have successively occupied the surface of the Earth. 83 



these allow us to attribute to them more value than to that en- 

 semble of numerous vegetables, the greater portion well determined 

 specifically, which are found in these anthracitic strata? In 1828 

 I gave a list of these fossils comprising 25 species, 20 of which 

 were determined specifically, and were all identical with the species 

 of the coal formation. Mr. Bunbury has just executed a similar 

 task on the collections deposited in the Museum of Turin, and 

 has arrived at the same result ; and I will add, that, several years 

 ago, I received from M. Scipio Gras, engineer-in-chief of mines 

 at Grenoble, collections of the fossils of the mines of Lamure and 

 La Tarentaise, which contained more than 40 species, among 

 which a great number belonged to the most characteristic genera 

 of the coal formations. Such are the Sigillarias, eight or nine 

 in number, five well determined ; Stigmaria ficoides, three Lepi- 

 dodendra, a Lepidophloios, Annularia longifolia and brevifolia ; in 

 a word, the whole ensemble of the coal vegetation, such as it is 

 exhibited at St. Etienne or Alais. 



With regard to the explanation drawn from a transport from 

 distant regions where this vegetation had persisted, it becomes 

 less admissible daily, as the number of specimens increases, and 

 as we see that not a single specimen of the plants peculiar to 

 the liassic period occurs intermixed with them. 



2. Permian Period. 



The nature of the plants which appear peculiar to this epoch 

 is far from being determined in a very positive manner, for the 

 very few localities in which have hitherto been found fossils that 

 we can regard as belonging to this period, are perhaps actually 

 not of completely identical and really contemporaneous formation. 

 Thus, are the bituminous and cupreous schists of the Mansfeld 

 country, referred by all geologists to the Zechstein, and the 

 sandstones of Russia classed by MM. Murchison and Verneuil 

 in the Permian formation, really contemporaneous ? Finally, 

 the slates of Lodeve, considered by MM. Dufresnoy and Elie de 

 Beaumont as dependents on the gres bigarre, but so different 

 from the gres bigarre of the Vosges in their flora, — are they more 

 properly classed in this period, which would thus be a sort of 

 passage from the coal formation, so well characterized, to the 

 Vosgesian period, or in that of the gi-es bigarre, which differs 

 from it in such a marked manner? 



These doubts as to the identity of the epoch of formation of 

 the three principal localities which would furnish the materials 

 for a flora of this period, lead mc to enumerate these three local 

 floras separately. 



