ITS FLORA. 43 



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 consolida- 

 tion 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 pre- 

 sent, 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 after- 

 wards seen, it is to the acrogens and gymnogens, and espe- 

 cially to extinct intermediate forms, that we are chiefly in - 

 debted for the coal-beds of the earlier formations. As food- 

 suppliers, 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 gyninogenous groups so universally 

 prevail. The Endogens the grasses, lilies, and palms 

 follow next in order, and present a still increasing variety, 

 both in form, habitat, and function. Tropical and tempe- 

 rate, 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 rep- 

 tiles, 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- 



