278 



THE GEOLOGIST. 



vancement of the science, has always found them ready to 

 forward my labours ; and thanks to their valuable communi- 

 cations, collections from every part of France, added to 

 those in my cabinet which I have myself procured, in the 

 researches I have made for that purpose, for more than seven 

 years, have placed at my disposal the most complete collec- 

 tion that can possibly be procured to illustrate a single 

 point, whether of individual species, or of specimens of 

 each of the latter, the only means of rigourously restricting 

 their limits. Far from having but 31 species of Ammonites 

 I find myself in the possession of the immense number of 

 one hundred and forty-four species from the cretaceous for- 

 mations, of which one hundred and thirteen were unknown 

 prior to my work. I have at this moment the lively satis- 

 faction of proving that France, so little known as regards its 

 fossils, and only small portions of which had been partially 

 studied in this point of view; that France, I say, in this 

 respect, proves itself one of the richest fields in the world, 

 when taken on the whole, and does not yield before any of 

 the numerous difficulties presented by this method of stu- 

 dying it. 



The great number of species of Ammonites in France is 

 not, in my opinion, of purely numerical interest. I hold it 

 of little consequence to describe some hundreds more or less 

 of new species ; but, as my chief aim is the application of 

 zoology to geology, the more the number increases, the more 

 the value of the materials for the application augments, by 

 furnishing me, both with a larger number of species for each 

 formation, and also with a greater number of identical forms 

 which may serve for the determination of the formations 

 themselves. In fact, after having studied the species of 

 Ammonites in this point of view, after having compared all 

 the other fossils which are always found with certain Ammo- 

 nites, after having personally verified in the north, south. 



