names we have given. We have represented the forms and dimensions of some of these monsters of a by-gone age as they have been pictured and described by geologists.

8. In closing our sketch of this Secondary period, we would remark, in the language of Hugh Miller, that at this period. in the history of our country, "at the close of the Cretaceous system, there existed no species of plant or animal that exists at the present time. We know that it is appointed for all individuals once to die, whatever their tribe or family, because hitherto all individuals have died; and geology, by extending our experience, shows us that the same fate awaits on species as on the individuals that compose them." Of the several periods of existence which measure animated nature, the briefest is allotted to individuals: species live longergenera longer still; while above them are orders and classes, the latter the most comprehensive of all.

GEOLOGICAL REMAINS OF ANIMALS OF THE TERTIARY PERIOD.

[The scale of feet is applicable to all but the shells.]

1, 2, 3, 4, 5, 6, 7, 8, fossil Shells of the Tertiary period-very numerous. 9, the Dinotherium, an animal not less than fifteen feet in height, with immense tusks curving downward, and the proboscis of an elephant 10, skeleton of a Mastodon, weighing 2000 pounds, found at Newburgh, N. Y., in 1845. 11, skeleton of a Megatherium; thigh-bone eleven inches in diameter, and claw-armed toes more than two feet in length. 12, 13, 14, and 15 are a group of extinct Pachydermata, which bear an affinity to the Tapir, Rhinoceros, and Hippopotamus. The largest, the Palæotherium magnum, was of the size of a horse, but more thick and clumsy.

1. STILL ascending, in the order of time, in the geological history of our globe, we next come to the Tertiary period, likewise of vast and indefinite extent, but constituting a series

of formations which link together the present and the past. We have evidences of numerous changes in the earth's crust in the beginnings of this epoch, of volcanic action of great extent and frequency, and of alternations of ocean beds with those of vast fresh-water lakes. The alternating strata of this period have been divided into three principal groups, characterized by the proportion of shells, allied to existing species, which they contain. Thus the lowest group, the eocene, signifying the dawn of the recent, contains not more than three or four per cent. of fossil shells allied to those of recent species; the next, the miocene, about twenty per cent.; and the upper, the pliocene, about eighty per cent."

2. But besides the marine and fresh-water shells which abound in this period, imbedded in vast layers of limestone rocks, the fossils of crabs, lobsters, and other Crustaceans are numerous; there have also been found the teeth of unknown sharks, and the remains of many genera of fishes, vast quantities of the remains of leaves, fruits, stems of plants, and trunks of trees perforated by the borer, together with the fossils of birds related to existing species. But what especially characterize the older Tertiary deposits are the numerous fossil remains of a class of pachydermata, of species now unknown, but bearing an affinity to the tapir, the rhinoceros, and the hippopotamus. Such are the numerous species of the palæotherium and the anoplotherium, some of which are represented in the engraving at the head of this lesson.

3. In the middle division of this period the seas became the habitation of numbers of marine mammalia, consisting of dolphins, whales, seals, and the manatee, although none of them were of the same species as those which exist at present. Here, also, are found the remains of the gigantic dinotherium -an animal not less than fifteen feet in height, with the proboscis of an elephant, and tusks curved downward as in the walrus. He seems to have formed a connecting link between

It may be regarded as a singular coincidence that the capitals of Great Britain and France are located on strata of the same geological epoch in the Tertiary period. Both Paris and London are situated on a vast alternation of marine and fresh-water beds, lying in basins of the chalk formation, the uppermost of the Secondary period. The annexed cut illustrates the geological formation of the two cities. These ancient basins or gulfs

London.

Paris.
ħ

were evidently open to the sea on one side, while on the other they were supplied by rivers charged with the spoils of the country through which they flowed, and carrying down the remains of animals and plants, with land and river shells. Changes in the relative level of the land and sea took place, and, lastly, the country was elevated to its present altitude above the sea.-MANTELL.

the pachydermata, his predecessors, and those later mammalia, the Cetacea, or whales. There is little doubt that he was an inhabitant of the lakes and marshes, and that he could anchor himself to the firm land by his huge tusks. His singu lar appearance has inspired some one to write the following:

4.

SONG OF THE DINOTHERIUM.

"My thirst I slake in the cooling lake,
Where I swim among the fishes,

And should hunger gnaw my vacant maw,
A dinner meets my wishes:

For bulbous roots or tender shoots

I dig or crop at pleasure,

And having dined, if to sleep inclined,

I lay me down at leisure.

As a ship will ride in the rushing tide
If her anchors meet the sand,

So when I sleep in the river deep,
My tusks are in the land."

Co

5. In the lower division of the Tertiary the bee first makes its appearance, the fossil remains of one having been found sealed up in a piece of amber-"an embalmed corpse in a crystal coffin," as Hugh Miller beautifully describes it. existent with the bee are the first of the Ophidians or serpents, as shown in a monster species allied to the modern python. Here also we first detect plants and trees belonging to wellknown existing genera and orders, but not of existing species.

