2O2 THE GENESIS AND MIGRATION OF PLANTS 



If such a primeval flora as that above indicated ever ex- 

 isted, it must have perished utterly before the incoming of the 

 next great age of the world that known as the Palaeozoic, 

 whose rocks are surpassingly rich in the remains of animals, 

 especially those of the lower or invertebrate classes and those 

 that inhabit the waters. 



In the oldest Palaeozoic rocks we find no plants certainly 

 terrestrial, but abundance of Algae or seaweeds, and some 

 gigantic members of the vegetable kingdom which seem to 

 have been trees, with structures more akin to those of aquatic 

 than to those of land plants. 1 At a somewhat early stage, how- 

 ever, in the rocks of this period, we discover a few undoubted 

 land plants. 2 These seem to be allied to the modern Club- 

 mosses and to their humble relations, the pillworts 3 and 

 other small plants of similar structure found in ponds and 

 swamps. Some of them, indeed, appear to be intermediate 

 between these groups. All these plants are Cryptogams, or 

 destitute of true flowers, but do not belong to the lowest forms 

 of that type. Thus, so far as we know, plant life on the land 

 began possibly with certain large trees of algoid structures, and 

 more certainly with the club mosses and pillworts and their 

 allies, and these last in the form of species not tree-like in 

 dimensions, but of very moderate size. The structures of 

 these plants are already sufficiently well known to inform us 

 that the plan and functions of the root, stem and leaf, and of 

 spores and spore case were set up ; and that the structures and 

 functions of vegetable cells, fibres and some kinds of vessels 

 were perfected, and all the apparatus introduced necessary for 

 the fertilization and reproduction of plants of some degree of 

 complexity. At the same time, the peculiar structures of the 

 higher Algae were brought to a pitch of perfection not surpassed 



1 Nematopliyton, etc. See "Geological History of Plants." 



2 Psilophyton, Protannularia, etc. 



3 Rhizocarpeae. 



