that characterize the embryo in the early perio Is o its development. Such are the numerous Crinoids, he Brachiopods, the Trilobites; and, in the fishes, the Ganöids of the Silurian epoch. Such are still the great Entomostraca of the carboniferous epoch, and in the vegetables the gigantic ferns, the horse-tails, (Equisetaceæ,) the palm trees, and the coniferous trees, the accumulated remains of which compose the immense beds of coal, provident nature has deposited for the present and future wants of human industry. The two first of these vegetable types belong to the inferior order of the cryptogamous plants; the third to that of the monocotyledons; the fourth, the coniferous, is scarcely placed higher.

We must abstain from pursuing here in its details the admirable history of the surface of our earth, and of the new beings which successively appear; this is the business of geology. Let us say, only, that one of the most beautiful of these results is the demonstration that the diversity of terrestrial forms, the variety of the types and species of organized beings, become always greater and greater. Every new revolution is a new progress; we see one elevation added to another; one surface after another emerging to increase the existing dry lands; one chain of mountains after another appearing and binding together the hitherto separate islands. The terrestrial masses enlarge in number and size; their contours are more varied, their surfaces more broken up.

Let us cast our eyes upon this chart, representing Europe at the commencement of the Tertiary epoch. Comparing it with the map of the Silurian epoch, we

shall be able to form an idea of the change that has been

Not only the number of the lands has been multiplied, but everywhere the primitive islands have been enlarged and consolidated. The centre of the continent, Germany and France, constitutes already a considerable collective region, unbroken save by a few interior basins. The British Isles form already two or three large islands, and the eastern part of England only is wanting. The three peninsulas of the south are clearly traced; Italy

only is still exposed along its coast to the encroachments of the sea; Scandinavia continues to form a large solitary island; the mountains are more elevated; the Pyrenees, the Appenines, a small part of the Alps, already mark out the great features of relief which characterize the continent.

During the tertiary epoch, the variety of physical circumstances is still increasing; a multitude of isolated basins, like those of Paris, of London, of Oeningen, assume a special physiognomy, and have their separate faunas. The natural physical regions are determined, and take their distinctive character. The climates are diversified with all the physical circumstances of a country, and are reflected in the ever-increasing diversity of animal and vegetable genera and species.

Meantime, this movement of specialization is not going to extremes. The masses of earth, while becoming more numerous, more various, more diversified in shape, are grouping themselves more and more; the contours of the continents are getting better defined; the tertiary basins are filling and drying up. The water of the seas disappearing from the interior, the atmospheric waters, which run on the surface, supply their place, scoop out their valleys, make the slopes regular, equalize the soil by spreading over it their precious alluvium. The diluvial torrents and the immense glaciers, contemporaneous with this epoch, complete the shaping of the soil and the preparing of this fertile loam, which will richly repay the toil of the laborer. The earth is ready to receive its lord.

It is thus, by a process of admirable simplicity, this

diversity of successive elevations is combined into a few great units, a few continents; these in turn are grouped in two worlds and form an organism, with some of the features of which we have already become acquainted.

This same progress is confirmed by palæontology, through all the successive ages of nature. The variety and the perfection of the types and species keep pace with the increasing diversity of the lands and the seas, and all the physical circumstances which serve as the basis and the condition for the life of plant and animal. In the insular or oceanic epoch, that of the paleozoic strata, we have seen animals entirely marine prevailing, and forming the inferior and embryonic types of the four divisions of the animal kingdom; it is the reign of the fishes, if we take the vertebrates as the type of development. During the formation of the secondary strata, which I would call the maritime epoch, on account of the great land-locked seas that characterize it, the huge reptiles, the monstrous Saurians of the Jurassic waters, are the prevailing form, and by their amphibious habits mark at once their more elevated position in the animal scale, and the increasing force of the land element. The numbers of living genera and species are much greater than at the palæozoic epoch, but the same types are still uniformly spread over vast spaces.

The tertiary epoch, which I would call the continental epoch, beholds the appearance of the superior animals, the mammifers, the life of which is almost exclusively attached to the solid land. The continental element triumphs; all the faunas become localized; each country of the globe has its appropriate animals; the variety of

animal and vegetable species grows almost to infinity. But the unity reappears with the creation of man, who combines in his physical nature all the perfections of the animal, and who is the end of all this long progression of organized beings.

If we cast a glance back upon the way we have just passed over, do we not, gentlemen, recognize a striking analogy between this successive formation, first of our solar system, then of the continents and the beings inhabiting them, and the formation of the animal in the egg? Is there not here the same law that we have recognized everywhere else? Do we not see, first, a homogeneous fluid, then the appearance of elementary organs at several points; finally, their definitive combination in an organic whole? Yes, gentlemen, there is between the two series of facts all the difference of organic and inorganic nature; but the formula of development is the same.

The consequences of this fact are numerous; let us point out the most important, those which are chiefly useful for our subject.

1. The law of development is applicable to the land, and to the continental forms.

2. In this order of facts, as elsewhere, the condition of a more active life is a greater variety of forms of nature, of relative situations; in a word, of more varied

contrasts.

3. Then other things being equal, we may consider, in advance, those continents as the best endowed, the best organized, the best prepared for the development of human societies, which present the most varied contours,