6. In the uppermost strata of this period are found remains of the mastodon, and also of numerous species of mammalia almost or nearly identical with many of the existing species. Thus, in vast caves of the later Tertiary period, accidentally opened in many places in Europe and Asia, have been found the skeletons of immense numbers of hyænas, mixed with the bones of the cave-tiger, the cave-bear, the mammoth, and the rhinoceros. The first traces also of ruminant animals appear at this time-of wild oxen, deer, camels, horses, and other creatures of the same class, and, even in high northern latitudes, the remains of species of elephants now unknown.

Yes! where the huntsman winds his matin horn,
And the couch'd hare beneath the covert trembles;
Where shepherds tend their flocks, and grows the corn;
Where Fashion on our gay parade assembles,

Wild horses, deer, and elephants have strayed,

Treading beneath their feet old Ocean's races.--HORACE SMITH.

LESSON VIII.—THE MODERN GEOLOGICAL PERIOD.

1. THE modern geological period embraces the two eras known as the Drift and the Alluvium. The Drift strata rest upon the Tertiary, and are spread over almost every part of the northern regions of the globe in the form of coarse sand and gravel, beds of clay, and rocks, called boulders, torn from the masses to which they belonged by the force of floods and glaciers; while the Alluvium consists of the surface soil, and layers of loam, sand, and fine gravel, evidently deposited by rivers, or in still water. In the Drift period, which was one of floods of vast extent, the climate of northern countries was evidently colder than during the Tertiary, and probably colder than at present. Hugh Miller describes our earth in this period as "a foundering land under a severe sky, beaten by tempests and lashed by tides, with glaciers half choking up its cheerless valleys, and with countless icebergs brushing its coasts and grating over its shallows."

2. Drift, embracing a period of repeated depressions and elevations of the land, is almost destitute of organic remains of animals and plants that lived during the time of its production; but it abounds in immense quantities of the bones of those large mammalia which must have existed at the close of the Tertiary period. These remains belong principally to animals related to the elephant, as the mammoth and mastodon, and the various species of hippopotamus, rhinoceros, horse, ox, deer, and the animals whose remains were found in the caves already mentioned, and also throughout the frozen regions of northern Asia. The mastodon and a few other monster mammalia, now extinct, appear to have lived as late as the time of the earliest of the alluvial deposits. It is in the Alluvial period only that the remains of MAN and his works have thus far been found. "Geology, scarce less certainly than Revelation itself, testifies that the last-born of creation was man, and that his appearance on earth is one of the most recent events of which it submits the memorials to its votaries."

"From harmony-from heavenly harmony

This universal frame began;

From harmony to harmony,

Through all the compass of the notes it ran,

The diapa'son closing full in man."

3. We have thus hastily glanced at the succession of ages which make up the geological history of our planet. We have seen land and water succeeding each other on our globe in

continual mutations; and we are thence prepared to admit the possibility that

"New worlds are still emerging from the deep,

The old descending in their turn to rise."

But what strikes us with the greatest force is the evidence of the successive creations which have peopled our planet; we have seen race after race of beings starting into existence, and then disappearing; for we know, by testimony which can not be controverted, that

"The earth has gathered to her breast again,

And yet again, the millions that were born
Of her unnumbered, unremembered tribes,"

and each tribe and race has been adapted to the circumstances in which it was placed, thereby affording the most evident proofs of the wisdom and overruling providence of the Creator. Reflecting on these phenomena, the mind recalls the impressive exclamation of the poet:

"My heart is awed within me when I think
Of the great miracle which still goes on
In silence round me-the perpetual work
Of THY creation, finished, yet renewed
Forever."

LESSON IX.-RETROSPECTIVE VIEW OF GEOLOGY.

LET us now reverse the order of viewing the geological history of our globe, starting from the present, and proceeding backward against the order of time. As the traveler who ascends to the regions of eternal snow gradually loses sight of the abodes of man, and of the groves and forests, till he arrives at sterile plains, where a few stinted shrubs alone meet his eye, and as he advances even these are lost, and mosses and lichens remain the only vestiges of organic life, and these too at length pass away, and he enters the confines of the inorganic kingdom of nature-in like manner the geologist who penetrates the secret recesses of the globe perceives at every step of his progress the existing forms of animals and vegetables gradually disappear, while the shades of other creations teem around him. These, in their turn, vanish from his sight; other new and strange modifications of organic structure supply their place; these also fade away; traces of animal and vegetable life become less and less manifest, till they altogether disappear; and he descends to the primary rocks, where all evidence of organization is lost, and the granite, like a pall thrown over the relics of a former world, conceals forever the earliest scenes of the earth's physical drama. MANTELL.