1848.] BUNBURY ON FOSSIL PLANTS. 135 



Mr. Horner, in his Anniversary Address, to which I have before 

 alluded, regards this phsenomenon as merely an instance of the per- 

 manence of certain species of plants ; and as illustrative of the law, 

 that species which have had a wide range in space have also had a 

 long duration in time. "We know," he observes, "that the same 

 species of plants are found in the coal-fields belonging to the palasozoic 

 carboniferous rocks of Europe and of North America, and in regions 

 with differences of more than thirty degrees of latitude ; and therefore 

 they may have been able to live through the many vicissitudes of con- 

 dition of the earth's surface that must have occurred between the car- 

 boniferous and liassic periods." This explanation, as it appears to 

 me, does not meet the difficulties of the case. If no plants different 

 from those in question occurred in the lias formation of Europe, and 

 if none of the intermediate rocks, between the carboniferous and the 

 liassic periods, were characterized by markedly distinct forms of vege- 

 table life, then the principle brought forward by Mr. Horner would 

 be strictly applicable ; and there would indeed, in such a case, be 

 nothing peculiarly anomalous or difficult of explanation. We should 

 merely have to conclude that vegetable remains were of no import- 

 ance whatever in determining the age of rocks. But the facts are far 

 different. The Permian system, indeed, which immediately follows 

 the coal, appears to resemble it closely in the character of its vege- 

 tation*. But in the Trias we have a very distinct flora, confined in- 

 deed to few localities, but marked by strong peculiarities both specific 

 and generic. The fossil vegetation of the Grcs hiymi'e of Alsace, so 

 well illustrated by Messrs. Schimper and Mougeot, is tolerably rich 

 in species, and is quite different from that of the carboniferous period ; 

 it is characterized particularly by numerous coniferee, of two genera 

 {Albertia and Voltzid), and by a very remarkable fern, Anomopteris 

 Mougeotiii to which nothing similar has been found in any other 

 formation. The number of ferns found in this deposit, at Soultz-les- 

 bains near Strasbourg, amounts altogether to eleven or twelve species, 

 all of which, without exception, are clearly distinct from those of the 

 coal-measures. Now we must bear in mind that the prevailing and 

 most common ferns, at the present day, are, with two or three ex- 

 ceptions, the same over nearly the whole of Europe ; and this ap- 

 pears to have been the case, in at least an equal degree, during the 

 carboniferous aera. Therefore, when we find the variegated sandstone 

 of Alsace, at so moderate a distance, comparatively speaking, from 

 some of the coal-fields of France and Germany f , characterized by an 

 entirely different set of ferns, with not even one species in common, 

 — we are warranted in concluding that a great change of climate or 

 other conditions, producing a remarkable change in the vegetation, 

 must have occurred between the deposition of the coal-measures and 

 that of the sandstones in question. Yet during that time, according 

 to the hypothesis I am considering, the Tarentaise and a small re- 

 gion near it continued to retain unchanged the vegetation of the coal 

 period ; although the distance from Soultz-les-bains to the Tarentaise 



* See Murchison's * Russia.' 



t It is scarcely twenty geographical miles from Saarbriick. 



