CARBONIFEROUS AGE. 347 



Spain. — In the Asturias (largest); near Cordova; Catalonia (small). 



Portugal. — Near Coimbra. 



Russia. — The Millstone-grit, aecording v to Murchison, occurs along the west flank of 

 the Ural, and to the southward in the region of Donetz, where there is some coal. But 

 the great Carboniferous area of Russia is mainly a region of Subcarboniferous lime- 

 stone; and the true Coal-measures are almost wholly wanting beneath the wide-spread 

 Permian beds. The Permian, Carboniferous, Devonian, and Silurian beds, which are 

 spread out nearly horizontally over the vast Russian plains, are folded up in the Urals 

 and partly metamorphosed, the making of these mountains having taken place after 

 the Permian era. 



Prestwich observes, with regard to a close parallelism in the several 

 coal-beds, between the different British coal-fields, and between these 

 and European coal-fields, that, while this is not to be looked for, some 

 general relations may be made out. The great dividing mass of rock, 

 2,000 to 3,000 feet thick, called Pennant, exists in both the Welsh 

 and Bristol coal-fields ; and the total thickness is not very different 

 in the two — about 10,500 feet in one and 8,500 in the other, with 

 seventy-six coal-beds in Wales, and fifty-five in Somerset. In the 

 Hainault (or Mons and Charleroi) basin, the measures are 9,400 feet 

 thick, with one hundred beds of coal ; in the Liege basin, 7,600 feet, 

 with eighty-five beds ; in Westphalia, 7,200 feet, with one hundred 

 and seventeen beds. Prestwich adds, further, that the earliest British 

 coal-beds are to the north, where they occur low down in the Subcar- 

 boniferous limestone ; but there the later are wanting ; while to the 

 south, coal-beds appear first above the Millstone-grit, and the mak- 

 ing of coal-bed debris continued long after it had ceased to the north. 

 Moreover, in Britain, the northern Coal-measures, excepting the Lan- 

 arkshire, are not half the thickness of the southern, and for the most 

 part hardly one-fourth. 



II. Life. 

 1. Plants. 



The same genera of plants are represented among the European 

 coal-beds as occur in America ; and very many of the species are iden- 

 tical. In this respect, the vegetable and animal kingdoms are in strong 

 contrast ; for the species of animals common to the two continents have 

 always been few. 



The following table contains the number of species of the different 

 genera of coal-plants peculiar to each continent, North America and 

 Europe (Britain included), and, in another column, those common to 

 both. 



