74: Miscellaneous, 



2nd. The Permian, Triassic and Jurassic rocks have hitherto 

 furnished us but few species for comparison, but the material is 

 increasing, and I have now on hand a large collection which has 

 not yet been studied. Enough is already known to show that the 

 great revolution which took place in Europe at the close of the 

 Permian epoch was matchedby a parallel though lesssudden change 

 in the flora of America. 



Here as there the Lepidodendroid trees, the SigillaricBy the 

 Nceggerathice^ the AsterophyllitcB^ and the great variety of ferns 

 that gave character to the Carboniferous vegetation were super- 

 seded by Voltzia^ Toeniopteris, Camptopteris and a varied and 

 beautiful Cycadaceous flora, in which were many species of 

 Zamites, Pterophyllum^ Nilsonia, &c.^ the representatives of those 

 of the " Age of Gymnosperms." which culminated in the Jurassic 

 epoch of Europe. 



During this great interval the generic correspondence between 

 the floras of Europe and America was perhaps as plainly marked 

 as durinor the Carboniferous ao^e, but the relative number of iden- 

 tical species was apparently smaller. 



3c?. At the commencement of the Cretaceous epoch the flora of 

 the continent was again revolutionized, and the vegetation of its 

 temperate portions given the general aspect that it now pre- 

 sents. 



This statement will surprise many, for the flora generally as- 

 cribed to the Chalk period is greatly different from that of the pre- 

 sent, linger has thus represented it, and Brongniart ealls it a 

 transition from the great Cycadaceous flora of the Jurassic period 

 to the Angiospermous flora of the Tertiary. In Europe the Cre- 

 taceous flora was apparently more like that of the Lias and Oolite 

 than in this country, for while the genera Salix, Acer, Fopulus 

 Alnus, Quercus, (&c., were then introduced there as here, its 

 general aspect was modified by the presence of numbers of Cycad- 

 acece, and its sub-tropical character attested by fan-palms. 



We may find hereafter in other parts of the continent than 

 those in which I have examined the Cretaceous strata, fossils 

 which shall assimilate our flora of that period more closely to that 

 of Europe ; but as far as at present known, our plants of this age 

 present an ensemble quite different. I have now some sixty or 

 seventy species of Cretaceous plants, collected in New Jersey and 

 in various parts of the great Cretaceous area of the interior of the* 

 continent, all of which indicate a flora very similar to that now 



