- 13 - intense, investigations of certain genera and species of European Tertiary flora, we shall recognize one of the most interesting pages in the history of the Eurasian continent. The abundance of so-called East-Asiatic subtropical and warm-temperate mountainous elements demonstrates that from the Eocene in the region of the enormous Tethys Sea, the maritime mountain systems and the archipelago of mountainous islands, including the large outcrops of carbonate rocks, were present. Moreover, the humid oceanic climate of the Tethys region brought about the development of a uniform, predominantly forest flora in those epochs from the shores of the Atlantic to the Pacific Ocean. At the lower elevations of the mountains along the shores of the Tethys a typical subtropical flora probably was developing and forests rich in subtropical evergreen species were widespread, while a warm-temperate and temperate forest flora developed on the slopes of the mountains at higher altitudes. This is evident from the occurrence of brown-coal flora in Turcv (Poland), as well as from a number of other Tertiary floras of Europe. Nearly all the species of this flora were widespread in the region of the Tethys Sea. Therefore, it is scarcely correct to speak about the so-called East-Asiatic center of origin and the migrations of this thermophilous forest flora only in a westerly direction. The western part of the Tethys, where the humid-subtropical climate was preserved, became a refugium for humid subtropical plants, while in the remaining part of the Mediterranean region a typically mediterranean climate with a hot and dry summer became established. Here many species of hemixerophilous nature were preserved, found also in some Tertiary floras of Europe and Colchys. This complex of hemixerophilous species is a relict of the Tertiary flora and vegetation in the same way as the Macaronesian humid subtropical forests are. In the Mediterranean region, because of the progressively increasing dryness of the climate, rapid evolution of species began in the Tertiary period. For this reason, there was a rapid migration of Mediterranean species toward the east and, to a lesser degree, to the north. These species are now widely spread in hemixerophytic forests and scrubs, as well as in steppe and even