78 Reign of Gymnosperms. 



This same formation has likewise been found in France, 

 near Eeauvais, by M. Graves, who observed there Lonchop- 

 teris MantelH, and some other plante, of which M. Brongniart 

 has not seen specimens, and which he quotes from Graves on 

 the geology of the department of the Oise. 



" These species, 61 in number, enumerated above, appear 

 to be all peculiar to this formation, with the exception, per- 

 haps, of Baiera Huttoni, which seems to be identical with the 

 species of the Bayreuth Lias and Scarborough Lias ; but 

 their generic forms are almost all the same as those of the 

 Lias and Oolitic formations. The Cycadeee, however, already 

 appear less numerous relatively to the ferns. 



"We further observe, that this fresh-waterformation, which, 

 according to our view, terminates the reign of the Gymnos- 

 perms is connected, by the whole of its characters with other 

 epochs of the vegetation of the Jurassic formation, and is 

 distinguished from the Cretaceous epoch, which succeeds it, 

 by the complete absence of every species which could be 

 arranged among the Angiospermous dicotyledons, both in 

 France and England, as well as in the deposits of northern 

 Germany, so rich in varied species. On the contrary, in the 

 lower chalk, cretaceous glaucoma, the quadersandstein or 

 planerkalk of Germany, we immediately find many kinds of 

 leaves evidently belonging to the great division of Angiosper- 

 mous dicotyledons, as well as some remains of palms, of 

 which no trace is observable in the Wealdean deposits. 



"I class among the Cycadese the stems of the Tilgate forest, 

 formerly designated by the name of Clatharia LyelHi, and 

 which I have considered as a stem related to the Bracoena. 

 The whole of its characters, although the almost entire 

 absence of the tissues prevents us examining its anatomy, 

 appear to me to render this connection most probable, and 

 particularly to indicate the relations between this stem and 

 that of Zamites gigas found at Scarborough. 



The abundance of Lonchopteris Mantelli is a character of 

 the Wealdean formations of the south of England and the de- 

 partment of the Oise, where this fossil seems to make its 

 appearance, at least in fragments, in the greater number of 

 localities, where these beds are exposed by the excavation of 



