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TO 
SIB WILLIAM LOGAN, LL.D., F.E.S., F.G.S., 
DIRECTOR-GENERAL OF THE GEOLOGICAL SURVEY OF CANADA, 
I DEDICATE THIS NEW EDITION OF 
SILURIA. 
The original ' Silurian System ' having been dedicated to my 
eminent associate, Professor Sedgwick, the earliest Edition 
of this Work was dedicated to my predecessor in office, Sir 
Henry T. De la Beche, who first adopted the use of the 
Silurian Classification in the publications and maps of the 
Geological Survey of Britain. 
The last Edition was naturally inscribed to my valued cotem- 
poraries, E. de Verneuil, A. von Keyserling, and Joachim 
Barrande, by whose labours the Silurian System has been 
successfully extended to various parts of the ivorld. 
