In at least one respect, every geological history must of necessity be unsatisfactory; and, ere I pass to the history of the two upper formations of the system, the reader must permit me to remind him of it. There have been individuals, it has been said, who, though they could see clearly the forms of objects, wanted, through some strange organic defect, the faculty of perceiving their distinguishing colors, however well marked these might be. The petals of the rose have appeared to them of the same sombre hue with its stalk; and they have regarded the ripe scarlet cherry as undistinguishable in tint from the green leaves under which it hung. The face of nature to such men must have for ever rested under a cloud; and a cloud of similar character hangs over the pictorial restorations of the geologist. The history of this and the last chapter is a mere profile drawn in black, an outline without color--in short, such a chronicle of past ages as might be reconstructed, in the lack of other and ampler materials, from tombstones and charnel-houses. I have had to draw the portrait from the skeleton. My specimens show the general form of the creatures I attempt to describe, and not a few of their more marked peculiarities; but many of the nicer elegancies are wanting; and the "complexion to which they have come" leaves no trace by which to discover the complexion they originally bore. And yet color is a mighty matter to the ichthyologist. The "fins and shining scales," "the waved coats, dropt with gold," the rainbow dyes of beauty of the watery tribes, are connected often with more than mere external character. It is a curious and interesting fact, that the hues of splendor in which they are bedecked are, in some instances, as intimately associated with their instincts--with their feelings, if I may so speak--as the blush which suffuses the human countenance is associated with the sense of shame, or its tint of ashy paleness or of sallow with emotions of rage, or feelings of a panic terror. Pain and triumph have each their index of color among the mute inhabitants of our seas and rivers. Poets themselves have bewailed the utter inadequacy of words to describe the varying tints and shades of beauty with which the agonies of death dye the scales of the dolphin, and how every various pang calls up a various suffusion of splendor.[BD] Even the common stickleback of our ponds and ditches can put on its colors to picture its emotions. There is, it seems, a mighty amount of ambition, and a vast deal of fighting sheerly for conquests' sake, among the myriads of this pygmy little fish which inhabit our smaller streams; and no sooner does an individual succeed in expelling his weaker companions from some eighteen inches or two feet of territory, than straight way the exultation of conquest converts the faded and freckled olive of his back and sides into a glow of crimson and bright green. Nature furnishes him with a regal robe for the occasion.