PREFACE. 7 



others that it would be impossible to enumerate all here by name. The author 

 much regrets that he has not been able to repay fully all the courtesy thus extended 

 to him ; but he hopes that any omissions in this respect will be excused : he has 

 done what he could with the copies of works at his command. 



To those friends in Dorset who, in the early days of his Ammonite studies, 

 subscribed and presented to him some important works, the author desires to 

 express again his hearty thanks. And he cannot refrain from mentioning that, in 

 connection with these and other studies, he has so often experienced the great 

 kindness of friends in their giving and lending of valuable works. 



For the use of specimens, whether by presentation, loan, or otherwise, the 

 author desires to express his great obligation to many of those who have been 

 mentioned above, and to Mr. E. T. Newton, F.R.S., for the kind loan of specimens 

 from the Jermyn Street Museum; to Mr. W. H. Hudleston, F.R.S. ; the late Mr. 

 J. F. Walker, F.G.S. ; Rev. H. H. Winwood, F.G.S. ; the late Mr. E. Wilson, F.G.S., 

 Curator of the Bristol Museum; the late Mr. T. C. Maggs, F.G.S.; Messrs. 

 J. W. Tutcher, J. W. D. Marshall, Charles Upton; the late Rev. F. Smithe, 

 F.G.S. ; Mr. B. Thompson, F.G.S., and many others. To several of these 

 geologists is he further indebted for presentations of works and papers. 



To Mr. C. Davies Sherborn, F.Z.S., the writer gives very many thanks for much 

 kind assistance in matters of bibliography, and also for the pains which he has 

 taken to check generic names as regards the matter of pre-occupation. The same 

 thanks are due to Mr. G. C. Crick, F.G.S., who has also taken much trouble to 

 reply to the author's inquiries, and who has always most willingly placed his great 

 knowledge of fossil Cephalopoda at the writer's service. 



As an official of the British Museum (Nat. Hist.) Mr. Crick's services have 

 often deserved the writer's grateful thanks ; and for similar kind assistance he is 

 greatly indebted to Dr. H. Woodward, F.R.S. ; Prof. Bigot; Dr. F. A. Bather, 

 F.G.S., and the officials of various museums, some of whom have been already 

 mentioned. Unfortunately the author has not had the time or the opportunity 

 to make visits to many museums to search for specimens. For many years all 

 efforts were directed towards collecting specimens in the field for the elucidation 

 of the stratigraphical problem, to freeing them from matrix, and to their scientific 

 study afterwards. It may be understood that on this account, coupled with the 

 regulations forbidding specimens to leave certain institutions, the collections of 

 museums have not been drawn upon so much as they deserve in connection with 

 this Monograph. 



To the Government Grant Committee of the Royal Society for assigning him a 

 grant to assist him in the labour of finishing this work ; to the Council of the 

 Palgeontographical Society for their liberality in the matter of plates ; to Prof. 

 Rupert Jones, F.R.S., for care given to the reading of proof sheets ; to the Editors, 



