614 



SCIENCE 



[N. S. Vol. XLII. No. 10»7 



years ago by L. Laurent of Marseilles.^ His 

 determination included ten dicotyledons and 

 one conifer and indicated a similar age to that 

 indicated by the overlying seed and fruit flora. 

 The latter is remarkable in including nearly 

 three hundred species, of which the botanical 

 position of about 77 per cent, is determined 

 with considerable certainty. This flora is 

 shown to present a striking similarity to the 

 living flora of the uplands of western China 

 and to its more or less allied geographical prov- 

 inces, i. e., Japan, the Himalayas, eastern 

 Tibet and the Malay Peninsula. A more re- 

 mote relationship is shown with the existing 

 flora of Europe or the Caucasus, and a stiU 

 more remote relationship with the existing 

 flora of North America. 



This oriental character is shown by the pres- 

 ence in Limburg of forms like Onetum 

 scandens, Zelhowa Tceaki, Pyrularia edulis. 

 Magnolia Tcohus, Prunus maximoviczii, 8te- 

 wartia pseudo-camellia, etc., no longer natives 

 of Europe, as well as by representatives of 

 genera such as Meliosma, Actinidia, Oorplopsis, 

 Camptotheca, etc., not found in the existing 

 European flora, but represented by closely 

 allied species in China. Even when the genus 

 is still a member of the European flora, the 

 fossil species appears to be closer to the exist- 

 ing Asiatic rather than the existing European 

 representative, as, for example, in the genera 

 Pterocarya, Styrax, Betula, Cornus, Olematis, 

 Eupatorium, etc. There are, however, among 

 the fossils a number of large-seeded forms that 

 are stiU represented in the flora of Europe, 

 among which may be mentioned Picea excelsa, 

 Quercus rohur, Oarpinus hetulus, Corylus 

 avellana, Prunus speciosa. Ilex aquifolium, 

 Vitis vinifera and Fagus cf. silvatica. 



The Eeuverian flora, as it has been called, 

 appears to indicate a climate about like that 

 of southern France of the present time, but 

 with a more abundant rainfall. It was richer 

 in species than the present flora of Central 

 Europe and the number of arborescent forms 

 was greater, both relatively and absolutely, 



3 In Jongmans, W., "Rapport over zijne paleo- 

 bot, " Bijksopsporing van Def staff en, Jahren, 

 1908-11, pp. 23-25. 



comprising fifty per cent, of the determined 

 forms. This and other conclusions which are 

 deduced from the present study are well known. 

 to paleobotanists, but seem to require constant 

 reiteration to get a hearing with botanists or 

 geologists. 



The authors' explanation of events is in 

 brief an immigration of this rich and varied 

 warm temperate flora into the Dutch region [a 

 survival in this region as a part of the rich 

 and more or less cosmopolitan flora of the 

 earlier Tertiary is probably a better way of 

 stating the case], where with the progressive 

 lowering of temperatures in the late Pliocene 

 as is indicated by the floras of Tegelen near 

 Venloo, Wylerberg near Nijmwegen and the 

 Cromer Forest bed, it found its retreat to the 

 southward cut oif by mountains, seas or deserts, 

 from the Pyrenees on the west eastward all of 

 the way to Tibet, so that aU but a few forms 

 like Quercus rohur, Corylus avellana and Picea 

 excelsa were subsequently exterminated. Even 

 those forms that succeeded in reaching ths 

 shores of the Mediterranean seem to have 

 found themselves in a climate that was too dry. 



Compared with Europe both North America 

 and eastern Asia afforded better facilities for 

 a continuous movement of plants to the south- 

 ward and back — North America with it« 

 mountains trending north and south, with the 

 broad valley of the Mississippi and the well- 

 watered Atlantic coastal plain — eastern Asia 

 with the coastal plain of China and the great 

 river-valley systems of that country. Eecoloni- 

 zation from the southward in post-glacial 

 Europe was a slow process and these are two 

 of the reasons why the existing Asiatic flora 

 or that of eastern North America is so much 

 richer than that of Europe. 



Among botanical items that I have not yet 

 mentioned are species of Ardisia, Mcesa, Lirio- 

 dendron, Cinnamomum, Hahea, Mimusops, 

 Diospyros, stones of a Nyssa indistinguishable 

 from our American sylvatica, as well as many 

 others that might be enumerated. It must 

 make the shade of Bentham turn over to hav« 

 an Englishman identify the fruits of Proteace* 

 in Europe. 



All of the material is carpological, i. e., the 



