INTRODUCTION. lvii 
monstrous proposition. I am certain that it is not derived from natural and connected 
groups—honestly worked out in the field, and backed by corresponding lists of fossils. On 
the contrary, it is gained by a positive abandonment of the very principles which give 
truth and meaning to the homely inductive logic of geology—the very logic whereby every 
real group of Siluria was lawfully established. “st Jupiter quodcunque vides,’ was once 
said by Dean Conybeare in mockery of the old despotic rule of the name Greywacké. 
A golden age of truth and reason, and slow, but secure, inductive logic, seemed to follow: 
but the jovial days of a new dynasty are to spring up, it seems, under a new name, not less 
despotic than the one which had ruled before it! If all the fossil-bearing rocks below the Old 
Red sandstone are to pass under one name, let us cling to the venerable name Greywacké. 
It can do no mischief while it describes things indefinite, simply because it is without 
meaning. But the name “Silurian System,” if used in the same extended sense, is preg- 
nant with mischief. It savours of a history that is fabulous; it leads us back to a false 
type; it unites together as one, two Systems that nature has put asunder; and it is 
geographically untrue. 
Two great mistakes were committed during the elaboration of the “Silurian System.” 
In the first place the nomenclature of the author was too ambitious. For even on the 
supposition that all his groups were correctly linked together and put in a true relation to 
the groups below them (which assuredly they were not), they never did make anything like 
a System—certainly not in the sense in which he afterwards endeavoured to enforce the 
meaning of that word. When his great work appeared in 1839, he believed—on no 
teaching of mine, but on evidence which he had examined for himself—that the Cambrian 
System of South Wales admitted of three principal subdivisions; and that the highest 
of the three subdivisions was not only inferior to, but actually, in several places, formed an 
ascending passage into, the Llandeilo Flag. At the same time he believed (and he believed 
correctly), on the evidence of the sections to which I had conducted him in 1834, that the 
Bala limestone was deep-seated in those groups which both he and I had called Upper 
Cambrian; and which, on his own interpretation, were below the Llandeilo Flag. 
We collected some of the most common, and therefore most characteristic, Bala 
fossils. They were carried off by my friend, and he did not find among them one species 
which was not also abundant in his “Lower Silurian” groups. An exactly similar result 
was published by myself full two years before the appearance of the great classical work 
on Siluria (1839): and in every instance in which I had occasion to allude to the fossils of 
my upper Cambrian groups, I described them (in the printed Syllabus of my Lectures 
and in two papers read before the Geological Society,) as exhibiting many species iden- 
tical with those of the “Lower Silurian” groups. My lists of fossils were meagre (for 
before 1843 the best part of my collection was inaccessible); but they were amply 
sufficient for a good general inference; and, as a matter of fact, they did not give me so 
much as one species which was an exception to the rule of identity with those of the 
Lower Silurian groups. 
h 
