PREFACE TO THE FIRST EDITION. XUl 



whose adoption is vvliat hcas mainly contributed to introduce in 

 the catalogue of beings, that confusion which deprives it of so 

 great a portion of its utility. 



I could, every where, have added great numbers of new 

 species, but as I could not refer to figures it would in that 

 case have been necessary to extend their descriptions beyond 

 the bounds of my limits ; I have preferred therefore depriv- 

 ing my work of that ornament, and have indicated those only 

 whose singular formation gives origin to new subgenera. 



My subgenera once established on undoubted relations, and 

 composed of well ascertained species, nothing remained but 

 to construct this great scaffolding of genera, tribes, families, 

 orders, classes and divisions which constitute the ensemble of 

 the animal kingdom. 



Here I have proceeded, partly by ascending from the in- 

 ferior to the superior divisions, by means of approximation 

 and comparison, and partly by descending from the superior 

 to the inferior divisions, on the principle of the subordination 

 of characters; carefully comparing the results of the two 

 methods, verifying one by the other, and always sedulously 

 establishing the correspondence of forms, external and inter- 

 nal, both of which constitute integral parts of the essence of 

 each animal. 



Such has been my mode of proceeding whenever it was ne- 

 cessary and possible to form new arrangements ; but I need 

 not observe, that in many places, the results to which it would 

 have conducted me, had been already so satisfactorily obtained, 

 that no other trouble was left to me than that of following the 

 track of my predecessors. Even in these cases, however, by 

 new observations I have confirmed and verified what was 

 previously acknowledged, and what I did not adopt until it 

 was subjected to a rigorous scrutiny. An idea of this mode 

 of examination maybe obtained from the Memoirs on the ana- 

 tomy of the Mollusca which have appeared in the " Annales 

 du Museumf" and of which I am now preparing a separate 

 and augmented collection. I venture to assure the reader, 

 that the labour I have bestowed upon the Vertebrated animals. 



