88 THE THEORY OF EVOLUTION 



the rocks, the immediate impression received is that 

 of constant, though not always uniform advance and 

 progress from the most ancient times, and, the more 

 nearly the present is approached in time, the closer is 

 the approximation to the modern animal and vege- 

 table worlds. This most obvious and striking fact 

 impressed itself upon the earlier paleontologists, like 

 Cuvier and Agassiz, who upheld the theory of special 

 creation and the immutability of species, and they 

 interpreted it as the carrying out of a systematic 

 creative plan, an interpretation which is not at all 

 invalidated by the acceptance of the evolutionary 

 theory. 



The latest of the eras, the Cenozoic, in which we 

 are now living, is characterized by a land vegetation 

 consisting chiefly of the flowering plants, such as the 

 trees, bushes and herbs, with which we are all famil- 

 iar, also palms, lilies and grasses. The conifers, or 

 "evergreens," pines, spruces, firs, etc., also belong to 

 the flowering plants, but to a lower grade, but of the 

 non-flowering or cryptogamic plants, only the ferns, 

 mosses and lichens can be called abundant; the fungi 

 and microscopic plants are left out of account, as so 

 little is known of their history. Certain groups which 

 contain but few species are of interest as being the 

 last survivors of what were once great and dominant 

 assemblages; the Cycads, or erroneously so-called 

 "Sago Palms," are now confined to the warmer parts 

 of the earth and, among the cryptogamic plants, the 

 little ground-pines, or lycopods, and the horse-tails 



