Need it then be urged, that no such incalculable cycles of ages would be required for the whole of this catalogue of animals fulfilling in their several epochs their allotted destiny upon the earth? Compared with the mass of inorganic matter in which they are entombed, their relics are literally as nothing. Only here and there, of certain classes, at remote intervals often, there is a fossil or its impression. And so entire and well-preserved are these organisms, that we have reason to presume there has been no great obliteration, absorption, or utter waste of the races to which they belonged. On the contrary, as their distribution is so persistent in their respective formations throughout the globe,—the same genera and species being common to the four quarters of the world,—the presumption is, that specimens of nearly all the tribes that ever dwelt on the earth or swarmed in its waters have been handed down to us; and thus the number of the actual relics found becomes, as it were, a chronometer or measure of the ages during which they subsisted. Look again at the demands of geology. Upward of SIXTEEN MILLIONS OF YEARS[14] are supposed to have elapsed since the creation of life upon the earth. The lowest of the rocks, in which that life has found its grave, have been reached. Their contents, upward, have been examined and catalogued. How many generations of animals must have subsisted within that period? How many individual skeletons must have been entombed and preserved, seeing that things of the filmiest texture, plants and animals, have been inclosed and handed down to us entire? Quadruple the ages of every one of the existing denizens of sea and land, and still, what countless millions of generations, succeeding each other, have lived and died during the eras that were to run? Geology presents us with her list, her whole lengthened organic roll, of scarcely four hundred generic, and less than eight hundred specific forms, gathered out of all the past cemeteries of the dead. The cemeteries themselves, of such vast walls and dimensions, may, according to the present mordant powers of the elements and the capacity of rivers for the transport of mud, have required the calculations usually assigned for their erection. But where, the question will ever recur, where is there anything like a corresponding amount of animal exuviæ apart from the calcareous supplies, to be found in the successive formations, conforming in any approximation to the existing powers and capacities of parturient nature? The fossil remains, inclosed from the beginning to the end of the inconceivable cycles of time, are the remains only of a few great families: their skeletons are admirably preserved, or their casts are minutely and accurately engraven on the rock; and do they not look as if they were the _identical individuals_ which rose in the dawn and were buried in the setting of their own geological epoch!