Foreign Geologists : French School. 515 



division of rocks, and they have distinguished the subdivisions by 

 conventional signs, in a similar manner to that emploj^ed in the map 

 of the Silurian region and Mr. Greenough's map of England. The 

 advantage of this certain method of showing the relations which 

 exist between the different parts of the same formation, is now 

 thoroughly recognised. 



Under the modest title of explanation of the map, the authors 

 will publish three quarto volumes, of which the first only has yet 

 appeared, and judging from this specimen we have a right to con- 

 clude that they will form one of the most splendid and useful works 

 ever executed on the geology of a great country. In the intro- 

 ductory chapter of the published volume the general principles of 

 the science are admirably given, and the succeeding chapters are 

 occupied by descriptions of the " Massif central de la France : 

 Presqu'ile de Bretagne, Ardennes : Vosges : Montagnes littorales du 

 Departement de Var : Terrains Houillers." The authors have di- 

 vided their descriptions into great geographical regions, beginning 

 with the most ancient formations ; and I cannot resist expressing 

 how much pleasure it has given me to see that these eminent men 

 have adopted the divisions and nomenclature which have been 

 proposed for the palaeozoic rocks of England. In the other volumes 

 the authors will describe the more recent formations, reserving for 

 the conclusion, the account of those parts of France where the ele- 

 vated and dislocated sedimentary deposits present problems most 

 difficult of solution, and which continue to raise doubts in the 

 minds of the best and most experienced observers. In their de- 

 scription of the rocks, the authors, faithful to what may be called 

 the " natural method," have classed together all those which appear 

 to have a common origin, such as granites, porphyries, basalts, tra- 

 chytes, (ic. 



In short, the geological map of France, and the volumes of ex- 

 planation to accompany it, will form one of the finest monuments 

 raised to science in our aera, and must be constantly consulted by 

 those who wish to understand tlie spirit of that school of geology, 

 which has cast such a brilliant light over France and throughout 

 Europe. Doubly grateful indeed is the production of the work to 

 ourselves, for in presenting it to this Society its authors liave 

 assured us that it was in our own islands they first acquired that 

 knowledge of classification which led them to attempt the great 

 enterprise, the completion of which so well sustains the high repu- 

 tation they enjoy. Further, when we recollect that the knowledge 

 of our foreign associates was one of the first fruits of the general 

 peace, well may we now view the noble structure they have reared 

 upon such a basis, as a convincing proof of the advantages con- 

 ferred on science by the friendly intercourse of nations, which now 

 rival each otlier only in advancing science and art ! 



Another most important work undertaken in France during the 

 last year, is ' La Paleontologie Fran(,aise' of M. Alcidc d'Orbigny. 

 Early initiated into the study of organic bodies and the anatomy of 

 mollusks, tiiis naturalist lias ac(|uired, during his extended travels, a 



