8 
SILUKIA. 
[Ciiap. I. 
abandon that view, and to adopt the opinion which I have maintained for 
a quarter of a century. I ascertained, in short, that in Bohemia, Scandi- 
navia, and Russia, the rich inferior zone of primeval life was the same Lower 
Silurian as in Britain and America. Indeed I made a transverse section 
in 1842, accompanied by my coadjutor A. von Keyserling, north-westward 
from Shropshire, and was convinced that all the undulating fossiliferous 
rocks of North Wales were mere extensions of Silurian types. During 
the same year the Government Geological Surveyors had arrived at si- 
milar results through their own labours in South "Wales. In that 
country, Professor Eamsay first discovered (1842) that, to the north and 
west of my typical position of Llandeilo, true Silurian rocks, charac- 
terized by their fossils, folded over, and occupied a wide region, which, in 
1836, and without examination, I had mapped as Cambrian (simply because 
it lay to . the north-west). Thenceforward Sir H. De la Beche and the 
Surveyors naturally coloured as Silurian all such hitherto undefined tracts *. 
My view of the equivalents of the Silurian rocks in North Wales, Russia, 
and Scandinavia, published in the year 1842 f, was adopted generally in 
Europe and America, through independent comparisons by numerous 
foreign geologists of their older formations with my British types. 
In extending researches to various distant lands, I found that as the 
base of all rocks containing Silurian fossils, in Bohemia, Scandinavia, and 
Russia, was clearly defined, and as the same fact was announced from 
North America, it was no longer difficult to describe the whole organic 
series, and thus to record the succession of crustaceans, mollusks, and other 
invertebrata from their earliest distinguishable types. In a word, as 
chroniclers of lost races, de Verneuil, von Keyserling, and myself were 
enabled to register, in our ' Russia and the Ural ■ Mountains 'J, the 
relative position of such ancient creatures. To the first chapters of that 
work, as explanatory of views which are here reiterated, the reader 
is referred. Then it was that positive proofs, derived from a wide field 
of observation, enabled us to commence the geological history of a re- 
gion occupying half the area of Europe, with an account of the entomb- 
ment of the earliest animals recognizable in that vast region, and also 
to indicate the successive conditions which prevailed upon the surface, in 
a long series of ages, and during the many changes of outline which long pre- 
ceded the present state of the planet. Looking to all the records of former 
life, as exhibited in the strata, it was then demonstrated, from phenomena 
in one great empire alone (as had to a great extent been shown in Britain), 
that, during the formation of the sediments which compose the crust of the 
earth, the animal kingdom had been at least three times entirely renovated, 
the Secondary and Tertiary periods having each been as clearly character- 
ized by a distinct fauna as the Primeval. In the work on Russia, the 
* See Ramsay's 'Geology of North Wales,' Society of London, 1842 ; Proceedings Geol. Soc. 
Memoirs of the Geological Survey, vol. iii. Lond. vol. iii. p. 640 &c. 
p. 6. I The general views were communicated in IS 12 
t Discourse of the President of the Geological The large work was published in 1845. 
