FLORA OF THE TRIAS AND LIAS EPOCHS. 



11 



In tliis reign the Acrogenous species are less numerous; 

 the Gymnosperms ahuost equal them in number, and ordinarily 

 surpass them in frequency. There are two periods in this 

 reign, one in which Coniferae predominate, while Cyca- 

 dacese scarcely appear; and another in which the latter 

 family preponderates as regards the number of species, 

 and the frequency and variety of generic forms. Cyca- 

 dacea3 occupied a more important place in the ancient 



ir:- .iiti 



-,..-f^ 



Fig. 74. 



than in the present yegetable world. They extend more or 

 less from the Trias formation up to the Tertiary. They are 

 rare in the Gres bigarr^ or lower strata of the Triassic system. 

 They attain their maximum in the Lias and Oolite, in each of 

 which upwards of 40 species have been enumerated, and they 

 disappear in the Tertiary formations. Schimper describes 13 

 genera of fossil Zamiee, and about 20 Cycadeae. He thinks 

 that Trigonocarpum (15 species), Rhabdocarpum (24 species), 



Fig. 74. Cycas revoluta, one of the false Sago-plants found in Japan. 

 Fig. 75. Encephalartos {Zamia) pimgens, another starch-yielding 

 Cycad. 



