PREFACE. xiii 
In determining a Geological nomenclature these two great principles must never be 
lost sight of—No true nomenclature can be in conflict with the actual succession of the 
physical deposits ; neither can it contradict the true succession of organic types. Nature 
does not contradict her own workmanship. This was the principle on which William 
Smith, whom we call the Father of English Geology, acted; and it was the principle 
on which Murchison acted when he first made known his beautiful succession in 
the upper part of (what he taught us to call) his Silurian System. That upper part 
of his System was thoroughly and beautifully worked out, was accepted at once, and 
continues to maintain its place. But below the Wenlock shale, in what he called the 
Lower Silurian groups, his fundamental sections utterly broke down, having no base to 
rest upon. He never made out the succession of his physical groups: some of them which 
required separation he confounded, and some he put in an inverted order; and _ thereby 
he brought an inevitable incongruity into his lists of the Older Paleozoic fossils. In short, 
I venture to affirm, that the Lower Silurian nomenclature, however widely adopted on the 
authority of its Author, was false: because it was built upon sections that were untrue 
to nature; and if this assertion be true—and it is true—the discussion requires no further 
argument. 
As a general rule, honest truth and good taste go hand-in-hand; and what can 
be more incongruous and tasteless than to erase the Classical name of Cambrian as 
applied to the grand mountain chains of Caernarvonshire and Merionethshire, and to 
substitute the word Silurian as their designation. This was done by the Author of the 
“Silurian System,” in the first instance no doubt by mistake, and in the hope of giving 
a greater extent and firmer basis to his System. But when the great errors of his 
fundamental groups were discovered, why continue such a monstrous abuse of nomen- 
clature ? Siluria supplies us neither with the best types of the older groups, nor with 
any sections which clearly define their succession: Cambria supplies both. Our business 
here is not to consider what great services the Author may have done in other regions: 
but to consider whether his work in Lower Siluria be true to nature. The first publication 
of his grand lists of “Lower Silurian Fossils” was a great boon to Geology; but the 
assumed stratigraphical arrangement and the grouping of the species has been a great 
mischief, and a drag upon its progress. 
I will pursue this subject no farther, but refer the reader to my Introduction to 
Prof. M’Coy’s Synopsis which I here adopt, because that which is true in a natural 
arrangement can never be materially changed. Nor should I have introduced even this 
notice of an old controversy, had it not been revived in an acute, animated, and very 
elaborate dissertation by Prof. Sterry Hunt (Nature, May 2, 9, and 16, 1872, reprinted from the 
