The inhabitants of higher parts of that dim, mysterious world, of which we know only that part revealed in the fossil record, were largely ancestors of our modern cone-bearing evergreens. They are known as _Cordaitales_ and have long since disappeared. Forming forests of huge size and making long, slender trunks with a crown of leaves at the top not unlike some modern conifers to which they are, of course, related, these progenitors of our pines and spruces must have been striking objects of that strange landscape. Rooted stumps of these ancient trees have been uncovered, and their narrow leaves, often three feet long, are common as fossils. By some our present conifers and the _Cordaitales_ are both thought to be descendants from a still more ancient group, of which the existence is only conjectured. We can, perhaps, best summarize our sketch of the plant life existing at the close of this period by saying that all the forms show unmistakable evidence of being crytogamous so far as their reproductive processes are concerned, or else, as in the progenitors of our conifers and cycads, the beginnings of a definite seed habit are indicated. Most of the lowland representatives of this flora were cryptogamous in their characters and ancestry, while some of them, and nearly all the flora of drier sites, appear to have shown the beginnings of flower production. Some of these flowers, which are always cones, are unmistakable as such, and pollen in tremendous quantities has been found among their buried remains. These cones belong to trees that are actual gymnosperms or obvious ancestors of them, for no herbs are known as yet. Nor are angiospermous flowering plants known from this period, nor have any ever been found in strata millions of years younger than the fossil-bearing strata of this age of the ancestors of our modern ferns, conifers, or cycads. Nor must we picture the development of these different plant inhabitants of that time as passing from one to another in orderly sequence, for that would give us the impression of a regular progression from simple to complex, which may or may not be the truth. There appears to be such a sequence, and the internal structure of the remains of many of these ancient types of plant life have greatly aided our ability to understand their relationships. But with the possibility of various reproductive processes or other structures appearing in quite unrelated forms, and with the comparative paucity of the fossil record in mind, no one can say for certain what are the true lines of descent. The necessity for water in the reproductive act of nearly all the crytogams, the origin of the vascular structure, and the consequent ability to live upon the land, and finally the production of a conelike flower structure with pollen, and all that that implies, are all found during this period.