It is remarkable that these organized beings belonged to genera now extinct. They were of an inferior class, having neither the delicacy, complexity, or sensibility of those which we now see. They were crude, and gross, corresponding to the condition of the earth at the time of their existence. It is also evident that they lived, and died, and were inhumed in the same places; as they present, generally, no marks of violence, and their most delicate parts are well preserved. These organic remains occupy vast districts of country, and constitute, principally, large masses of marbles, sometimes many hundreds of feet in the interior of mountains. They are identified with the rock, and frequently impart to it its beauty. 7. The reader will readily perceive that this class of rocks marks the _commencement_ of _sensitive_ existence. And it would seem, from an examination of fossil remains generally, that the creation of animals and vegetables was _progressive_, produced with structures and functions adapted to the condition of the globe, at the time of their creation. _Secondary Rocks._ 1. _These rocks are so called, because they are the second great deposit, after the grand foundation of the primitive rocks were laid._ Of course they point out the third great geological period. 2. _Their position is horizontal, corresponding to the general curve of the earth._ This regards their natural position. They are found, under particular circumstances, inclined to the horizon. They occupy a lower position on the sides of mountains, resting on the transition class, which is immediately subjacent _in natural order_. 3. _This class is much less chemical, indeed very little so, in its structure._ It is the result of mechanical deposition, after the chemical action had nearly ceased in the great primitive and retiring abyss. 4. _These rocks abound more in fragments of other rocks, and in the remains of organized beings, than the preceding class._ This would be natural, as a greater extent of the earth’s surface would be exposed to the elements, and thus the destruction would be greater: and as the condition of the earth was better for sustaining sensitive beings, these would of course be more abundant both in _kind_ and _number_. It is also well ascertained, from the fossil remains found in this class of rocks, that during their deposition, there existed many species of animals and plants which do not now exist: that many of the animals were _monsters_ of incredible size and voracity; of such hugeness, grossness, and ferocity as were suitable to the then prevailing condition of the earth.