On the Orif/i?! and DistrUmtion of the Jhitish Flora. 71 



first of these lines of passage Mr. Darwin has suggested^ that 

 the northern forms existing in their own homes in greater 

 numbers, owing to the greater extent of Lind in the north, 

 have attained a higher stage of perfection or dominating 

 power; but Dr. Asa Gray's^ botanical confirmation of the 

 truth of Bishop Berkeley's dictum that "westward the 

 course of empire takes its way" remains at present an 

 ultimate fact. 



In seeking for the geological origin of our existing floras it 

 seems of little use to travel backwards beyond the Cretaceous 

 period. The flora of the Jurassic consists mainly of ferns, 

 conifers and cycads, the oldest known dicotyledon being a 

 species of poplar [Populus jyrlmeva), found in beds of Middle 

 Neocomian age at Kome, in North-west Greenland;^ the 

 flora of this locality consisting in the main, however, of 

 ferns and conifers, among the latter being the genus Sequoia. 

 At the neighbouring locality of Atane a totally distinct flora 

 is found,'' in beds belonging to the Upper Cretaceous, and 

 including, with few cycads, sequoias, and other conifers, a 

 predominance of dicotyledons ; among which are a fig, two 

 magnolias, and plants apparently belonging to the orders 



must have first become fit for organic life, Count Saporta proceeds to 

 assume that the termination of the azoic period coincided with a cooHng 

 of the waters to the point at which coagulation of albumen does not take 



place, when organic life appeared in the water itself The Polar area 



was the centre of origination of all the successive phases of vegetation that 

 have aj)peared on the globe, all being developed in the north ; and the 

 development of flowering i^lants was enormously augmented by the intro- 

 duction during the latter part of the secondary period of flower-feeding 

 insects, which brought about cross-fertilisation." 

 ^ ' Origin of Species,' chap, xii., p. 340, in ed. 6. 



4 'Darwiniana.' 



5 Professor Nordenskjold, in a lecture to the Koyal Swedish Academy, 

 given in the ' Geological Magazine,' November, 1875, p. 529 ; and Professor 

 Oswald Heer, in 'Plora fossilis Arctica,' Zurich, 18G8 — 1875. For these 

 and other references to the geological part of my subject I am indebted 

 to an article on " The Cretaceous Flora," by Professor Morris, 'PojDular 

 Science Keview,' 1876, pp. 40 — 59. 



*■' Nordenskjold, loc. cit., and Dr. E. H. Scott, ' Geol, Mag.,' February, 

 1872, p. 71. 



