356 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 19, 



The results of most value deducible from the above Table are those 

 suggested by the fossil Mollusca. The total number of these enu- 

 merated is 157, but some of them can only be determined generically 

 from casts, and others are new and as yet undescribed. The num- 

 ber of named species is 122, and no less than 106 of these are com- 

 mon to the Eocene beds of England and France : 1 02 being of the 

 age of the Barton and Bracklesham beds of England or the corre- 

 sponding Calcaire grossier of France, while only four belong exclu- 

 sively to the London Clay proper or to the Sables inferieurs of France. 

 The identity, therefore, of this portion of the Cassel and Brussels 

 tertiary series with the British Middle Eocene group is very striking. 

 In regard to the unnamed fossils, some of them are probably peculiar 

 to French Flanders and Belgium, but most of them might be iden- 

 tified with British species, if we had the means of comparing them 

 in London with large numbers of English Eocene fossils still un- 

 described. 



The next result worthy of notice is derived from the " Upper 

 Brussels" column relating to the shells, obtained, chiefly by the exer- 

 tions of Capt. Le Hon, from Laeken, Jette, and other localities of 

 the same " Upper Nummulitic" strata near Brussels. These species, 

 belonging to what has been termed by M. Dumont the Systeme 

 Laekenien, are sixty-five in number, eighteen of which are at pre- 

 sent peculiar, but I have no doubt that this proportion might easily 

 be reduced, inasmuch as the researches of the late Mr. Dixon in the 

 Eocene deposit of Bracklesham, near Chichester, have brought to 

 light many Mollusca and Bryozoa identical with Laeken fossils. Out 

 of fifty-seven named Laeken shells, no less than forty-four are com- 

 mon to the Calcaire grossier, or beds of the same age in England. 

 Such being the case, we have no reason to feel surprised that the 

 fossils of the ferruginous sands of Mont Noir, near Cassel, which 

 overlie strata corresponding in age to the Laeken beds of Brussels, 

 should nevertheless contain shells which agree with the Bagshot and 

 Bracklesham fauna of England. In other words, the Systeme 

 Laekenien is simply one of several upper divisions of the Calcaire 

 grossier. 



It may, at first sight, seem strange that there are not more species 

 common to the Cassel and Brussels lists, only thirty-two named 

 species being common out of a total of 122 ; also that in each district 

 so few species are common to the upper and lower divisions, at 

 Cassel only sixteen out of sixty-two named species being common to 

 the upper and lower series, and at Brussels only fifteen out of ninety- 

 two species. How are we to reconcile such a result with the fact 

 that each of these sets of fossils, when compared to the Calcaire 

 grossier or Middle Eocene of England and France, exhibits nearly an 

 equal amount of identity ? The apparent inconsistency is, I think, 

 removed when we recollect that each of the asterisk columns of 

 Table XIII. represents a mere fraction of a great fauna obtained from 

 the Middle Eocene beds of the south-east of England or from the Paris 

 Basin. The analogous degree of relationship of the Cassel and Brussels 

 fauna to one and the same foreign equivalent shows that they would 



