part of this formation, and descending still lower in order, is the _Cambrian_ formation of Professor Sedgwick. And since the races of organic beings, as we thus descend through successive strata, seem to be fewer and fewer in their general types, till at last they disappear; these lower members of the geological series have been termed, according to their succession, _Palæozoic_, _Protozoic_, and _Hypozoic_ or _Azoic_. The general impression on the minds of geologists has been, that, as we descend in this long staircase of natural steps, we are brought in view of a state of the earth in which life was scantily manifested, so as to appear to be near its earliest stages. 16. Each of these formations is of great thickness. Several of the members of each formation are hundreds, many of them thousands of feet thick. Taken altogether, they afford an astounding record of the time during which they must have been accumulating, and during which these successive groups of animals must have been brought into being, lived, and continued their kinds. 17. We must add, that over the Secondary strata there are found, in patches, generally of more limited extent, another, and of course, newer mass of strata, which have been termed _Tertiary Formations_. Of these, the strata, near and under Paris, lying in a hollow of the subjacent strata, and hence termed the _Paris Basin_, attracted prominent notice in the first place. And these are found to contain an immense quantity of remains of animals, which, being well preserved, and being subjected to a careful and scientific scrutiny by the great naturalist George Cuvier, had an eminent share in establishing in the minds of Geologists the belief of the extinct character of fossil species, and of the possibility of reconstructing, from such remains, the animals, different from those which now live, which had formerly tenanted the earth.