VI PREFACE. 



invaluable assistance, without which it would not have 

 been possible for me to accomplish what has been 

 done : to him also is due the arrangement of the List 

 of Published Papers. 



On account (except in a few cases) of the scarcity of 

 original letters, those from friends and correspondents 

 have been inserted when they have served to elucidate 

 the subjects under discussion at the time. To M. 

 Albert Gaudry, of the Institute of France, I am in- 

 debted for his sympathy and encouragement, and also 

 for allowing me the use of letters. To Professor 

 Capellini of Bologna, and to Professor Louis Lartet 

 of Toulouse, I have likewise to record my grateful 

 acknowledgments. 



Professor Jules Marcou of Cambridge, Massachusetts, 

 who took an eager interest in the preparation of this 

 Memoir, has, alas ! not lived to witness its completion. 

 Mr William Colchester, an old and attached friend who 

 so lately wrote expressing his wish for the speedy pub- 

 lication of this volume, has likewise passed away. The 

 recent death of Sir Douglas Galton, the dear friend 

 and companion of Joseph Prestwich in geological ex- 

 cursions at home and abroad, has been a personal grief, 

 and is the severance of another link with the past. 



Among the friends to whom I am indebted for letters 

 and data may be mentioned the Rev. R. Ashington 

 Bullen, the Rev. Osmond Fisher, Mr Benjamin Harri- 

 son, Sir Joseph D. Hooker, Professor Judd, Sir John 

 Lubbock, Mr Mansel-Pleydell, Mr S. R. Pattison, and 

 many others. I have also to express my thanks to Dr 



