PREFACE. 



we speak from personal experience, and have ventured to pronounce 

 judgment on many disputed points. This paper makes no attempt 

 at correlation with English beds, although we have deemed it 

 advisable to give the generally accepted classification by repro- 

 ducing the views of Professor Prestwich, F.R.S. (see table, p. 2). 

 At the same time, we do not necessarily endorse this classification 

 in its entirety. 



During the preparation of this work we have received 

 assistance from various Geologists, both at home and on the Con- 

 tinent ; and we gladly avail ourselves of this opportunity to 

 acknowledge the same. We have to thank Dr. Henry Woodward, 

 F.R.S., for his kindness in permitting us to examine in detail the 

 magnificent collection of Paris basin Tertiary Mollusca contained 

 in the British Museum (Natural History) ; to M. Cossmann we 

 are indebted for much valuable information and co-operation in 

 the revision of the lists of fossil Mollusca, as well as for the 

 valuable additions given in Appendix I. ; M. Gustave DoUfus has 

 kindly looked over the proofs relating to the stratigraphy of 

 the basin and assisted us in various ways ; whilst Dr. Maurice 

 Hovelacque has been our guide in many of the classical districts, 

 and his maps and note-books have most generously been placed 

 at our disposal during our different excursions in the Parisian area. 

 Mr. R. B. Newton, F.G.S., of the Natural History Museum, has 

 aided us in revising the nomenclature of the Mollusca ; Messrs. 

 A. Smith Woodward, F.G.S., and J. W. Gregory, F.G.S., of the 

 same Museum, have critically examined and revised those portions 

 of the palseontological section relating to the Vertebrata and 

 Echinoidea respectively ; Mr. J. Starkie Gardner, F.G.S., has 

 looked over our remarks concerning the fossil plants ; and 

 Mr. C. Davies Sherborn, F.G.S., has assisted us with the biblio- 

 graphy. We have also to record our appreciation of the many 

 invaluable suggestions made by Mr. F. A. Bather, M.A., F.G.S., 

 in the course of his editing and passing the work through the 

 press. Lastly, we have to thank the Council of the Geologists' 

 Association for their kind consideration in issuing this lengthy 

 paper as a separate publication. 



Geo. F. Harris, 

 20, Craster Road, Upper Tiilse Hill, London, S.W. 



Ai/i::iisf, 1 89 1. Henry W. Burrows, 



94. Kim Park. Brixton Hill, London. S.W. 



