PREFACE TO THE FIRST EDITION. 9 
better means of verifying the species of Commerson, and of some of other travellers ; 
and, upon this point, I am much indebted to a review of the drawings of Commerson, and 
of the dried fishes which he brought with him, by M. Dumeril, but which have only 
been very lately recovered ; — resources to which I have added those presented to 
me in the fishes brought by Peron from the Indian Ocean and Archipelago, those 
which I obtained in the Mediterranean, and the collections made on the coast of 
Coromandel by the late M. Sonnerat, at the Mauritius by M. Matthieu, in the Nile 
and Red Sea, by M. Geoffroy, &c. I was thus enabled to verify most of the species 
of Bloch, Russell, and others, and to prepare the skeletons and viscera of nearly all 
the sub-genera ; so that this part of the work will, I presume, offer much that is new 
to Icthyologists. 
As to my division of this class, I confess its inconvenience, but I believe it, never- 
theless, to be more natural than any preceding one. In publishing it some time ago, 
I only offered it for what it is worth ; and if any one should discover a better principle 
of division, and as conformable to the organization, I shall hasten to adopt it. 
It is admitted that all the works on the general division of the invertebrated 
animals, are mere modifications of what I proposed in 1795, in the first of my memoirs ; 
and the time and care which I have devoted to the anatomy of mollusks in general, and 
principally to the naked mollusks, are well known. The determining of this class, as 
well as of its divisions and subdivisions, rests upon my own observations ; the magni- 
ficent work of M. Poli had alone anticipated me by descriptions and anatomical 
researches useful for my design, but confined to bivalves and multivalves only. I have 
verified all the facts furnished by that able anatomist, and I believe that I have more 
justly marked the functions of some organs. I have also endeavoured to determine the 
animals to which belong the principal forms of shells, and to arrange the latter from 
that consideration ; but with regard to the ulterior divisions of those shells of which the 
animals resemble each other, I have examined them only so far as to enable me to describe 
briefly those admitted by MM. de Lamarck and de Montfort ; even the small number 
of genera and sub-genera which are properly mine, are principally derived from observa- 
tions on the animals. In citing examples, I have confined myself to a certain number of 
the species of Martini, Chemnitz, Lister, and Soldani ; and that only because, the volume 
in which M. Lamarck treats of this portion not having yet appeared, I was compelled 
to fix the attention of my readers on specific objects. But in the choice and determin- 
ing of these species, I lay no claim to the same critical accuracy which I have employed 
for the vertebrated animals and naked mollusks. 
The excellent observations of MM. Savigny, Lesueur, and Desmarest, on the com- 
pound Ascidians, approximate this latter family of mollusks to certain orders of 
zoophytes : this is a curious relation, and a further proof of the impracticability of 
arranging animals in a single line. 
I believe that I have extricated the Annelides, — the establishing of which, although 
not their name, belongs virtually to me, — from the confusion in which they had hitherto 
been involved, among the Mollusks, the Testacea, and the Zoophytes, and have placed 
them in their natural order ; even their genera have received some elucidation only 
by my observations, published in the Dictionnaire des Sciences Naturelles, and else- 
where. 
Of the three classes contained in the third volume, I have nothing to remark. 
