PREFACE TO THE FIRST EDITION. xill 
whose adoption is what has 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 may be obtained from the Memoirs on the ana- 
tomy of the Mollusca which have appeared in the ‘* Annales 
du Muséum,” 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, 
