72 ())i the OrU/in and Distribution of the British Flora. 



ProteacecB aud Lef/iiminosa. At La LouviereJ in Hainault, in 

 clays belonging to the period of the Gaiilt, is a flora consisting 

 of conifers and cycads, like those of Kome and Folkestone ; 

 whilst at Aix-la-Chapelle,^ in sands of Upper Chalk age, 

 we have a far different assemblage of j)lauts, including, 

 with the ferns, Aspleniiim, Lygodium and Gleichenia ; with 

 Sequoia and other conifers, species of screw-pine and nume- 

 rous FroteacecB (amounting to nearly 70 species out of 200), 

 some belonging to such genera as Banksia, Dryandra and 

 Leucospennum, which are now confined to Australia and the 

 Cape. With these are Eucalyptus, fig, bog-myrtle, willow, 

 poplar, oak, and beech. In the lignites of the Dakotah group,^ 

 on the plains of Eastern Kansas and Nebraska, a remarkable 

 flora has been discovered, embracing such forms as poplar, 

 willow, birch, oak, bay, cinnamon, liquidambar, magnolia, 

 tulip-tree, maple, and plum ; and in New Zealand,^" in beds 

 also of Cretaceous age, we have the beech, with many repre- 

 sentatives of the Myrtacea, and of genera still existing in 

 that country. Professor Lesquereux is of opinion" that the 

 existing arborescent flora of North America originated in the 

 Dakotah group, and subsequently migrated to Europe. In the 

 London clay, at Slieppey, we have fruits of Proteaceous 



7 Coemans, ' Mem. de I'Acad. roy. de Belgique,' tome xxxvi. 

 « Lyell, ' Student's Elements of Geology,' 1st ed., p. 278, Morris, op. cit., 

 pp. 49 — 51, and the numerous papers there quoted. 



9 Admirably described and discussed by Professor Lesquereux, ' The 

 Cretaceous Flora,' Washington, 1874. 



10 Dr. Hector, ' Trans. New Zealand Institute,' vols. ii. and vi. 



" Op. cit, and ' Geol. Survey of Montana,' 1871, p. 314. Note also 

 Mr. De Eance's remarks in the geological appendix to Sir George Nares' 

 ' Narrative of a Voyage to the Polar Sea ' : — " In the overlying American 

 Eocenes occur types of plants occurring in the European Miocenes and 

 still n\ing, pro\ing the truth of Professor Lesquereux's postulate that the 

 plant types appear in America a stage in advance of their advent in 

 Europe. These plants point to a far higher mean temperature than those 

 of the Dakotah group." " This," adds Mr. A. R. Wallace (' Island Life,' 

 p. 183), " is very important as adding further proof to the view that the 

 climates of former periods are not due to any general refrigeration, but to 

 causes which were subject to change and alternation in former ages 

 as now." 



