and Australia. While a few similar or even identical types may
be recognized in both floras, there can be no doubt that, during
a considerable period subsequent to that represented by the Lower
Carboniferous or Culm rocks, there existed two distinct floras, one
of which had its headquarters in the northern hemisphere, while
the other flourished in a vast continental area in the south. Recent
discoveries have shown that representatives of the two floras
coexisted in certain regions; there was, in fact, a dovetailing between
the northern and southern botanical provinces. In 1895 Professor
Zeiller described several plants from the province of Rio Grande do
Sul in South America (Map A, G2), including a few typical members
of the Glossopteris flora associated with a European species, Lepidophloios
laricinus, one of the characteristic types of the Coal period,
and with certain ferns resembling some
species from European Permian rocks. A
similar association was found also in
Argentine rocks by Kurtz (Map A, G1), and
from South Africa Sigillaria Brardi, Psygmophyllum,
Bothrodendron and other northern
types are recorded in company with Glossopteris,
Glangamopteris and Naeggerathiopsis.
| |||
| Map A.—G1—G6, Glossopteris Flora. | |||
| I, II. | Upper Carboniferous plants of the northern hemisphere facies, in the Zambesi district and in China. | ||
| III. | Rhaetic flora of Tongking (Glossopteris, &c.; associated with northern types). | ||
| IV. | Carboniferous plants (prov. Kansu). | ||
| V. | Glossopteris, &c., in Permian rocks in prov. Vologda. | ||
| VI. | Permian (Pechora valley). | VII. | Upper Carboniferous (Herakleion). |
| VIII. | Rhaetic (Honduras). | IX. | Lower Jurassic, Upper Gondwana (Argentine). |
| X. | Rhaetic (Persia). | XI. | Triassic—Cretaceous. |
|
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The Coal-bearing strata which occupy a considerable area in China (Map A, II.), contain abundant samples of a vegetation which appears to have agreed in their main features with the Permo-Carboniferous floras of the northern hemisphere. In his account of some plants from the Coal Measures of Kansu (Map A, IV.) Dr Krasser has drawn attention to the apparent identity of certain leaf-fragments with those of Naeggerathiopsis Hislopi, a typical member of the Glossopteris flora; but this plant, so far as the evidence of vegetative leaves may be of value, differs in no essential respects from certain species of a European genus Cordaites. A comparatively rich fossil flora was described in 1882 from Tongking (Map A, III. by Professor Zeiller—and this author has recently made important additions to his original account—which demonstrates an admixture of Glossopteris types with others which were recognized as identical with plants characteristic of Rhaetic strata in Europe. In the Tongking area, therefore, a flora existed during the Rhaetic period consisting in part of genera which are abundant in the older Glossopteris beds of the south, and in part of well known constituents of European Rhaetic floras. A characteristic member of the southern botanical province, Schizoneura gondwanensis (fig. 2) of India, is represented also by a closely allied if not an identical species—S. paradoxa—in the Lower Trias (Bunter) sandstones of the Vosges Mountains, associated with European species which do not occur in the Glossopteris flora. Another plant found in the Vosges sandstones—Neuropteridium grandifolium—is also closely allied to species of the same “fern” recorded from the Lower Gondwana strata of India (fig. 4), South America and South Africa. These two instances—the Tongking beds of Rhaetic age and the Bunter sandstones of the Vosges—afford evidence of a
