct as compared with recent forms of mammalia.

But, in pointing out how local changes might affect large quadrupeds, I * Proceedings of the Linnean Society, August 1858, p. 49.

† "The powerful retractile talons of the falcon- and the cat-tribes have not been produced or increased by the volition of those animals; but among the different varieties which occurred in the earlier and less organized forms of these groups, those always survived longest which had the greatest facilities for seizing their prey." -Wallace, p. 61.

‡ "Neither did the giraffe acquire its long neck by desiring to reach the foliage of the more lofty shrubs, and constantly stretching its neck for the purpose; but because any varieties which occurred among its antetypes with a longer neck than usual at once secured a fresh range of pasture over the same ground as their shorter-necked companions, and on the first scarcity of food were thereby enabled to outlive them."-lb. p. 61.

have refrained from speculating on dwarf-varieties surviving such influences as being the origin of existing representatives of extinct giants. A small sloth coexisted with the Megatherium, a small armadillo with the Glyptodon, the Apteryx with the Dinornis.

The aboriginal laws of geographical distribution of plants and animals have been modified from of old by geological and the concomitant climatal changes; but they have been much more disturbed by man since his introduction upon the globe.

The serviceable plants and animals which he has carried with him in his migrations have flourished and multiplied in lands the most remote from the habitats of the aboriginal species. Man has, also, been the most potent and intelligible cause of the extirpation of species within historic times.

He alone, with one of the beasts which he has domesticated-the dog-is truly cosmopolitan. The human species is represented by a few well-marked varieties; and there is a certain amount of correspondence between their localities and general zoological provinces: thus the Australian variety of man is as well-marked and circumscribed as the Australian fauna generally; the Papuans of New Guinea present the same difference from, with degree of affinity to, the Australians, as we find in comparing the respective faunsæ of Papua and Australia. But, with regard to the alleged conformity between the geographical distribution of man and animals, which has of late been systematically enunciated, and made the basis of deductions as to the origin and distinction of the human varieties, I would submit the following remarks as affecting the system referred to *.

Using Blumenbach's term in the sense of the later terms 'Indo-European' and 'Aryan,' we find the 'Caucasian' race extended from Iceland to the mouth of the Ganges. There is no corresponding distinction in the animals and plants of the Europæo-Asiatic continent, which is bisected by the oblique line dividing the Mongolian from the Caucasian varieties of mankind. The Persian fauna extends into Tartary; the Himalayan into Thibet.

As two primary varieties of mankind exist in one great zoological province in the Old World, so a third great variety extends over at least two zoological provinces in the New World. All authors divide the North American or 'Nearctic' from the South American or 'Neotropic' region, whatever class of organic life they may treat of geographically; but the red or copper-coloured American is the same, physically and linguistically, to the extent of the characteristics of a primary race, from the 60th degree of north latitude to the 53rd degree of south latitude.

The Lapps of Arctic Europe differ linguistically and physically, as a race, from the Norwegians and Swedes: the zoological province is essentially one. As such it extends over the same parallels of latitude in America, where the Mongolian Esquimaux and the American Chippawas inhabit.

* Agassiz, in Gliddon and Nott's 'Types of Mankind, 1854; and Indigenous Races of the Earth,' 1857.