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Miocene period, the sea-shells seem to have been more different than at present. In1 the Tertiary period, according to Lyell, the shells of N. America and Europe were less related than at present, and during the Cretaceous still less like; whereas, during this same Cretaceous period, the shells of India and Europe were more like than at present. But going further back to the Carbonaceous period, in N. America and Europe, the productions were much more like than they now are2. These facts harmonise with the conclusions drawn from the present distribution of organic beings, for we have seen, that from species being created in different points or areas, the formation of a barrier would cause or make two distinct geographical areas; and the destruction of a barrier would permit their diffusion 3. And as long-continued geological changes must both destroy and make barriers, we might expect, the further we looked backwards, the more changed should we find the present distribution. This conclusion is worthy of attention; because, finding in widely different parts of the same main division of the world, and in volcanic islands near them, groups of distinct, but related, species; and finding that a singularly analogous relation holds good with respect to the beings of past times, when none of the present species were living, a person might be tempted to believe in some mystical relation between certain areas of the world, and the production of certain organic forms; but we now see that such an assumption would have to be complicated by the admission that such a relation, though holding good for long revolutions of years, is not truly persistent.

I will only add one more observation to this

1 (Note by the author.) All this requires much verification.

2 This point seems to be less insisted on in the Origin.

3 Origin, Ed. i. p. 356, vi. p. 504.

section. Geologists finding in the most remote period with which we are acquainted, namely in the Silurian period, that the shells and other marine productions1 in North and South America, in Europe, Southern Africa, and Western Asia, are much more similar than they now are at these distant points, appear to have imagined that in these ancient times the laws of geographical distribution were quite different than what they now are: but we have only to suppose that great continents were extended east and west, and thus did not divide the inhabitants of the temperate and tropical seas, as the continents now do; and it would then become probable that the inhabitants of the seas would be much more similar than they now are. In the immense space of ocean extending from the east coast of Africa to the eastern islands of the Pacific, which space is connected either by lines of tropical coast or by islands not very distant from each other, we know (Cuming) that many shells, perhaps even as many as 200, are common to the Zanzibar coast, the Philippines, and the eastern islands of the Low or Dangerous Archipelago in the Pacific. This space equals that from the Arctic to the Antarctic pole! Pass over the space of quite open ocean, from the Dangerous Archipelago to the west coast of S. America, and every shell is different: pass over the narrow space of S. America, to its eastern shores, and again every shell is different! Many fish, I may add, are also common to the Pacific and Indian Oceans.

1 (Note by the author.) D'Orbigny shows that this is not so.

Summary on the distribution of living and
extinct organic beings.

Let us sum up the several facts now given with respect to the past and present geographical distribution of organic beings. In a previous chapter it was shown that species are not exterminated by universal catastrophes, and that they are slowly produced: we have also seen that each species is probably only once produced, on one point or area once in time; and that each diffuses itself, as far as barriers and its conditions of life permit. If we look at any one main division of the land, we find in the different parts, whether exposed to different conditions or to the same conditions, many groups of species wholly or nearly distinct as species, nevertheless intimately related. We find the inhabitants of islands, though distinct as species, similarly related to the inhabitants of the nearest continent; we find in some cases, that even the different islands of one such group are inhabited by species distinct, though intimately related to one another and to those of the nearest continent:-thus typifying the distribution of organic beings over the whole world. We find the floras of distant mountain-summits either very similar (which seems to admit, as shown, of a simple explanation) or very distinct but related to the floras of the surrounding region; and hence, in this latter case, the floras of two mountainsummits, although exposed to closely similar conditions, will be very different. On the mountainsummits of islands, characterised by peculiar faunas and floras, the plants are often eminently peculiar. The dissimilarity of the organic beings inhabiting nearly similar countries is best seen by comparing the main divisions of the world; in each of which some districts may be found very similarly

exposed, yet the inhabitants are wholly unlike ;far more unlike than those in very dissimilar districts in the same main division. We see this strikingly in comparing two volcanic archipelagoes, with nearly the same climate, but situated not very far from two different continents; in which case their inhabitants are totally unlike. In the different main divisions of the world, the amount of difference between the organisms, even in the same class, is widely different, each main division having only the species distinct in some families, in other families having the genera distinct. The distribution of aquatic organisms is very different from that of the terrestrial organisms; and necessarily so, from the barriers to their progress being quite unlike. The nature of the conditions in an isolated district will not explain the number of species inhabiting it; nor the absence of one class or the presence of another class. We find that terrestrial mammifers are not present on islands far removed from other land. We see in two regions, that the species though distinct are more or less related, according to the greater or less possibility of the transportal in past and present times of species from one to the other region; although we can hardly admit that all the species in such cases have been transported from the first to the second region, and since have become extinct in the first: we see this law in the presence of the fox on the Falkland Islands; in the European character of some of the plants of Tierra del Fuego; in the Indo-Asiatic character of the plants of the Pacific; and in the circumstance of those genera which range widest having many species with wide ranges; and those genera with restricted ranges having species with restricted ranges. Finally, we find in each of the main divisions of the land, and probably of the sea, that the existing organisms are related to those lately extinct.

Looking further backwards we see that the past geographical distribution of organic beings was different from the present; and indeed, considering that geology shows that all our land was once under water, and that where water now extends land is forming, the reverse could hardly have been possible.

Now these several facts, though evidently all more or less connected together, must by the creationist (though the geologist may explain some of the anomalies) be considered as so many ultimate facts. He can only say, that it so pleased the Creator that the organic beings of the plains, deserts, mountains, tropical and temperature forests, of S. America, should all have some affinity together; that the inhabitants of the Galapagos Archipelago should be related to those of Chile; and that some of the species on the similarly constituted islands of this archipelago, though most closely related, should be distinct; that all its inhabitants should be totally unlike those of the similarly volcanic and arid Cape de Verde and Canary Islands; that the plants on the summit of Teneriffe should be eminently peculiar; that the diversified island of New Zealand should have not many plants, and not one, or only one, mammifer; that the mammifers of S. America, Australia and Europe should be clearly related to their ancient and exterminated prototypes; and so on with other facts. But it is absolutely opposed to every analogy, drawn from the laws imposed by the Creator on inorganic matter, that facts, when connected, should be considered as ultimate and not the direct consequences of more general laws.

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