3 oo HISTORICAL PALEONTOLOGY. 



enjoyed in the Mesozoic, are now relegated to a subordinate 

 though well-defined place in the terrestrial vegetation. The 

 great majority of the Eocene plants are referable to the groups 

 of the Angiospermous Exogens and the Monocotyledons; and 

 the vegetation of the period, upon the whole, approximates 

 closely to that now existing upon the earth. The plants of the 

 European Eocene are, however, in the main most closely allied 

 to forms which are now characteristic of tropical or sub-tropical 

 regions. Thus, in the London Clay are found numerous fruits 

 of Palms (Nipadites, fig. 213), along with various other plants, 

 most of which indicate a warm climate 

 as prevailing in the south of England 

 at the commencement of the Eocene 

 period. In the Eocene strata of North 

 America occur numerous plants belong- 

 ing to existing types such as Palms, 

 Conifers, the Magnolia, Cinnamon, Fig, 

 Dog-wood, Maple, Hickory, Poplar, 

 Plane, &c. Taken as a whole, the 

 Eocene flora of North America is nearly 

 related to that of the Miocene strata of 

 Europe, as well as that now existing 



in the American area. We may con- Fte. 213. Nipaauet eiiipti- 



, , , .. cut, the fruit of a fossil Palm. 



elude, therefore, that the forests of London Clay, Isle of Sheppey. 



the American Eocene resembled those 



of the European Miocene, and even of modern America" 



(Dana). 



As regards the animals of the Eocene period, the Protozoans 

 are represented by numerous Foraminifera, which reach here 

 their maximum of development, both as regards the size of 

 individuals and the number of generic types. Many of the 

 Eocene Foraminifers are of small size; but even these not 

 uncommonly form whole rock-masses. Thus, the so-called 

 "Miliolite Limestone" of the Paris basin, largely used as a 

 building-stone, is almost wholly composed of the shells of a 

 small species of Miliola. The most remarkable, however, of 

 the many members of this group of animals which flourish in 

 Eocene times, are the " Nummulites " (Nummulina\ so called 

 from their resemblance in shape to coins (Lat. nummus, a coin). 

 The Nummulites are amongst the largest of all known Fora- 

 minifera, sometimes attaining a size of three inches in circum- 

 ference; and their internal structure is very complex (fig. 214). 

 Many species are known, and they are particularly character- 



