Successors of the exterminated Tribes.--The Gap slowly filled.--Proof that the Vegetation of a Formation may long survive its Animal Tribes.--Probable Cause.--Immensely extended Period during which Fishes were the Master-existences of our Planet.--Extreme Folly of an Infidel Objection illustrated by the Fact.--Singular Analogy between the History of Fishes as Individuals and as a Class.--Chemistry of the Lower Formation.--Principles on which the Fish-enclosing Nodules were probably formed.--Chemical Effect of Animal Matter in discharging the Color from Red Sandstone.--Origin of the prevailing tint to which the System owes its Name.--Successive Modes in which a Metal may exist.--The Restorations of the Geologist void of Color.--Very different Appearance of the Ichthyolites of Cromarty and Moray, 226-242 CHAPTER XIV. The Cornstone Formation and its Organisms.--Dwarf Vegetation.--_Cephalaspides._--Huge Lobster.--Habitats of the existing Crustacea.--No unapt representation of the Deposit of Balruddery, furnished by a land-locked Bay in the neighborhood of Cromarty.--Vast Space occupied by the Geological Formations.--Contrasted with the half-formed Deposits which represent the existing Creation.--Inference.--The formation of the _Holoptychius_.--Probable origin of its Siliceous Limestone.--Marked increase in the Bulk of the Existences of the System.--Conjectural Cause.--The Coal Measures.--The Limestone of Burdie House Conclusion, 243-259 Ichthyolites of the Old Red Sandstone--from Agassiz's "Poissons Fossiles," 261-288 EXPLANATIONS OF THE SECTIONS AND PLATES. SECTION I.