RESULTS OF PAL^EONTOLOGICAL RESEARCH 55 



By the evolution of numerous variations this primary 

 type attains its period of maximum development also 

 in the Coal period. 



The Cordaites become more numerous ; they also 

 begin to vary in form. 



In the Devonian of Bohemia Potonie has found 

 also the remains of Ginkgo-like plants 1 as representa- 

 tive of a further group of Gymnosperms. 



In the coal seams of the Carboniferous age, accord- 

 ing to an appropriate remark of Potonie, 3 tropical 

 marshlands (Sumpffiachmoore) have come down to us 

 in a fossilized state, and by both these terms c tropical ' 

 and ( marshland ' the flora of that period appears to 

 be well indicated. 



The growths which, in conjunction with flowering 

 plants, also at present form the main constituents of 

 such ' reedbeds/ are represented, and in a manner 

 befitting the most luxuriant environmental conditions, 

 by gigantic tree-like forms of the three classes of 

 Pteridophytes, the true Ferns ; then the Club Mosses 



1 J. P. Lotsy : Vorlesungen uber Descendenztheorien (Hit besonderer 

 BeriicJcsichtigung der Botanischen Seite der Frage) II, Jena, 1908, p. 466. 

 The Ginkgos externally resemble our leafy trees. The only species still 

 existent Oinkgo biloba (on account of the two-lobed leaves) is indigenous 

 in China and Japan, but as quite solitary specimens. It may frequently 

 be seen in our parks. They form a quite peculiar group, which Lotsy thus 

 describes : ' Gymnosperms with conifer-like wood with male and female 

 inflorescence widely differing from the Cycads, but with ovaries and seed 

 resembling those of Cycads.' Lotsy : Vortrdge tiher Bot. Stammesgeschichte, 

 II, Jena, 1909, p. 778. (Not to be confounded with the work above 

 cited. ) (Cycads and conifers are two chief groups of recent Gymnosperms. ) 

 The Ginkgo was therefore no more a transitional form in the Carboniferous 

 period than it is to-day, as we shall see later on. 



2 Die Entstehung der Steinkohle, etc., p. 186. 



