136 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Nov. 29, 



is trifling when compared to that between the British and the Sile- 

 sian coal-fields, which have so many plants in common. 



The few traces of vegetable remains which have been found in the 

 variegated sandstone in other parts of Europe, agree, as far as they 

 go, with those of Alsace. 



In the Keuper formation we have again another very distinct 

 assemblage of plants, more numerous than those of the Gres bigarre, 

 and still more different from the coal-measure plants, — indeed, much 

 more approximating to the flora of the oolite. In truth, it is diflScult, 

 as far as fossil plants are concerned, to fix a limit between the Keuper 

 and the lias : some of the beds most rich in vegetable remains (such 

 as the sandstone of Hoer in Scania, and the '^Lettenkohle'" of Ba- 

 reuth,) are referred by some authorities to the one of these forma- 

 tions, and by others to the other ; and many species really seem to 

 be common to both. Of not less than sixty-eight species or forms, 

 enumerated in linger' s Synopsis as belonging to the Keuper, not one 

 has been discovered in the coal-measures, and the Pecopteins Meriani 

 seems to be the only one that has even any close resemblance to a 

 plant of the true carboniferous age. 



There may be some difficulty in precisely defining the fossil flora 

 of the lias, for although linger gives a long list of plants from this 

 formation, many of them seem to belong more properly to the lower 

 oolite ; while the sandstone of Hoer in Scania, which M. Adolphe 

 Brongniart referred to the age of the lias, is considered by M. Schim- 

 per as equivalent to the Keuper. As far as it is known, the fossil 

 vegetation of the lias is scarcely distinguishable, on the whole, from 

 that of the middle and lower oolites. I need not dwell on the flora of 

 these latter formations, which is so well displayed in our own coun- 

 try, and is so rich in species and so strongly characterized. It is 

 abundantly distinguished from the coal-measure flora, not only by an 

 invariable difference of species, but by the prevalence of altogether 

 different tribes of plants, and especially by the great number of Cy- 

 cadese. Nor are these characteristics of the Jurassic vegetation con- 

 fined to Europe : the only rocks of that age which are known in the 

 United States (namely those constituting the Richmond coal-field in 

 Virginia) agree remarkably in their vegetable remains with the 

 oolites of Europe ; and even in so distant a region as Cutch, the Ju- 

 rassic rocks are characterized by similar, though not identical, species 

 of fossil plants. 



It is worth while to mention that, as is stated by M. Scipion Gras, 

 in the Bulletin of the Geological Society of France, Jurassic strata in 

 their ordinary condition appear in the department of the Isere, at no 

 very great distance from the limits of the anthracite formation of the 

 Alps ; and these strata contain impressions of plants, entirely different 

 from those of the Alpine anthracite, and exhibiting the usual charac- 

 teristics of the oolitic flora. We must bear in mind that the Alpine 

 formation in question is considered by M. Elie de Beaumont as equi- 

 valent, not only to the lias, but to all the lower and middle part of 

 the Jurassic system. It is difficult to conceive such a peculiarity of 

 local circumstances, as could have occasioned one limited tract of the 



