ANNIVERSARY ADDRESS OF THE PRESIDENT. GV 



right to express also the obhgations which all geologists must feel 

 to Sir R. I. Murchison for the zealous manner in which, as Director 

 of the Survey, he has promoted the publication of the last scientific 

 researches of Edward Forbes. 



In the ])apers which have passed in review before us, the compa- 

 rison has necessarily been made between the English and French 

 Tertiaries, and the terms of the comparison have principally de- 

 pended on the catalogued MoUusca then known. But now, after 

 the many years which have been devoted to the study of the Paris 

 Basin, M. Deshayes resumes his labours, and in the first two parts of 

 a new * Description des Animaux sans Vertebres decouverts dans le 

 Bassin de Paris,' brings forward so many additions to the formerly 

 known fauna, that Tertiary-geologists will probably have to revise 

 their calculations, if not their conclusions. M. Deshayes, in his 

 introduction, points out also the interesting fact, that our know- 

 ledge of the recent fauna has gone on advancing with that of the 

 fossil, the list of 5000 living moUusca having in thirty years been 

 quadrupled in number, or raised to 20,000 ; and, as every day 

 increases the number, either the organic difference between the 

 existing and the Tertiary epochs must have been lessened or aug- 

 mented, according as the newly discovered MoUusca have afforded a 

 greater or less per-centage of species common to the two periods than 

 that derived from the former lists. In a similar manner the dis- 

 covery of additional Tertiary species must either narrow or widen 

 the difference between the recent and ancient faunae, in proportion 

 as more or less recent species are found amongst them. 



The results of the new researches have been most surprising : M. 

 Deshayes observes, that a study of the phsenomena leads to the first 

 grand division of the Paris Basin into three deposits of two periods, 

 each, of course, capable of further subdivision. The first deposits 

 after the Chalk ])eriod were generally of a sandy nature, but the 

 most ancient of all is the most interesting, as affording indications of 

 the existence of dry land, and of an extensive lake. Within this lake 

 lived lacustrine animals, with the remains of which were mixed those 

 of mud animals in the marly deposits, which were then spread over 

 the bottom of the lake. These fossil remains are classed under the 

 designation of the fauna of Rilly, which, though unknown at the 

 time the first work of M. Deshayes was published, has, through 

 the labours of M. Boissy, since dead, yielded thirty-nine species. 

 According to this statement, the Tertiaries commence in the Paris 

 Basin by a freshwater formation, not by a marine one as in that of 

 London To the Rilly series succeeds a marine formation of sand 

 of very considerable extent, and, in some of its beds, rich in fossils ; 

 Beauvais, Bracheux, Noailles, and other localities are named, be- 

 sides Chalons sur Yesles, at which and another point the recent 

 researches of M. Deshayes have made known 100 species, almost all 

 new. To this follows the series of Soissons and Laon, the sands of 

 which contain beds of lignites ; and here by M. Tilley have been 

 found many new species, as well as near Laon, in a dej)osit be- 

 longing to, and on the northern edge of, the l^pper Calcaire Grossier. 



