120 



BRITISH EOCENE ELOUA. 



Supposed Cycadaceae occur in the Upper Carboniferous/ and in the Permian several 

 genera are distinguishable. In the Rhsetic series representatives of Cycas were already 

 differentiated from the rest, or Zamiese, but even v^hen most numerous and diversified the 

 limits within which they varied were very circumscribed. Their oldest known ancestor is 

 Noeggerathia foliosa, of the Middle Carboniferous ; and although the leaves even in this 

 are pinnate, those destined to bear the organs of reproduction are little metamorphosed 

 and but slightly smaller than the foliage-leaves. The ovules also were smaller and far 

 more numerous than at present, and for these reasons Noeggerathia is justly regarded by 

 Saporta and Marion as a primitive type of Cycad in process of evolution. Pterophgllum 

 and Nilssonia succeeded it, and already in the Secondary Period the numerous genera did 

 not (with the exception of Bennettites) differ in any essential points of structure, so far 

 as is known, from the species living in the present day. They become increasingly rare 



c 



Fia. 39. — The last "European" Cycads. A. Zamites epihiiis, Sap., from the Oligocene of Bonnieus 

 (Vaucluse) ; a frond of small size. B. Zamiostrohus Saportanus, Schimp., female cone from the 

 Oligocene of Armissan (Aude). C. Eneephalartos Oorceixianus, Sap., middle part of a frond from 

 the Miocene of Kumi (Euboea), two thirds natural size. — After Saporta and Marion. 



as Cretaceous times are passed, and appear to have completely died out in Europe with 

 the Tertiary Period, evidently declining under the competition of newer forms and only 

 surviving in specially favorable stations. 



In arriving at the " true Gymnospermic " stage of Saporta and Marion we definitely 

 leave behind all those genera of ambiguous and prototypic character which we have 

 hitherto had under consideration. In these we have traced step by step how the purely 



^ Pterophyllum Grand'' Euryanum, Sap. and Mar., a plant discovered by M. Grand'Eury, is regarded 

 by Saporta and Marion as a primitive Cycad. ' Evolution des Phanerogames,' vol. i, p. 109, fig. 58. 



