62 THE THEORY OF EVOLUTION 



inhabitants of damp and humid habitats that have 

 been preserved in great numbers which do not permit 

 of an absolutely certain decision, it is very probable 

 that the Gymnosperms followed the Pteridophytes 

 and the Angiosperms the Gymnosperms. 1 



2. Inter-relations between the larger groups, families 

 (series), and classes. 



As above for the animal world, we put the question 

 also here, whether the larger groups were derived 

 from each other in succession, so that, for instance, the 

 Angiosperms represent only a higher development of 

 the Gymnosperms. 



(1) In the system generally in use, there stand upon 

 the lowest step the so-called Thallophytes (Algse and 

 Fungi), then follow the Mosses, the Ferns (really ferns), 

 Club Mosses, Equisetums, and Hydropterides (Water- 

 Ferns), the Gymnosperms, and, finally, the Angiosperms 

 (Monocotyledons and Dicotyledons). 



Whence the Ferns, the first indubitable plant re- 

 mains, come, no one knows. In the pre-Silurian forma- 

 tions we know certainly of no mosses which, purely a 

 priori, come next to them in consideration, and not 

 even of clear traces of Thallophytes which permit of 

 any recognizable connection with ferns. 



1 By ' Ferns,' ' Gymnosperms,' and ' Angiosperms ' we mean here only 

 those foliage plants or trees, in short, those forms which the layman finds 

 so named only in botanical works. Science differentiates all these plants 

 by a double generation (of which more later). The sense of our above 

 remark is simply that Ferns, Gymnosperms, etc., followed each other 

 successively. 



