PKEFACii TO THE FIRST EDITION. XXVU 



M. Sonnerat, at the Isle of France by M. Mathieu, in the Nile and Red 

 Sea by M. Geoffroy, &c. I was thus enabled to verify most of the 

 species of Bloch, Russel, and others, and to have prepared the skeletons 

 and viscera of nearly all the subgenera, so that this portion of the work 

 will, I presume, present to icthyologists much that is new. 



As to my division of this class, I confess its inconvenience, but I still 

 think it more natural than any preceding one. When 1 some time ago 

 published it, I put it forth for what it was worth ; and if any one discovers 

 a better principle of division, and as conformable to the organization, I 

 shall hasten to adopt it*. 



It is well known that all the works, on the general division of the 

 Invertebrated animals, are mere modifications of what I proposed in 1795, 

 in the earliest of my memoirs ; and the time and care I have devoted to 

 the anatomy of the MoUusca in general, and principally to the know- 

 ledge of the naked Mollusca, are likewise well known. The determina- 

 tion of this class, as well as of its divisions and subdivisions, rests on 

 my observations ; the magnificent work of M. Poll had alone anticipated 

 me by descriptions and anatomical researches, useful to me it is true, but 

 confined to bivalves and multivalves only. I have verified all the facts 

 furnished to me by that skilful anatomist, and I have, I think, marked 

 with greater accuracy the functions of some organs. I iiave also endea- 

 voured to ascertain the animals to which the principal forms of shells 

 belong, and to arrange the latter from that consideration ; but as to the 

 ulterior divisions of those shells whose animals resemble each other, I 

 have examined them only so far as to enable me to describe those admitted 

 by Messrs. de Lamarck and de Montfort; even the small number of 

 genera or subgenera which are properly mine, are 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. de Lamarck is to treat this 

 branch, not being yet published, I was compelled to fix the attention of 

 the reader on specific objects. In the selection and determining of these 

 species, however, I lay no claim to the same critical accuracy I have em- 

 ployed for the Vertebrated animals and the naked Mollusca. 



The excellent observations of Messrs. Savigny, Lesueur, and Desmarest, 

 on the compound Ascidia, approximate the latter faniily of the Mollusca 

 to certain orders of Zoophytes — a curious relation, and an additional proof 

 of the impracticability of arranging animals on one single line. 



The Annulata (the establishing of which order, although not the name, 

 belongs de facto to me) have, I think, been extricated from the confusion 



• The Second Edition, however, as will be seen in the Second Volume of this 

 Translation, contains a new arrangement of the class of Fishes, whici), though pre- 

 senting some deficiencies in precision, still possesses the advantage of not breaking 

 in upon its natural families. — Eno. Ed. 



