( ix ) 



PREFACE. 



The Guide to the Fossil Invertebrates and Plants " having 

 run out of print, it is in part replaced by this book dealing 

 with the Invertebrate Animals, while it is proposed that the 

 Fossil Plants shall form the subject of a separate Guide. By 

 describing the Galleries and their contents in a different 

 order from that followed in the previous Guide, it is attempted 

 to present the whole as a connected story. At the same 

 time the book does not profess to be a complete systematic 

 treatise, but relates only to the specimens actually exhibited 

 in the Galleries. 



As in the other Guides to the fossil animals, the present 

 one assumes on the part of the reader at least so much 

 knowledge of the existing world of life as is conveyed by the 

 corresponding Guides to the Department of Zoology. Since, 

 however, many of the groups of animals herein dealt with 

 are entirely or almost entirely extinct (e.g. Graptolites, 

 Cystids, Trilobites, Ammonites), they have been treated more 

 fully than those which are more familiar. 



The book has been written by Dr. Francis Arthur Bather, 

 Assistant Keeper of Geology, who desires to acknowledge 

 the kind help that he has received from his colleagues : 

 Mr. K. Bullen Newton and Mr. G. C. Crick in connection 

 with the Mollusca ; Mr. W, D. Lang in connection with the 

 Bryozoa and Coelentera; and Dr. W. T. Caiman in con- 

 nection with the Arthropoda. Thanks are also due, for 

 similar assistance, to Mr. S. S. Buckman, Mr. H. W. Burrows, 

 Mr. C. D. Sherborn, and Mr. B. B. Woodward. For per- 

 mission to use copyright illustrations the Trustees are 

 indebted to Messrs. A. & C. Black, Messrs. Archibald Con- 

 stable & Co., Messrs. Longmans & Co., the Cambridge 

 University Press, the Council of the Geological Society, and 

 Dr. Henry Woodward, F.Pt.S. (Editor of the Geological 

 Magazine). 



E. KAY LANKESTER, 



Director. 



British Museum (Natural History), 

 23 April, 1907. 



