Believing that it would be useful for the members of the Assoc- 

 iation to have a concise account of the Eocene and Oligocene 

 beds of the Paris basin laid before them, according to the most 

 recent views of Geologists who have written on the subject, we beg 

 to submit the following description of that interesting area for 

 their consideration. In doing so, it may be stated that we were led 

 to study the Paris Tertiaries from aconviction that it was impossible 

 to satisfactorily solve many important stratigraphical and palaeonto- 

 logical problems by an examination of English beds of correspond- 

 ing age alone — and we have not been disappointed. In fact, at the 

 outset, we will go so far as to say that no adequate conception 

 can be formed as to the meaning and value of our own Tertiary 

 beds and their organic remains without conjointly studying those 

 on the other side of the Channel — especially in regard to the 

 palseontological aspect of the subject. Attempts hitherto made to 

 correlate the Tertiary beds of England with those of France and 

 Belgium have been mainly based on the evidence afforded by the 

 MoUusca, and rightly so, seeing that the remains of these latter are 

 so abundantly distributed throughout the whole area. Their 

 occurrence in such large numbers, and in such a perfect state of 

 preservation, in the Paris basin enables us to work out the 

 sequence and life history of the Eocenes and Oligocenes with much 

 greater facility and precision in that area than in England or 

 Belgium ; and the student will, consequently, do well to direct 

 his attention to the French area in the first instance. In this con- 

 nexion, allusion may be made to the fact that many of the recog- 

 nised English Lower Tertiary Mollusca have been referred to 

 species occurring in the Paris basin, and already described by 

 French authors ; and that the types of these must consequently be 

 sought in that area. In order to determine accurately many of 

 the genera and species, it is absolutely necessary to possess perfect 

 specimens ; and these, so commonly found in the Paris Tertiaries, 

 are exceedingly difficult, and sometimes impossible, to obtain 

 from the English beds of the same period. 



In studying this subject we have paid many visits to the Paris 

 basin, both separately and together ; have seen practically all the 

 typical sections described in the following pages ; and have traced 

 the beds over considerable areas. To a certain extent, therefore. 



