Xxli PREFACE TO THE FIRST EDITION. 
I have verified and confirmed 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 anatomy 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, the Annulata, the Radiata, and many of 
the Insects and Crustacea, is equally extensive. I have not deemed it 
necessary to publish it with the same detail; but all my preparations are 
exposed in the Cabinet of Comparative Anatomy in the Jardin du Roi, 
and will serve hereafter for my Treatise on Anatomy. 
Another work of considerable labour, but whose proofs cannot be made 
so authentic, is the critical examination of species. I have verified all 
the figures adduced by authors, and as often as possible referred each to 
its true species, before making a choice of those I have cited; it is from 
this verification alone, and never from the arrangement of preceding clas~ 
sifiers, that I have referred to my subgenera the species that belong to 
them. Such is the reason why no astonishment should be experienced 
on finding that such or such a genus of Gmelin is now divided and dis- 
tributed even in different classes and divisions; that numerous nominal 
species are reduced to a single one, and that vulgar names are very dif 
ferently applied. There is not a single one of these changes that I an 
not prepared to justify, or of which the reader himself may not obtai: 
the proof by recurring to the sources I have indicated. 
In order to diminish this trouble, I have taken care to select for each 
class a principal author, generally the richest in good original figures, and 
I quote secondary works only in those cases in which the former are 
silent, or where it was useful to set up some comparison, for the sake ot 
better establishing synonymes. 
My subject could have been made to fill many volumes, but I consi- 
dered it my duty to condense it, by contriving abridged means of publi- 
cation. I have obtained these by graduated generalities; by never 
repeating for a species what could be said of a whole subgenus, nor for a 
genus what might be applied to an entire order, and thus is it that we ar- 
rive at the greatest possible economy of words. To this my endeavours 
have been, above all, particularly directed, inasmuch as this was the prin- 
cipal end of my work. It may be observed, however, that I have not 
employed many technical terms, and that I have endeavoured to commu- 
nicate my ideas without that barbarous apparatus of factitious words, 
which, in the works of so many modern naturalists, prove so very repul- 
sive. I cannot perceive, however, that I have thereby lost any thing in 
precision or clearness, 
I have been compelled, unfortunately, to introduce many new names, 
