[46] "Though perfect knowledge is not possessed, yet there are reasons for believing that the duration of life to testacean individuals of the present race is several years. But who can state the _proportion_ which the average length of life to the individual mollusc or conchifer, bears to the duration appointed by the Creator to the species? Take any one of the six or seven thousand known recent species; let it be a _Buccinum_, of which 120 species are ascertained, (one of which is the commonly known _whelk_;) or a _Cypraea_, comprising about as many, (a well-known species is on almost every mantel-piece, the _tiger-cowry_;) or an _Ostrea_ (_oyster_), of which 130 species are described. We have reason to think that the individuals have a natural life of at least six or seven years; but we have no reason to suppose that any one species has died out, since the Adamic creation. May we then, for the sake of an illustrative argument, take the duration of testacean species, one with another, at one thousand times the life of the individual? May we say six thousand years? We are dealing very liberally with our opponents. Yet in examining the vertical evidences of the cessations of the fossil species, marks are found of an entire change in the forms of animal life; we find such cessations and changes to have occurred MANY times in the thickness of but a few hundred feet of these late-rocks."--DR. J. PYE SMITH, _Scripture and Geology_, 5th Ed. p. 376. [47] "One of the laminated formations [in Auvergne] may be said to furnish a chronometer for itself. It consists of sixty feet of siliceous and calcareous deposits, each as thin as pasteboard, and bearing upon their separating surfaces the stems and seed-vessels of small water-plants in infinite numbers; and countless multitudes of minute shells, resembling some species of our common snail-shells. These layers have been formed with evident regularity, and to each of them we may reasonably assign the term of one season, that is a year. Now thirty of such layers frequently do not exceed one inch in thickness. Let us average them at twenty-five. The thickness of the stratum is at least sixty feet; and thus we gain, for the whole of this formation alone, eighteen thousand years."--DR. J. P. SMITH, _Scripture and Geology_, 5th Edition, p. 137. [48] "This fact has now been verified in almost all parts of the globe, and has led to a conviction that at successive periods of the past the same area of land and water has been inhabited by species of animals and plants as distinct as those which now people the antipodes, or which now co-exist in the arctic, temperate, and tropical zones. It appears that from the remotest periods there has been ever a coming in of new organic forms, and an extinction of those which pre-existed on the earth; some species having endured for a longer, others for a shorter time; but none having ever re-appeared, after once dying out."--LYELL'S _Elements of Geology_, p. 275.