PREFACE TO THE FIRST EDITION. 9 



better means of verifying the species of Cummerson, 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 tlie Indian Ocean and Archipelago, those 

 wliich 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. Geuflroy, &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 ail 

 the sub-genei-a ; so that this part of the Vv'ork 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- 

 tlieless, 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 iuvertebrated 

 animals, are mere modifications of what I proposed in 179.5, in the first of my memoirs ; 

 and the time and care which I have devoted to the anatomy of moUusks in general, and 

 principally to the naked moUusks, are ^vell 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. Poll 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 moUusks. 



The excellent observations of MM. Savigny, Lesueur, and Desmarest, on the com- 

 pound Ascidians, approximate this latter family of moUusks 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 MoUusks, the Testacea, and the Zoophj'tes, and have placed 

 them in their natural order ; even their genera have received some elucidation only 

 by my observations, pubhshed in the Dictionnaire des Sciences Naturelles, and else- 

 where. 



Of the three classes contained in the third volume, I have nothing to remark. 



