ion that those sandstones are older than the Carboniferous
Age, or even older than the Trias. Besides these, the most
ancient traces of reptilian remains occur in the coal-me as-
ures, which were deposited during the decline of the empire
of fishes in the latter part of the Carboniferous Age.

The geological history of reptiles possesses many poin's
of extreme interest; and, in order to make them clear to
the reader, and to give precision to the brief account which
I am about to furnish, I shall endeavor to recall in fow
words the classification of this group of vertebrates,

Reptiles proper, in point of rank, are next above the Batrachians, which come next above the Fishes, Reptiles are purely aerial in their respiration; Fishes purely aquatie; while the Batrachians breathe water in infancy, and air at maturity, exhibiting thus a compromise between the ichthyic and reptilian modes of respiration. The body of the reptile is always covered with scales or bony plates, wh..le that of all modern batrachians is smooth or "naked." The vertebræ of most reptiles are concave at one extremitygenerally the anterior-and convex at the other; the ver tebræ of batrachians are concave at both extremities, like those of fishes. There are other distinctions to which I need not refer. The frog is the type of the highest order of existing batrachians, the salamander of the second, and the "fish-lizard" of the lowest. The first is possessed of a tail only in the young or tadpole state; the second retains its tail during life; and the third retains both its tail and aquatic or embryonic-mode of respiration.

Of reptiles, three orders which have played a most conspicuous and important role in the history of the world are entirely extinct, and three others still survive. The turtles, saurians, and serpents, in descending order, embrace existing reptiles. The first are inclosed in a carapace or shell;" the second have elongated forms, generally clothed

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CHAPTER XV.

THE SCOUTS OF THE REPTILE HORDE.

MPIRES rose upon the earth, and crumbled in succes

EMPI

sion to decay, a thousand ages before the foot of Adam had pressed the soil of the Garden of Eden. A series of dynasties flitted like shadows over the face of our planet, and disappeared beneath the dim horizon of the past, while the empire of man was but an idea dwelling in the Almighty Mind. Here were morning and evening, invigorating sunlight and cooling dew, softly-wooing breeze and fiercely-maddened tempest, springtime and autumn, weeping clouds and placid evening sky, Winter piping his melancholy song upon the withered reeds of Summer, oceansurges waging everlasting battle with the rocky shore, God alone spectator of the progress of the mighty work which was being accomplished. But there was life, and motion, and consciousness, and enjoyment, and death through all those dim and distant ages. Those dim and distant ages-how imagination halts, and faints, and falters in the effort to shoot back over the infinite stretch of years! Life was here, but without a voice, without a wing, without a footstep. The ignoble mollusc held dominion in the sea through all the morning twilight of animated existence.

The mute fish reared his empire on the ruins of that of the mollusc. In the middle Paleozoic ages this first and lowest form of vertebrate existence appeared in all the seas -not fishes clothed in horny scales like those which swarm in the waters of the human era, but fishes clad in coat of mail, bucklered aud helmeted with bony plates, and armed

with long and powerful spines, or, in a later age, with a fearful array of sharp and conical teeth. The dynasty of the fishes sprang up in that period when the limestones of Buffalo, in New York, and of Columbus, Sandusky, and Kelly's Island, in Ohio, were accumulating as sediments in the bottom of the sea; when Canada West was the ocean's bed, and the last crop of zoophytes was growing upon it; when the beautiful island of Mackinac was a submarine plantation, and the embryo fastnesses of Old Fort Mackinac witnessed an onslaught and a massacre more bloody and destructive than that of 1761. The empire of the fishes waxed more powerful during the succeeding epochs, when the "black shales" of the West, and, later, the beautiful sandstones of Waverly and Cleveland, Ohio, were the ocean's bed, and hordes of marine forms roamed over the area of Southern New York, and nearly the whole of Michigan, Indiana, and Illinois. The Marshall epoch probably covers the latter part of the period of the Old Red Sandstone of Scotland, whose ichthyic populations have been so graphically described by the author of the "Asterolepis of Stromness."

The reign of the fishes was prolonged through the Carboniferous period; but the types which wielded the sceptre during the later ages of the empire assumed less questionable forms, and began to approach the external configuration of the fishes of our day. They were mostly clothed, however, with bony scales, and the backbone extended into the upper lobe of the tail, which was longer than the lower; or, what is probably a more correct view of this structure, the tail was supplied upon the under side with a supernumerary fin, the development of which deflected upward the true caudal fin-the tail of the sturgeon and the garpike being as truly "homocercal" as that of the whitefish. It is sad to think of the ancient populousness and prowess of

a

CHAPTER XV.

THE SCOUTS OF THE REPTILE HORDE.

EMPIRES

MPIRES rose upon the earth, and crumbled in succession to decay, a thousand ages before the foot of Adam had pressed the soil of the Garden of Eden. A series of dynasties flitted like shadows over the face of our planet, and disappeared beneath the dim horizon of the past, while the empire of man was but an idea dwelling in the Almighty Mind. Here were morning and evening, invigorating sunlight and cooling dew, softly-wooing breeze and fiercely-maddened tempest, springtime and autumn, weeping clouds and placid evening sky, Winter piping his melancholy song upon the withered reeds of Summer, oceansurges waging everlasting battle with the rocky shore, God alone spectator of the progress of the mighty work which was being accomplished. But there was life, and motion, and consciousness, and enjoyment, and death through all those dim and distant ages. Those dim and distant ages-how imagination halts, and faints, and falters in the effort to shoot back over the infinite stretch of years! Life was here, but without a voice, without a wing, without a footstep. The ignoble mollusc held dominion in the sea through all the morning twilight of animated existence.

The mute fish reared his empire on the ruins of that of the mollusc. In the middle Paleozoic ages this first and lowest form of vertebrate existence appeared in all the seas -not fishes clothed in horny scales like those which swarm in the waters of the human era, but fishes clad in coat of mail, bucklered aud helmeted with bony plates, and armed