Ch. XVI.] LOWER EOCENE FORMATIONS, ENGLAND. 291 



(Drgandra, &c), and the fig tribe are abundant, as well as the cinna- 

 mon and several other laurineas, with some papilionaceous plants. On 

 the whole they remind the botanist of the types of tropical India and 

 Australia.'" 



Heer has mentioned several species which are common to this Alum 

 Bay flora and that of Monte Bolca, near Yerone, so celebrated for its 

 fossil fish, and where the strata contain nummulites and other Middle 

 Eocene fossils.f He has particularly alluded to Aralia primigenia, De 

 la Harpe ; Daphnogene Veronensis, Massalongo sp. ; and Ficus grana- 

 dilla, Mass. sp., as among the species common to and characteristic of 

 the Isle of Wight and Italian Eocene beds ; and he observes that in 

 the flora of this period those forms of a temperate climate which con- 

 stitute a marked feature in the European Miocene formations, such as 

 the willow, poplar, birch, alder, elm, hornbeam, oak, fir, and pine, 

 are wanting. The American types are also absent, or much more 

 feebly represented than in the Miocene period. The number of exotic 

 forms which are common to the Eocene and Miocene strata of Europe 

 demonstrate the remoteness of the times in which the geographical 

 distribution of living plants originated. A great majority of the 

 Eocene genera have disappeared from our temperate climates, but not 

 the whole of them ; and they must all have exerted some influence on 

 the assemblage of species which succeeded them. Many of these are 

 indeed so closely allied to the flora now surviving as to make it ques- 

 tionable, even in the opinion of naturalists opposed to the doctrine of 

 transmutation, whether they are not genealogically related the one to 

 the other, 



LOWER EOCENE FORMATIONS, ENGLAND. 



London Clay proper (C. 1, Table, p. 281). — This formation under- 

 lies the preceding, and consists of tenacious brown and bluish-gray 

 clay, with layers of concretions called septaria, which abound chiefly 

 in the brown clay, and are obtained in sufficient numbers from sea- 

 cliffs near Harwich, and from shoals off the Essex coast, to be used 

 for making Eoman cement. The principal localities of fossils in the 

 London Clay are Highgate Hill, near London, the island of Sheppey, 

 and Bognor in Hampshire. Out of 133 fossil shells, Mr. Prestwich 

 found only 20 to be common to the calcaire grossier (from which 600 

 species have been obtained), while 33 are common to the "Lits 

 Coquilliers" (p. 304), in which 200 species are known in France. 

 \Ye may presume, therefore, that the London clay proper is older 

 than the calcaire grossier. This may perhaps remove a difficulty 

 which M. Adolphe Brongniart has experienced when comparing the 

 Eocene Flora of the neighborhoods of London and Paris. The fossil 



* Heer, Climat et Vegetation du Pays Tertiaire, p. IV 2. 



f Fo^ remarks on the Monte Bolca rocks, see below, Chap. XXXII. 



