THE EVOLUTION OF THE PLANT- WORLD 23 



elm, a Viburnum, a water-lily, and other species have been 

 recorded, suggestive of the present climate 25 to the 

 south ; and in Disco Island (70 N. lat.), Ginkgo, Platanus, 

 and Sequoia. It has been suggested that this temperate 

 flora in Arctic latitudes belongs to the Eocene period, 

 being more or less contemporaneous with tropical con- 

 ditions in Central Europe, and that, subsequently 

 migrating southward, it became the temperate Miocene 

 flora of the latter area. 



The isolation of existing provinces during Lower 

 Eocene times is further illustrated by Australia, which 

 had then a peculiar flora rich in Proteacecs, Myrtacece, 

 and Amentacece, and more related to the existing flora 

 of that area than to those of other continents. 



The Oligocene plants of the Hampshire Basin, includ- 

 ing the coniferous A rthrotaxis now confined to Tasmania, 

 and the ferns Gleichenia and Lygodium, suggest a climate 

 somewhat cooler than that of the Bournemouth Eocene 

 beds; as also do the abundant remains found in ex- 

 cellent preservation in the amber, or fossil resin of Pinus 

 succinifera, belonging to this period, in the east of 

 Prussia. These include several species of oak, chestnut, 

 elder, and holly. 



One of the best represented periods in the history of 

 plants is the Upper Miocene, from which over 900 species 

 have been recorded in Switzerland, 500 from one 

 locality, (Eningen near Lake Constance. These show 

 a marked increase in the proportion that deciduous 

 trees bear to the whole flora, with a decrease of palms 

 and other tropical groups. Though there are 1 1 palms, 

 the last Cycads to be recorded in Europe, a Bromelia, 

 a Zingiber, several species of Lygodium and many other 

 ferns, Proteacea, the American genus Liriodendron, and 

 no less than 130 Leguminosce, while Monocotyledons 

 form a sixth of the whole flora, the presence of 94 Cupres- 

 sinece and 90 A mentacece indicate merely warm temperate 

 conditions. Evergreen oaks, figs, and laurels were 

 specially abundant; while from the evolutionary point 

 of view it is interesting to note the complete absence of 

 many orders of Gamopetalce, such as Campanulacece, 

 Labiates, Solanacece, and Primulacece, and the slight 

 representation of Composites and others among the 

 most highly organised. 



During Pliocene times there is clear evidence of a 



