192 THE GEOLOGICAL HISTORY OF PLANTS. 



the supposed Lower Cretaceous of Kome, in Greenland 

 (Fig. 68). Two species, a Sterculia and a Laurus or 

 Salix, occur among fossils described by me in the upper 

 part of the Kootanie series of the Eocky Mountains, and 

 Fontaine has recently found in the Potomac group of 

 Virginia believed to be of Neocomian age several angio- 

 spermous species (Sassafras, Menispermites, Sapindus, 

 Aralia, Populus, &c. ) mixed with a rich flora of cycads 

 and pines. These are the early forerunners of the mod- 

 ern angiospermous flora ; but so far as known they do 

 not occur below the Cretaceous, and in its lower portions 

 only very rarely. When, however, we ascend into the 

 Upper Cretaceous, whether of Europe or America, there 

 is a remarkable incoming of the higher plants, under 

 generic forms similar to those now existing. This is, in 

 truth, the advent of the modern flora of the temperate 

 regions of the earth. A very interesting tabular view of 

 its early distribution is given by Ward, in the "American 

 Journal of Science " for 1884, of which the following is a 

 synopsis, with slight emendations. I may add that the 

 new discoveries made since 1884 would probably tend to 

 increase the proportionate number of dicotyledons in the 

 newer groups. 



DICOTYLEDONOUS TREES IN THE CRETACEOUS. 



Upper Senonian 179 species. 



(Fox Hill group of America.) 



Lower Senonian 81 species. 



Upper white chalk of Europe; Fort Pierre 

 group of America; coal-measures of Na- 

 naimo ? 



Turonian 20 species. 



Lower white chalk ; New Jersey marls ; 

 Belly R. group. 



Cenomanian 357 species. 



(Chalk-marl, greensand, and Gault, Niobrara 

 and Dakota groups of America) ; Dun- 

 vegan group of Canada ; Amboy clays of 

 New Jersey. 



