the paleontologist exceed his warrant when he presumes that such they ever have been from the moment they first

clustered over the rocks or spread their leathery lobes in

the waters? Next in order come the Acrogens-the mosses, equisetums, and ferns-the lovers of the swamp and shade, and the colonists of emerging and new-formed lands. Of rapid and widespread growth, they have ever contributed to the consolidation of alluvial soils, and their remains mingle largely with the coals and shales of the past, as they

do now with the peat-bogs and mud-silts of the present day. Less cosmopolitan than the amphigens, they still have

an extensive range; but, like them, their function is largely physical, and comparatively few of the animal races find subsistence on their stems or foliage. As the peaty marsh, the silty lake, and the shady river-swamp are now their established headquarters, so the increment and consolidation of these by their annual growth and decay has ever been their geological function. Higher than these, and of more varied aspect, come the Gymnogens-the cycads, and yews, and pines-the gregarious forest growths of the present, as of former ages. Lovers of the temperate and coldly temperate zones-inhabitants alike of the swamp, the arid plain, and the mountain-they exhibit an enlarged diversity of habit, and form, and function. Like the acrogens, many of them are swamp and coal formers; and, as will be afterwards seen, it is to the acrogens and gymnogens, and especially to extinct intermediate forms, that we are chiefly indebted for the coal-beds of the earlier formations. As foodsuppliers, their function is comparatively limited—their dry rigid foliage, their scaly seeds and fleshless berries, being little fitted for the miscellaneous requirements of the higher animals. And it is a curious coincidence that so few of the higher animals appear in the geological periods where these acrogenous and gymnogenous groups so universally prevail. The Endogens-the grasses, lilies, and palmsfollow next in order, and present a still increasing variety, both in form, habitat, and function. Tropical and temperate, but unfitted for the extremes of climate, they assume more diversified areas of localisation, and become more and more fitted for the sustenance of a varied terrestrial fauna. While radiates, molluscs, and crustacea may feed on the thallogens, and insects, and it may be a few birds and reptiles, find their food and shelter among the acrogens and gymnogens, it is certainly to the endogens and exogens that the higher terrestrial animals turn for their main depend

ence.

The formative or geological function so prominent in the lower groups, now gives place to the alimentative;

and though the grassy carpet may conserve the soil from waste, and the palm-grove may induce the accumulation of vegetable matter, still the relations of the endogens are mainly and obviously zoological. Highest and last come

the Exogens-the herbs, and shrubs, and timber-treeswhich, in their beauty and variety and dignity of aspect,

crown the long line of vegetable existences. Slower of growth, but of greater longevity, the beauty of their flowers, the utility of their seeds and fruits, the durability of their structure, and the diversity of their habits and forms, all point to them as the culminating orders of the vegetable