PalcBOZoic Fossil Plants. 217 



its uniform character may doubtless be in part owing to a 

 greater uniformity of climate then prevailing throughout the 

 globe. Mr Bunbury has, I think, successfully pointed out in 

 your Journal, that the peculiarity of the carboniferous climate 

 consisted more in the humidity of the atmosphere and the 

 absence of cold, or rather the equable temperature preserved 

 in the different seasons of the year, than in its tropical heat ;* 

 but we must still presume that colder climates existed at 

 higher elevations above the sea. 



That there was really a scarcity of flowering plants, other 

 than the dicotyledonous gymnosperms, in those peculiar 

 stations where that carboniferous flora grew with which we 

 are acquainted, is, I think, most probable, for the predomi- 

 nance of Conifers and Ferns, Lepidodendra and Sigillarise, 

 would tend, by the mere occupancy of space, to cause other 

 tribes to be feebly represented. This argument is not based 

 on negative evidence, for botanists conceive that they have 

 already obtained 250 species of ferns of the carboniferous 

 era, whereas the whole of Europe does not produce at pre- 

 sent more than fifty species of the same family. 



The flora of the palaeozoic period, or of the carboniferous 

 and Permian strata, is called by Brongniart the age of Acro- 

 gens, from the great number of Ferns and Lycopodiums 

 which then flourished ; and he styles the secondary period 

 the age of Gymnosperms, because the Conifers and Cycads 

 then prevailed in great numbers. But before we pass to the 

 vegetation of the secondary rocks, we are met with a geolo- 

 gical point of controversy of the utmost moment, on which 

 we ought, if possible, to make up our minds, as it affects 

 nearly all our generalizations when we contrast the fossil 

 plants of the primary and those of the secondary rocks. Are 

 the species of the Alpine anthracite palaeozoic or secondary, 

 carboniferous or liassic \ If plants of the Petit-Coeur near 

 Moutiers in the Tarantaise, all identical with the species of 

 the carboniferous era, and unmixed with any of an oolitic 

 character, be correctly referred to the lias, such an excep- 

 tion to the rule of the restriction of particular assemblages 



* Quart. Journ. Geol. Soc. 1846, vol. ii., p. 87. 



