296 SAGACITY AND MORALITY OF PLANTS. 



especially fragmentary character. Still, both in its 

 general make-up and dissimilar origin, it is very 

 nearly related to that of the mainland of Europe. 



Of the British flora in pre -Tertiary times, its 

 origin and geographical migrations, we know very 

 little, except that during the Oolitic and Wealden 

 Periods the dry land was certainly richly clad with 

 Zaniias, and other Cycadaceous plants, as well as 

 with peculiar kinds of Conifers. In the mid-Second- 

 ary epoch a great northern continent, uncovered, 

 perhaps, with ice and snow, stretched to the north 

 pole. It was watered by mighty rivers, vast as 

 those now peculiar to the tropics, some of which 

 converged, and when they poured their waters into 

 the sea formed banks of sedimentary material which 

 ultimately grew into a delta. The Wealden forma- 

 tion represents such an ancient delta in British 

 geology. It formerly extended in unbroken con- 

 tinuity, after its upheaval, to France, Belgium, and 

 even into Germany, but it has been severed by the 

 denudation of the English Channel. This Wealden 

 formation in places contains abundant relics of ter- 

 restrial vegetation ; and, what is still more to the 

 point, as attesting the luxuriant vegetation which 

 the continental conditions and warmer climate may 

 have spread to the pole itself, there are remains 

 of Igiimtodons and other remarkable herbivorous 

 reptiles, whose presence indicates abundance of 

 vegetation and forest conditions. 



