Xl PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



Paris, brought from beds at the Col de Chardonet, near Briancon, 

 referred " to the uppermost part of the Alpme Anthracite formation, 

 and probably equivalent to the Oxford clay." It thus appears that 

 the researches of Mr. Bunbury lead him to conclude, with M. Adolphe 

 Brongniart, that the plants from the beds noticed present a general 

 agreement with those found in the coal-measures. 



It will be fresh in your recollection, that the mixture or rather al- 

 ternation of beds containing belemnites with others full of plants re- 

 sembling those commonly found in our coal-measures engaged the 

 attention of my predecessor in this Chair, Mr. Horner, and that he 

 pointed to the probability that it might be an instance of species 

 which had a wide range in space having had also a long duration in 

 time, calling your attention to the wide spread of similar plants over 

 certain northern regions of our globe at apparently the same geologi- 

 cal time. This explanation does not satisfy Mr. Bunbury, inasmuch 

 as other plants are known to be found elsewhere in European accu- 

 mulations between the periods of the coal-measures and the oolitic 

 series inclusive, admitting however that in the Permian system of 

 Sir Roderick jMurchison the character of the entombed plants closely 

 resembles that of those of the coal-measures. He more particularly 

 observes on the difference of the plants in the gres higarre of Alsace, 

 remarking on the common spread of certain ferns at the present day 

 over Europe, and of the same tribe of plants over wide areas at the 

 period of the coal-measures. He also points out the small geogra- 

 phical distance of the localities in which the remains of these dissimilar 

 plants are found in the rocks noticed, and calls attention to the 

 observations of M. Scipion Gras, who states that the Jurassic rocks, 

 occurring in their ordinary condition in the department of the Isere, 

 contain impressions of plants entirely different from those of the 

 Alpine anthracite. He admits however at the same time that there 

 are instances of the isolated occurrence of tropical plants, especially 

 Ferns and Lycopodia, in temperate regions, far beyond their ordinary 

 geographical range, as, for example, the growth of Trichomanes ra- 

 dicans in Ireland, and of Lycojjodium cermmm in the Azores. Mr. 

 Bunbury then adverts to the hypotheses of M. Adolphe Brongniart, 

 that the plants in question may have been drifted from regions in 

 which the coal-measure plants still continued to grow, — in the same 

 manner as seeds are now drifted from the tropical regions on the 

 American side of the Atlantic to the shores of Europe, in part, per- 

 haps, becoming enveloped in deposits near land, where plants similar 

 to those producing such seeds do not occur. While he admits that 

 this hypothesis is the most plausible under existing information, and 

 that he has none more satisfactory to offer, Mr. Bunbury does not 

 see his way out of the difficulty. 



Of all organic remains, perhaps those of land plants would appear 

 to afford us the least direct information as to the climate, at different 

 geological periods, of the low or slightly elevated countries bordering 

 seas in various parts of the world, except we can obtain something 

 like evidence of the plants themselves having flourished so near the 

 level of the seas of the time, that slight changes m that level pro- 



