vi 
PREFACE. 
been of great service to me. This work, when complete, will leave 
nothing to desire in respect to this great division of the British Silurian 
Fauna, — a group most useful to the field-geologist, who must ever be to a 
great extent dependent on this class of fossils, on account of their more 
frequent occurrence than other animal remains. As founder of the ' Silu- 
rian System,' I naturally feel highly honoured that Mr. Davidson should 
have dedicated this work to me, and that he should have invited me to 
write an Introduction to the Monograph published by the Palaeontogra- 
phical Society. 
The last volume brought out by M. Barrande has prominently exhibited 
the skill of that eminent paleontologist in the great additions he has made 
to the number and variety of forms, particularly of the Cephalopoda, in his 
rich and classical ' Bassin Silurien de Boheme ; ' and it has therefore been 
my earnest endeavour to do justice to the highly valuable additions made 
by him. 
These labours of my cotemporaries are about to be augmented by a 
comprehensive and very useful publication of the veteran geologist Dr. 
Bigsby, who, with unwearied assiduity and acumen, has tabulated the 
results of the labours of palaeontologists of various countries, and combined 
them with his own extensive observations on the Silurian rocks of North 
America, in his work ' Thesaurus Siluricus.' 
The mere mention of these productions indicates the large additions that 
have been made to our acquaintance with the animal life of the remote 
Silurian era. These works have naturally cheered me, inasmuch as they 
one and all support the name and classification which I proposed so many 
years ago, after long researches in England and Wales. 
Numerous other improvements have indeed been made in this edition 
of ' Siluria.' Among the most notable in respect to England, are the 
proofs, as established by Professor Harkness, that no deposit in the slaty 
region or Lake Country of Cumberland is of higher antiquity than the 
Lower Llandeilo formation, though the previous belief was that the oldest 
of those rocks was more ancient than anything Silurian. Again, large 
tracts in Westmoreland, previously mapped as New Eed Sandstone, are 
now classed with the Permian deposits, as proved by the researches of 
Professor Harkness and myself. I have further endeavoured to synchro- 
nize more perfectly certain rocks in the south-west of Ireland with the 
Lower Devonian rocks of West Somerset and North Devon, and have, as 
formerly, referred what used to be called the Old Red Sandstone by Sir 
E. Griffith and the earlier geologists in Ireland, to the upper member only 
of the Devonian or Old Red system. 
The Permian rocks of Ayrshire, the Scotch Coal-fields, and the structure 
of the Pentland Hills, have been elucidated by the recent researches of Mr. 
Geikie, now Director of the Geological Survey of Scotland, as shown by 
his descriptions and sections illustrating this new edition. 
