General Conclusions.
We have seen from the examples cited in the last four sections, that all of the four existing great Classes of the grand Division of Articulated animals, viz. Annelidans, Crustaceans, Arachnidans, and Insects, and many of their Orders, had entered on their respective functions in the natural world, at the early Epoch of the Transition Formations. We find evidences of change in the Families of these Orders, at several periods of the Secondary and Tertiary series, very distant from one another; and we further find each Family variously represented during different intervals by Genera, some of which are known only in a fossil state, whilst others (and these chiefly in the lower Classes,) have extended through all geological Eras unto the present time.
On these facts we may found conclusions which are of great importance in the investigation of the physical history of the Earth. If the existing Classes, Orders, and Families of Marine and terrestrial Articulated animals have thus pervaded various geological epochs, since life began upon our planet, we may infer that the state of the Land and Waters, and also of the Atmosphere, during all these Epochs, was not so widely different from their actual condition as many geologists have supposed. We also learn that throughout all these epochs and stages of change, the correlative Functions of the successive Representatives of the animal and vegetable kingdoms have ever been the same as at the present moment; and thus we connect the entire series of past and present forms oft organized beings, as parts of one stupendously grand, and consistent, and harmonious Whole.
