On the sweet summer wind its purple wings,
In gulfs enchanted, where the siren sings,

And coral reefs lie bare,

Where the cold sea-maids rise to sun their streaming hair.

"Its webs of living gauze no more unfurl;

Wrecked is the ship of pearl!

And every chambered cell,

Where its dim dreaming life was wont to dwell,
As the frail tenant shaped his growing shell,
Before thee lies revealed-

Its irised ceiling rent, its sunless crypt unsealed!

"Year after year beheld the silent toil

That spread his lustrous coil;

Still, as the spiral grew,

He left the past year's dwelling for the new,
Stole, with soft step, its shining archway through,

Built up its idle door,

Stretched in his last found home, and knew the old no more.

"Thanks for the heavenly message brought by thee,

Child of the wandering sea,

Cast from her lap forlorn!

From thy dead lips a clearer note is born
Than ever Triton blew from wreathéd horn!

While on my ear it rings,

Through the deep caves of thought I hear a voice that sings:

"Build thee more stately mansions, oh, my soul,

As the swift seasons roll!

Leave thy low-vaulted past!

Let each new temple, nobler than the last,
Shut thee from heaven with a dome more vast,

Till thou at length art free,

Leaving thine outgrown shell by life's unresting sea!"

The "pearly nautilus" exemplifies the structure of a "chambered shell." Such shells in their endless variations played a most conspicuous part in the history of ancient life, though one genus alone survives to recite the glory and illustrate the economy of his cephalopodous ancestors. The variable elements in the shell are the form of the sep

tum, the position of the siphon, and the plan of enrollment. The septum may be plain, or angulated, or lobed, or foliated around its outer margin. The siphon may be external, or internal, or central. The enrollment may be close, loose, half-coiled, arcuate, or straight. Of how many combinations, three in a set, do these characters admit! And yet almost every possible combination has been realized in the history of the world. In the earliest periods were the species with simple septa and straight shells (orthoceratites, Fig. 47); next came those with simple septa and coiled shells (Nautili, Fig. 48); then those with angulated septa and coiled shells (Clymenia, Fig. 49); then those with lobed septa and coiled shells (Goniatites, Fig. 50); lastly appeared those with foliated or very complicated septa,

Fig. 52. Ammonites canalicula- with their straight (Baculites, Fig. 51), arcuate (Hamites), closely (Ammonites, Fig. 52), and variously coiled forms. So we see that in the various ages of the world, some type of "chambered shells" has constituted a leading character

ล

Fig. 53. Plans of Septa among different families of Chambered Shells. a. Septum in Nautilus family. b. Septum in Clymenia family. c. Septum in Goniatite family (Goniatites Marshallensis). d. Šeptum in Ammonite family.

istic of the marine fauna. One thing which is very remarkable is the fact that the existing pearly nautilus is

Fig. 54. Garpikes of North America. a. Lepidosteus Huronensis. b. Lepidosteus oculatus

(the

Spotted Garpike), the latter now for the first time figured.

a

closely related to the most ancient formsspecimen creature of primeval times-the key to the inscriptions on the preadamite rocks. The orthoceratites were nautili with straight shells. They were the "carnivora" of the sea. They often attained to formidable dimensions. I have found remains of individuals on St. Joseph's Island, in Lake Huron, which were twelve feet in length. A reliable gentleman of Utica, New York, informed me that he had traced one in the "Black River Limestone" to the distance of thirty-two feet! Imagine a hollow cone of limestone, of the dimensions of a "saw-log," animated, with a "Kraken octopod" ensconced in the open end, staring with glassy, sinister eyes to the right and left, and numerous slimy, muscular, insinuating arms feeling in every direction for their prey.

Is not this an enemy from which the lesser tenants of the deep would flee without pausing to raise the question of supremacy? These monsters maintained the ascendency till the introduction of fishes, toward the close of the Upper Silurian, or later. Their decline dates from this epoch; and when the voracious fishes of the Old Red Sandstone and the Carboniferous Limestone came upon the stage of being, the orthoceratites dwindled away. Their last representatives barely saw the rising of Mesozoic Time. Not a trace of a straight plain-chambered shell has been found in any of the rocks above the Trias. They fulfilled their end in creation and retired. Other carnivorous animals of a higher order were better adapted to the advancing state of the earth's preparation. Garpikes appeared. A new dynasty arose, to be in turn overthrown by the dynasty of the Mesozoic reptiles.

F

THE

CHAPTER XII.

ONWARD THROUGH THE AGES.

HE evening shades of one of eternity's æons are gathering around us. The darkness upon which we are entering is the gloom of a tempest and the night of death to the teeming populations of the globe. A throe of Nature heaves still higher the germinal ridges of the continent, robs the ocean of another strip of his domain, and seals up the record of the life of the Lower Silurian..

The elevation which marked the close of this great interval of terrestrial history brought to light the basin of Lake Superior, Northern Wisconsin, and Minnesota, the northern and eastern portions of New York, and considerable portions of New England. The line of sea-coast passed westward through Central New York, along the bed of the future Lake Ontario, thence northwestward to Georgian Bay, following the trend of the future Lake Huron, sweeping round by the Sault Ste. Marie, and arching downward again through Wisconsin along a line a few miles west of the present Lake Michigan. Thence it swept westward and northwestward in the direction of Lake Winnipeg and the Arctic Sea. All to the south of this line was yet the empire of the Atlantic. On those vast submarine plains the Pacific joined hands with the Atlantic, and the two sang dirges over the land that was to become the scene of fraternal conflict.

It might weary the casual reader of geological history to recite the details of the periods which follow. What has been narrated of the birth and death of populations