84 Keign of Angiosperms. 



" Almost all these Algae appear to belong to the same group, 

 the genus Chondrites ; and although the species are pretty 

 numerous, they pass from one to another by almost insensible 

 shades. The Algae of the neighbourhood of Vienna, placed 

 in the genus Munsteria, are very ill characterised, and per- 

 haps are not congenerous with those of the Jurassic lime- 

 stone of Solenhofen ; but they appear to me to have been 

 found in the same formation, designated by the name of gray 

 calcareous slate, of the sandstone of Vienna, as the Chon- 

 drites of the same country." 



The Flora of the fucoidean sandstone is constituted by 

 twelve species of Algae (Chondrites and Munsteria.) 



" What is remarkable in this series of species is, that they 

 have nothing in common, either with the Algee of the Subcre- 

 taceous epoch, or with those of the Eocene epoch, and parti- 

 cularly of Monte-Bolca, with which this Flora should be 

 almost cotemporary, according to many geologists. The iden- 

 tity of these species of Algae is likewise remarkable in all the 

 localities, however distant from each other — ^localities so nu- 

 merous, in regard to the greater number of these species, 

 that I have been unable to enumerate them. 



" The Chondrites targionii, or perhaps a distinct species, but 

 very nearly related, is the only one presented in another for- 

 mation, in the greensand and gault of the Isle of Wight, in 

 England, according to M. Fitton ; and in this same formation, 

 in the department of the Oise, according to M. Graves. 



*' M. Kurr has likewise described and figured, under the 

 name of Chondrites bollensis, a fucus of the Lias — the very 

 varied forms of which are almost identical with the Chond- 

 rites targionii, aequalis, and difformis. 



" VI. Tertiary Period, — Considered as a whole, the vege- 

 tables of this period, cotemporary with all the Tertiary de- 

 posits, and continued even in the vegetation which now 

 covers the earth's surface, is one of the best characterised. 

 The abundance of Angiospermous dicotyledons, that of the 

 monocotyledons of diverse families, but especially the Palms, 

 during a part at least of this period, immediately distinguish 

 it from the most ancient periods. Yet the observations 

 made on the Cretaceous epoch have established a kind of 



