Wealdean Epoch. 77 



and Zamites; Ctenis, Pterophyllum, and Nilsonia have not 

 yet been observed ; lastly, the Coniferse of the genus Brachy- 

 phyllum are there particularly abundant, and more frequent 

 than in the other localities. 



" In Germany, it is more especially in the slaty limestone of 

 Solenhofen, near Aichsteedt, that these fossils have been 

 observed, and particularly those of the family of Algae. M. 

 Gseppert likewise notices many Cycadeee in the Jurassic for- 

 mation of Ludwigsdorf, near Kreuzburg, in Silesia. 



" But these localities, so diverse, are referrible to very dif- 

 ferent stages of the Oolithic series, and perhaps will constitute, 

 when they are better known, and more fully explored, dis- 

 tinct epochs. 



" The distinctive characters of this epoch, comprising the 

 whole extent we have assigned to it, from the Lias to the 

 Wealdean formation exclusively, are ; among the Ferns, the 

 rarity of ferns with reticulated nervures, so numerous in the 

 Lias ; among the Cycadese, the frequency of Otozamites and 

 Zamites, properly so called ; that is to say, Cycadeae most 

 analogous to those of the existing period, and the diminution 

 of Ctenis J Pterophyllum, and Nilsonia, genera much more re- 

 mote from living species ; finally, the greater frequency of 

 Coniferse, viz., Brachyphyllum and Thuites, much rarer in the 

 Lias. 



** Wealdean Epoch. — This epoch affords, Amphigenous 

 cryptogams, the Algae ; among Acrogenous cryptogams. 

 Ferns, Marsileacew, ^m^ Equisetacece ; among Gymnospermous 

 dicotyledons, Cycadece and Coniferoe ; lastly, some Carpolithes 

 as plants of a doubtful class. 



" This enumeration results principally from discoveries 

 made, in recent years, in the Wealdean formations of the north 

 of Germany, at Osterwald, Schaumberg, Buckeburg, Ober- 

 kirke, &c., of which the fossil plants were first described by M. 

 Rsemer, and afterwards in a more complete manner by M. 

 Dunker, in his monograph of these formations. To these 

 species must be added others, less numerous and varied, pre- 

 viously discovered in the Wealds of England, near Tilgate 

 Forest, and Hastings in Sussex, and which are so well de- 

 scribed by M. Man tell." 



