176 On Fossil Plants from Northern China. 
sures (and probably the entire range of the Coal-measures 
of Europe and America) ; the latter not yet capable of so defi- 
nite classification, but probably referable to both the Rheetic 
and Lias. 
The fossil plants brought by Mr. Hague from China, repre- 
senting as they do not only the characteristic genera of the 
Coal-measures in Europe and America, but identical or 
closely allied spectes, cannot fail to interest both geologists 
and botanists :—the first, by the confirmation they afford of the 
classification adopted for the stratified rocks, based on the 
fossils they contain ; the latter, from the evidence they fur- 
nish of the practical identity of the acrogenous flora of the 
Coal period over so large a portion of the earth’s surface, and 
the remarkable persistence which specific characters exhibit 
in the wide range of migration and the incalculable lapse of 
time through which the dispersion was effected. 
Since none of the higher plants were in existence upon the 
earth’s surface during the Carboniferous age, wherever a ter- 
restrial flora prevailed it could only be composed of acrogens 
and gymnosperms; but how it happens that within these 
limits there was so little diversity 1s incomprehensible. During 
the Coal-measure epoch the same genera, and to a large degree 
the same species, seem to have lived in North America, Kurope, 
Brazil, and China. 
No one who has any acquaintance with fossil plants would 
fail to recognize at once most of the species in the collection 
brought by Mr. Hague; but if shown seven out of the ten he 
could not say whether they came from America, Hurope, or 
Asia. And yet in the interval between the deposition of the 
Coal-measures and the Triassic rocks the whole flora of the 
globe was revolutionized. Before the Bunter was laid down 
Lepidodendron, Sigillaria, Annularia, Sphenophyllum, Cor- 
daites, and indeed a the characteristic forms of the coal flora 
had disappeared. ‘The Cycads in great variety, true Equiseta, 
and peculiar genera of Conifers and Ferns gave new aspects 
to nature, and this again over the whole world. From the 
desert of Atacama, from Sonora, New Mexico, North Caro- 
lina, Europe, India, and China we obtain the remains of the 
unmistakable Mesozoic flora with species which are common 
to all these widely separated localities. 
Hence we are safe in fixing by fossil plants the geological 
horizon of the Mesozoic coal-basins of China; but the identity 
of species in the Mesozoic flora, though surprising, 1s not quite 
so marked as in that of the Carboniferous age. 
In the Middle Cretaceous came another great revolution, 
and the angiosperms succeeded the gymnosperms so rapidly 
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