376 Geological Society. 



that Mr. Lyell was beginning to unfold the true papyri of geo- 

 logical history ; and his subsequent discoveries in Sicily proved, 

 that there were many places in which the extinct species had nearly 

 disappeared, and that amid vast accumulations of marine shells, 

 entering into the composition of mountains of no inconsider- 

 able altitude, nearly all were specifically identical with those now 

 inhabiting the adjoining sea. At this period, therefore, he had, by a 

 series of inductions, completely effaced from his mind as arbitrary and 

 untrue, those lines of demarcation between, what had been termed, 

 the ancient and existing orders of nature, — fixed by those who had 

 observed the results of her subterranean workings only in countries, 

 where her internal energies have long been dormant. 



On the return of Mr. Lyell to Paris in February 1829, M. Desnoyers 

 had just published the first part of his invaluable memoir " On 

 the Tertiary Formations, more recent than the Paris Basin." From 

 that gentleman he learnt, that M. Deshayes, from a mere inspection of 

 the fossil shells of his rich collection, had already conceived the idea of 

 classing the tertiary formations chronologically, according to the re- 

 lative number of species in each group, which could be identified 

 with those now living *. Henceforward, Mr. Lyell became anx- 

 ious to obtain the co-operation of M. Deshayes in his intended clas- 

 sification of the tertiary strata, and therefore submitted to him 

 the shells which he had procured from Sicily, Italy, the South of 

 France, and the English Crag. M. Deshayes at the same time under- 

 took to hasten the completion of a series of tables of tertiary fossils, 

 intended to form part of a " Manual of Fossil Conchology," in order 

 that they might accompany Mr. Lyell's forthcoming volume. I am 

 happv to announce to the Society that these tables have been for 

 some time printed, and that we may expect them to be soon com- 

 municated to the English public in the third volume of the " Princi- 

 ples of Geology." 



After the study of these modern deposits, Mr. Lyell was prompted 

 to examine, with increased attention, tlie effects of the various causes 

 now in operation on the surface of the globe, and it is the execution 

 of this task which has delayed the publication of his views relating 

 to Italy and Sicily. 



In the former volume we were made acquainted with his ideas upon 

 the operations of the inorganic forces of nature ; and in the present 

 he offers to us his interpretation of an abundant collection of facts, 

 connected with the fluctuations in the organic world. So ample are 

 the data in natural history, upon which the author has established 

 his conclusions, that they cannot fail of relieving him from the charge 

 of visionary speculation. They must indeed demonstrate — that he has 

 anxiously sought for the truth of the laws of Nature in her own works 

 — that he has not only led the way in pointing out a method of inquiry 

 hitherto almost untried, but has, with great skill and patient research, 

 brought the detached accounts of naturalists in every branch of their 



* See M. Desnoyers, Sur tin ensemble S^c. Ann. des Sci. Nat. torn. xvi. 

 pp. 216. 441 . (1829), in which he announces the views of JM. Deshayes and 

 of Mr. Lyell. 



respective 



