fishes of the Ctenoid and Cycloid orders, the former having scales like the perch, the latter like the salmon.

The Fauna of the Tertiary group, (comprehending all the rocks above the chalk) introduces us to a creation departing widely from all that preceded it, and approximating in its great features to that amidst which we live. It is characterised by numerous genera of large terrestrial quadrupeds, of which no types are found in the previous groups, but most of which have their "representatives" in the living creation, though all of them are extinct. It is here we find ourselves surrounded by forms with which the present Fauna has made us familiar -elephants, rhinoceroses, hippopotami, tigers, bears, deers, sloths, hyenas, camels, oxen, horses, swine, baboons, whales, seals, serpents, but all of different species from those now existing. The vulture and eagle are denizens of this group, and the gigantic Dinornis of New Zealand. Nor have the large reptiles disappeared, for the Megalochelys, a turtle with a carapace, or shield, 20 feet long, is a Tertiary fossil. New genera of Mollusks, Annelides, &c., accompany all these changes.

It must be kept in mind that as the entire number of species in any one group is not yet completely known, the classification may undergo some change from future discoveries; and, more especially, that some genera now known as existing only in the newer groups, may hereafter be found in the older.

Naturalists sometimes divide the whole existing and extinct Faunas into four groups, characterised by the most perfect or highly organised animal then existing.

Thus in the Primary or Palæozoic Fauna we have the "Reign of Fishes," because a vertebrate fish was the most perfect animal then existing. In the Secondary Fauna we have the "Reign of Reptiles;" in the Tertiary the "Reign of Quadrupeds;" and the present Fauna constitutes the "Reign of Man." It has recently been found, however, that reptiles existed, though sparingly, in the Paleozoic Fauna, and the character here assigned to it belongs only to the very lowest portion of it. The three first "reigns" comprehend a period of enormous duration, compared with which the fourth "reign," embracing the whole of man's sojourn upon the earth, shrinks into a mere point; and idle alarms have been raised about the vast antiquity thus assigned to the globe, and its supposed inconsistency with the language of the Scriptures. On this subject we quote the words of a very high authority:

"The Bible instructs us that man and other living things have been placed but a few years upon the earth; and the physical monuments of the world bear witness to the same truth. If the astronomer tells us of myriads of worlds not spoken of in the sacred records, the geologist in like manner proves, (not by arguments from analogy, but by the incontrovertible evidence of physical phenomena,) that there were former conditions of our planet, separated from each other by vast intervals of time, during which man and the other creatures of his own date had not been called into being. Periods such as these belong not, therefore, to the moral history of our race, and come neither within the letter nor the spirit of

revelation. Between the first creation of the earth and that day on which it pleased God to place man upon it, who shall dare to define the interval ?" 1

In the existing creation, each considerable region has certain tribes of animals in common with other regions, and certain tribes peculiar to itself. The same division of zoological life into distinct provinces is found to have prevailed to some extent in ancient times. In the extinct Faunas of America and Europe of corresponding age, there are some species common to both; but the majority have merely such a degree of resemblance as constitutes them the "analogues" or "representatives," the one of the other. The number of fossil species of animals known, of all kinds, exceeds 20,000.

C. M.

1 Discourse on the Studies of the University, by the Rev. ADAM SEDGWICK, Woodwardian Professor, Trinity College, Cambridge.

PART II.-BODIES CIRCULATING ABOUT THE SUN AS A PRIMARY.

PART III-BODIES REVOLVING ABOUT PLANETS AS PRIMARIES.

Satellites of the Planets.

PART I. THE THREE BODIES.

1. THE EARTH,-SYMBOL .

Shape and size, approximately, sphere 8000 miles in diameter.

Shape and size, accurately a spheroid, with

Polar dimensions =7898 miles.

Equatorial dimensions 7924 miles.

Mean density, i.e. specific gravity = 5.67, distilled water being = 1.

Force of gravitation at the surface = 16 feet movement in 1st second.

Force of gravitation at the distance of Moon = 0.004 feet in 1st second.

Rotation on axis, measured by the Sun, or solar day, =24 hours solar time.

Rotation on axis, measured by the Stars, or sidereal day, 23h. 56m. 4.0906s. solar time.

=

Inclination of axis to plane of orbit, or " obliquity of ecliptic," 23° 27′ 56.5."

=

Centrifugal force at equator = 0.00346.

Light, derived from the Sun.

Light occupies in its passage from Sun to Earth = 8m. 13.3s.

Orbitual motion of Earth in that space of time, and conse